Modulation of multidrug resistance P-glycoprotein activity by antiemetic compounds in human doxorubicin-resistant sarcoma cells (MES-SA/Dx-5): implications on cancer therapy.

Multidrug resistance (MDR) in cancer cells is often caused by the high expression of the plasma membrane drug transporter P-glycoprotein (Pgp) associated with an elevated intracellular glutathione (GSH) content in various human tumors. Several chemosensitizers reverse MDR but have significant toxicities. Antiemetic medications are often used for controlling chemotherapy-induced nausea and vomiting in cancer patient. In this in vitro study we investigated if the effects of two common antiemetic drugs such as dimenhydrinate (dime) and ondansentron (onda) and a natural compound (6)-gingerol (ginger), the active principle of ginger root, interfere on Pgp activity and intracellular GSH content in order to evaluate their potential use as chemosensitizing agents in anticancer chemotherapy. The human doxorubicin (doxo) resistant uterine sarcoma cells (MES-SA/Dx5) that overexpress Pgp, were treated with each antiemetic alone (1, 10 and 20 microM) or in combination with different doxo concentrations (2, 4, and 8 microM). We measured the intracellular accumulation and cytotoxicity of doxo (MTT assay), the cellular GSH content (GSH assay) and ROS production (DFC-DA assay), in comparison with verapamil (Ver), a specific inhibitor for Pgp, used as reference molecule. We found that exposure at 2, 4 and 8 microM doxo concentrations in the presence of dime, onda and ginger enhanced significantly doxo accumulation and cytotoxicity on resistant MES-SA/Dx5 cells when compared with doxo alone. Moreover, treatment with ginger (20 microM) increased cellular GSH content (greater than 10 percent) in resistant cells, while ROS production remained below the control values for all antiemetic compounds at all concentrations. These findings provide the rationale for innovative clinical trials of antiemetics or their derivatives as a new potential generation of chemosensitizers to improve effectiveness of the anticancer drugs in MDR human tumours.

Inhibition of P-glycoprotein-mediated transport by S-adenosylmethionine and cynarin in multidrug-resistant human uterine sarcoma MES-SA/Dx5 cells.

Multidrug resistance (MDR) to anticancer chemotherapy is often mediated by the overexpression of the plasma membrane drug transporter P-glycoprotein (Pgp) encoded by multidrug resistance gene (MDR1). Various chemosensitizing agents are able to inhibit Pgp activity but their clinical application is limited by their toxicity. Furthermore, hepatotoxicity related to chemotherapy causes delays of treatment in cancer patients and often requires supplementation of anti-tumour therapy with hepatoprotective agents. In this in vitro study, we investigated the effectiveness of an endogenous hepatoprotective agent, S-adenosylmethionine (SAMe), and a natural hepatoprotective compound, Cynarin (Cyn), to inhibit Pgp activity in order to evaluate their potential use as chemosensitizing agents. Human doxorubicin (doxo) resistant uterine sarcoma cells (MES-SA/Dx5) expressing high levels of Pgp were treated with two hepatoprotectors at various concentrations (1, 5 and 10 microM) that are clinically achievable, in the presence or absence of three different concentrations of doxo (2, 4 and 8 microM). In order to evaluate the effects of both hepatoprotectors, we measured the intracellular accumulation and cytotoxicity of doxo, the cellular GSH level, ROS production and catalase (CAT) activity. We found that treatment with 2, 4 and 8 microM doxo in the presence of SAMe or Cyn significantly increased the doxo accumulation and cytotoxicity on MES-SA/Dx5 cells, when compared to control cells receiving doxo alone. Moreover, treatment with SAMe or Cyn significantly increased GSH content, greater than 80 percent and 60 percent, respectively) and CAT activity greater than 60 and 150 percent, respectively) in resistant cancer cells, while ROS production was below the values of corresponding untreated control cells. Our in vitro findings provide a rationale for the potential clinical use of these hepatoprotectors both as chemosensitizing agents, to reverse Pgp-mediated MDR, and as antioxidants to protect normal cells from chemotherapy-induced cytotoxixity.

