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Sugiki T, Lee YH, Alsanousi N, Murata K, Kawamura I, Fujiwara T, Hanada K, Kojima C. A hybrid strategy combining solution NMR spectroscopy and isothermal titration calorimetry to characterize protein-nanodisc interaction. Anal Biochem 2021; 639:114521. [PMID: 34906540 DOI: 10.1016/j.ab.2021.114521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 12/03/2021] [Accepted: 12/04/2021] [Indexed: 11/19/2022]
Abstract
NMR is a powerful tool for characterizing intermolecular interactions at atomic resolution. However, the nature of the complex interactions of membrane-binding proteins makes it difficult to elucidate the interaction mechanisms. Here, we demonstrated that structural and thermodynamic analyses using solution NMR spectroscopy and isothermal titration calorimetry (ITC) can clearly detect a specific interaction between the pleckstrin homology (PH) domain of ceramide transport protein (CERT) and phosphatidylinositol 4-monophosphate (PI4P) embedded in the lipid nanodisc, and distinguish the specific interaction from nonspecific interactions with the bulk surface of the lipid nanodisc. This NMR-ITC hybrid strategy provides detailed characterization of protein-lipid membrane interactions.
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Affiliation(s)
- Toshihiko Sugiki
- Institute for Protein Research, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Young-Ho Lee
- Institute for Protein Research, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan; Research Center for Bioconvergence Analysis, Korea Basic Science Institute, Chungcheongbuk-do, 28119, South Korea; Bio-Analytical Science, University of Science and Technology, Daejeon, 34113, South Korea; Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon, 34134, South Korea
| | - Nesreen Alsanousi
- Institute for Protein Research, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kaito Murata
- Graduate School of Engineering Science, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Izuru Kawamura
- Graduate School of Engineering Science, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan
| | - Toshimichi Fujiwara
- Institute for Protein Research, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Chojiro Kojima
- Institute for Protein Research, Osaka University, Yamadaoka, Suita, Osaka, 565-0871, Japan; Graduate School of Engineering Science, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama, 240-8501, Japan.
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James Abraham J, Moossa B, Tariq HA, Kahraman R, Al-Qaradawi S, Shakoor RA. Electrochemical Performance of Na 3V 2(PO 4) 2F 3 Electrode Material in a Symmetric Cell. Int J Mol Sci 2021; 22:12045. [PMID: 34769476 PMCID: PMC8584735 DOI: 10.3390/ijms222112045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/03/2021] [Accepted: 11/05/2021] [Indexed: 11/16/2022] Open
Abstract
A NASICON-based Na3V2(PO4)2F3 (NVPF) cathode material is reported herein as a potential symmetric cell electrode material. The symmetric cell was active from 0 to 3.5 V and showed a capacity of 85 mAh/g at 0.1 C. With cycling, the NVPF symmetric cell showed a very long and stable cycle life, having a capacity retention of 61% after 1000 cycles at 1 C. The diffusion coefficient calculated from cyclic voltammetry (CV) and the galvanostatic intermittent titration technique (GITT) was found to be ~10-9-10-11, suggesting a smooth diffusion of Na+ in the NVPF symmetric cell. The electrochemical impedance spectroscopy (EIS) carried out during cycling showed increases in bulk resistance, solid electrolyte interphase (SEI) resistance, and charge transfer resistance with the number of cycles, explaining the origin of capacity fade in the NVPF symmetric cell. Finally, the postmortem analysis of the symmetric cell after 1000 cycles at a 1 C rate indicated that the intercalation/de-intercalation of sodium into/from the host structure occurred without any major structural destabilization in both the cathode and anode. However, there was slight distortion in the cathode structure observed, which resulted in capacity loss of the symmetric cell. The promising electrochemical performance of NVPF in the symmetric cell makes it attractive for developing long-life and cost-effective batteries.
