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mol/L Concentration (l + concentration)
Selected AbstractsDirect automatic determination of free and total anesthetic drugs in human plasma by use of a dual (microdialysis,microextraction by packed sorbent) sample treatment coupled at-line to NACE,MSELECTROPHORESIS, Issue 10 2009Gabriel Morales-Cid Abstract This paper reports for the first time the use of microextraction by packed sorbent in combination with CE. The combined system was used to determine anesthetic drugs in human plasma. A microdialysis fiber was coupled on-line to the microextraction unit in order to distinguish between free and total concentrations of drugs. The system was automated by connecting the microextraction unit to a syringe pump and interfacing it to a computer. The ensuing method allows the determination of 10,,g/L concentrations of free drugs and 1,,g/L concentrations of total drugs from only 200,,L of sample with an RSD of less than 9%. [source] Gonadal differentiation in frogs exposed to estrogenic and antiestrogenic compoundsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2003Constanze A. Mackenzie Abstract Exposure of amphibians to endocrine disrupting compounds (EDCs) may alter differentiationof gonads, especially when exposures begin during early life stages. Gonadal differentiation was observed in leopard frogs (Rana pipiens) and wood frogs (Rana sylvatica) exposed as tadpoles to estrogenic (estradiol, ethinylestradiol, nonylphenol) and antiestrogenic compounds (an aromatase inhibitor, flavone, and an antiestrogen, ICI 182780). Exposure to all compounds at ,g/L concentrations altered gonadal differentiation in some animals by inducing either complete feminization or an intersex condition, and altered testicular tubule morphology, increased germ cell maturation (vitellogenesis), and oocyte atresia. Comparisons between the two species indicate that R. pipiens are more susceptible to sex reversal and development of intersex gonads. However, R. sylvatica also showed alterations to testicular morphology, germ cell maturation, and ooctye atresia. These laboratory results indicate that amphibians could be susceptible to altered gonadal differentiation and development when exposed to estrogenic and antiestrogenic compounds in aquatic environments, such as those impacted by agricultural, industrial, and municipal runoff. [source] Simple method for determination of cocaine and main metabolites in urine by CE coupled to MSELECTROPHORESIS, Issue 12 2009José Luiz da Costa Abstract In this work, a simple method for the simultaneous determination of cocaine (COC) and five COC metabolites (benzoylecgonine, cocaethylene (CET), anhydroecgonine, anhydroecgonine methyl ester and ecgonine methyl ester) in human urine using CE coupled to MS via electrospray ionization (CE-ESI-MS) was developed and validated. Formic acid at 1,mol/L concentration was used as electrolyte whereas formic acid at 0.05,mol/L concentration in 1:1 methanol:water composed the coaxial sheath liquid at the ESI nozzle. The developed method presented good linearity in the dynamic range from 250,ng/mL to 5000,ng/mL (coefficient of determination greater than 0.98 for all compounds). LODs (signal-to-noise ratio of 3) were 100,ng/mL for COC and CET and 250,ng/mL for the other studied metabolites whereas LOQ's (signal-to-noise ratio of 10) were 250,ng/mL for COC and CET and 500,ng/mL for all other compounds. Intra-day precision and recovery tests estimated at three different concentration levels (500, 1500 and 5000,ng/mL) provided RSD lower than 10% (except anhydroecgonine, 18% RSD) and recoveries from 83,109% for all analytes. The method was successfully applied to real cases. For the positive urine samples, the presence of COC and its metabolites was further confirmed by MS/MS experiments. [source] Enantioselective analysis of pheniramine in urine by charged CD-mediated CZE provided with a fiber-based DAD and an on-line sample pretreatment by capillary ITPELECTROPHORESIS, Issue 15 2007Jozef Marák Abstract Application potentialities of CZE on-line coupled with capillary ITP and DAD to the identification and determination of trace concentration levels (,g/L) of pheniramine (PHM) enantiomers and their metabolites present in complex ionic matrices of biological origin (urine) are shown. An