The effect of the plasticizer diethylhexyl phthalate on transport activity and expression of P-glycoprotein in parental and doxo-resistant human sarcoma cell lines.

Multidrug resistance (MDR) to cancer therapy is frequently associated with the over-expression of the multidrug transporter MDR1 gene product P-glycoprotein (Pgp) in several types of human tumours. Various chemosensitizers have been used to inhibit Pgp activity but toxicity limits their clinical application. Di(2-ethylhexyl)phthalate (DEHP) is a plasticizer that is released from polyvinyl chloride (PVC) medical devices. Therefore, cancer patients undertaking chemotherapy are exposed to a clinically important amount of DEHP through blood and blood component transfusions, apheresis products, intravenous chemotherapy, parenteral nutrition and other medical treatments. The present study was designed to investigate the effects of DEHP on transport activity and expression of Pgp in order to evaluate its potential use as a chemosensitizer in cancer therapy. Human doxorubicin (doxo) resistant sarcoma cells (MES-SA/Dx5) that over-express Pgp were treated with different doses of doxo (2, 4 and 8 µM) in the presence or absence of various concentrations of DEHP (3, 6 and 12 µM) that were clinically achievable in vivo. Our results show that co-treatment with 2, 4 and 8 µM doxo in the presence of the lowest concentration of DEHP (3 µM) enhanced significantly doxo accumulation in MES-SA/Dx5 cells and, consistently increased the sensitivity to doxo, when compared to controls receiving only doxo. In contrast, higher DEHP concentrations (6 and 12 µM) induced MES-SA/Dx5 to extrude doxo decreasing doxo cytotoxicity toward resistant cells below control values. These results are consistent with the increase in Pgp expression levels in parental MES-SA cells treated with 3, 6 and 12 µM DEHP for 24 h and compared to untreated controls. All in all, these findings suggest a potential clinical application of DEHP as a chemosensitizer to improve effectiveness of the antineoplastic drugs in MDR human tumours.

Cardiovascular risk in subjects with left ventricular concentric remodeling at baseline examination: a meta-analysis.

It is debated whether subjects with concentric remodeling (CR, normal left ventricular mass index (LVMI) and increased relative wall thickness (RWT)) are at higher cardiovascular risk than those with normal geometry (NG, normal LVMI and RWT). The aim of this study was to perform a meta-analysis of studies evaluating cardiovascular events in subjects with CR and NG according to baseline classification. We searched for articles evaluating cardiovascular outcome in subjects with CR compared with those with NG, and reporting adjusted hazard ratio (HR) and 95% confidence interval (CI). Six studies were included in the meta-analysis. The pooled population consisted of 7465 subjects with CR and NG. During the follow-up, they experienced 852 events. When compared with NG, the overall adjusted HR was 1.36 (95% CI 1.03-1.78) for CR, P<0.03. There was some heterogeneity between studies. Subgroup meta-analysis showed that increased cardiovascular risk in subjects with CR was more relevant in studies evaluating hypertensive and Caucasian subjects and reporting both fatal and non-fatal events. Cardiovascular risk is significantly higher in subjects with CR than in those with NG. This aspect is more evident in studies including hypertensive patients and Caucasian populations and reporting global cardiovascular risk.

Modulation of multidrug resistance p-glycoprotein activity by flavonoids and honokiol in human doxorubicin- resistant sarcoma cells (MES-SA/DX-5): implications for natural sedatives as chemosensitizing agents in cancer therapy.

