Olive oil consumption, plasma oleic acid, and stroke incidence: the Three-City Study.

OBJECTIVE: To determine whether high olive oil consumption, and high plasma oleic acid as an indirect biological marker of olive oil intake, are associated with lower incidence of stroke in older subjects. METHODS: Among participants from the Three-City Study with no history of stroke at baseline, we examined the association between olive oil consumption (main sample, n = 7,625) or plasma oleic acid (secondary sample, n = 1,245) and incidence of stroke (median follow-up 5.25 years), ascertained according to a diagnosis validated by an expert committee. RESULTS: In the main sample, 148 incident strokes occurred. After adjustment for sociodemographic and dietary variables, physical activity, body mass index, and risk factors for stroke, a lower incidence for stroke with higher olive oil use was observed (p for trend = 0.02). Compared to those who never used olive oil, those with intensive use had a 41%(95% confidence interval 6%-63%, p = 0.03) lower risk of stroke. In the secondary sample, 27 incident strokes occurred. After full adjustment, higher plasma oleic acid was associated with lower stroke incidence (p for trend = 0.03). Compared to those in the first tertile, participants in the third tertile of plasma oleic acid had a 73% (95% confidence interval 10%-92%, p = 0.03) reduction of stroke risk. CONCLUSIONS: These results suggest a protective role for high olive oil consumption on the risk of stroke in older subjects.

Association between antioxidant nutritional indicators and the incidence of dementia: results from the PAQUID prospective cohort study.

OBJECTIVE: To analyse the relation between antioxidant vitamins A, E, and malondialdehyde (MDA) lipoperoxidation product plasma concentrations with incident dementia. DESIGN: : A nested case-control within the PAQUID (Personnes Agées QUID) cohort. SETTING: The PAQUID population-based prospective cohort in southwestern France. SUBJECTS: Among 626 subjects with blood collection at baseline, 46 developed a dementia during the follow-up and were considered to be cases. Each case was matched (on age and sex) to three controls. RESULTS: Plasma vitamin E concentrations were lower among cases (mean value at 22.62 micromol/l (s.d.: 7.38) vs 24.99 (s.d.: 6.73 among controls). The same trend was observed for vitamin A concentrations, but the difference was not significant. On the contrary, MDA concentrations tended to be higher (mean value 1.35 micromol/l (s.d.: 0.53) vs 1.23 (s.d.: 0.44)) among cases. In logistic regression models, plasma values were split into tertiles. Adjusted for confounders, the risk of dementia was significantly increased in the lowest vitamin E tertile (< or =21.0 micromol/l) (OR=3.12, P=0.033) compared to the highest one (> or =25.5 micromol/l). The risk of Alzheimer's disease was also increased, with borderline significance (OR=3.06, P=0.053). Risks associated with vitamin A were nonsignificant. Similarly, there was a trend to an increased risk of dementia in the highest tertile of MDA (OR=1.67, P=0.31). CONCLUSIONS: These results suggest that subjects with low plasma vitamin E concentrations are at a higher risk of developing a dementia in subsequent years.

Correlations of soluble interleukin-2 and tumor necrosis factor type II receptors with immunologic and virologic responses under HAART.

We assessed the correlations between some plasma markers of immune activation (soluble receptors of interleukin 2 (sIL2-R) and TNFap75 (sTNFII-R) and usual markers of HIV infection in patients treated with protease-inhibitors (PI). Forty-six PI-naive HIV-1-infected adults were included in a 1-year prospective cohort from the initiation of a P1-containing regimen (M0). Measurements of CD4+cell count, plasma HIV-RNA, sIL2-R and sTNFII-R were performed at M0, M6, and M12. The evolution of sIL2-R from baseline to M12 was significantly different between immunological responders (IR) (CD4+count above 200/mm3 for subject having less than 200 CD4 +/mm3 at inclusion, or increase of at least 50 CD4+/mm3 for others) (58 UI/ml) and non-IR (+28 UI/ml) (P =0.01). The evolution of sTNFII-R between M0 and M12 was significantly different between virological responders (VR) (plasma HIV-1 RNA less than 500 copies/ml at M12) (-2.5 ng/ml) and non-VR (+0.2 ng/ml) (P = 0.02). Our study shows significative correlations between the evolutions of soluble interleukin-2 and TNFR-II receptors and those of CD4+T-lymphocytes or HIV-RNA responses in patients under HAART.

