1,621 research outputs found
Expression and clinical significance of multidrug resistance proteins in brain tumors
<p>Abstract</p> <p>Background</p> <p>To investigate the mechanisms of multidrug resistance of brain tumors, to identify the site of cellular expression of P-gp in human brains in situ and to morphologically determine whether an association may exist between P-gp and caveolin-1.</p> <p>Methods</p> <p>Immunohistochemistry was used to detect the expression and location of P-glycoprotein (P-gp), Multidrug resistance-associated protein (MDR), Lung resistance-related protein (LRP), Topoisomerase II (Topo II) and Glutathione-S-Ï (GST-Ï) in 30 patient tumor tissues and 5 normal brain tissues. The sections were subjected to double labeling for P-gp (TRITC labeled) and caveolin-1 (FITC labeled). The location and characteristics of expression of the two proteins in the blood brain barrier(BBB) was observed using a laser scanning microscope.</p> <p>Results</p> <p>High expression of P-gp was detected in vessel walls and the tissue surrounding the vessels. However, expression of P-gp was low in tumor cells. The expression of the other 4 multidrug resistance proteins was not observed in the vessel walls. Laser scanning microscopy showed P-gp and caveolin-1 co-expression: the two proteins co-localized either in the luminal endothelial compartment or at the border of the luminal/abluminal compartments.</p> <p>Conclusion</p> <p>Chemotherapeutics drugs are interrupted in the end-feet of neuroepithelial cells of the BBB by P-gp, which weakens the chemotherapeutic effect. P-gp marks the BBB, and the transporter is localized in the luminal endothelial compartment where it co-localizes with caveolin-1.</p
Feasibility and effect of para-right bundle branch pacing in patients with atrial fibrillation and complete atrioventricular block
Background: Chronic right ventricular apex (RVA) pacing can induce negative clinical effects. The aim of the present study was to compare RVA pacing with para-right bundle branch (para-RBB) pacing in terms of electrocardiogram (ECG) and echocardiographic (ECHO) features.
Methods: Forty-one consecutive persistent atrial fibrillation patients with an indication for permanent pacing treatment due to complete atrioventricular block were randomly assigned to receive a screw-in lead either in the RVA (n = 22) or at the para-RBB (n = 19). Para-RBB pacing leads were located according to the RBB potential recorded by electrophysiology catheter. ECG was recorded before and after implantation. All patients underwent the pacemaker proÂgramming at 1 day, 6 months, 12 months and 24 months after implantation. ECHO examinaÂtion was performed during follow-up at 6, 12 and 24 months after implantation to assess the heart function and synchronism.
Results: There was no significant difference in pacing lead parameters between para-RBB pacing group and RVA pacing group. Compared with RVA pacing group, the para-RBB pacing group obtained a narrower QRS complex, more synchronic ventricular systole, and less negaÂtive effect on heart function (p < 0.05).
Conclusions: Para-RBB pacing has potential clinical benefits and may be a physiological pacing site.
Phosphocreatine Preconditioning Attenuates Apoptosis in Ischemia-Reperfusion Injury of Rat Brain
Phosphocreatine (PCr) is an endogenous compound containing high-energy phosphate bonds. It has been confirmed that PCr is effective in preventing and treating cardiac and renal ischemia-reperfusion injury. In this study, rat cerebral ischemia-reperfusion injury models were constructed. Apoptotic cells in the cortex region were measured by TUNEL method. Malondialdehyde (MDA) content was detected by chromatometry, and calmodulin (CaM) activity was detected by ELISA. Compared with sham-operated group (sham group), TUNEL-positive cells, MDA, and level of CaM activity increased in ischemia-reperfusion group (I/R group) and PCr preconditioning group (PCr group); compared with I/R group, TUNEL-positive cells, MDA content, and level of CaM activity decreased in PCr group. This study indicated that PCr can decrease the morphological damage and the neuron apoptosis of the ischemia-reperfusion injury brain through attenuating abnormalities of calcium balance and production of oxygen free radicals
An efficient ICT-based ratio/colorimetric tripodal azobenzene probe for the recognition/discrimination of Fâ, AcOâ and H2PO4â anions
The tripodal probe L was readily prepared via introducing rhodamine and azobenzene groups in a two-step procedure. Studies of the recognition properties indicated that probe L exhibited high sensitivity and selectivity towards Fâ, AcOâ and H2PO4â through a ratiometric colorimetric response with low detection limits of the order of 10â7âŻM. The complexation behaviour was fully investigated by spectral titration, 1H NMR spectroscopic titration and mass spectrometry. Probe L not only recognizes Fâ, AcOâ and H2PO4â, but can also distinguish between these three anions via the different ratiometric behaviour in their UVâvis spectra (387/505âŻnm for L-H2PO4â, 387/530âŻnm for L-AcOâ and 387/575âŻnm for L-Fâ complex) or via different colour changes (light coral for L-H2PO4â, light pink for L-AcOâ and violet for the L-Fâ complex). Additionally, given the presence of NH and OH groups in probe L, which can be protonated and deprotonated, probe L further exhibited an excellent pH response over a wide pH range (pHâŻ3 to pHâŻ12)
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