Fabrizio Costantini

In Vivo Formation of 8-Iso-Prostaglandin F2α and Platelet Activation in Diabetes Mellitus Effects of Improved Metabolic Control and Vitamin E Supplementation

Background—Diabetes mellitus (DM) is associated with enhanced lipid peroxidation and persistent platelet activation. We tested the hypothesis that the in vivo formation of the F2-isoprostane 8-iso-prostaglandin (PG)F2α, a bioactive product of arachidonic acid peroxidation, is enhanced in DM and contributes to platelet activation. Methods and Results—Urine samples were obtained from 85 diabetic patients and 85 age- and sex-matched healthy subjects for measurement of immunoreactive 8-iso-PGF2α and 11-dehydro-thromboxane B2 (TXM), an in vivo index of platelet activation. Sixty-two had non–insulin-dependent (NID)DM, and 23 had insulin-dependent (ID) DM. Vitamin E supplementation, metabolic control, and cyclooxygenase inhibitors were used to investigate the mechanisms of formation of 8-iso-PGF2α in this setting. Urinary 8-iso-PGF2α excretion was significantly higher (P=0.0001) in NIDDM patients (419±208 pg/mg creatinine; range 160 to 1014) than in age-matched control subjects (208±92; 41 to 433). Urinary 8-iso...

In Vivo Formation of 8-Epi-Prostaglandin F2α Is Increased in Hypercholesterolemia

Abstract F2-isoprostanes are bioactive prostaglandin (PG) -like compounds that are produced from arachidonic acid through a nonenzymatic process of lipid peroxidation catalyzed by oxygen free-radicals. 8-Epi-PGF2α may amplify the platelet response to agonists, circulates in plasma, and is excreted in urine. We examined the hypothesis that the formation of 8-epi-PGF2α is altered in patients with hypercholesterolemia and contributes to platelet activation in this setting. Urine samples were obtained from 40 hypercholesterolemic patients and 40 age- and sex-matched control subjects for measurement of immunoreactive 8-epi-PGF2α. Urinary excretion of 11-dehydro-thromboxane (TX) B2, a major metabolite of TXA2, was measured as an in vivo index of platelet activation. Low-dose aspirin, indobufen, and vitamin E were used to investigate the mechanism of formation and effects of 8-epi-PGF2α on platelet activation. Urinary 8-epi-PGF2α was significantly ( P =.0001) higher in hypercholesterolemic patients than in control subjects: 473±305 versus 205±95 pg/mg creatinine. Its rate of excretion was inversely related to the vitamin E content of LDL and showed a positive correlation with urinary 11-dehydro-TXB2. Urinary 8-epi-PGF2α was unchanged after 2-week dosing with aspirin and indobufen despite complete suppression of TX metabolite excretion. Vitamin E supplementation was associated with dose-dependent reductions in both urinary 8-epi-PGF2α and 11-dehydro-TXB2 by 34% to 36% and 47% to 58% at 100 and 600 mg daily, respectively. We conclude that the in vivo formation of the F2-isoprostane 8-epi-PGF2α is enhanced in the vast majority of patients with hypercholesterolemia. This provides an aspirin-insensitive mechanism possibly linking lipid peroxidation to amplification of platelet activation in the setting of hypercholesterolemia. Dose-dependent suppression of enhanced 8-epi-PGF2α formation by vitamin E supplementation may contribute to the beneficial effects of antioxidant treatment.

Vitamins E, C and lipid peroxidation in plasma and arterial tissue of smokers and non-smokers

An imbalance between pro-oxidants and antioxidants is operative in atherosclerosis. Cigarette smoke is a major risk factor of atherosclerosis and has been reported to contain large amounts of oxidants. We assessed arterial (internal mammary artery) and plasma levels of vitamins E and C and lipid peroxides in 48 male patients, 24 smokers and 24 non-smokers, undergoing coronary bypass surgery. Lipid peroxidation was studied using fluorescent products of lipid peroxidation (FPLs). Tissue vitamins E and C levels were significantly lower and FPLs significantly higher in smokers than in non-smokers (P < 0.0006, 0.0005 and 0.0005, respectively). This pattern was associated with lower vitamin C and higher lipid peroxide plasma levels in smokers than in non-smokers (P < 0.0002 and 0.0005, respectively). Vitamins E and C plasma levels were strongly related to their tissue content both in smokers (r = 0.60, P < 0.005 and r = 0.57, P < 0.01) and in non-smokers (r = 0.42, P < 0.05 and r = 0.46, P < 0.05). Moreover, vitamin E content was significantly related to that of vitamin C only in the arterial tissue of both groups, pointing to the existence of a functional interaction between these antioxidants. In both groups, FPLs were significantly and inversely related to vitamin C in plasma and to vitamin E in tissue, suggesting the antioxidant primary of vitamin C and vitamin E in the plasma and arterial tissue compartments, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Copper/zinc ratio and systemic oxidant load: effect of aging and aging-related degenerative diseases

