1
|
Enhanced Electrocatalytic Detection of Choline Based on CNTs and Metal Oxide Nanomaterials. Molecules 2021; 26:molecules26216512. [PMID: 34770919 PMCID: PMC8588103 DOI: 10.3390/molecules26216512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/18/2021] [Accepted: 10/20/2021] [Indexed: 11/17/2022] Open
Abstract
Choline is an officially established essential nutrient and precursor of the neurotransmitter acetylcholine. It is employed as a cholinergic activity marker in the early diagnosis of brain disorders such as Alzheimer's and Parkinson's disease. Low levels of choline in diets and biological fluids, such as blood plasma, urine, cerebrospinal and amniotic fluid, could be an indication of neurological disorder, fatty liver disease, neural tube defects and hemorrhagic kidney necrosis. Meanwhile, it is known that choline metabolism involves oxidation, which frees its methyl groups for entrance into single-C metabolism occurring in three phases: choline oxidase, betaine synthesis and transfer of methyl groups to homocysteine. Electrocatalytic detection of choline is of physiological and pathological significance because choline is involved in the physiological processes in the mammalian central and peripheral nervous systems and thus requires a more reliable assay for its determination in biological, food and pharmaceutical samples. Despite the use of several methods for choline determination, the superior sensitivity, high selectivity and fast analysis response time of bioanalytical-based sensors invariably have a comparative advantage over conventional analytical techniques. This review focuses on the electrocatalytic activity of nanomaterials, specifically carbon nanotubes (CNTs), CNT nanocomposites and metal/metal oxide-modified electrodes, towards choline detection using electrochemical sensors (enzyme and non-enzyme based), and various electrochemical techniques. From the survey, the electrochemical performance of the choline sensors investigated, in terms of sensitivity, selectivity and stability, is ascribed to the presence of these nanomaterials.
Collapse
|
2
|
Hosseini ES, Tabar Heydar K. Preparation of two amide-bonded stationary phases and comparative evaluation under mixed-mode chromatography. J Sep Sci 2021; 44:2888-2897. [PMID: 34043871 DOI: 10.1002/jssc.202100291] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 11/10/2022]
Abstract
In this work, the conventional reactions were used to functionalize the silica surface with amide and hydrocarbon chain groups affording two different mixed-mode stationary phases (Sil-amide-C11 and Sil-C12-amide). The prepared stationary phases were analyzed by elemental analysis and thermogravimetric analysis. The retention of benzene, phenol, pyridine, and aniline was investigated and compared with synthesized and commercial columns, and this led to prove the existence of different interactions on the synthesized stationary phases. The mixed-mode stationary phases showed multiple interactions, and different chromatography modes were found under distinct chromatographic conditions. According to the type of amide group (either free or within the hydrocarbon chain), different interactions can be made on the columns. The alkylbenzenes and polycyclic aromatic hydrocarbons, as nonpolar hydrocarbons, were chromatographed under reversed-phase liquid chromatography modes, in which amide groups on the silica could efficiently separate polar analytes under hydrophilic interaction liquid chromatography mode in both prepared stationary phases. The performance of the columns was compared by the separation of the carboxylic acid group and biological samples. The bonding method and the type of amide group showed different interactions leading to different separation and performance.
Collapse
|
3
|
Hosseini ES, Tabar Heydar K. Preparation and evaluation a mixed-mode stationary phase with C 18 and 2-methylindole for HPLC. Biomed Chromatogr 2021; 35:e5068. [PMID: 33450065 DOI: 10.1002/bmc.5068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 01/02/2021] [Accepted: 01/06/2021] [Indexed: 11/11/2022]
Abstract
A modified C18 column (Silpr-2MI-C18) was prepared using 2-methylindole and C18 reagent. The extent of C18 hydrocarbon chain, conjugative rings and anion exchange site provided multiple retention mechanisms, including reversed-phase liquid chromatography (RPLC), π-π interaction, hydrophilic interaction liquid chromatography (HILIC) and anion exchange chromatography (AEC). The separation of protected amino acids was investigated on the commercial C18 and Silpr-2MI-C18 columns, while the chromatographic conditions, including methanol content and pH of the mobile phase, were studied. The separation arrangement of the hydrophilic amino acids was different on the Silpr-2MI-C18 column compared to the commercial C18 column under RPLC mode. Furthermore, these amino acids were separated on the Silpr-2MI-C18 column under HILIC mode. The modified C18 column was employed to separate amino acids, alkylbenzenes and polycyclic aromatic hydrocarbons under RPLC mode and inorganic anion under AEC mode. The results confirm that this new stationary phase of RPLC/HILIC/AEC has multiple interactions with different analytes. Effective retention of biological samples was found on the Silpr-2MI-C18 column by comparing the results obtained from the commercial C18 column.
