Background: Xanthine oxidoreductase (XOR) is a rate-limiting enzyme for uric acid (UA) production and plays an important role in generating reactive oxygen species (ROS). Overproduction of ROS is reported to contribute to the pathophysiology of atrial fibrillation (AF), however, the prognostic impact of plasma XOR activity in patients with heart failure (HF) with AF is undetermined.
Methods: We measured plasma XOR activity in 475 HF patients, including those with sinus rhythm (HF-SR, n = 211), and those with AF (HF-AF, n = 264). The type of AF included paroxysmal (n = 128) and persistent (n = 136) AF. All patients were prospectively followed up for a median period of 804 days.
Results: HF-AF patients had significantly higher plasma XOR activity and serum UA levels compared with HF-SR patients. Both plasma XOR activity and serum UA levels were higher in patients with persistent AF than in those with SR and with paroxysmal AF. Multivariate linear regression analysis showed that persistent AF was independently associated with increased XOR activity. During the follow-up period, there were 79 major adverse cardiovascular events (MACEs). HF-AF patients with MACEs had higher plasma XOR activity compared with those without MACEs, while there were no significant differences in serum UA levels. Multivariate Cox proportional analysis showed that high XOR activity was an independent risk factor for MACEs after adjustment for confounding factors. Kaplan-Meier analysis revealed that the high XOR activity group had a higher risk of MACEs than the low XOR activity group. The prediction model was significantly improved by the addition of XOR activity to the basic predictors.
Conclusions: HF-AF patients had significantly higher plasma XOR activity compared with HF-SR patients. Plasma XOR activity proved to be a reliable indicator for MACEs in HF-AF patients.
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http://dx.doi.org/10.1016/j.jjcc.2023.02.003 | DOI Listing |
Free Radic Biol Med
February 2025
Although the relative extent of xanthine oxidoreductase (XOR) varies considerably in human tissues, the greatest specific activity is reported in the liver and intestines. Unlike murine models, where primary hepatocytes are readily available, human counterparts are not. As such, investigators often utilize the human carcinoma cell line HepG2 for in vitro experimentation as these cells proliferate well in culture medium.
View Article and Find Full Text PDFPhys Rev E
December 2024
Lawrence Berkeley National Laboratory, Molecular Foundry, 1 Cyclotron Road, Berkeley, California 94720, USA.
We show that the time-resolved dynamics of an underdamped harmonic oscillator can be used to do multifunctional computation, performing distinct computations at distinct times within a single dynamical trajectory. We consider the amplitude of an oscillator whose inputs influence its frequency. The activity of the oscillator at fixed times is a nonmonotonic function of its inputs, so it can solve problems such as XOR that are not linearly separable.
View Article and Find Full Text PDFArterioscler Thromb Vasc Biol
March 2025
Department of Cardiovascular Medicine (H. Yagi, H.A., Q.L., A.S.-K., M.U., H.K., R.M., A.S., S.O., H.T., Norifumi Takeda, I.K.), The University of Tokyo, Bunkyo-ku, Japan.
Background: Marfan syndrome (MFS) is an inherited disorder caused by mutations in the gene encoding fibrillin-1, a matrix component of extracellular microfibrils. The main cause of morbidity and mortality in MFS is thoracic aortic aneurysm and dissection, but the underlying mechanisms remain undetermined.
Methods: To elucidate the role of endothelial XOR (xanthine oxidoreductase)-derived reactive oxygen species in aortic aneurysm progression, we inhibited in vivo function of XOR either by endothelial cell (EC)-specific disruption of the gene or by systemic administration of an XOR inhibitor febuxostat in MFS mice harboring the missense mutation p.
Biochim Biophys Acta Mol Cell Res
January 2025
School of Natural Sciences, Laurentian University, Sudbury, Canada; Cardiovascular and Metabolic Research Unit, Laurentian University, Sudbury, Canada. Electronic address:
Hydrogen sulfide (HS) is an important gasotransmitter that regulates a wide range of pathophysiological processes. Higher uric acid levels are associated with an increased risk of metabolic diseases. The causal mechanism linking HS signalling and uric acid metabolism in skeletal muscles has not yet been elucidated.
View Article and Find Full Text PDFAntioxidants (Basel)
November 2024
Barts & The London Faculty of Medicine & Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK.
The majority of naturally occurring mutations of the human gene , are associated with reduced or completely absent xanthine oxidoreductase (XOR) activity, leading to a disease known as classical xanthinuria, which is due to the accumulation and excretion of xanthine in urine. Three types of classical xanthinuria have been identified: type I, characterised by XOR deficiency, type II, caused by XOR and aldehyde oxidase (AO) deficiency, and type III due to XOR, AO, and sulphite oxidase (SO) deficiency. Type I and II are considered rare autosomal recessive disorders, a condition where two copies of the mutated gene must be present to develop the disease or trait.
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