Antioxidant defences and oxidative stress markers in erythrocytes and plasma from normally nourished elderly Alzheimer patients.

OBJECTIVES: to investigate blood markers of oxidative stress, and enzymatic and non-enzymatic antioxidants in normally nourished elderly people with Alzheimer's disease. DESIGN: case-control study. SUBJECTS: twenty patients with Alzheimer's disease and 23 elderly control subjects, living at home, free from disease and not undergoing any treatment known to have a strong influence on blood oxidative stress markers or antioxidant defence systems. METHODS: we performed a nutritional evaluation, including anthropometric and biological measures and a 3-day dietary record. We determined concentrations of antioxidant vitamins (alpha-tocopherol, retinol) and malondialdehyde in plasma and erythrocytes. We also measured erythrocyte enzymatic activities of glutathione peroxidase and copper-zinc superoxide dismutase. RESULTS: the two groups were similar in age, body mass index, dietary record and serum albumin concentration. After adjustment for age, sex and cardiovascular co-morbidity, mean plasma concentration of alpha-tocopherol was lower in those with Alzheimer disease than in control subjects (15+/-3.5 mg/l compared with 18.2+/-3.5; P=0.002), as was the mean plasma concentration of retinol (0.54+/-0.2 mg/l vs 0.7+/-0.2; P=0.014). The mean concentration of free plasma malondialdehyde was higher in those with Alzheimer's disease (0.70+/-0.2 mmol/l vs 0.5+/-0.1; P=0.036). In Alzheimer disease patients, free plasma malondialdehyde concentrations were inversely correlated with levels of alpha-tocopherol (P=0.002) and retinol (P=0.025). Erythrocyte levels of vitamins and enzymatic activities were similar in the two groups. CONCLUSION: lower plasma concentrations of alpha-tocopherol and retinol in normally nourished elderly patients with Alzheimer's disease than in controls could suggest that these antioxidant vitamins had been consumed as a result of excessive production of free radicals.

Prognostic value of plasma markers of immune activation in patients with advanced HIV disease treated by combination antiretroviral therapy.

We assessed the prognostic role of plasma levels of beta2-microglobulin, TNF-alpha, sTNFR-II, and IFN-gamma on the progression to AIDS in patients mostly treated with combination antiretroviral therapies. HIV-1-infected patients with advanced HIV disease (baseline CD4+ cell count between 50 and 250 x 10(6)/L) were included in a prospective cohort followed up for 36 months. In the 113 patients included, 22 first AIDS-defining events were reported. Cumulative probability of AIDS was 12% at M12, 18% at M24, and 20% at M36. Using a Cox model, the baseline level of sTNFR-II (hazard ratio of 3.75 for sTNFR-II > or =10 ng/ml vs < 10 ng/ml, P = 0.01) was associated with progression to AIDS. sTNFR-II remained a prognostic factor before and after the introduction of combinations of antiretrovirals. Whether or not this marker is of value in patients exclusively treated with highly active antiretroviral therapy needs to be assessed in specific studies.

Nutritional factors in cerebral aging and dementia: epidemiological arguments for a role of oxidative stress.

There is increasing evidence that oxidative stress is involved in cerebral aging and dementia. The objective of this review is to give a progress report on the more recent results of the various epidemiologic cohorts studied for the association between nutrition of older people, the evolution of cognitive performances and the risk of later occurrence of dementia or stroke. The oxidative theory of pathological brain ageing is supported by animal laboratory experiments. Furthermore, experimental research has consistently suggested that diet-related factors play an important role in cognitive functions in ageing. In humans, a number of epidemiological case-control and prospective studies analyzed the association between nutrition, particularly fatty acids and antioxidant molecules (vitamins A, E, C, beta-carotene and polyphenols) and cognition. In the context of evidence already available, further studies are needed to identify the specific role of various nutrients, their interactions and the influence of genetic factors and living habits on cerebral aging and dementia. Vascular dementia and Alzheimer's disease, that share several risk factors, might be targets for primary prevention through nutritional recommendations and/or supplementation.

The place of electron spin resonance methods in the detection of oxidative stress in type 2 diabetes with poor glycemic control.