Collapse
Affiliation(s)
- Elham Sadat Hosseini
- Faculty of Clean Technologies, Chemistry & Chemical Engineering Research Center of Iran, Tehran, Iran
| | - Kourosh Tabar Heydar
- Faculty of Clean Technologies, Chemistry & Chemical Engineering Research Center of Iran, Tehran, Iran
| |
Collapse
|
4
|
Immobilized Enzyme Reactors: an Overview of Applications in Drug Discovery from 2008 to 2018. Chromatographia 2018. [DOI: 10.1007/s10337-018-3663-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
5
|
Park SY, Choi SU, Lee KH, Yang JB, Cho SW, Ro J, Kim H, Khadka P, Lee J, Cho CW. Discriminative Measurement and Pharmacokinetic Evaluation of Choline Alphoscerate against Endogenous Choline in Human. B KOREAN CHEM SOC 2015. [DOI: 10.1002/bkcs.10409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Suck-Yong Park
- College of Pharmacy; Chungnam National University; Daejeon 305-764 Korea
| | - Sung-Up Choi
- Department of Food Science & Biotechnology; Dongnam Health University; Suwon 440-714 Korea
| | - Kyoung-Hae Lee
- Department of Food Science & Biotechnology; Dongnam Health University; Suwon 440-714 Korea
| | - Jong-Beom Yang
- Department of Food Science & Biotechnology; Dongnam Health University; Suwon 440-714 Korea
| | - Seong-Wan Cho
- Department of Pharmaceutics & Biotechnology, Medical Engineering College; Konyang University; Nonsan 320-711 Korea
| | - Jieun Ro
- Pharmaceutical Formulation Design Laboratory, College of Pharmacy; Chung-Ang University; Seoul 156-756 Korea
| | - Hyeongmin Kim
- Pharmaceutical Formulation Design Laboratory, College of Pharmacy; Chung-Ang University; Seoul 156-756 Korea
| | - Prakash Khadka
- Pharmaceutical Formulation Design Laboratory, College of Pharmacy; Chung-Ang University; Seoul 156-756 Korea
| | - Jaehwi Lee
- Pharmaceutical Formulation Design Laboratory, College of Pharmacy; Chung-Ang University; Seoul 156-756 Korea
| | - Cheong-Weon Cho
- College of Pharmacy; Chungnam National University; Daejeon 305-764 Korea
| |
Collapse
|
6
|
Rijpma A, Meulenbroek O, van Hees AMJ, Sijben JWC, Vellas B, Shah RC, Bennett DA, Scheltens P, Olde Rikkert MGM. Effects of Souvenaid on plasma micronutrient levels and fatty acid profiles in mild and mild-to-moderate Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2015. [PMID: 26213579 PMCID: PMC4513634 DOI: 10.1186/s13195-015-0134-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
INTRODUCTION Circulating levels of uridine, selenium, vitamins B12, E and C, folate, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) have been shown to be lower in patients with Alzheimer's disease (AD) than in healthy individuals. These low levels may affect disease pathways involved in synapse formation and neural functioning. Here, we investigated whether, and to what extent, circulating levels of micronutrients and fatty acids can be affected by oral supplementation with Souvenaid (containing a specific nutrient combination), using data derived from three randomized clinical trials (RCT) and an open-label extension (OLE) study with follow-up data from 12 to 48 weeks. METHODS Subjects with mild (RCT1, RCT2) or mild-to-moderate AD (RCT3) received active or control product once daily for 12-24 weeks or active product during the 24-week OLE following RCT2 (n = 212-527). Measurements included plasma levels of B vitamins, choline, vitamin E, selenium, uridine and homocysteine and proportions of DHA, EPA and total n-3 long-chain polyunsaturated fatty acids in plasma and erythrocytes. Between-group comparisons were made using t tests or non-parametric alternatives. RESULTS We found that 12-24-week active product intake increased plasma and/or erythrocyte micronutrients: uridine; choline; selenium; folate; vitamins B6, B12 and E; and fatty acid levels of DHA and EPA (all p < 0.001). In the OLE study, similar levels were reached in former control product/initial active product users, whereas 24-week continued active product intake showed no suggestion of a further increase in nutrient levels. CONCLUSIONS These data show that circulating levels of nutrients known to be decreased in the AD population can be increased in patients with mild and mild-tomoderate AD by 24-48-week oral supplementation with Souvenaid. In addition, to our knowledge, this is the first report of the effects of sustained dietary intake of uridine monophosphate on plasma uridine levels in humans. Uptake of nutrients is observed within 6 weeks, and a plateau phase is reached for most nutrients during prolonged intake, thus increasing the availability of precursors and cofactors in the circulation that may be used for the formation and function of neuronal membranes and synapses in the brain.