Multidrug resistance (MDR) in cancer cells is often caused by the high expression of the plasma membrane drug transporter P-glycoprotein (Pgp) associated with an elevated intracellular glutathione (GSH) content in various human tumors. Several chemosensitizers reverse MDR but have significant toxicities. Sedatives are often used to control anxiety and depression in cancer patients. In this in vitro study we investigated the effects of three plant derived sedatives such as apigenin (Api), fisetin (Fis), flavonoids and honokiol (Hnk) on Pgp activity and cellular GSH content in order to evaluate their potential use as chemosensitizing agents in anticancer chemotherapy. Human doxorubicin (doxo) resistant uterine sarcoma cells (MES-SA/Dx5) that overexpress Pgp, were treated with each sedative alone (10 microM) or in combination with different doxo concentrations (2-8 microM). We measured the intracellular accumulation and cytotoxicity of doxo (MTT assay), the cellular GSH content (GSH assay) and ROS production (DFC-DA assay), in comparison with verapamil (Ver), a specific inhibitor for Pgp, used as reference molecule. We found that exposure at 2 and 8 microM doxo concentrations in the presence of Api, Fis and Hnk enhanced significantly doxo accumulation by 29+/-3.3, 20+/-4.8, 24+/-6.6 percent and 14+/-1.7, 8.3+/-4.2, 10.7+/-3.1 percent, respectively, when compared with doxo alone. These results were consistent with the increase of sensitivity towards doxo in MES-SA/Dx5, resulting in 1.7, 1.2, 1.4-fold and 1.2, 1.0 and 1.1-fold increases, respectively. Moreover, treatment with Api decreased markedly cellular GSH content (18 percent) and increased ROS production (greater than 20 percent) on MES-SA/Dx5 cells, while a significant reduction in ROS levels was observed in Hnk and Fis treated cells, when compared to untreated control. Our in vitro findings provide a rationale for innovative clinical trials to assess the use of natural sedatives or their derivatives as potential adjuvants to anticancer treatment for overcoming multidrug resistance Pgp-mediated in cancer patients.

Short- and long-term risk of cardiovascular events in white-coat hypertension.

The prognostic impact of white-coat hypertension is not yet completely clear. In this study, we investigated cardiovascular outcome in sustained hypertension, white-coat hypertension and normotension in the short and long term. The occurrence of fatal and nonfatal cardiovascular events was evaluated in 1732 subjects with clinical hypertension (1333 with sustained and 399 with white-coat hypertension) and 305 with normotension. White-coat hypertension was defined as clinical hypertension and daytime blood pressure <135/85 mm Hg. During the period of observation (mean 6.4 years, range 0.7-13.1), 152 cardiovascular events occurred. The event rate per 100 patient-years in subjects with normotension, white-coat and sustained hypertension was 0.38, 0.44 and 1.58, respectively. Event-free survival was significantly different among the groups (P<0.0001). After adjustment for several covariates, Cox regression analysis showed that cardiovascular risk was significantly higher in patients with sustained than in those with white-coat hypertension (relative risk (RR) 3.32, 95% confidence interval (CI) 1.81-6.12, P=0.0001), whereas there was no significant difference between normotension and white-coat hypertension. When events were analysed separately, cardiac and cerebrovascular risk were significantly higher in sustained than in white-coat hypertension (RR 4.16, 95% CI 1.48-11.6, P=0.007, and RR 4.12, 95% CI 1.62-10.5, P=0.003, respectively) and not significantly different between white-coat hypertension and normotension. Event-free survival had the same trend for the whole period of observation both when cardiovascular events were examined together and when cardiac and cerebrovascular events were analysed separately. In this study, cardiovascular risk in white-coat hypertension was significantly lower than that in sustained hypertension and not significantly different from normotension both in the short and long term.

Eosinophilic esophagitis is a component of the anticonvulsant hypersensitivity syndrome: description of two cases.

Anticonvulsant hypersensitivity syndrome is a rare syndrome caused by a specific, severe unusual reaction to antiepileptic agents; anticonvulsant hypersensitivity syndrome develops 1 week to 3 months after the introduction of the drug and most frequently consists of a multisystemic and multiorgan involvement. Drug withdrawal usually leads to rapid improvement of symptoms. Up to now no oesophageal damage has been described. We present two cases of carbamazepine hypersensitivity syndrome with concomitant development of eosinophilic oesophagitis that resolved after drug withdrawal.

Microsatellite polymorphism of the human leptin gene (LEP) and risk of cardiovascular disease.

