In fact, MDA showed significant positive associations with plasma glucose only, as well as MPO and hypertension. == Table 6. in the entire population (R2=0.086;P=0.02). In HF patients only, 4HNE-P was even more strongly associated with LA (P=0.003) and HDL-cholesterol (p<0.0002). Our results demonstrate that 4HNE-P levels, expressed relative to HDL-cholesterol, increase as HDL-cholesterol plasma levels decrease in the HF group only. == Conclusion == Results from this study emphasize the importance of considering changes in lipids and lipoproteins in the interpretation of measurements of lipid peroxidation products. Further studies appear warranted to explore the possibility that HDL-cholesterol particles may be a carrier of 4HNE adducts. Abbreviations:4HNE, 4-hydroxynonenal; 4HNE-P, 4-hydroxynonenal bound to circulating thiol proteins; AA, arachidonic acid; CRP, C-reactive protein; DHA, docosahexanaenoic acid; eGFR, estimated glomerular filtration rate; EPA, eicosapentaenoic acid; GSH, reduced glutathione; GSSG, oxidized glutathione; HF, heart failure; HFC-MHI, heart failure clinic of the Montreal Heart Institute; HOMA-IR, homeostatic model assessment of insulin resistance; LA, linoleic acid; MDA, malondialdehyde; MPO, myeloperoxidase; NT-pro-BNP, N-terminal proB-type natriuretic peptide; NYHA, New York Heart Association; PUFA, polyunsaturated fatty acids; RAS, renin-angiotensin system; TBARS, thiobarbituric acid-reactive substances; TNF, tumor necrosis factor Keywords:4-Hydroxynnonenal, Oxidative stress, FR901464 Lipid peroxidation, Linoleic acid, Polyunsaturated fatty acids, Heart failure patients == Graphical abstract == == Highlights == Peroxidation ofn-6polyunsaturated fatty acids (PUFA) forms 4-hydroxynonenal (4HNE). Heart failure (HF) patients have lower plasma levels ofn-6 PUFA linoleic acid (LA). Blood levels of FR901464 4HNE bound to proteins (4HNE-P) in HF patients are similar to controls. 4HNE-P levels are associated with those of LA in the entire population (p<0.02). 4HNE-P levels are strongly associated with LA and HDL-cholesterol in HF patients. == Introduction == While considerable evidence supports the role of oxidative stress in the development and progression of chronic diseases such as heart failure (HF)[1],[2],[3],[4], clinical trials with natural antioxidant interventions conducted in the last two decades have yielded controversial results[5],[6],[7],[8],[9]. However, until 2000, the few clinical studies that documented circulating biomarkers of oxidative stress predominantly measured the plasma level of malondialdehyde Itgb8 (MDA) using the highly criticized thiobarbituric acid-reactive substances (TBARS) method without chromatographic separation[3],[10],[11],[12],[13]. More recently, urinary and plasma isoprostanes, which arise from the peroxidation of then-6polyunsaturated fatty acid (PUFA) arachidonic acid (AA), have been FR901464 advocated for the in vivo assessment of oxidative stress status for human studies[14],[15],[16]. However, it appears unlikely that the measurement of a single biomarker will provide a comprehensive picture of the various oxidative stress-related events that may contribute to progression of cardiovascular diseases[17]. Another peroxidation product of then-6PUFAs AA and linoleic acid (LA) that has generated considerable research interest for its potential as a biomarker of oxidative stress is 4-hydroxynonenal (4HNE)[18]. This aldehyde readily binds covalently to nucleophilic residues of proteins, peptides, phospholipids, and nucleic acids and thereby exhibits cytotoxic effects. 4HNE can also modulate signaling pathways involved in cell proliferation, fibrosis, apoptosis and inflammation, which are all hallmarks of cardiovascular diseases, especially HF[19],[20],[21]. Interestingly, Nakamura et al. showed that the myocardial levels of protein-bound 4HNE were decreased after treatment with carvedilol in patients with HF[22], and were also correlated with left ventricular dilatation and systolic dysfunction in patients with hypertrophic cardiomyopathy[23]. Recently, we developed and validated a method using gas chromatography-mass spectrometry to quantify, with precision, blood levels of total protein-bound 4HNE thioether adducts (4HNE-P)[24]. Using this method, we reported a higher accumulation of blood 4HNE-P in spontaneously hypertensive rats than in normal rats, which correlated FR901464 positively with left ventricular diastolic dysfunction[24],[25], and in hypercholesterolemic rabbits[26]. These findings support a role for.