Collapse
Affiliation(s)
- Anne Rijpma
- Radboud Alzheimer Center, Department of Geriatric Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Olga Meulenbroek
- Radboud Alzheimer Center, Department of Geriatric Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Anneke M J van Hees
- Nutricia Research, Nutricia Advanced Medical Nutrition, Utrecht, The Netherlands
| | - John W C Sijben
- Nutricia Research, Nutricia Advanced Medical Nutrition, Utrecht, The Netherlands
| | | | - Raj C Shah
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL USA
| | - David A Bennett
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL USA
| | - Philip Scheltens
- Alzheimer Center, VU University Medical Center, Amsterdam, The Netherlands
| | - Marcel G M Olde Rikkert
- Radboud Alzheimer Center, Department of Geriatric Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| |
Collapse
|
7
|
Development and validation of a simple UHPLC–MS/MS method for the simultaneous determination of trimethylamine N-oxide, choline, and betaine in human plasma and urine. J Pharm Biomed Anal 2015; 109:128-35. [DOI: 10.1016/j.jpba.2015.02.040] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 02/16/2015] [Accepted: 02/20/2015] [Indexed: 11/23/2022]
|
8
|
Rhee I, Paeng KJ. Simultaneous determination of betaine and choline using derivatization by HPLC with UV detection. ANALYTICAL SCIENCE AND TECHNOLOGY 2015. [DOI: 10.5806/ast.2015.28.2.112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
9
|
Plasma choline concentration varies with different dietary levels of vitamins B6, B12 and folic acid in rats maintained on choline-adequate diets. Br J Nutr 2011; 107:1408-12. [PMID: 21917195 DOI: 10.1017/s0007114511004570] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Choline is an important component of the human diet and is required for the endogenous synthesis of choline-containing phospholipids, acetylcholine and betaine. Choline can also be synthesised de novo by the sequential methylation of phosphatidylethanolamine to phosphatidylcholine. Vitamins B6, B12 and folate can enhance methylation capacity and therefore could influence choline availability not only by increasing endogenous choline synthesis but also by reducing choline utilisation. In the present experiment, we determined whether combined supplementation of these B vitamins affects plasma choline concentration in a rat model of mild B vitamin deficiency which shows moderate increases in plasma homocysteine. To this end, we measured plasma choline and homocysteine concentrations in rats that had consumed a B vitamin-poor diet for 4 weeks after which they were either continued on the B vitamin-poor diet or switched to a B vitamin-enriched diet for another 4 weeks. Both diets contained recommended amounts of choline. Rats receiving the B vitamin-enriched diet showed higher plasma choline and lower plasma homocysteine concentrations as compared to rats that were continued on the B vitamin-poor diet. These data underline the interdependence between dietary B vitamins and plasma choline concentration, possibly via the combined effects of the three B vitamins on methylation capacity.