BACKGROUND: No data have been so far reported on the relationship between polymorphisms of LEP gene and cardiovascular disease. PATIENTS AND METHODS: We genotyped a tetranucleotide repeat mapped in the 3'UTR of the LEP gene (LEP-tet) in 109 subjects with cardiovascular events and in 109 control subjects. RESULTS: Univariate analysis and multivariate logistic regression analysis adjusted for age, gender, smoking status, history of hyperlipidemia, hypertension or diabetes showed not significant association between the genotype of the LEP-tet and cardiovascular diseases. Moreover, no differences were observed in the plasma leptin concentrations between cases and control subjects (22 +/- 19 vs 22 +/- 14 ng/ml, P = 0.52) and in relation to the LEP-tet classes or carriage of specific alleles (P = 0.76 for the association between LEP-tet classes and leptin levels in overall analysis). CONCLUSIONS: In conclusion, our data do not support an association between the LEP-tet microsatellite polymorphism of the human LEP gene and cardiovascular diseases.

Enhanced soluble CD40 ligand contributes to endothelial cell dysfunction in vitro and monocyte activation in patients with diabetes mellitus: effect of improved metabolic control.

AIMS/HYPOTHESIS: Inflammation plays a pathogenic role in the development of accelerated atherosclerosis in diabetes. Soluble CD40 ligand (sCD40L) is enhanced in diabetes; however, the molecular mechanisms linking sCD40L to accelerated atherosclerosis in diabetes are still unclear. We tested the hypothesis that sCD40L may be involved in the vascular complications in diabetes and exerts its effect by triggering inflammatory reactions on mononuclear and endothelial cells (ECs). METHODS: We studied 70 patients, 40 with type 2 and 30 with type 1 diabetes, with a history or physical examination negative for cardiovascular disease, and 40 non-diabetic and 30 healthy subjects, matched with the type 2 and type 1 diabetic patients, respectively. Plasma and serum sCD40L, and plasma soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, E-selectin and monocyte chemo-attractant protein-1 (MCP-1) were measured. Adhesion molecules and MCP-1 release, the ability to repair an injury in ECs, and O2- generation in monocytes were analysed in vitro after stimulation with serum from patients or controls. RESULTS: Type 2 and type 1 diabetic patients had significantly higher sCD40L levels than controls. Furthermore, high sCD40L was associated with in vitro adhesion molecules and MCP-1 release, impaired migration in ECs and enhanced O2- generation in monocytes. Improved metabolic control was associated with a reduction of plasma sCD40L by 37.5% in 12 type 1 diabetic patients. Furthermore, elevated sCD40L in diabetic patients was significantly correlated with HbA1c levels. CONCLUSIONS/INTERPRETATION: Upregulation of sCD40L as a consequence of persistent hyperglycaemia in diabetic patients results in EC activation and monocyte recruitment to the arterial wall, possibly contributing to accelerated atherosclerosis development in diabetes.

Relationship between reduced BCL-2 expression in circulating mononuclear cells and early nephropathy in type 1 diabetes.

Microalbuminuria is the earliest clinical evidence of diabetic nephropathy, but the mechanisms linking hyperglycemia and kidney complications are not clear. The aim of this study was to evaluate whether enhanced oxidative stress in patients with microalbuminuria can contribute to diabetic nephropathy development through downregulation of the antiapoptotic gene Bcl-2 that promotes in turn a pro-inflammatory status. We studied 30 patients with type 1 diabetes (15 with and 15 without microalbuminuria) compared to 15 matched healthy controls. Plasma oxidant status, and expression of Bcl-2, activated NF-kB, inducible Nitric Oxide synthase (iNOS), and monocyte chemoattractant protein (MCP)-1 in circulating monocytes were evaluated at baseline and after 8-week oral vitamin E treatment (600 mg b.i.d.). Bcl-2 expression was significantly reduced in microalbuminuric diabetic patients as a consequence of increased oxidant burden secondary to persistent hyperglycemia. Bcl-2 down-regulation was associated with enhanced expression of NF-kB, iNOS and MCP-1, and showed a strong correlation with the albumin excretion rate. Low Bcl-2 expression and high inflammatory status were normalized by vitamin E both in vivo and in vitro. Our study showed that Bcl-2 down-regulation in diabetic patients with poor glycemic control results in the activation of the NF-kB pathway leading to the development of nephropathy. Vitamin E might provide a novel form of therapy for prevention of nephropathy in diabetic patients in which an acceptable glycemic control is difficult to achieve despite insulin therapy.

