[Show abstract][Hide abstract] ABSTRACT: Contrast induced acute kidney injury is one of the most frequent causes of hospital acquired acute kidney injury. The present study aims to investigate the efficacy of vitamin E or N-acetylcysteine as an adjunct to current standard therapy in the prevention of this clinical predicament. We tested the hypothesis that vitamin E or N-acetylcysteine added to standard therapy with 0.45 % saline is superior in preserving renal function in patients with chronic kidney disease stage 1-4 undergoing elective computer-assisted tomography with nonionic radiocontrast agents when compared to 0.45 % saline alone.
Prospective, randomized, single-center, double-masked, double dummy, placebo-controlled, parallel clinical trial.
The patients were randomized to either vitamin E (total dose 2160 mg i.v.) or N-acetylcysteine (total dose 4800 mg p.o.) in addition to 0.45 % saline (1 mL/kg/h over 24 h) or saline alone. Serum creatinine change between baseline and 24 h after radiocontrast was the primary outcome. Contrast induced acute kidney injury was defined as a rise in serum creatinine > 25 % over the baseline value within 48 h.
Thirty patients (mean age 74.6 years; 17 females; 9 diabetics; all Caucasians; mean serum creatinine 1.35 mg/dL; mean creatinine clearance 56 mL/min) were enrolled. No patient developed contrast induced acute kidney injury. There was no significant difference in serum creatinine change between the three study arms.
Following radiocontrast administration, neither vitamin E nor N-acetylcystein in addition to saline demonstrated an additional beneficial effect on kidney function when compared to saline alone.
No preview · Article · Apr 2012 · Wiener klinische Wochenschrift
[Show abstract][Hide abstract] ABSTRACT: Expression and activation of the Ste20-like kinase, SLK, is increased during kidney development and recovery from ischemic acute kidney injury. SLK promotes apoptosis, and it may regulate cell survival during injury or repair. This study addresses the role of phosphorylation in the regulation of kinase activity. We mutated serine and threonine residues in the putative activation segment of the SLK catalytic domain and expressed wild type (WT) and mutant proteins in COS-1 or glomerular epithelial cells. Compared with SLK WT, the T183A, S189A, and T183A/S189A mutants showed reduced in vitro kinase activity. SLK WT, but not mutants, increased activation-specific phosphorylation of c-Jun N-terminal kinase (JNK) and p38 kinase. Similarly, SLK WT stimulated activator protein-1 reporter activity, but activation of activator protein-1 by the three SLK mutants was ineffective. To test if homodimerization of SLK affects phosphorylation, the cDNA encoding SLK amino acids 1-373 (which include the catalytic domain) was fused with a cDNA for a modified FK506-binding protein, Fv (Fv-SLK 1-373). After transfection, the addition of AP20187 (an FK506 analog) induced regulated dimerization of Fv-SLK 1-373. AP20187-stimulated dimerization enhanced the kinase activity of Fv-SLK 1-373 WT. In contrast, kinase activity of Fv-SLK 1-373 T183A/S189A was weak and was not enhanced after dimerization. Finally, apoptosis was increased after expression of Fv-SLK 1-373 WT but not T183A/S189A. Thus, phosphorylation of Thr-183 and Ser-189 plays a key role in the activation and signaling of SLK and could represent a target for novel therapeutic approaches to renal injury.
Preview · Article · Dec 2011 · Journal of Biological Chemistry