Collapse
|
10
|
Déchamps S, Shastri S, Wengelnik K, Vial HJ. Glycerophospholipid acquisition in Plasmodium - a puzzling assembly of biosynthetic pathways. Int J Parasitol 2010; 40:1347-65. [PMID: 20600072 DOI: 10.1016/j.ijpara.2010.05.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Revised: 05/24/2010] [Accepted: 05/25/2010] [Indexed: 01/06/2023]
Abstract
Throughout the Plasmodium life cycle, malaria parasites repeatedly undergo rapid cellular growth and prolific divisions, necessitating intense membrane neogenesis and, in particular, the acquisition of high amounts of phospholipids. At the intraerythrocytic stage, glycerophospholipids are the main parasite membrane constituents, which mostly originate from the Plasmodium-encoded enzymatic machinery. Several proteins and entire pathways have been characterized and their features reported, thereby generating a global view of glycerophospholipid synthesis across Plasmodium spp. The malaria parasite displays a panoply of pathways that are seldom found together in a single organism. The major glycerophospholipids are synthesized via ancestral prokaryotic CDP-diacylglycerol-dependent pathways and eukaryotic-type de novo pathways. The parasite exhibits additional reactions that bridge some of these routes and are otherwise restricted to some organisms, such as plants, while base-exchange mechanisms are largely unexplored in Plasmodium. Marked differences between Plasmodium spp. have also been reported in phosphatidylcholine and phosphatidylethanolamine synthesis. Little is currently known about glycerophospholipid acquisition at non-erythrocytic stages, but recent data reveal that intrahepatocytic parasites, oocysts and sporozoites import various host lipids, and that de novo fatty acid synthesis is only crucial at the late liver stage. More studies on the different Plasmodium developmental stages are needed, to further assemble the different pieces of this glycerophospholipid synthesis puzzle, which contains highly promising therapeutic targets.
Collapse
Affiliation(s)
- Sandrine Déchamps
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR 5235, Centre National de la Recherche Scientifique (CNRS) - Universite Montpellier 2, cc 107, Place Eugene Bataillon, 34095 Montpellier Cedex 05, France
| | | | | | | |
Collapse
|
11
|
Déchamps S, Maynadier M, Wein S, Gannoun-Zaki L, Maréchal E, Vial HJ. Rodent and nonrodent malaria parasites differ in their phospholipid metabolic pathways. J Lipid Res 2010; 51:81-96. [PMID: 19561325 DOI: 10.1194/jlr.m900166-jlr200] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Malaria, a disease affecting humans and other animals, is caused by a protist of the genus Plasmodium. At the intraerythrocytic stage, the parasite synthesizes a high amount of phospholipids through a bewildering number of pathways. In the human Plasmodium falciparum species, a plant-like pathway that relies on serine decarboxylase and phosphoethanolamine N-methyltransferase activities diverts host serine to provide additional phosphatidylcholine and phosphatidylethanolamine to the parasite. This feature of parasitic dependence toward its host was investigated in other Plasmodium species. In silico analyses led to the identification of phosphoethanolamine N-methyltransferase gene orthologs in primate and bird parasite genomes. However, the gene was not detected in the rodent P. berghei, P. yoelii, and P. chabaudi species. Biochemical experiments with labeled choline, ethanolamine, and serine showed marked differences in biosynthetic pathways when comparing rodent P. berghei and P. vinckei, and human P. falciparum species. Notably, in both rodent parasites, ethanolamine and serine were not significantly incorporated into phosphatidylcholine, indicating the absence of phosphoethanolamine N-methyltransferase activity. To our knowledge, this is the first study to highlight a crucial difference in phospholipid metabolism between Plasmodium species. The findings should facilitate efforts to develop more rational approaches to identify and evaluate new targets for antimalarial therapy.
Collapse
Affiliation(s)
- Sandrine Déchamps
- Dynamique des Interactions Membranaires Normales et Pathologiques, UMR 5235, Centre National de la Recherche Scientifique (CNRS) - Universite Montpellier II, cc 107, Place Eugene Bataillon, 34095 Montpellier Cedex 05, France
| | | | | | | | | | | |
Collapse
|
12
|
Electrochemical detection of acetylcholine and choline: application to the quantitative nonradiochemical evaluation of choline transport. Anal Bioanal Chem 2008; 392:651-62. [DOI: 10.1007/s00216-008-2307-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Accepted: 07/17/2008] [Indexed: 01/31/2023]
|
13
|
Girelli AM, Mattei E. Application of immobilized enzyme reactor in on-line high performance liquid chromatography: A review. J Chromatogr B Analyt Technol Biomed Life Sci 2005; 819:3-16. [PMID: 15797515 DOI: 10.1016/j.jchromb.2005.01.031] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2004] [Accepted: 01/31/2005] [Indexed: 11/17/2022]
Abstract
This review summarizes all the research efforts in the last decade (1994-2003) that have been spent to the various application of immobilized enzyme reactor (IMER) in on-line high performance liquid chromatography (HPLC). All immobilization procedures including supports, kind of assembly into chromatographic system and methods are described. The effect of immobilization on enzymatic properties and stability of biocatalysts is considered. A brief survey of the main applications of IMER both as pre-column, post-column or column in the chemical, pharmaceutical, clinical and commodities fields is also reported.