There is evidence that copper and zinc have pro-oxidant and antioxidant properties, respectively, so that their imbalance may be expected to condition oxidative stress status. Oxidative stress is relevant in aging and in age-related degenerative diseases. In this study, blood content of copper, zinc, and ceruloplasmin as well as of lipid peroxides were investigated in 81 healthy and 62 disabled octo-nonagenarians affected by chronic degenerative diseases, and in 81 healthy adults. Serum copper/zinc ratio and ceruloplasmin were significantly higher in the elderly than in the healthy adults. Moreover, all these parameters were significantly higher in the disabled than in the healthy elderly. Notably, the increased copper/zinc ratio found in healthy elderly was due to high copper values, whereas in the disabled, both high copper and low serum zinc concentrations were present. The copper/zinc ratio was significantly and positively related to systemic oxidative stress status in all groups. The higher the serum copper/zinc ratio the higher the lipid peroxides plasma content. We conclude that there is a strict relationship between copper/zinc ratio and systemic oxidant burden. Moreover, advanced age and, particularly, advanced age-related chronic degenerative diseases are associated with a significant increase in the copper/zinc ratio and systemic oxidative stress.

Effect of Thyroid Function on LDL Oxidation

In this study, the effect of different levels of thyroid hormone and metabolic activity on low density lipoprotein (LDL) oxidation was investigated. Thus, in 16 patients with hyperthyroidism, 16 with hypothyroidism, and 16 age- and sex-matched healthy normolipidemic control subjects, the native LDL content in lipid peroxides, vitamin E, beta-carotene, and lycopene, as well as the susceptibility of these particles to undergo lipid peroxidation, was assessed. Hyperthyroidism was associated with significantly higher lipid peroxidation, as characterized by a higher native LDL content in lipid peroxides, a lower lag phase, and a higher oxidation rate than in the other two groups. This elevated lipid peroxidation was associated with a lower LDL antioxidant concentration. Interestingly, hypothyroid patients showed an intermediate behavior. In fact, in hypothyroidism, LDL oxidation was significantly lower than in hyperthyroidism but higher than in the control group. Hypothyroidism was also characterized by the highest beta-carotene LDL content, whereas vitamin E was significantly lower than in control subjects. In hyperthyroidism but not in the other two groups, LDL oxidation was strongly influenced by free thyroxine blood content. In fact in this group, the native LDL lipid peroxide content and the lag phase were directly and indirectly, respectively, related to free thyroxine blood levels. On the contrary, in hypothyroidism LDL oxidation was strongly and significantly related to serum lipids. In conclusion, both hypothyroidism and hyperthyroidism are characterized by higher levels of LDL oxidation when compared with normolipidemic control subjects. In hyperthyroid patients, the increased lipid peroxidation was strictly related to free thyroxine levels, whereas in hypothyroidism it was strongly influenced by serum lipids.

Effect of a Standardized Grape Seed Extract on Low-Density Lipoprotein Susceptibility to Oxidation in Heavy Smokers

The aim of our study was to evaluate the effect of a standardized formulation of a polyphenolic extract of grapes (Leucoselect-Phytosome [LP]) on low-density lipoprotein (LDL) susceptibility to oxidation in a group of heavy smokers. A randomized, double-blind, crossover study was undertaken in 24 healthy male heavy smokers, aged > or = 50 years. Enrolled subjects were given 2 capsules twice daily for 4 weeks (phase 1). Each capsule contained 75 mg of a grape procyanidin extracts and soy-phosphatidlcholine or placebo consisiting of 75 mg lactose and soy-phosphatidlcholine. A wash out period of 3 weeks was then followed by 4 weeks of the opposite treatment (phase 2). Blood samples were taken at baseline and at the end of each phase and assayed for plasma lipids and LDL susceptibility to oxidation. Compliance was good, and no adverse effects were recorded. Subjects did not show significant modification of total cholesterol (TC), triglycerides (TG), high-density lipoprotein-cholesterol (HDL-C) and LDL-C during LP treatment. Among oxidative indices, thiobarbituric acid reactive substances (TBARS) concentration was significantly reduced in subjects taking LP (-14.7% +/- 21.1% v +5.0% +/- 18.1%, P <.01), and the lag phase prolonged (+15.4% +/- 24.4% v -0.1% +/- 16.0%, P <.05) compared with placebo and basal values. The antioxidant potential of grape seed extract polyphenols may prove effective in a model of oxidative stress (smoking); however more investigational data are needed before use in wider clinical settings.

