Ken Okamoto

Learn More
Uridine-diphosphate glucuronosyltransferase 1A (UGT1A) is a key enzyme involved in irinotecan metabolism, and polymorphisms in the UGT1A gene are associated with irinotecan-induced toxicity. The aim of this study was to elucidate the allele frequencies of UGT1A polymorphisms in healthy Uzbek volunteers, and to compare them with those of the Japanese(More)
Xanthine oxidoreductase (XOR), which is widely distributed from humans to bacteria, has a key role in purine catabolism, catalyzing two steps of sequential hydroxylation from hypoxanthine to xanthine and from xanthine to urate at its molybdenum cofactor (Moco). Human XOR is considered to be a target of drugs not only for therapy of hyperuricemia and gout,(More)
Xanthine oxidoreductase (XOR), a complex flavoprotein, catalyzes the metabolic reactions leading from hypoxanthine to xanthine and from xanthine to urate, and both reactions take place at the molybdenum cofactor. The enzyme is a target of drugs for therapy of gout or hyperuricemia. We review the chemical nature and reaction mechanisms of the molybdenum(More)
Febuxostat, a drug recently approved in the US, European Union and Japan for treatment of gout, inhibits xanthine oxidoreductase (XOR)-mediated generation of uric acid during purine catabolism. It inhibits bovine milk XOR with a K(i) in the picomolar-order, but we found that it is a much weaker inhibitor of Rhodobacter capsulatus XOR, even though the(More)
Xanthine oxidoreductase (XOR) catalyzes the conversion of hypoxanthine to xanthine and xanthine to uric acid with concomitant reduction of either NAD+ or O(2). The enzyme is a target of drugs to treat hyperuricemia, gout and reactive oxygen-related diseases. Human diseases associated with genetically determined dysfunction of XOR are termed xanthinuria,(More)
Global cerebral ischemia and reperfusion (I/R) often result in high mortality. Free radicals play an important role in global cerebral I/R. Xanthine oxidoreductase (XOR) inhibitors, such as allopurinol, have been reported to protect tissues from damage caused by reactive oxygen species (ROS) by inhibiting its production through XOR inhibition. The recently(More)
AIM To determine the distance between the branching point of the left colic artery (LCA) and the inferior mesenteric artery (IMA) by computed tomography (CT) scanning, for preoperative evaluation before laparoscopic colorectal operation. METHODS From February 2004 to May 2005, 100 patients (63 men, 37 women) underwent angiography performed with a(More)
BACKGROUND Aortic valve surgery in patients with severely calcified aortas is technically challenging. Additionally, the choice of arterial cannulation site and whether to perform an aortic clamp to prevent neurological complications are poorly defined. CASE PRESENTATION We describe a patient with a severely calcified aorta and stenosis of its side(More)
We demonstrated that 3-nitrotyrosine and 4-hydroxy-2-nonenal levels in mouse brain were elevated from 1 h until 8 h after global brain ischemia for 14 min induced with the 3-vessel occlusion model; this result indicates that ischemia reperfusion injury generated oxidative stress. Reactive oxygen species production was observed not only in the hippocampal(More)