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Affiliation(s)
- Jeffin James Abraham
- Center for Advanced Materials (CAM), Qatar University, Doha P.O. Box 2713, Qatar; (J.J.A.); (B.M.); (H.A.T.)
| | - Buzaina Moossa
- Center for Advanced Materials (CAM), Qatar University, Doha P.O. Box 2713, Qatar; (J.J.A.); (B.M.); (H.A.T.)
| | - Hanan Abdurehman Tariq
- Center for Advanced Materials (CAM), Qatar University, Doha P.O. Box 2713, Qatar; (J.J.A.); (B.M.); (H.A.T.)
| | - Ramazan Kahraman
- Department of Chemical Engineering, College of Engineering, Qatar University, Doha P.O. Box 2713, Qatar;
| | - Siham Al-Qaradawi
- Department of Chemistry & Earth Sciences, College of Arts and Science, Qatar University, Doha P.O. Box 2713, Qatar;
| | - R. A. Shakoor
- Center for Advanced Materials (CAM), Qatar University, Doha P.O. Box 2713, Qatar; (J.J.A.); (B.M.); (H.A.T.)
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Giaccari A, Bonadonna RC, Buzzetti R, Perseghin G, Cucinotta D, Fanelli C, Avogaro A, Aimaretti G, Larosa M, Pagano V, Bolli GB. Similar glycaemic control and risk of hypoglycaemia with patient- versus physician-managed titration of insulin glargine 300 U/mL across subgroups of patients with T2DM: a post hoc analysis of ITAS. Acta Diabetol 2021; 58:789-796. [PMID: 33586058 PMCID: PMC8110495 DOI: 10.1007/s00592-021-01675-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 01/09/2021] [Indexed: 12/02/2022]
Abstract
AIMS The Italian Titration Approach Study (ITAS) demonstrated comparable HbA1c reductions and similarly low hypoglycaemia risk at 6 months in poorly controlled, insulin-naïve adults with T2DM who initiated self- or physician-titrated insulin glargine 300 U/mL (Gla-300) in the absence of sulphonylurea/glinide. The association of patient characteristics with glycaemic and hypoglycaemic outcomes was assessed. METHODS This post hoc analysis investigated whether baseline patient characteristics and previous antihyperglycaemic drugs were associated with HbA1c change and hypoglycaemia risk in patient- versus physician-managed Gla-300 titration. RESULTS HbA1c change, incidence of hypoglycaemia (any type) and nocturnal rates were comparable between patient- and physician-managed arms in all subgroups. Hypoglycaemia rates across subgroups (0.03 to 3.52 events per patient-year) were generally as low as observed in the full ITAS population. Small increases in rates of 00:00-pre-breakfast and anytime hypoglycaemia were observed in the ≤ 10-year diabetes duration subgroup in the patient- versus physician-managed arm (heterogeneity of effect; p < 0.05). CONCLUSIONS Comparably fair glycaemic control and similarly low hypoglycaemia risk were achieved in almost all patient subgroups with patient- versus physician-led Gla-300 titration. These results reinforce efficacy and safety of Gla-300 self-titration across a range of phenotypes of insulin-naïve people with T2DM. CLINICAL TRIAL REGISTRATION EudraCT 2015-001167-39.
