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Relationship between an increased serum kynurenine/tryptophan ratio and atherosclerotic parameters in hemodialysis patients
Author(s) -
KATO Akihiko,
SUZUKI Yuzo,
SUDA Takafumi,
SUZUKI Masako,
FUJIE Michio,
TAKITA Takako,
FURUHASHI Mitsuyoshi,
MARUYAMA Yukitaka,
CHIDA Kingo,
HISHIDA Akira
Publication year - 2010
Publication title -
hemodialysis international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.658
H-Index - 47
eISSN - 1542-4758
pISSN - 1492-7535
DOI - 10.1111/j.1542-4758.2010.00464.x
Subject(s) - kynurenine , quartile , medicine , tryptophan , endocrinology , common carotid artery , hemodialysis , body mass index , carotid arteries , chemistry , biochemistry , amino acid , confidence interval
Essential amino acid tryptophan (Trp) is mainly catabolized by indoleamine 2,3‐dioxygenase, which leads to the formation of kynurenine (Kyn). In this study, we reexamined whether an increased indoleamine 2,3‐dioxygenase activity, as estimated by the Kyn/Trp ratio (μM/mM), is associated with atherosclerotic parameters in hemodialysis (HD) patients. Serum Trp and Kyn were measured in 243 HD patients by liquid chromatography/electrospray ionization tandem mass spectrometry. We measured carotid artery intima‐medial thickness, brachial‐ankle pulse wave velocity, ankle‐brachial pressure index, and the cardio‐ankle vascular index. Log‐transformed Kyn/Trp ratio was significantly correlated with log‐transformed time on HD (ρ=0.28, P<0.01), log‐transformed highly sensitive C‐reactive protein (ρ=0.20, P<0.01), and peripheral total lymphocyte count (ρ=−0.13, P<0.05). A significant association was found between log‐transformed Kyn/Trp ratio and mean carotid artery intima‐medial thickness (ρ=0.18, P<0.01). Mean carotid artery intima‐medial thickness was significantly higher in the lowest quartile of Kyn/Trp ratio (<165) (0.62±0.12 mm) when compared with the highest quartile (≥304) (0.68±0.15 mm) (P<0.01). Ankle‐brachial pressure index was lower in the second quartile (1.01±0.20), the third quartile (1.01±0.19), and the fourth quartile (1.03±0.15) compared with that in the first quartile (1.09±0.13) (P<0.05). It follows from these findings that the Kyn/Trp ratio increases with time on HD, and is associated with advanced atherosclerotic changes in chronic HD patients.