Carbonyl Cyanide M-chlorophenyl Research Articles

Effects of antibiotics plus efflux pump inhibitors on mutant selection window of Pseudomonas aeruginosa in vitro

To explore the effects of antibiotics plus efflux pump (EPI) inhibitors on mutant selection window of Pseudomonas aeruginosa in vitro. In standard strains, the minimum inhibitory concentrations (MICs) of meropenem, ceftazidime, amikacin and ciprofloxacin alone were measured. Then the MICs of four antibiotics respectively plus EPI, including reserpine, omeprazole, azithromycin, carbonyl cyanide m-chlorophenyl- hydrazone (CCCP) and Phe-Arg-β-naphtylamide (PAβN), were measured by checkerboard test. And the mutant prevention concentrations (MPC) of antibiotics alone and antibiotics plus different EPIs were also measured by agar dilution method. Selection indices (SI) were acquired through MPC divided by MIC. Similarly, the SI of meropenem, ceftazidime and ciprofloxacin which respectively plus amikacin and amikacin plus ciprofloxacin were measured. In clinical strains, MIC, MPC and SI of antibiotics alone and four antibiotics plus CCCP were measured. In standard strains, the SI of meropenem, ceftazidime, amikacin and ciprofloxacin alone were >32, >32, 16 and 16. After adding EPI, the SI of four antibiotics were 16, 16, 16, 8 (reserpine), 16, 32, 16, 8 (omeprazole), 8, 16, 16, 8 (azithromycin), 8, 8, 16, 8 (CCCP) and 8, 16, 16, 8 (PAβN). The SI of meropenem, ceftazidime and ciprofloxacin plus amikacin were 4, 4, 8. And the SI of amikacin plus ciprofloxacin was 4. In clinical strains, the SI of ciprofloxacin significantly decreased after adding CCCP. Both MIC and MPC of meropenem, ceftazidime and ciprofloxacin decreased significantly after adding EPI. The mutant selection window decreased when ciprofloxacin was combined with CCCP.

Pulses of extracellular K + produce two cytosolic Ca 2+ transients that display different temperature dependence and carbonyl cyanide m-chlorophenyl sensitivity in SH-SY5Y cells

In SH-SY5Y cells we have shown that stimulation with high extracellular K + ([K +] e) evokes a transient increase in cytoplasmic Ca 2+ ([Ca 2+] cyt) (K + on) that is triggered by the opening of voltage-dependent Ca 2+ channels and followed by Ca 2+-induced Ca 2+ release from the endoplasmic reticulum (Xu, F., Zhang, J., Recio-Pinto, E. and Blanck, T.J., Halothane and isoflurane augment depolarization-induced cytosolic CA2+ transients and attenuate carbachol-stimulated CA2+ transients, Anesthesiology, 92 (2000) 1746–56). The removal of high-[K +] e results in a second transient increase in [Ca 2+] cyt (K + off) that is independent of extracellular Ca 2+ (Corrales, A., Montoya, G.J., Sutachan, J.J., Cornillez-Ty, G., Garavito-Aguilar, Z., Xu, F., Blanck, T.J. and Recio-Pinto, E., Transient increases in extracellular K+ produce two pharmacological distinct cytosolic Ca2+ transients, Brain Res., 1031 (2005) 174–184). In this study we further characterize the properties of K + off. We found that K + off was detectable at near physiological temperatures (34–36 °C) but, depending on the level of [K +] e, it was undetectable or highly diminished at room temperature. In contrast, K + on was increased by lowering the temperature. Extracellular Na +-replacement with K + did not affect K + off, indicating that K + off was not generated by osmolarity changes. Replacement of extracellular Na + with choline + did not affect K + off, indicating that K + off did not result from activity changes of the plasma membrane Na +/Ca 2+ exchanger. Caffeine decreased K + on but not K + off. CCCP (carbonyl cyanide m-chlorophenyl), a protonophore uncoupler that decreases mitochondrial Ca 2+ uptake, decreased K + on but not K + off. CGP37157, an inhibitor of the mitochondria Na +/Ca 2+ exchanger, decreased K + off when added alone but not when added simultaneously with CCCP. Clonazepam had similar effects as CGP37157. These findings indicate that the generation of K + off is strongly temperature-dependent and its pharmacology is distinct from the [Ca 2+] cyt changes observed previously at room temperature.

Monitoring Phloem Unloading and Post-Phloem Transport by Microperfusion of Attached Wheat Grains.

Phloem unloading and post-phloem transport in developing wheat (Triticum aestivum L.) grains were investigated by perfusing the endosperm cavities of attached grains. Relative unloading ratio (RUR) and the rate of sucrose release into the endosperm cavity (SRR) were calculated, respectively, from 14C import and from sucrose washout from the cavity. RUR and SRR continued at or near in vivo rates over a wide range of cavity sap osmolality (90 to approximately 500 milliosmolal) and sucrose concentration (14-430 mM) and for long times (29 h). These are much greater ranges than have been observed for the endosperm cavity in vivo (230-300 milliosmolal, and 40-120 mM, respectively), indicating that neither the cavity sap osmolality nor sucrose concentration are controlling factors for the rate of assimilate import into the cavity. The maintenance of in vivo transport rates over a wide range of conditions strongly implicates the role of transport processes within the maternal tissues of the wheat grain, rather than activities of the embryo or endosperm, in determining the rate of assimilate import into the grain. RUR was decreased by high concentrations of sucrose and sorbitol, but not of mannitol. By plasmolyzing some chalazal cells, sorbitol appeared to block symplastic transport across the crease tissues, but neither sucrose nor mannitol caused plasmolysis in maternal tissues of attached grains. The inhibition of RUR by KCN and carbonyl cyanide m-chlorophenyl (CCCP) and the continued import of sucrose into grains against its concentration gradient suggest that solute movement into the endosperm cavity might occur by active membrane transport. However, the evidence is weak, since KCN and CCCP appeared to act primarily on some aspect of symplastic (i.e. nonmembrane) transport. Also, sucrose could move from the endosperm cavity into the maternal tissues (i.e. opposite to the normal direction of sucrose movement), suggesting that transmembrane movement in the nucellus may be a reversible process. Pressure-driven flow into the grain could account for movement against a concentration gradient.