A pilot assessment of xanthine oxidase activity in plasma from patients with hematological malignancies using a highly sensitive assay

Xanthine oxidase (XO) is a rate limiting enzyme for production of uric acid. The activity of XO in plasma is reported to elevate in patients with familial hypercholesterolaemia and cardiovascular diseases. Such an increase in plasma XO activity was also demonstrated in patients with a variety of cancers. However, there have been few reports evaluating the plasma XO activity in patients with hematological malignancies during course of allogeneic hematopoietic stem cell transplantation (allo-HSCT) and chemotherapies. We explored the relationship between plasma XO activity and clinical symptoms/biochemical parameters in 10 patients with hematological malignancies. The XO activity was measured by a highsensitivity fluorescence technique. Plasma XO activity in hematological malignancies before chemotherapy was not elevated compared to healthy subjects. In patients receiving allo-HSCT, no apparent increase in plasma XO activity was observed at the appearance of graft-versus-host disease (GVHD). Noticeably, however, the value of plasma XO activity was closely associated with that of serum level of liver transaminases in the course of allo-HSCT and chemotherapies. To our knowledge, the present study is the first to investigate consecutively the value in plasma XO activity in patients with hematological malignancies. Despite small numbers analyzed, value of plasma XO activity was tightly associated with that of serum level of liver transaminases in the course of allo-HSCT and chemotherapies, suggesting that the value may reflect liver damage related with a variety of therapeutic interventions.博士(医学)琉球大

Activity of xanthine oxidase in plasma correlates with indices of insulin resistance and liver dysfunction in patients with type 2 diabetes mellitus and metabolic syndrome: A pilot exploratory study

Abstract Aims/Introduction There is controversy as to whether hyperuricemia is an independent risk factor for cardiometabolic diseases. The serum level of uric acid is affected by a wide variety of factors involved in its production and excretion. In contrast, evidence has accumulated that locally‐ and systemically‐activated xanthine oxidase (XO), a rate‐limiting enzyme for production of uric acid, is linked to metabolic derangement in humans and rodents. We therefore explored the clinical implication of plasma XO activity in patients with type 2 diabetes mellitus and metabolic syndrome (MetS). Materials and Methods We enrolled 60 patients with type 2 diabetes mellitus and MetS. MetS was defined according to the 2005 International Diabetes Federation guidelines. Plasma XO activity was measured by highly‐sensitive fluorometric assay measuring the conversion of pterin to isoxanthopterin, and explored associations between the value of plasma XO activity and metabolic parameters. Results The value of plasma XO activity was correlated with indices of insulin resistance and the level of circulating liver transaminases. In contrast, the level of serum uric acid was not correlated with indices of insulin resistance. The value of plasma XO activity was not correlated with the serum uric acid level. Conclusions Plasma XO activity correlates with indices of insulin resistance and liver dysfunction in Japanese patients with type 2 diabetes mellitus and MetS. Through assessing the plasma XO activity, patients showing normal levels of serum uric acid with higher activity of XO can be screened, thereby possibly providing a clue to uncovering metabolic risks in type 2 diabetes mellitus and MetS patients