The Activities of Paraoxonase, Xanthine Oxidase, Adenosine Deaminase and the Level of Nitrite in Pseudoexfoliation Syndrome

Abstract

Aim: Our purpose was to investigate the possible roles of nitrite levels and the activity of paraoxonase (PON), xanthine oxidase (XO) and adenosine deaminase (ADA) in the pathogenesis of pseudoexfoliation (PEX) syndrome. Methods: Serum samples were taken from 43 patients with PEX and 41 control subjects. The serum PON, XO and ADA activities and nitrite levels were assayed by spectrophotometric methods. Results: The PON, ADA and XO activities and nitrite levels (means ± standard deviation) were 81.72 ± 42.56 U/ml, 19.75 ± 5.72 U/l, 0.16 ± 0.09 U/l and 94.23 ± 27.72 μmol/l in the PEX group, respectively. In the control group, the PON, ADA and XO activities and the nitrite levels were 111.02 ± 43.51 U/ml, 15.21 ± 3.93 U/l, 0.13 ± 0.06 U/l and 61.96 ± 19.05 μmol/l, respectively. The serum PON activity was significantly lower in the PEX group when compared with the control group. The serum XO and ADA activities and nitrite levels were significantly higher in the patients with PEX when compared with the control subjects. Conclusion: Decreased PON (an antioxidant enzyme) activity as well as increased ADA and XO activities and nitrite levels indicate that oxidative stress is increased and purine metabolism is altered in PEX syndrome.

Serum and aqueous xanthine oxidase levels, and mRNA expression in anterior lens epithelial cells in pseudoexfoliation

“…Sex was shown to affect XO, although it is still controversial [24][25][26][27]. One of the possible reasons for the contradictory result can be the gender distribution among test groups which was not stated by Yagci et al [4]. In our study, distribution of sex in the PEX and normal groups was the same (Table 2).…”

“…Because PEX is SD standard deviation, n/a not applicable, BUN blood urea nitrogen, AST aspartate aminotransferase, ALT alanine aminotransferase, WBC white blood cell, HGB hemoglobin, HCT hemotocrit, PLT platelet, APTT active parsiel prothrombin time, PT prothrombin time, INR international normalized ratio known as a systemic disease, we decided to determine serum XO levels of PEX. In this study, we found that serum levels of XO in subjects with PEX were not different than a normal group (Table 3), although higher serum XO in PEX was reported by Yagci et al [4]. We used a colorimetric method for quantification of serum and aqueous XO, while Yagci used a spectrophotometric method [23].…”

“…In addition to its occurrence within the eye, fibrillary material is found in different parts of the body, including the heart, lungs, liver and spleen [2], which suggests PEX is an ocular manifestation of a systemic disease. Although the pathogenesis of PEX, an age-related disorder, has not been fully clarified, there is increasing evidence that oxidative stress plays an important role in the pathogenesis of PEX [3][4][5].…”

“…During inflammatory conditions and hypoxia [12,13], XDH is converted to xanthine oxidase (XO), which catalyzes two consecutive reactions at the end of purine metabolism, from which the end product is uric acid with superoxide (O 2 − ) and hydrogen peroxide (H 2 O 2 ). XO, which can serve as an important source of reactive oxygen species (ROS), was shown to be decreased in the serum of patients with PEX [4]. Although anterior chamber hypoxia was reported in PEX [14], aqueous levels of XO have not yet been reported.…”

“…Although serum XO levels in PEX were shown to be increased [4], XO levels and mRNA expression in the aqueous and anterior lens capsule, where the clinical manifestations of PEX are mostly represented, have not yet been studied. In this study, we analyzed serum and aqueous levels of XO, and mRNA expression in the anterior lens capsule in order to identify the possible role of XO, an ROS-producing enzyme, in PEX, which can be a step in understanding the pathogenesis of the syndrome.…”