Role of antibiotic sensitivity testing before first-line Helicobacter pylori eradication treatments.

BACKGROUND: The resistance of Helicobacter pylori to antibiotics has been advocated as a major cause of treatment failure, and antimicrobial sensitivity testing has been proposed to improve efficacy; however, its role before first-line therapy has not been investigated in detail. AIM: To assess whether antimicrobial sensitivity testing improves the eradication rate of first-line anti-Helicobacter treatments and to compare the effectiveness of ranitidine bismuth citrate and omeprazole in the presence of H. pylori resistance to antibiotics. METHODS: Two hundred and forty-two patients were assigned to either empirical or antimicrobial sensitivity testing-based treatment; within each group, subjects were further randomized to receive ranitidine bismuth citrate, 400 mg b.d., tinidazole, 500 mg b.d., and clarithromycin, 500 mg b.d., or omeprazole, 20 mg b.d., clarithromycin, 500 mg b.d., and amoxicillin, 1 g b.d., for 1 week, with substitution of the resistant antibiotic in the antimicrobial sensitivity testing-based treatment group. RESULTS: Eradication rates were 67% [confidence interval (CI), 55-79%] in the empirical treatment group and 76% (CI, 65-87%) in the antimicrobial sensitivity testing-based group (P=N.S.). The overall success rate was 60% (CI, 51-69%) with omeprazole and 82% (CI, 73-91%) with ranitidine bismuth citrate (P<0.03); the latter overcame antibiotic resistance in 12 of 15 strains vs. zero of eight strains by omeprazole. CONCLUSIONS: Antimicrobial sensitivity testing before first-line treatment does not improve the eradication rate, which is greater when ranitidine bismuth citrate is included in the treatment.

High preprocedural non-HDL cholesterol is associated with enhanced oxidative stress and monocyte activation after coronary angioplasty: possible implications in restenosis.

OBJECTIVE: To investigate whether enhanced oxidant stress in patients undergoing percutaneous transluminal coronary angioplasty (PTCA) is associated with a higher concentration of non-high density lipoprotein (HDL) cholesterol at baseline, and whether this contributes to the inflammatory reaction and luminal renarrowing after PTCA. DESIGN: An ex vivo and in vitro study of 46 patients who underwent PTCA and who had repeat angiograms after six months. Blood samples were collected immediately before PTCA, and at 24 hours, 48 hours, and 15 days after. SETTING: Tertiary referral centre. SUBJECTS: 46 patients (30 male, 16 female; mean (SD) age, 62 (5) years) with stable or unstable angina who underwent elective PTCA. MAIN OUTCOME MEASURES: Continuous variable luminal loss as defined by change in minimum lumen diameter during follow up, normalised for vessel size; lag phase of low density lipoprotein to in vitro oxidation; plasma fluorescent products of lipid peroxidation (FPLP); plasma vitamin C and E; interleukin (IL) 1beta secretion from unstimulated monocytes; plasma C reactive protein (CRP). RESULTS: Restenosis occurred in 12 patients (26%). Oxidant stress after PTCA was greater (p < 0.0001 at 15 days) in the patients with restenosis and showed a significant correlation with the preprocedural concentration of non-HDL cholesterol (p < 0.001). Inflammatory reaction (as reflected by IL-1beta production and CRP) and late lumen loss were linearly correlated (p < 0.001) with lag phase and FPLP throughout the study, and inversely (p < 0.05) with vitamin C and E measured at two and 15 days after PTCA. CONCLUSIONS: This study provides evidence for the critical role of cholesterol dependent oxidant stress in the pathophysiology of restenosis after PTCA. The findings raise the possibility that drugs capable of modulating oxidant status might provide a novel form of adjuvant treatment in patients with hypercholesterolaemia undergoing PTCA.

