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Anionic Compounds (anionic + compound)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Evaluation of CE methods for global metabolic profiling of urine

ELECTROPHORESIS, Issue 14 2010
Rawi Ramautar
Abstract In this study, the usefulness of noncovalently coated capillaries with layers of charged polymers is investigated to obtain global electrophoretic profiles of urinary metabolites covering a broad range of different compound classes in a highly repeatable way. Capillaries were coated with a bilayer of polybrene (PB) and poly(vinyl sulfonate) (PVS), or with a triple layer of PB, dextran sulfate (DS) and PB. The bilayer and triple layer coatings were evaluated at acidic (pH 2.0) and alkaline (pH 9.0) separation conditions, thereby providing separation conditions for basic and acidic compounds. A representative metabolite mixture and spiked urine samples were used for the evaluation of the four CE methods. Migration time repeatability (RSD<2%) and plate numbers (N, 100,000,400,000) were similar for the test compounds in all CE methods, except for some multivalent ions that may exhibit adsorption to oppositely charged coatings. The analysis of cationic compounds with the PB-DS-PB CE method at low pH (i.e. after the EOF time) provided a larger separation window and number of separated peaks in urine compared to the analysis with the PB-PVS CE method at low pH (i.e. before the EOF time). Approximately, 600 molecular features were detected in rat urine by the PB-DS-PB CE-MS method whereas about 300 features were found with the PB-PVS CE-MS method. This difference can be attributed to reduced comigration of compounds with the PB-DS-PB CE-MS method and a related decrease of ion suppression. With regard to the analysis of anionic compounds by CE-MS, in general analyte responses were significantly lower than that for cationic compounds, most probably due to less efficient ionization and to ion suppression effects caused by the background electrolyte. Hence, further optimization is required for the sensitive CE-MS analysis of anionic compounds in body fluids. It is concluded that the selection of a CE method for profiling of cationic metabolites in urine depends on the purpose of the study. For high-throughput analyses, the PB-PVS CE-MS method is favored whereas the PB-DS-PB CE-MS method provides a more information-rich metabolic profile, but at the cost of prolonged analysis time. [source]

Dual injection capillary electrophoresis: Foundations and applications

ELECTROPHORESIS, Issue 23-24 2004
Feliciano Priego-Capote
Abstract The state of the art of capillary electrophoresis (CE) approaches based on dual injection is here reported. Dual injection strategies have been proposed with three main objectives: (i) to provide information about reaction kinetics and/or related parameters, (ii) to perform in-capillary derivatization for improving separation and/or determination, (iii) to develop electrophoretic methods for the simultaneous analysis of anionic and cationic compounds. For the first two purposes, dual injection, which involves sample and reagent, can be realized either from the same end of the capillary (electrophoretically mediated microanalysis, EMMA) or from the two ends of the capillary (electroinjection analysis, EIA). The third objective, with dual injection of sample from the two ends of the capillary, takes advantage of moving cationic and anionic compounds with opposite directions. The foundations of each alternative, conditions necessary for working with them, restrictions, applications as well as perspectives are reviewed in order to establish the advantages, shortcomings, and convenience or no of their use in comparison to conventional CE. [source]

Transport characteristics of L -citrulline in renal apical membrane of proximal tubular cells

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 3 2009
Keisuke Mitsuoka
Abstract L -Citrulline has diagnostic potential for renal function, because its plasma concentration increases with the progression of renal failure. Although L -citrulline extracted by glomerular filtration in kidney is mostly reabsorbed, the mechanism involved is not clearly understood. The present study was designed to characterize L -citrulline transport across the apical membranes of renal epithelial tubular cells, using primary-cultured rat renal proximal tubular cells, as well as the human kidney proximal tubular cell line HK-2. L -Citrulline was transported in a Na+ -dependent manner from the apical side of both cell types cultured on permeable supports with a microporous membrane. Kinetic analysis indicated that the transport involves two distinct Na+ -dependent saturable systems and one Na+ -independent saturable system in HK-2 cells. The uptake was competitively inhibited by neutral and cationic, but not anionic amino acids. Relatively large cationic and anionic compounds inhibited the uptake, but smaller ones did not. In HK-2 cells, mRNA expression of SLC6A19 and SLC7A9, which encode B0AT1 and b0,+AT, respectively, was detected by RT-PCR. In addition, L -citrulline transport was significantly decreased in HK-2 cells in which either SLC6A19 or SLC7A9 was silenced. Hence, these results suggest that amino acid transporters B0AT1 and b0,+AT are involved in the reabsorption of L -citrulline in the kidney, at least in part, by mediating the apical membrane transport of L -citrulline in renal tubule cells. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Human liver-specific organic anion transporter-2 is a potent prognostic factor for human breast carcinoma

CANCER SCIENCE, Issue 10 2007
Mitsuhisa Muto
Human liver-specific organic anion transporter-2 (LST-2/OATP8/SLCO1B3) has been demonstrated to be expressed in various gastrointestinal carcinomas and also to play pivotal roles in the uptake of a wide variety of both endogenous and exogenous anionic compounds, including bile acids, conjugated steroids and hormones, into hepatocytes in the human liver. However, the biological significance of LST-2 in human carcinomas remains unknown. In the present study, we examined the expression of LST-2 in 102 cases of breast carcinoma using immunohistochemistry and correlated the findings with various clinicopathological parameters in order to examine the possible biological and clinical significance of LST-2. LST-2 immunoreactivity was detected in 51 cases (50.0%); of these 51 positive cases, LST-2 immunoreactivity was inversely correlated with tumor size (P = 0.0289). In addition, LST-2 immunoreactivity was significantly associated with a decreased risk of recurrence and improved prognosis by both univariate (P = 0.02 and P = 0.01) and multivariate (P = 0.03 and P = 0.01) analyses. In the estrogen receptor-positive groups, the LST-2-positive patients showed good prognoses. Considering that LST-2 transports estrone-3-sulfate, these results suggest that LST-2 overexpression is associated with a hormone-dependent growth mechanism of the breast cancer. The results of our present study demonstrate that LST-2 immunoreactivity is a potent prognostic factor in human breast cancer. (Cancer Sci 2007; 98: 1570,1576) [source]