Collapse
Affiliation(s)
- Anna Maria Girelli
- Dipartimento di Chimica, Università degli Studi di Roma La Sapienza, P.le A. Moro 5, 00185 Roma, Italy.
| | | |
Collapse
|
14
|
You T, Niwa O, Tomita M, Hirono S. Characterization of platinum nanoparticle-embedded carbon film electrode and its detection of hydrogen peroxide. Anal Chem 2003; 75:2080-5. [PMID: 12720344 DOI: 10.1021/ac026337w] [Citation(s) in RCA: 272] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A method for the highly sensitive determination of acetylcholine (ACh) and choline (Ch) that employs a graphite-like carbon film electrode containing 6.5% platinum (Pt) nanoparticles was developed for use as a detector in microbore liquid chromatography (LC) with a postcolumn enzyme reactor. The film electrode was prepared by RF cosputtering carbon and Pt, which requires only a one-step formation process. This method can control the Pt content of the film at a relatively low deposition temperature (below 200 degrees C). The average size of the Pt nanoparticles was 2.5 nm. The film electrode showed excellent electrocatalytic activity, high sensitivity, and negligible baseline drift when detecting hydrogen peroxide. The electrode was modified with glucose oxidase and responded rapidly to glucose with a much more stable baseline current than at a Pt bulk electrode based sensor. Therefore, it is appropriate to employ the electrode to detect trace amounts of biomolecules, such as neurotransmitters and hormones combined with various oxidase enzymes. We used the electrode as a detector for microbore LC and observed a low detection limit of 2.5 and 2.3 fmol (10-microL injection) for ACh and Ch, respectively, which is approximately 1 order of magnitude lower than that of a Pt bulk electrode.
Collapse
Affiliation(s)
- Tianyan You
- NTT Microsystem Integration Laboratories, 3-1 Morinosato, Wakamiya, Atsugi, Kanagawa 243-0198, Japan
| | | | | | | |
Collapse
|
15
|
Holm PI, Ueland PM, Kvalheim G, Lien EA. Determination of choline, betaine, and dimethylglycine in plasma by a high-throughput method based on normal-phase chromatography-tandem mass spectrometry. Clin Chem 2003; 49:286-94. [PMID: 12560353 DOI: 10.1373/49.2.286] [Citation(s) in RCA: 254] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The quaternary ammonium compounds, choline and betaine, and dimethylglycine (DMG) reside along a metabolic pathway linked to the synthesis of neurotransmitters and membrane phospholipids and to homocysteine remethylation and, therefore, folate status. Lack of a convenient, high-throughput method for the determination of these compounds has prevented population-based studies of their possible associations with lifestyle, nutrition, and chronic diseases. METHODS Serum or plasma samples were deproteinized by mixing with three volumes of acetonitrile that contained d(9)-choline and d(9)-betaine as internal standards. We used a normal-phase silica column for the separation of choline (retention time, 2.8 min), betaine (1.3 min), DMG (1.15 min), and internal standards, which were detected as positive ions by tandem mass spectroscopy in the multiple-reaction monitoring mode, using the molecular transitions m/z 104-->60 (choline), m/z 113-->69 (d(9)-choline), m/z 118-->59 (betaine), m/z 127-->68 (d(9)-betaine), and m/z 104-->58 (DMG). RESULTS For all three metabolites, the assay was linear in the range 0.4-400 micromol/L, and the lower limit of the detection (signal-to-noise ratio = 5) was < or =0.3 micromol/L. The within- and between-day imprecision (CVs) was 2.1-7.2% and 3.5-8.8%, respectively. The analytical recovery was 87-105%. The fasting plasma concentrations (median, 25th-75th percentiles) were 8.0 (7.0-9.3) micromol/L for choline, 31.7 (27.0-41.1) micromol/L for betaine, and 1.66 (1.30-2.02) micromol/L for DMG in 60 healthy blood donors. In individuals who had eaten a light breakfast, plasma concentrations of all three metabolites were significantly (25-30%) higher than in fasting individuals. CONCLUSION This is the first method for the combined measurement of choline, betaine, and DMG in human plasma or serum. The assay is characterized by simple sample preparation, no derivatization, high throughput, imprecision (CV) <10%, detection limits below the values seen in volunteers, and the high specificity provided by tandem mass spectroscopy.