Simple renal cysts in hypertensive patients: relation between cyst growing and anti-hypertensive therapy.

The study investigates relationship between simple renal cyst enlargement studied by ultrasonography and anti-hypertensive treatment. To this purpose we enrolled 42 patients with newly diagnosed hypertension affected by simple renal cysts. Fourteen were randomly assigned to treatment with ACE-Inhibitors (group 1), twelve to diuretics (group 2) and sixteen to Ca-Antagonists (group 3). Patient performed a basal ultrasonography to evaluate basal cyst dimension before starting anti-hypertensive treatment. Following 12 months of the anti-hypertensive regimen, a new echograph was performed to evaluate changes in cyst size. A control group consisting of 15 patients with normal blood pressure and simple renal cysts was enrolled (group 0). An enlargement of cysts was detected in all patients. However, the enlargement observed in patients treated by Ca-Antagonists was significantly greater than that observed in the other groups (p<0.05). Our study supports the hypothesis that Ca-Antagonists may favor cyst enlargement by enhancing cyclic AMP production. In fact, cAMP and cAMP agonists stimulate fluid secretion by lining cells of the cyst wall, inducing cyst enlargement.

Circulating homocysteine levels in sustained and white coat hypertension.

Although white coat hypertension has been widely studied in the last years, its risk profile is not yet completely clear. The aim of this study was to evaluate circulating homocysteine levels, an emerging cardiovascular risk factor, in subjects with white coat and sustained hypertension. We selected 31 sustained hypertensive subjects, 31 white coat hypertensive subjects and 31 normotensive subjects matched for age, gender, body mass index and occupation. Women were also matched for menopausal status. Subjects with smoking habit, dyslipidaemia and diabetes mellitus were excluded from the study. White coat hypertension was defined as clinical hypertension and daytime ambulatory blood pressure <135/85 mmHg. Blood samples were drawn after a fasting period of 12 h for routine laboratory tests and homocysteine determination. Homocysteine levels were evaluated by fluorescence polarization immunoassay. Creatinine, glucose, cholesterol and triglycerides were not different among the groups. White coat hypertensive subjects had significantly lower homocysteine levels than sustained hypertensive patients (8.2+/-2.0 vs 12.6+/-3.9 micromol/l, P=0.0003). No significant difference was observed between white coat hypertensive and normotensive subjects regarding this parameter (8.2+/-2.0 vs 7.6+/-1.9 micromol/l, P=0.9). In conclusion, our data show that middle-aged white coat hypertensive subjects without other cardiovascular risk factors have lower circulating homocysteine levels than sustained hypertensive patients suggesting that they are at lower cardiovascular risk.

Overexpression of functionally coupled cyclooxygenase-2 and prostaglandin E synthase in symptomatic atherosclerotic plaques as a basis of prostaglandin E(2)-dependent plaque instability.

BACKGROUND: Studies have implicated a role for prostaglandin (PG) E(2)-dependent matrix metalloproteinase (MMP) biosynthesis in the rupture of atherosclerotic plaque. Cyclooxygenase-2 (COX-2) and PGE synthase (PGES) are coregulated in nucleated cells by inflammatory stimuli. The aim of this study was to characterize the expression of COX-2 and PGES in carotid plaques and to correlate it with the extent of inflammatory infiltration and MMP activity and with clinical features of patients' presentation. METHODS AND RESULTS: Plaques were obtained from 50 patients undergoing carotid endarterectomy and divided into 2 groups (symptomatic and asymptomatic) according to clinical evidence of recent transient ischemic attack or stroke. Plaques were analyzed for COX-2, PGES, MMP-2, and MMP-9 by immunocytochemistry and Western blot, whereas zymography was used to detect MMP activity. Immunocytochemistry was used to identify CD68+ macrophages, CD3+ T lymphocytes, and HLA-DR+ cells. The percentage of macrophage-rich areas was larger (P<0.0001) in symptomatic plaques. COX-2, PGES, and MMPs were detected in all specimens; enzyme concentration, however, was significantly higher in symptomatic plaques. COX-2, PGES, and MMPs were especially noted in shoulders of symptomatic plaques, colocalizing with HLA-DR+ macrophages. All symptomatic plaques contained activated forms of MMPs. Finally, inhibition of COX-2 by NS-398 was accompanied by decreased production of MMPs that was reversed by PGE(2). CONCLUSIONS: This study demonstrates the colocalization of COX-2 and PGES in symptomatic lesions and provides evidence that synthesis of COX-2 and PGES by activated macrophages is associated with acute ischemic syndromes, possibly through metalloproteinase-induced plaque rupture.