OBJECTIVE: Chronic production of reactive oxygen species (ROS) and/or deficiency in the antioxidant defense system are observed in non-insulin-dependent diabetes mellitus (NIDDM) patients. As an adjunct to the usual indirect parameters for evaluating oxidative stress, we assessed the feasibility of oxyradicals detection in venous blood by electron spin resonance spectroscopy (ESR). Detection of the ascorbate pool was also performed using the validated ESR analysis of the ascorbyl free radial (AFR)-dimethyl sulfoxide (DMSO) complex. METHODS AND RESULTS: Plasma lipoperoxidation was characterized by higher levels of total MDA (1.50 +/- 0.08 nmol/L), lower levels of GSH (0.54 +/- 0.02 mmol/L) and of vitamin A (2.13 +/- 0.52 mumol/L) in the NIDDM group than in the controls (0.75 +/- 0.05 nmol/L, 0.90 +/- 0.05 mmol/L, 3.52 +/- 1.04 mumol/L, respectively). Improvement of the ESR measurement of oxyradical adducts has been previously obtained by addition of a new sensitive nitrone (DEPMPO), which acts as a spin-trap. However, in our experiment the ESR signal-to-noise ratio was too low to detect significative oxyradicals adducts in total venous blood of NIDDM patients having a weak production of ROS. A significant difference (p < 0.002) was observed in DMSO/AFR index between controls (24.00 +/- 4.10 nmol/L) and NIDDM patients (7.28 +/- 2.36 nmol/L) suggesting ascorbate depletion related to the free radical production. CONCLUSION: The DMSO/AFR index could be an interesting additional marker of oxidative stress during a chronic production of ROS.

In vitro influence of ascorbate on lipid peroxidation in rat testis and heart microsomes.

Lipid peroxidation (LPO) in rat testis and heart microsomes was compared using the ADP/Fe2+ as initiator with and without ascorbate at different concentrations. The extent of LPO was estimated by the levels of TBARS and PUFA. Without ascorbate, LPO was higher in heart than in testis despite elevated levels of catalase in heart. With increased ascorbate concentrations, a biphasic effect of LPO was observed. For a concentration < or = 0.2 mM, ascorbate acted as pro-oxidant and increased TBARS correlated with decreased PUFA were observed both in testis and heart. Above 0.2 mM, ascorbate acts as antioxidant but differences in the rate of LPO were observed. In heart decreased TBARS correlated with increased PUFA whereas in testis TBARS only decreased, PUFA were not significantly modified. These results suggest different mechanisms in LPO initiation in the two organs. Increasing concentrations of H2O2 produced directly elevated TBARS levels in testis while a lag phase was observed in heart before the increase, suggesting that H2O2 was the essential ROS produced by ascorbate-ADP/Fe2+. The effects of scavengers such as catalase and ethanol showed an inhibitory effect on TBARS production only in testis, suggesting the role of H2O2/OH. as an initiator of LPO. In heart, catalase produced a slight increase in TBARS levels whereas no modification was observed with ethanol, suggesting a possible direct activation by ADP/Fe2+ through a metal-oxo intermediate.

Short-term insulin therapy and normoglycemia. Effects on erythrocyte lipid peroxidation in NIDDM patients.