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Affiliation(s)
- Andrea Giaccari
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome and Università Cattolica del Sacro Cuore, Rome, Italy
| | - R. C. Bonadonna
- Division of Endocrinology and Metabolic Diseases and Department of Medicine and Surgery, University of Parma and AOU of Parma, Parma, Italy
| | - R. Buzzetti
- Sapienza University of Rome, Piazzale Aldo Moro, 5, 00185 Rome, RM Italy
| | - G. Perseghin
- University of Milan Bicocca, Piazza dell’Ateneo Nuovo, 1, 20126 Milan, MI Italy
| | - D. Cucinotta
- University of Messina, Piazza Pugliatti, 1, 98122 Messina, Italy
| | - C. Fanelli
- Section of Endocrinology and Metabolism, Department of Medicine, Perugia University Medical School, Piazzale Gambuli, 1, 06129 Perugia, PG Italy
| | - A. Avogaro
- University of Padua, Via 8 Febbraio 1848, 2, 35122 Padua, PD Italy
| | - G. Aimaretti
- University of the Eastern Piedmont, Via del Duomo, 6, 13100 Vercelli, VC Italy
| | | | - V. Pagano
- OPIS s.r.l., Palazzo Aliprandi, Via Matteotti, 10, 20832 Desio, Italy
| | - G. B. Bolli
- Section of Endocrinology and Metabolism, Department of Medicine, Perugia University Medical School, Piazzale Gambuli, 1, 06129 Perugia, PG Italy
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McKenzie-Coe A, Shortt R, Jones LM. THE MAKING OF A FOOTPRINT IN PROTEIN FOOTPRINTING: A REVIEW IN HONOR OF MICHAEL L. GROSS. Mass Spectrom Rev 2021; 40:177-200. [PMID: 32400038 PMCID: PMC7849054 DOI: 10.1002/mas.21632] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/17/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
Within the past decade protein footprinting in conjunction with mass spectrometry has become a powerful and versatile means to unravel the higher order structure of proteins. Footprinting-based approaches has demonstrated the capacity to inform on interaction sites and dynamic regions that participate in conformational changes. These findings when set in a biological perspective inform on protein folding/unfolding, protein-protein interactions, and protein-ligand interactions. In this review, we will look at the contribution of Dr. Michael L. Gross to protein footprinting approaches such as hydrogen deuterium exchange mass spectrometry and hydroxyl radical protein footprinting. This review details the development of novel footprinting methods as well as their applications to study higher order protein structure. © 2020 The Authors. Mass Spectrometry Reviews published by John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Alan McKenzie-Coe
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
| | - Raquel Shortt
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
| | - Lisa M Jones
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
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Zhao W, Michalik D, Ferguson S, Hofstetter W, Lemaître J, von Rechenberg B, Bowen P. Rapid evaluation of bioactive Ti-based surfaces using an in vitro titration method. Nat Commun 2019; 10:2062. [PMID: 31048680 PMCID: PMC6497645 DOI: 10.1038/s41467-019-09673-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 03/16/2019] [Indexed: 11/25/2022] Open
Abstract
The prediction of implant behavior in vivo by the use of easy-to-perform in vitro methods is of great interest in biomaterials research. Simulated body fluids (SBFs) have been proposed and widely used to evaluate the bone-bonding ability of implant materials. In view of its limitations, we report here a rapid in vitro method based on calcium titration for the evaluation of in vivo bioactivity. Using four different titanium surfaces, this method identifies that alkaline treatment is the key process to confer bioactivity to titanium whereas no significant effect from heat treatment is observed. The presence of bioactive titanium surfaces in the solution during calcium titration induces an earlier nucleation of crystalline calcium phosphates and changes the crystallization pathway. The conclusions from this method are also supported by the standard SBF test (ISO 23317), in vitro cell culture tests using osteoblasts and in vivo animal experiments employing a pelvic sheep model.
