Association between 4-year all-cause mortality and carnitine profile in maintenance hemodialysis patients.

BACKGROUND:Patients on dialysis are in a chronic carnitine-deficient state. This condition may be associated with abnormalities of the fatty acid and organic acid metabolisms. Carnitine is required for β-oxidation of the long-chain fatty acids; therefore, carnitine deficiency decreases the efficiency of ATP synthesis and may incur death. However, the details of this association remain unknown. We examined the relationship between β-oxidation efficiency represented by the carnitine profile and 4-year all-cause mortality in hemodialysis patients. METHODS:The carnitine profiles of 122 hemodialysis patients were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The associations between the 4-year all-cause mortality and carnitine profile as well as the clinical backgrounds of the patients were investigated. A survival analysis was conducted by the Kaplan-Meier survival method and multivariable Cox proportional hazard analysis. The bootstrap method was performed to confirm the stability and robustness of our model. RESULTS:Of the 122 subjects analyzed, 111 were selected and 24 died during the observation period. Stepwise multivariable Cox regression demonstrated that diabetes state [Hazard ratio (95% confidence interval), 4.981 (2.107-11.77)], age [HR (95% CI), 1.052 (1.014-1.091)], and the acetylcarnitine/(palmitoylcarnitine+octadecenoylcarnitine) [C2/(C16+C18:1)] ratio [HR (95% CI), 0.937 (0.904-0.971)] were independent significant factors of 4-year all-cause mortality. The bootstrap method confirmed the significance of these three factors. CONCLUSION:The 4-year all-cause mortality negatively correlated with the C2/(C16+C18:1) ratio. Improvement of the impaired β-oxidation state after L-carnitine administration may ameliorate prognosis

Comparison between liquid chromatography/tandem mass spectroscopy and a novel latex agglutination method for measurement of hepcidin-25 concentrations in dialysis patients with renal anemia: A multicenter study

Background and aims: Hepcidin-25 is an iron regulatory factor that plays an important role in anemia in patients with chronic kidney disease. Although liquid chromatography/tandem mass spectroscopy (LC-MS/MS) is the gold standard for measuring hepcidin-25 concentrations, results cannot be obtained immediately at clinical sites. In contrast, the latex immunoassay (LIA) can be performed using general clinical laboratory equipment, and the results can be obtained quickly. The aim of this study was to evaluate hepcidin-25 concentrations obtained by LC-MS/MS and a novel LIA method and compare the two methods. Materials and methods: Hepcidin-25 was measured by LIA and LC-MS/MS in 182 hemodialysis patients. A hepcidin-25-specific reagent and an automatic analyzer were used for LIA, and a commercially available system was used for LC-MS/MS. The Passing-Bablok regression analysis method was used. Results: On Passing-Bablok regression analysis, the slope was 1.000, with an intercept of 0.359. Very strong associations were obtained, and the measured values were almost identical. Conclusion: The hepcidin-25 concentrations measured using LIA and those measured by LC-MS/MS were significantly correlated. LIA can be performed using general clinical examination equipment and has a higher throughput than LC-MS/MS. Therefore, measurement of hepcidin-25 concentrations by LIA can be useful for routine laboratory testing

Creation of a Binuclear Purple Copper Site within a <i>de Novo</i> Coiled-Coil Protein

Although various kinds of metal binding proteins have been constructed by <i>de novo</i> design, the creation of a binuclear metal binding site remains especially challenging. The purple copper site in subunit II of COX, referred to as the Cu_A site, has two copper ions bridged by two Cys residues. We constructed the Cu_A site consisting of two Cys and two His residues in a <i>de novo</i> designed four-helical coiled-coil protein. The protein bound two copper ions and exhibited a purple color, with relatively intense absorption bands at 488 and 530 nm in the UV–vis spectrum. The EPR spectrum displayed unresolved hyperfine splittings in the <i>g</i>_∥ region, which was similar to the native or engineered Cu_A site with an <i>A</i>_∼480/<i>A</i>_∼530 > 1. The extended X-ray absorption structure analyses of the protein revealed the presence of the Cu₂S₂ core structure, with two typical N­(His)–Cu bonds per core at 1.90 Å, two S (Cys)–Cu bonds at 2.21 Å, and the Cu–Cu bond at 2.51 Å, which are also characteristic structures of a purple copper site