Reaction conditions affecting the relationship between thiobarbituric acid reactivity and lipid peroxides in human plasma.

The thiobarbituric acid (TBA) reactivity of human plasma was studied to evaluate its adequacy in quantifying lipid peroxidation as an index of systemic oxidative stress. Two spectrophotometric TBA tests based on the use of either phosphoric acid (pH 2.0, method A) or trichloroacetic plus hydrochloric acid (pH 0.9, method B) were employed with and without sodium sulfate (SS) to inhibit sialic acid (SA) reactivity with TBA. To correct for background absorption, the absorbance values at 572 nm were subtracted from those at 532 nm, which represent the absorption maximum of the TBA:MDA adduct. Method B gave values of TBA-reactive substances (TBARS) 2-fold higher than those detected with method A. SS lowered TBARS by about 50% with both methods, indicating a significant involvement of SA in plasma TBA reactivity. Standard SA, at a physiologically relevant concentration of 1.5 mM, reacted with TBA, creating interference problems, which were substantially eliminated by SS plus correction for background absorbance. When method B was carried out in the lipid and protein fraction of plasma, SS inhibited by 65% TBARS formation only in the latter. Protein TBARS may be largely ascribed to SA-containing glycoproteins and, to a minor extent, protein-bound MDA. Indeed, EDTA did not affect protein TBARS assessed in the presence of SS. TBA reactivity of whole plasma and of its lipid fraction was instead inhibited by EDTA, suggesting that lipoperoxides (and possibly monofunctional lipoperoxidation aldehydes) are involved as MDA precursors in the TBA test. Pretreatment of plasma with KI, a specific reductant of hydroperoxides, decreased TBARS by about 27%. Moreover, aspirin administration to humans to inhibit prostaglandin endoperoxide generation reduced plasma TBARS by 40%. In conclusion, reaction conditions affect the relationship between TBA reactivity and lipid peroxidation in human plasma. After correction for the interfering effects of SA in the TBA test, 40% of plasma TBARS appears related to in vivo generated prostaglandin endoperoxides and only about 60% to lipoperoxidation products. Thus, the TBA test is not totally specific to oxidant-driven lipid peroxidation in human plasma.

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. DESIGN: A longitudinal study started in 1992 and completed in 1997. SETTING: Community-based, outpatient. PARTICIPANTS: 102 apparently healthy, community-dwelling subjects age 80 and older from the Vibrata valley, Teramo, Italy. MEASUREMENTS: Plasma vitamin E, beta-carotene, vitamin C, fluorescent products of lipid peroxidation (FPLPs), and serum lipids were determined at enrollment. RESULTS: Thirty-two cardiovascular events were recorded in 47.4 months of follow-up. The subjects with vitamin E levels in the highest quartile had a risk of cardiovascular events one-sixth those with vitamin E levels in the lowest quartile (relative risk (RR) = 0.16; 95% confidence interval (CI) = 0.04-0.55). The subjects with FPLPs in the highest quartile had a risk seven times greater than those with FPLPs in the lowest quartile (RR = 7.61; 95% CI = 2.23-25.96). No association was observed for vitamin C, beta-carotene, or total cholesterol. Multivariate adjustment for known risk factors did not significantly change the results. CONCLUSIONS: Our results suggest that in apparently healthy, community-dwelling very old subjects, base-line plasma concentration of vitamin E and FPLPs predicts the risk of future cardiovascular events. We confirm previous data showing that total cholesterol is not a predictor of cardiovascular disease in people age 80 and older.