OBJECTIVE: To evaluate erythrocyte lipid peroxidation (LPO) before and after an adaptive short-term insulin therapy in NIDDM patients who were chronically hyperglycemic. RESEARCH DESIGN AND METHODS: Twenty-six patients with NIDDM (mean HbA1c, 11.28%) aged 53.04 +/- 2.03 years were submitted for 3 days to constant intravenous glucose and continuous insulin perfusion at an adaptable rate to maintain glycemia within the normal range. An evaluation of LPO at baseline and after euglycemic insulin therapy was determined by erythrocyte free and total malondialdehyde (MDA) levels, polyunsaturated fatty acid (PUFA) percentage, vitamin E and glutathione content, and the following antioxidant enzymatic activity determinations: glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT). Fasting serum glucose, HbA1c, triglycerides, cholesterol, and HDL cholesterol levels were also determined at these time points. RESULTS: At baseline, erythrocyte free and total MDA were significantly higher in NIDDM patients than in control subjects (11.14 +/- 0.80 vs. 1.74 +/- 0.11 nmol/g Hb [P < 0.0001] for free MDA; 18.04 +/- 1.79 vs. 7.85 +/- 0.55 nmol/g Hb [P < 0.0001] for total MDA). PUFAs, particularly C20:4 and C22:5, were increased (14.69 +/- 0.34 vs. 12.03 +/- 0.31 and 2.31 +/- 0.04 vs. 1.71 +/- 0.03% of total fatty acids, respectively). Vitamin E and glutathione were reduced significantly (6.16 +/- 0.61 vs. 14.84 +/- 0.64 nmol/g Hb and 0.42 +/- 0.04 vs. 0.97 +/- 0.06 mmol/l, respectively). No difference was observed for the enzymatic activities. After euglycemic insulin therapy, triglycerides significantly decreased compared with baseline concentrations (1.55 +/- 0.13 vs. 2.42 +/- 0.22 mmol/l; P < 0.001), whereas other lipidic parameters were unchanged. Free MDA significantly decreased (8.60 +/- 0.76 vs. 11.14 +/- 0.80 nmol/g Hb [P < 0.01]), while vitamin E increased (7.93 +/- 0.73 vs. 6.16 +/- 0.61 nmol/g Hb [P < 0.05]). No difference was observed for PUFAs, glutathione, or total MDA. CONCLUSIONS: The observed erythrocyte LPO in NIDDM decreased after a short-term adaptive insulin therapy. This decrease could be principally attributed to the normalized glycemia that reduces reactive oxygen species (ROS) production, which in turn may explain the increase in erythrocyte membrane vitamin E and the decrease in MDA. This study shows the value of a euglycemic environment in NIDDM to reduce LPO and, at long range, to minimize clinical diabetes complications.

Antioxidant effects of a supplemented very low protein diet in chronic renal failure.

Increased peroxidation of lipids in red blood cells (RBC) in patients with advanced chronic renal failure (CRF) reflects increased generation of reactive oxygen species (ROS), which may contribute to the metabolic damage induced by CRF and to its progression. We have evaluated parameters indicative of lipoperoxidation (LPO) of RBC at baseline in patients with CRF compared to controls, and the effects of a very low protein diet supplemented with amino and keto acids and vitamins A, C, E (VLPD) over a 6-month period. The presence of peroxidation damage in CRF patients before the administration VLPD was demonstrated by elevated levels of free malondialdehyde (MDA) (p < .0003) and decreased levels of polyunsaturated fatty acids (PUFA), particularly C20:4 (p < .001), C22:4 (p < .0001) and C22:5 (p < .0001) when compared to controls. Similarly, RBC vitamin E content was significantly decreased (p < .0001) while enzymatic activities were unalterated. VLPD reduced erythrocyte LPO as suggested by (a) decreased levels of free and total RBC MDA (p < .003 and p < .03, respectively), (b) increased levels of PUFA, particularly C22:4 and C22:5 (p < .003 and p < .03, respectively), and (c) increased levels of vitamins A and E (p < .001 and p < .04, respectively) as compared to prediet results. Antioxidant enzyme activities were not modified. These results suggest that VLPD has a protective role against LPO of erythrocytes in patients with CRF.

The enzymatic antioxidant system in blood and glutathione status in human immunodeficiency virus (HIV)-infected patients: effects of supplementation with selenium or beta-carotene.

To investigate the effects of selenium or beta-carotene supplementation in human immunodeficiency virus (HIV)-infected patients, who are known to have deficiencies of selenium and vitamin A, we evaluated the blood enzymatic antioxidant system, including superoxide dismutase (SOD), selenodependent glutathione peroxidase (GPX), and catalase (Cat); glutathione (GSH) status; and plasma selenium concentration. The placebo group consisted of 18 HIV-infected patients with no supplementation, the selenium group was composed of 14 patients receiving oral selenium treatment, and the beta-carotene group comprised 13 patients receiving oral beta-carotene supplementation. All groups were studied for 1 y. At the beginning of the study, a significantly higher SOD activity (P < 0.001) was observed in all HIV-infected patients compared with uninfected control subjects, and GPX activity at baseline was higher in the placebo (P < 0.004) and selenium (P < 0.014) groups than in the control subjects. These higher enzyme activities could be related to an increased synthesis of these enzymes in erythrocyte precursors under oxidative stress. Moreover, we observed significantly lower GSH values in all HIV-infected patients than in control subjects at the beginning of the study (P < 0.001). After selenium or beta-carotene supplementation, no significant difference was observed for SOD activity compared with baseline. On the contrary, GPX activity increased significantly after selenium treatment (P < 0.04 between 3 and 6 mo), whereas a slight increase was found after beta-carotene treatment. Similarly, a significant increase in GSH values was observed at 12 mo compared with baseline both after selenium supplementation (P < 0.001) and beta-carotene supplementation (P < 0.01). Because GPX and GSH play an important role in the natural enzymatic defense system in detoxifying hydrogen peroxide in water, selenium supplementation could be of great interest in protecting cells against oxidative stress. The lower efficiency of beta-carotene could be attributed to the seriousness of the pathology at the time of recruitment into the beta-carotene group.