Collapse
Affiliation(s)
- Pål I Holm
- LOCUS for Homocysteine and Related Vitamins, University of Bergen, N-5021 Bergen, Norway
| | | | | | | |
Collapse
|
16
|
Inoue T, Kirchhoff JR, Hudson RA. Enhanced measurement stability and selectivity for choline and acetylcholine by capillary electrophoresis with electrochemical detection at a covalently linked enzyme-modified electrode. Anal Chem 2002; 74:5321-6. [PMID: 12403587 DOI: 10.1021/ac020286l] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enzyme-modified microelectrodes were developed for the indirect amperometric detection of acetylcholine and choline following separation by capillary electrophoresis. Electrodes were prepared by first sequentially electrodepositing polypyrrole and polytyramine from the monomers on a 200-microm platinum electrode. The polymer bilayer provides enhanced selectivity and pendant amino groups for covalent coupling of acetylcholinesterase (AChE) and choline oxidase (ChO) by their reaction with glutaraldehyde. The AChE/ChO-modified electrode was then employed as an end-column detector to determine acetylcholine and choline with and without the internal standard butyrylcholine. Excellent operational stability during 2 days of continuous use was observed, with detection limits of 2 microM or 50 fmol for both acetylcholine and choline. The response from potential interferences, such as dopamine, catechol, and norepinephrine, were significantly reduced in comparison to a bare platinum electrode. The utility of this approach was demonstrated by monitoring the uptake of choline into synaptosomes.
Collapse
Affiliation(s)
- Takayo Inoue
- Department of Chemistry, College of Arts & Sciences, University of Toledo, Ohio 43606, USA
| | | | | |
Collapse
|
17
|
Papke RL, Porter Papke JK. Comparative pharmacology of rat and human alpha7 nAChR conducted with net charge analysis. Br J Pharmacol 2002; 137:49-61. [PMID: 12183330 PMCID: PMC1573461 DOI: 10.1038/sj.bjp.0704833] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. Pharmacological studies of alpha7 nicotinic acetylcholine receptors are confounded by the fact that rapid desensitization to high agonist concentration causes alpha7 peak responses to occur well in advance of complete solution exchange. For this reason, peak currents are an invalid measure of response to applied agonist concentrations. We show that results comparable to those that have been corrected for instantaneous concentration are obtained if net charge is used as the measure of receptor response. 2. Dose response curves obtained with these methods indicate that alpha7 receptors are approximately 10 fold more sensitive to agonist than previously reported. The agonists, ACh, choline, cytisine, GTS-21, 4OH-GTS-21 and 4-MeO-CA have the same rank order potency for both human and rat receptors: 4-MeO-CA > 4OH-GTS-21 > GTS-21 > cytisine > ACh > choline. However, differences in efficacy exist between rat and human receptors. GTS-21 is more efficacious for rat than human alpha7 receptors and cytosine more efficacious for human than rat alpha7 receptors. 3. Choline is the least potent agonist for both human and rat alpha7, with a potency approximately 10 fold lower than that of ACh. While the EC50 for the activation of alpha7 receptors by choline (400-500 microM) is outside the normal physiological range (10-100 microM), choline can nonetheless produce detectable levels of channel activation in the physiological concentration range. Since these concentrations are relatively non-desensitizing, the contribution of choline-activated alpha7 receptor current may play a significant role in the regulation of calcium homeostasis in alpha7-expressing neurons.
Collapse
Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, Box 100267 JHMHSC, University of Florida, Gainesville, Florida, FL 32610-0267, USA.
| | | |
Collapse
|
18
|
Kamimori H, Konishi M. Evaluation and application of liquid chromatographic columns coated with "intelligent" ligands. (III). Immobilized phospholipid column. ANAL SCI 2001; 17:1085-9. [PMID: 11708064 DOI: 10.2116/analsci.17.1085] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Immobilized enzyme columns have been developed for use as high-performance liquid chromatographic enzyme reactors. Enzyme reactors were prepared by immobilizing trypsin or cytochrome-c on phospholipid columns. Dynamic coating was employed to prepare the reactors by recycling a buffer solution containing trypsin or cytochrome-c through a phospholipid-coated column, on which the enzymes were immobilized by hydrophobic binding. The immobilized trypsin column displayed hydrolytic activity which catalyzed the hydrolysis of L-amino acid esters to amino acid. The immobilized cytochrome-c column exhibited oxidation activity which catalyzed N-demethylation of N,N-dimethylaniline, codeine, and dihydrocodeine in the presence of hydrogen peroxide as an oxygenating agent. The enzyme reaction proceeded rapidly in the column; both product and substrate could be separated and detected simultaneously. The immobilized enzyme columns could be readily regenerated using the original phospholipid column by repeating the dynamic coating. These immobilized enzyme columns could be utilized as enzyme reactors in the high-performance liquid chromatographic mode. Complete hydrolysis of amino acid ester was observed with the trypsin column. Demethylation of codeine and of dihydrocodeine were observed with the cytochrome-c column.