Systemic Oxidative Stress and Its Relationship with Age and Illness

OBJECTIVE: It has recently been proposed that increased oxidative stress may play a role in the aging process and age‐associated degenerative diseases.

Vitamin E and lipid peroxide plasma levels predict the risk of cardiovascular events in a group of healthy very old people.

OBJECTIVES: To assess whether systemic oxidative stress can predict the risk of first myocardial infarction, ischemic stroke, and congestive heart failure.

Low-Density Lipoprotein Oxidation and Vitamins E and C in Sustained and White-Coat Hypertension

Low-density lipoprotein oxidation and antioxidant vitamins E and C were investigated in white-coat hypertension in comparison with sustained hypertension and normotension. We selected 21 sustained hypertensive subjects, 21 white-coat hypertensive subjects, and 21 normotensive subjects matched for gender, age, and body mass index. White-coat hypertension was defined as clinical hypertension and daytime ambulatory blood pressure <139/90 (subjects were also reclassified using 134/90 and 135/85 mm Hg as cutoff points for daytime blood pressure). Blood samples were drawn for lipid profile determination, assessment of fluorescent products of lipid peroxidation in native LDL, evaluation of susceptibility to LDL oxidation in vitro (lag phase and propagation rate), and determination of LDL vitamin E and plasma vitamins E and C contents. Compared with sustained hypertensive subjects, white-coat hypertensives had significantly lower fluorescent products of lipid peroxidation (15.4+/-3.4 versus 10.2+/-3 units of relative fluorescence/mg LDL protein, P<.05), longer lag phase (54+/-10 versus 88+/-10 minutes, P<.05), lower propagation rate (8.2+/-2.5 versus 5.95+/-2.1 nmol diene/min per mg LDL cholesterol, P<.05), higher LDL vitamin E content (8.3+/-1.1 versus 10.1+/-1.8 nmol/mg LDL cholesterol, P<.05), and plasma vitamin C content (40+/-13 versus 57+9 micromol/L, P<. 05). No significant difference was observed between white-coat hypertensive and normotensive subjects. The results did not change after reclassification of subjects. Our data show that white-coat hypertensive subjects do not show an enhanced propensity to LDL oxidation or reduction in antioxidant vitamins. Given the role of LDL oxidation in the development of atherosclerosis and that of vitamin E and C in protecting against it, these findings suggest that white-coat hypertension per se carries a low atherogenic risk.

Increased Systemic Oxidative Stress After Elective Endarterectomy Relation to Vascular Healing and Remodeling

It has been reported that systemic and local redox state may have an important role in the functional and organic changes characterizing the process of vascular response to injury. Carotid endarterectomy to remove atherosclerotic plaque is followed by a long lasting healing and remodeling process that can be carefully followed over time with noninvasive ultrasonography. Plasma vitamin C concentration and native LDL (n-LDL) content in lipid peroxides, vitamin E, beta-carotene, and lycopene as well as LDL susceptibility to peroxidation were assessed in 45 patients undergoing elective endarterectomy for internal carotid stenosis, at baseline, 24 hours, 3 and 15 days, and 1 month after surgery. Serial duplex scans were performed in all patients postoperatively and 3, 6, and 12 months. The changes in far wall thickness (FW) and % renarrowing from postoperatively to 12 months were used as remodeling indices. Plasma antioxidant vitamins and lag-phase showed a sharp and significant decrease during the first 24-hours after surgery remaining unchanged until the third day, whereas, an opposite trend was evidenced for n-LDL content in lipid peroxides and serum ceruloplasmin. After the third day all the parameters returned progressively to baseline within one month from endarterectomy. Interestingly, the n-LDL lipid peroxide content, the serum ceruloplasmin and the plasma vitamin C concentration, measured at 24 and 3 days from surgery, were significantly associated to the change in % renarrowing from postoperatively to 12 months. The higher the LDL content in lipid peroxides, the higher the serum level of ceruloplasmin, the lower the plasma content in vitamin C and the higher the % of vessel renarrowing. In conclusion, carotid endarterectomy with atherosclerotic plaque removal is associated with an acute and prolonged increase in systemic oxidative stress that influences vascular healing and late luminal loss.