Lipoprotein(a) in 505 hospitalized patients with various pathological states: correlations with cardiovascular diseases and therapies.

OBJECTIVE: Our aim was to study the lipoprotein (a) (Lp(a)) levels in various pathological states. EXPERIMENTAL DESIGN: This investigation was prospective and included a healthy control group. SETTING: This study was carried out in two internal medicine and angiology services in teaching hospitals. PATIENTS: 505 patients were included with various diseases: 66 acute infections, 9 HIV infections, 25 cancers, 86 diabetes, 36 systemic diseases, 94 atheromatous vascular disease, 27 arterial hypertensions. A control group was composed of 21 healthy subjects. INTERVENTIONS: There was no therapeutic intervention but cardiovascular treatments were recorded. MEASURES: Serum Lp(a), total cholesterol, triglycerides, HDL-cholesterol, calculated LDL-cholesterol, apolipoproteins A-I and B were measured together with inflammatory parameters, serum creatinine, proteinuria, serum aminotransferase activity. RESULTS: There was no difference in Lp(a) levels between controls and each patient group. However, a correlation was found in systemic diseases between Lp(a) and C reactive protein (r = 0.371, p = 0.026) or serum albumin concentration (r = 0.453, p = 0.006). In hypertension, Lp(a) correlated with serum creatinine (r = 0.420, p = 0.03). In the whole patient population, Lp(a) was correlated with cholesterol (r = 0.156, p = 0.0001), apolipoprotein B (r = 0.215, p = 0.0001), age (r = 0.108, p = 0.015), arterial events (r = 0.174, p = 0.0001) and platelet anti-aggregant drugs (r = 0.169, p = 0.0001). CONCLUSIONS: Lp(a), was related to atheromatous events and in systemic diseases to inflammation, suggesting that Lp(a) might vary in some patients in a manner similar to acute phase proteins.

Asymptomatic atherosclerosis in HIV-positive patients: A case-control ultrasound study.

Atherosclerosis has been reported in some HIV-positive subjects without any known risk factor. The purpose of the present study was to investigate cervical arteries, abdominal aorta and femoral arteries by B-mode ultrasonography and doppler in 30 HIV-positive subjects matched to 18 controls for sex, age, tobacco consumption and arterial hypertension. Although no haemodynamically or clinically relevant lesions were found, plaques occurred more often in patients than in controls (11 patients, 36.7% vs. 2, 11.1%; P = 0.05). Compared to the HIV-positive patients without plaques, those with plaques had a tendency to have decreased lower HDL cholesterol, higher tobacco consumption and lower CD4-cell count (77 +/- 85/mm3 vs. 220 +/- 202/mm3). The patients with plaques (but not those without plaques) had lower HDL cholesterol than controls (P = 0.03). Asymptomatic atherosclerosis seems to be more frequent in HIV-positive patients and is associated to lower HDL cholesterol.

Fatty acids and plasma antioxidants in HIV-positive patients: correlation with nutritional and immunological status.

OBJECTIVE: To investigate red blood cell (RBC) and plasma fatty acids (FA) in HIV-positive patients in relation to oxidative stress and nutritional or immunological status. DESIGN AND METHODS: FA, plasma selenium, vitamins A and E were measured in 95 patients divided into four groups according to CD4 cells. RESULTS: Poly- and di-unsaturated FA (PUFA, DUFA) decreased and saturated FA (SFA) increased in RBC in the patients below 400/mm3 and in plasma in the patients below 50/mm3. RBC SFA correlated to CD4 cells, PUFA to MDA. Unlike vitamin E, plasma vitamin A and selenium decreased in most groups. Plasma SFA and MUFA correlated negatively to selenium and PUFA and DUFA to vitamin E. No correlation was found between PUFA and nutritional markers. CONCLUSION: FA seem to be modified during HIV infection by oxidative stress and disease evolution, but not by denutrition.

