Indomethacin corrects alterations associated with ischemia/reperfusion in an in vitro proximal tubular model.

BACKGROUND/AIMS: Recent in vivo data indicate that indomethacin improves renal outcome after ischemia via improvement of renal cell survival and function. To examine direct effects of indomethacin on isolated proximal tubular cells, we investigated the influence of indomethacin on markers of ischemia/reperfusion (I/R) damage in an established in vitro model of ischemia and reperfusion. METHODS: Ischemia was applied for 2 h followed by reperfusion for up to 48 h. Indomethacin was added at the beginning of reperfusion. Parameters were investigated after 6, 24 or 48 h of reperfusion. RESULTS: Indomethacin diminished cell death by necrosis and apoptosis, release of prostaglandin E2, induction of I/R-induced protein, dedifferentiation or induction of inducible nitric oxide synthase. Moreover, indomethacin totally prevented the ischemia-induced inhibition of basolateral organic anion transport. Indomethacin did not affect ischemia-mediated induction of nuclear factor-kappaB or monocyte chemoattractant protein 1. Ischemia did not induce matrix protein synthesis. CONCLUSIONS: We have shown that: (a) indomethacin applied after ischemia has a beneficial effect on proximal tubule cell survival after model ischemia and impairs changes of parameters characteristically induced by ischemia via direct action on proximal tubule cells; (b) the inflammatory response of proximal tubule cells was not affected by indomethacin, and (c) fibrosis does not take place after model ischemia in isolated proximal tubule cells.

Low-dose indomethacin after ischemic acute kidney injury prevents downregulation of Oat1/3 and improves renal outcome.

We have previously shown that expression of renal organic anion transporters Oat1 and Oat3 is diminished by prostaglandin E(2) (PGE(2)) and that both transporters are downregulated after renal ischemia. Because PGE(2) is increased after renal ischemia and is generated by cyclooxygenases (COX), we investigated the effect of the COX inhibitor indomethacin on expression of Oat1/3 after ischemic acute kidney injury (iAKI). iAKI was induced in rats by bilateral clamping of renal arteries for 45 min. Indomethacin (1 mg/kg) was given intraperitoneally as soon as reperfusion started. Sham-treated animals served as controls. Oat1/3 were determined by qPCR and Western blot. PGE(2) in blood and urine was measured by enzyme-linked immunosorbent assay. Invasion of monocytes/macrophages was determined. Glomerular filtration rate and renal plasma flow were determined. All parameters were detected 24 h after ischemia. PAH net secretion, as well as clearance and secretion of PGE(2) were calculated. In clamped animals, indomethacin restored expression of Oat1/3, as well as PAH net secretion, PGE(2) clearance, or PGE(2) secretion. Additionally, indomethacin substantially improved kidney function as measured by glomerular filtration and PAH clearance. Indomethacin did not affect ischemia-induced invasion of monocytes/macrophages. In conclusion, our study indicates that low-dose indomethacin applied after ischemia prevents ischemia-induced downregulation of Oat1/3 during reperfusion and has a substantial protective effect on kidney function after iAKI. The beneficial effect of low-dose indomethacin on renal outcome is likely due to an effect different from inhibition of inflammation. In accordance to the decreased PAH net secretion, renal excretion of an endogenous organic anion (PGE(2)) is also impaired after ischemia and reperfusion.

Structure of amorphous poly-(ethylmethacrylate): a wide-angle x-ray scattering study.

The local, temperature dependent structure of poly-(ethylmethacrylate) was studied with wide-angle x-ray scattering. The results were set into context to recent wide-angle neutron scattering results as well as to the results from a multitude of studies of the dynamics of this polymer. The temperature dependence of the wide angle x-ray results point to the development of local order which is backed by the neutron scattering results and which is connected to characteristic temperatures of the relaxation dynamic T(g) and T(c). The poly-(ethylmethacrylate) was studied in its predominantly syndiotactic as well as predominantly isotactic state displaying vastly different local structures as manifested in the x-ray results.

Synthesis of spherical porous silicas in the micron and submicron size range: challenges and opportunities for miniaturized high-resolution chromatographic and electrokinetic separations.

Classical silica technology has reached its limit with respect to an ultimate minimum particle size of about 2 microm in diameter. Here, a novel process is presented which allows one to synthesize porous silica beads and control their particle diameter in situ, within the range of 0.2-2.0 microm. As a result, no sizing is required and losses of silica are avoided. Furthermore, the process enables one to control in situ the pore structural parameters and the surface chemistry of the silica beads. Even though surface funtionalized silicas made according to this process can principally be applied in fast HPLC the column pressure drop will be high even for short columns. In addition, the column efficiency, expressed in terms of the theoretical plate height is about H-2d(p) in the best case and limited by the A and C term of the Van Deemter equation. In other words the gain in total plate number when using 1-2 microm silica beads in short columns is minimal as compared to longer columns packed with 5 microm particles. Capillary electrochromatography (CEC) as a hybrid method enables the application of micron size as well as submicron size particles. This consequently enhances column efficiency by a factor of 5-10 when compared to HPLC. The use of short CEC columns packed with submicron size silicas provides the basis for fast and efficient miniaturized systems. The most significant feature of CEC as compared to HPLC is that the former allows one to resolve polar and ionic analytes in a single run. An alternative method for miniaturization is capillary electrophoresis (CE) which generates extremely high efficiencies combined with fast analysis. Its application, however, is limited to ionic substances.