Tehran University Medical Journal

Background: Ureteral obstruction, leading to urinary stasis and elevated pressure in the proximal part of urinary tract, causes progressive renal dysfunction. This study was designed to evaluate the status of oxidative stress and metabolic defect in acute unilateral ureteral obstruction (UUO).

Methods: Experiments were performed on three groups of male Sprague-Dawley rats (n=10 in each group). In the UUO group, rats were lightly anesthetized by ether and the left ureter was occluded by means of a sterile surgical procedure. Twenty-four hours after UUO-induction, both kidneys were removed and stored at -70 °C. In the sham group, anesthesia and surgery were performed without ureteral occlusion, and the control group received no surgical procedure. The kidney samples were assessed to measure the levels of ATP and ADP by the luciferin-luciferase method for determining metabolic status. In addition, the levels of malondialdehyde (MDA) and ferric reducing/antioxidant power (FRAP) of the kidneys were measured to evaluate the redox state. Data are expressed as means ±SEM per gram of kidney weight (gKW). The comparisons were performed using paired t-test for intra-group analysis, and ANOVA followed by Duncan's post-hoc test and then LSD test for inter-group analysis. Significance was taken at p<0.05.

Results: The comparisons between the UUO and sham groups indicated that 24 hours of UUO increased levels of MDA (51.42±1.86 vs. 38.64±1.02 nmol/gKW, respectively p<0.001) and ADP (0.67±0.04 vs. 0.47±0.045 µmol/gKW, respectively p<0.01), but decreased levels of FRAP (2.44±0.18 vs. 4.28±0.27 µmol/gKW, respectively), ATP (1.09±0.10 vs. 2.26±0.19 µmol/gKW, respectively) and ATP/ADP ratio (1.64±0.14 vs. 5.11±0.56, respectively) in the obstructed kidneys, all p<0.001. In the non-obstructed kidneys, the levels of ATP and ADP were higher (p<0.01 and p<0.001, respectively), while the levels of MDA and ATP/ADP ratio were equal to those of the sham group.

Conclusion: Twenty-four hours of acute UUO induces oxidative stress and reduces the aerobic metabolism in obstructed kidneys, whereas non-obstructed kidneys with a normal redox state show the higher levels of metabolism.

Background: Finding an acute brain lesion by diffusion-weighted (DW) MRI upon an episode of transient ischemic attack (TIA) is a predictor of imminent stroke in the near future. Therefore, exploring risk factors associated with lesions in DW-MRI of the brain is important in adopting an approach to TIA management. In the current study, we tried to determine the risk factors associated with lesions in DW-MRI of the brain in patients experiencing TIA episodes.
Methods: Fifty patients with TIA were recruited consecutively in Sina Hospital, Tehran, Iran, over a 6-month period between July 2008 and January 2009. All of the patients underwent a complete neurological examination and laboratory tests. Brain DW-MRIs were performed for all the patients within 72 hours of a TIA episode.
Results: DW-MRI revealed an acute lesion in 16% of the participants. There was a significant correlation between presence of an acute lesion in DW-MRI and TIA duration, history of diabetes mellitus and presence of unilateral facial palsy (P=0.0003, P=0.02 and P=0.008, respectively). Other variables such as age, hypertension, hyperlipidemia, past history of TIA, headache, vertigo, and sensory or visual disturbances had no significant relation with the presence of an acute lesion in DW-MRI.
Conclusion: Duration of TIA, presence of diabetes mellitus and unilateral facial palsy are risk factors for an acute lesion in DW-MRI, meaning that patients with such risk factors are at risk for stroke in the near future.