enhanced (enantio)selectivity of the CZE separation system obtained by the addition of carboxyethyl-,-CD (CE-,-CD) to the carrier electrolyte provided CZE conditions for a reliable identification of similar/identical DAD spectra of structurally related compounds (PHM enantiomers and their metabolites) in clinical urine samples differing in qualitative and quantitative composition of sample matrix constituents. A high sample loadability (a 30,,L sample injection volume), partial sample clean-up (removing macroconstituents from the sample), and preconcentration of the analytes in ITP stage resulted in the decrease of concentration LOD for PHM enantiomers in urine to 5.2 and 6.8,,g/L (2.2×10,8 and 2.8×10,8,mol/L), without using any sample pretreatment technique. The background correction and smoothing procedure applied to the raw DAD spectra provided analytically relevant DAD spectra of PHM enantiomers and their metabolites also when they were present in urine sample (30,,L injection volumes of ten-times diluted urine sample) at a 9×10,8,mol/L concentration. DAD spectra of PHM enantiomers present in urine samples matched their reference spectra with reasonable certainties. DAD spectra of PHM metabolites were compared with the reference spectra of PHM enantiomers and a good match was found which indicates the similarities in the structures of enantiomers and their metabolites detected in the urine samples. This fact allows performing the quantitative analyses of PHM metabolites in the urine samples by applying the calibration parameters of PHM enantiomers also for PHM metabolites and the results show the possibilities of using the ITP,CZE,DAD combination for the direct analysis of PHM enantiomers and/or their metabolites in urine without any sample pretreatment. ITP,CZE,DAD method with oppositely charged selector is suggested to use in clinical research as it provides favorable performance parameters including sensitivity, linearity, precision, recovery, and robustness with minimal demands on sample preparation. [source] PX-478, an inhibitor of hypoxia-inducible factor-1,, enhances radiosensitivity of prostate carcinoma cells,INTERNATIONAL JOURNAL OF CANCER, Issue 10 2008Sanjeewani T. Palayoor Abstract Overexpression of hypoxia-inducible factor-1, (HIF-1,) in human tumors is associated with poor prognosis and poor outcome to radiation therapy. Inhibition of HIF-1, is considered as a promising approach in cancer therapy. The purpose of this study was to test the efficacy of a novel HIF-1, inhibitor PX-478 as a radiosensitizer under normoxic and hypoxic conditions in vitro. PC3 and DU 145 prostate carcinoma cells were treated with PX-478 for 20 hr, and HIF-1, protein level and clonogenic cell survival were determined under normoxia and hypoxia. Effects of PX-478 on cell cycle distribution and phosphorylation of H2AX histone were evaluated. PX-478 decreased HIF-1, protein in PC3 and DU 145 cells. PX-478 produced cytotoxicity in both cell lines with enhanced toxicity under hypoxia for DU-145. PX-478 (20 ,mol/L) enhanced the radiosensitivity of PC3 cells irradiated under normoxic and hypoxic condition with enhancement factor (EF) 1.4 and 1.56, respectively. The drug was less effective in inhibiting HIF-1, and enhancing radiosensitivity of DU 145 cells compared to PC3 cells with EF 1.13 (normoxia) and 1.25 (hypoxia) at 50 ,mol/L concentration. PX-478 induced S/G2M arrest in PC3 but not in DU 145 cells. Treatment of PC3 and DU 145 cells with the drug resulted in phosphorylation of H2AX histone and prolongation of ,H2AX expression in the irradiated cells. PX-478 is now undergoing Phase I clinical trials as an oral agent. Although the precise mechanism of enhancement of radiosensitivity remains to be identified, this study suggests a potential role for PX-478 as a clinical radiation enhancer. Published 2008 Wiley-Liss, Inc. [source] Determination of oxalate in beer by zone electrophoresis on a chip with conductivity detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2003Marián Masár Abstract The use of a poly(methylmethacrylate) capillary electrophoresis chip, provided with a high sample load capacity separation system (a 8500 nL separation channel combined with a 500 nL sample injection channel) and a pair of on-chip conductivity detectors, for zone electrophoresis (ZE) determination of oxalate in beer was studied. Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the chip were suppressed and electrophoresis was a dominant transport process in the separations performed on the chip. A low pH of the carrier electrolyte (3.8), implemented by aspartic acid and bis-tris propane, provided an adequate selectivity in the separation of oxalate from anionic beer constituents and, at the same time, also a sufficient sensitivity in its conductivity detection. Under our working conditions, this anion could be detected at a 0.5 ,mol/L concentration also in samples containing chloride (a major anionic constituent of beer) at a 1800 higher concentration. Such a favorable analyte/matrix concentration ratio made possible accurate and reproducible [typically, 2,5% relative standard deviation (RSD) values of the peak areas of the analyte in dependence on its concentration in the sample] determination of oxalate in 500 nL volumes of 20,50-fold diluted beer samples. Short analysis times (about 200 s), minimum sample preparation, and reproducible migration times of this analyte (0.5,1.0% RSD values) were characteristic for ZE on the chip. [source] Free Zn2+ enhances inhibitory effects of EGCG on the growth of PC-3 cellsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 4 2008Shi-li Sun Abstract Epigallocatechin-3-gallate (EGCG), a major component of green tea, has both preventive and therapeutic beneficial actions in prostate cancer. In the present study, we compared the growth inhibitory effects and the antioxidant and ability to modify cell membrane permeation of zinc-EGCG complex and Zn2+/EGCG mixture on androgen-insensitive prostate cancer (PC-3) cells. It was noted that free Zn2+ enhanced the growth inhibitory effects of EGCG on PC-3 cells at 160 ,mol/L concentration, whereas zinc-EGCG complex was ineffective. EGCG showed potent free radical scavenging ability in the presence of Zn2+. EGCG in the presence of Zn2+ was more effective than EGCG alone in enhancing the permeability of the cell membrane, whereas zinc-EGCG complex had no effect on PC-3 cell membrane permeability. These results indicate that though Zn2+ enhanced the action of EGCG on PC-3 cells, zinc-EGCG complex is highly unlikely to be formed in the presence of Zn2+ and EGCG to explain the potentiating action of Zn2+ on the growth inhibitory property of EGCG on PC-3 cells. [source] Effects of the synthetic estrogen ethinylestradiol on early life stages of mink frogs and green frogs in the wild and in situENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2005Bradley J. Park Abstract Estrogenic contaminants are known to disrupt growth and development in amphibians. Field-based research is needed to elucidate their potential impacts on wild populations. Hatch success, larval growth and development rates, and gonad development were examined in native amphibians exposed to low ng/L concentrations of 17,-efhinylestradiol (EE2) in a whole-lake addition experiment at the Experimental Lakes Area, northwestern Ontario, Canada. Egg masses were reared in situ in the EE2-amended lake and in two reference lakes in 2001 and 2002. Hatching success was reduced significantly in green frogs (Rana clamitans) but not in mink frogs (Rana septentrionalis) exposed to EE2. Ethinylestradiol had no consistent effect on mass or development stage of hatchlings in the early larval stages of the caging study. Ethinylestradiol had no effect on sex ratios of either species in situ, and no intersex gonads were observed in exposed or reference green frog tadpoles or in reference mink frog tadpoles. However, 5.6% (total n = 18) and 12.5% (total n = 56) of EE2-exposed mink frog tadpoles were intersex in the 2001 and 2002 caging studies, respectively. Wild mink frog tadpoles also were examined, and EE2 had no effect on sex ratios. No intersex gonads were observed in reference lake tadpoles or in tadpoles from the experimental lake prior to EE2 additions; however, 2.4, 0, and 28.6% of wild EE2-exposed first-year tadpoles had intersex gonads (2001, 2002, and 2003, respectively). These results indicate that exposure to EE2 in the wild and in situ at concentrations comparable to those detected in effluents and, occasionally, in surface waters can impact gonad development and hatch success in native amphibians. [source] | ||||||||||