Renal tubular function and urinary N-acetyl-ß-d-glucosaminidase and kidney injury molecule-1 levels in asthmatic children.

BACKGROUND: Asthma is a chronic inflammatory disorder of the airways which results in chronic hypoxia. Chronic hypoxia and inflammation can affect renal tubular function. OBJECTIVES: The aim of this study was to investigate renal tubular function and early kidney injury molecules such as urinary N-acetyl-betaglucosaminidase (NAG) and kidney injury molecule-1 (KIM-1) excretion in children with asthma. METHODS: Enrolled in the study were 73 children diagnosed with asthma and 65 healthy age- and gender-matched control subjects. Urine pH, sodium, phosphorus, potassium, microalbumin, creatinine, NAG, KIM-1, and serum creatinine, sodium, phosphorus were evaluated. The diagnosis of asthma and classification of mild or moderate were done according to the Global Initiative for Asthma guidelines. RESULTS: Serum sodium, phosphorus, creatinine, and urinary microalbumin were within normal levels in the both groups. Urinary pH, sodium, potassium, phosphorus, microalbumin, and KIM-1 excretions were similar between the control and study groups. Tubular phosphorus reabsorption was within normal limits in two groups. Urine NAG was elevated in the study group (P = 0.001). Urinary KIM-1 and NAG levels were positively correlated (r = 0.837; P = 0.001). When children with mild and moderate asthma were compared, all of the parameters were similar (P >0.05). CONCLUSIONS: This study showed that chronic asthma can lead to subtle renal impacts. We suggest that in children with asthma, urinary NAG level is a more valuable parameter to show degree of renal tubular injury than markers such as microalbumin and KIM-1. Chronic hypoxy and inflammation probably contributes to these subclinical renal effects.

A novel antioxidant agent caffeic acid phenethyl ester prevents long-term mobile phone exposure-induced renal impairment in rat. Prognostic value of malondialdehyde, N-acetyl-beta-D-glucosaminidase and nitric oxide determination.

Caffeic acid phenethyl ester (CAPE), a flavonoid like compound, is one of the major components of honeybee propolis. It has been used in folk medicine for many years in Middle East countries. It was found to be a potent free radical scavenger and antioxidant recently. The aim of this study was to examine long-term applied 900 MHz emitting mobile phone-induced oxidative stress that promotes production of reactive oxygen species (ROS) and, was to investigate the role of CAPE on kidney tissue against the possible electromagnetic radiation (EMR)-induced renal impairment in rats. In particular, the ROS such as superoxide and nitric oxide (NO) may contribute to the pathophysiology of EMR-induced renal impairment. Malondialdehyde (MDA, an index of lipid peroxidation) levels, urinary N-acetyl-beta-D-glucosaminidase (NAG, a marker of renal tubular injury) and nitric oxide (NO, an oxidant product) levels were used as markers of oxidative stress-induced renal impairment and the success of CAPE treatment. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in renal tissue were determined to evaluate the changes of antioxidant status. The rats used in the study were randomly grouped (10 each) as follows: i) Control group (without stress and EMR), ii) Sham-operated rats stayed without exposure to EMR (exposure device off), iii) Rats exposed to 900 MHz EMR (EMR group), and iv) A 900 MHz EMR exposed + CAPE treated group (EMR + CAPE group). In the EMR exposed group, while tissue MDA, NO levels and urinary NAG levels increased (p < 0.0001), the activities of SOD, CAT, and GSH-Px in renal tissue were reduced (p < 0.001). CAPE treatment reversed these effects as well (p < 0.0001, p < 0.001 respectively). In conclusion, the increase in NO and MDA levels of renal tissue, and in urinary NAG with the decrease in renal SOD, CAT, GSH-Px activities demonstrate the role of oxidative mechanisms in 900 MHz mobile phone-induced renal tissue damage, and CAPE, via its free radical scavenging and antioxidant properties, ameliorates oxidative renal damage. These results strongly suggest that CAPE exhibits a protective effect on mobile phone-induced and free radical mediated oxidative renal impairment in rats.