Collapse
Affiliation(s)
- H Kamimori
- Shionogi Research Laboratories, Shionogi & Co., Ltd., Fukushima, Osaka 553-0002, Japan.
| | | |
Collapse
|
19
|
Niwa O, Horiuchi T, Kurita R, Torimitsu K. On-line electrochemical sensor for selective continuous measurement of acetylcholine in cultured brain tissue. Anal Chem 1998; 70:1126-32. [PMID: 9530003 DOI: 10.1021/ac970257o] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An on-line acetylcholine (ACh) sensor was developed in order to determine extracellular ACh concentrations without interference from choline (Ch). The sensor is composed of a small-volume enzymatic prereactor (22-microL inner volume) in which choline oxidase and catalase are immobilized in series. Carbon electrodes were modified with an acetylcholine esterase (AChE), choline oxidase (ChOx), and osmium poly(vinylpyridine)-based redox polymer containing horseradish peroxidase (Os-gel-HRP). The sensor sensitivity was 43.7 nA/microM (+/- 0.15, n = 3) for ACh under optimized conditions. Almost no response was seen when 100 microM Ch was continuously injected. The detection limit for ACh with the sensor was comparable to that obtained using liquid chromatography with electrochemical detection combined with an enzymatic reactor. The electrical stimulation of cultured rat hippocampal tissue resulted in an extracellular ACh increase of 20 nM (+/- 11 nM, n = 3). This increase was observed continuously with our online sensor combined with a microcapillary sampling probe located very close to the tissue. The continuous measurement of ACh and Ch using a split disk carbon film dual electrode in which one electrode surface was modified with ChOx/Os-gel-HRP and the other with AChE-ChOx/Os-gel-HRP bilayer film was also demonstrated to improve the response time by eliminating the prereactor.
Collapse
Affiliation(s)
- O Niwa
- NTT Basic Research Laboratories, Kanagawa, Japan
| | | | | | | |
Collapse
|
20
|
Pierce SK, Dragolovich J, Crombie BN. Variations in intracellular choline levels may account for differences in glycine betaine synthesis between conspecific oyster populations responding to hyperosmotic stress. ACTA ACUST UNITED AC 1997. [DOI: 10.1002/(sici)1097-010x(19970801)278:5<283::aid-jez2>3.0.co;2-l] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
21
|
Horiuchi T, Torimitsu K, Yamamoto K, Niwa O. On-line flow sensor for measuring acetylcholine combined with microdialysis sampling probe. ELECTROANAL 1997. [DOI: 10.1002/elan.1140091209] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
22
|
Chen S, Soneji V, Webster J. Determination of choline in pharmaceutical formulations by reversed-phase high-performance liquid chromatography and postcolumn suppression conductivity detection. J Chromatogr A 1996; 739:351-7. [PMID: 8765854 DOI: 10.1016/0021-9673(96)00215-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Choline is a primary degradation product of succinylcholine chloride. Determination of low concentration choline in succinylcholine chloride bulk drug and formulation is a challenge, due to the lack of sensitive detection methods. A reversed-phase separation method with postcolumn suppression conductivity detection is described for the determination of choline. Hexanesulfonic acid is employed as an ion-pair reagent in the mobile phase, which allows the accomplishment of both reversed-phase separation and a sensitive conductivity detection. Detection sensitivity is significantly enhanced by passing the mobile phase through a postcolumn cation suppressor, where hexanesulfonic acid is removed and the background conductance is reduced. This method is simple and sensitive. No sample derivatization procedure is required. The detection limit for choline is about 10 pmol.
Collapse
Affiliation(s)
- S Chen
- Abbott Laboratories, Department 98U, Abbott Park, IL 60064, USA
| | | | | |
Collapse
|
23
|
|