Antioxidant activity of amiodarone on human lipoprotein oxidation.

Lipoprotein oxidation is crucial in atherogenic processes. Amiodarone is a lipophilic antiarrhythmic/antianginal drug which is able to influence the physicochemical status of biological lipid components. Since oxidation of lipids is affected by their physicochemical state and amiodarone binds to lipoproteins, we hypothesized that the drug may exert an antioxidant activity on human lipoprotein oxidation. Dose-dependent effects of therapeutically achievable amiodarone concentrations (1.5, 3, 5, 7 and 10 microM) were studied on copper-catalysed oxidation of the non-HDL fraction in vitro. Amiodarone inhibited oxidation as judged by generation of thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH) and fluorescent products of lipoperoxidation (FPL) as well as from the kinetics of conjugated diene formation. This antioxidant activity was significant at 1.5 microM with total inhibition at 10 microM and an IC(50) of 4 microM. The primary in vivo metabolite of amiodarone, namely desethylamiodarone, also exhibited specific antioxidant properties although it was less effective than amiodarone with an IC(50) of 7 microM. In further in vivo experiments, susceptibility to copper-mediated oxidation of the non-HDL fraction was investigated before and 4 weeks after oral amiodarone administration to humans. Following treatment, significant inhibition of TBARS, LOOH and FPL generation was observed in comparison with baseline levels and a placebo-treated control group, highlighting an effective antioxidant capacity of amiodarone in vivo. Amiodarone did not change lipoprotein vitamin E and phospholipid content in vivo and did not show scavenging effects on oxidizing species involved in lipoprotein oxidation, such as peroxyl radicals, nor metal-binding/inactivating properties, suggesting that physicochemical modifications of lipoprotein lipids induced by the lipophilic drug may be involved in its antioxidant activity. In conclusion, amiodarone, and its primary metabolite desethylamiodarone, show previously unrecognized antioxidant activity on human lipoprotein oxidation. This effect is also evident in vivo and at therapeutically achievable drug concentrations. Thus, amiodarone may act as an antioxidant/antiatherosclerotic agent in humans, although this issue warrants further clinical study.

Elevated circulating levels of monocyte chemoattractant protein-1 in patients with restenosis after coronary angioplasty.

Inflammation plays a pathogenic role in the development of restenosis after percutaneous transluminal coronary angioplasty (PTCA). Monocyte chemoattractant protein-1 (MCP-1) is a potent chemoattractant of monocytes; however, its role in the pathophysiology of restenosis is still unclear. We set out to investigate the role of MCP-1 in restenosis after PTCA. In addition, we tested the hypothesis that MCP-1 exerts its effect, at least in part, by inducing O(2)(-) generation in circulating monocytes. Plasma levels of MCP-1 were measured before and 1, 5, 15, and 180 days after PTCA in 50 patients (30 males and 20 females, aged 62+/-5 years) who underwent PTCA and who had repeated angiograms at 6-month follow-up. Restenosis occurred in 14 (28%) patients. The MCP-1 level was no different at baseline between patients with or without restenosis. However, after the procedure, restenotic patients, compared with nonrestenotic patients, had statistically significant (P<0.0001) elevated levels of MCP-1. In contrast, plasma levels of other chemokines, such as RANTES and interleukin-8, did not differ between the 2 groups after PTCA. Higher MCP-1 throughout the study was correlated with restenosis. Moreover, increased MCP-1 was significantly correlated with increased monocyte activity, as reflected by enhanced O(2)(-) generation. Finally, multivariate regression analysis showed that the MCP-1 plasma level measured 15 days after PTCA was the only statistically significant independent predictor of restenosis (beta=0.688, P<0.0001). This study suggests that MCP-1 production and macrophage accumulation in the balloon-injured vessel may play a pivotal role in restenosis after PTCA. MCP-1 may induce luminal renarrowing, at least in part, by inducing O(2)(-) release in monocytes. Further understanding of the mechanism(s) by which MCP-1 is produced and acts after arterial injury may provide insight into therapies to limit the progression of atherosclerosis and restenosis after balloon angioplasty.