Evaluation of red blood cell lipoperoxidation in hemodialysed patients during erythropoietin therapy supplemented or not with iron.

To investigate the effects of erythropoietin (rHuEPO) therapy supplemented or not with iron on hemolysis in hemodialysed patients (HD) we evaluated lipoperoxidation (LPO) by assaying (i) the red blood cell (RBC) antioxidant enzymatic system including superoxide dismutase (SOD), glutathione peroxidase, and catalase (Cat), (ii) RBC polyunsaturated fatty acids (PUFA) and (iii) malondialdehyde (MDA). Group 1 included 12 HD patients, group 2 had 7 HD patients with iron supplementation, group 3 comprised 12 HD patients with rHuEPO therapy and group 4 included 9 HD patients with both iron and rHuEPO therapies. No LPO was found in group 1 as regards MDA and PUFA levels. However, SOD and Cat activities were significantly elevated as compared to controls (p < 0.001). In the second group, a significant decrease in PUFA percentage was observed, particularly in 20:4(n-6) and 22:4(n-6) (the main ones involved in LPO) as compared to the other groups, whereas total MDA level was higher than that of the other groups. Similarly a decreased SOD activity was observed as compared to group 1 (p < 0.001), indicating its inactivation subsequent to an hyperproduction of reactive oxygen species through iron injection. In groups 3 and 4 no change was observed in MDA levels or PUFA percentages indicating no LPO. However, marked differences were observed in the enzymatic defense system. Particularly in group 3, SOD and Cat activities decreased when compared to group 1 (p < 0.001) whereas the association of erythropoietin and iron (group 4) increased the three enzymatic activities (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma lipids in HIV-infected patients: a prospective study in 95 patients.

The present study aimed to determine plasma lipid levels in 95 HIV-infected patients divided into four groups according to the CD4 lymphocyte counts comparatively to a control group of 20 HIV-negative normolipidaemic subjects. A relationship between lipidic abnormalities and immune or nutritional status was also investigated. The patients below 200 CD4 lymphocyte mm-3 (groups 1 and 2) had significantly lower total cholesterol than the controls. The patients below 400 CD4 lymphocytes mm-3 (groups 1, 2, 3) had significantly higher triglycerides and Lp(a) but lower LDL-cholesterol than the controls. In all HIV-positive patients, whatever their CD4 lymphocyte count, HDL-C and apoA1 were lower than in the controls. By multivariate analysis triglycerides were positively correlated to acute opportunistic infections and to interferon-alpha levels, while cholesterol was negatively correlated to TNF-alpha, and LDL-C was positively correlated to albuminaemia. The latter parameter was the only lipidic value to correlate with nutritional markers. The contamination route, or the presence of wasting, was not correlated to any lipidic disorder.

Lipoperoxidation in plasma and red blood cells of patients undergoing haemodialysis: vitamins A, E, and iron status.

In 14 patients undergoing haemodialysis, lipoperoxidation (LPO) processes were determined in plasma and red blood cells (RBC) before and after a dialysis session by determining (a) the direct substrate, polyunsaturated fatty acids (PUFA); (b) the end product of LPO, malondialdehyde (MDA); and (c) the hydrophobic antioxidant systems, vitamins A and E. In plasma before dialysis, linoleic and arachidonic acid, and the antioxidant vitamin E, were significantly lowered as compared to the healthy controls (p < 0.05). On the contrary, the free MDA level was enhanced (p < 0.05). These results were emphasized by a dialysis session. In RBC of these patients, no difference in linoleic acid, free MDA, or vitamin E level were observed before or after dialysis when compared to controls. However, only vitamin A was significantly higher in haemodialysis patients (before and after dialysis) and in renal failure patients (p < 0.05) than in the healthy control group. The present results suggest that increased RBC vitamin A may offer some degree of protection against oxidative stress in erythrocytes, but not in plasma where LPO is demonstrated.