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Affiliation(s)
- Weitian Zhao
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - David Michalik
- Musculoskeletal Research Unit, University of Zürich, Zürich, Switzerland
| | - Stephen Ferguson
- Institute for Biomechanics, ETH-Zürich, Zürich, Switzerland
- Competence Center for Applied Biotechnology and Molecular Medicine (CABMM), University of Zurich, Zurich, Switzerland
| | - Willy Hofstetter
- Graduate School of Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Jacques Lemaître
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Brigitte von Rechenberg
- Musculoskeletal Research Unit, University of Zürich, Zürich, Switzerland
- Competence Center for Applied Biotechnology and Molecular Medicine (CABMM), University of Zurich, Zurich, Switzerland
| | - Paul Bowen
- Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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Luo A, Zheng Y, Chen X, Cong F. Undergraduate laboratory experiment on determination of total protein content in milk powder by moving reaction boundary titration. Biochem Mol Biol Educ 2018; 46:644-651. [PMID: 30387293 DOI: 10.1002/bmb.21177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 08/27/2018] [Accepted: 09/10/2018] [Indexed: 06/08/2023]
Abstract
Laboratory exercises focused on protein quantification are frequently conducted in traditional undergraduate biochemistry laboratory curriculum. The laboratory course described here is designed to provide students with experience in measurement of protein content in milk powder by moving reaction boundary titration (MRBT), a new rapid technique for total protein content determination in milk. In addition, this approach is weakly influenced by nonprotein nitrogen reagents such as melamine and urea. The course was done as three weekly laboratory exercises. First, students established a standard curve for milk protein concentration by MRBT method. Then, students investigated the influence of nonprotein nitrogen reagents on MRBT method. Finally, students made a comparison among three different protein quantification methods (MRBT, Biuret, and Kjeldahl method). From the experiments, students grasped the concept and advantages of MRBT and deepened the understanding of protein quantification. This course offer students the opportunity to be exposed to an advanced technique, which may have practical significance to their future study and work in the life science field. © 2018 International Union of Biochemistry and Molecular Biology, 46(6):644-651, 2018.
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Affiliation(s)
- Anling Luo
- Department of Biochemistry and Molecular Biology, School of life Sciences and Biotechnology, Shanghai Jiaotong University, Shanghai, China
| | - Youli Zheng
- Department of Biochemistry and Molecular Biology, School of life Sciences and Biotechnology, Shanghai Jiaotong University, Shanghai, China
| | - Xinxin Chen
- Department of Biochemistry and Molecular Biology, School of life Sciences and Biotechnology, Shanghai Jiaotong University, Shanghai, China
| | - Fengsong Cong
- Department of Biochemistry and Molecular Biology, School of life Sciences and Biotechnology, Shanghai Jiaotong University, Shanghai, China
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Young M, Gilmore EA, McDonald-Gibson RG, Elliott JA. A Comparison of Gas-Liquid Chromatography and a Titration Method for the Determination of Plasma Non-Esterified Fatty Acid Levels during Pregnancy. Ann Clin Biochem 2016; 12:249-51. [PMID: 15637883 DOI: 10.1177/000456327501200165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The level of plasma non-esterified fatty acids (NEFA) was measured by gas-liquid chromatography (GLC) and a titration method in 194 samples collected during pregnancy and from four days to 24 weeks post partum. Both techniques indicated a similar pattern of changes in plasma NEFA associated with pregnancy. The titration estimates of NEFA level were usually greater than those measured by GLC, and there was some suggestion that the disparity between the methods was increased at the end of pregnancy and was reduced at six weeks after delivery.
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Affiliation(s)
- M Young
- M.R.C. Reproduction and Growth Unit, Princess Mary Maternity Hospital, Newcastle upon Tyne NE2 3RD
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Mayberry C, Mawson P, Maloney SK. Plasma cholinesterase activity of rats, western grey kangaroos, alpacas, sheep, cattle, and horses. J Pharmacol Toxicol Methods 2015; 72:26-8. [PMID: 25598182 DOI: 10.1016/j.vascn.2015.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 01/06/2015] [Accepted: 01/07/2015] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Plasma cholinesterase activity levels of various species may be of interest to toxicologists or pathologists working with chemicals that interfere with the activity of plasma cholinesterase. METHODS We used a pH titration method to measure the plasma cholinesterase activity of six mammalian species. RESULTS Plasma cholinesterase activity varied up to 50-fold between species: sheep (88 ± 45 nM acetylcholine degraded per ml of test plasma per minute), cattle (94 ± 35), western grey kangaroos (126 ± 92), alpaca (364 ± 70), rats (390 ± 118) and horses (4539 ± 721). DISCUSSION We present a simple, effective technique for the assay of plasma cholinesterase activity levels from a range of species. Although labour-intensive, it requires only basic laboratory equipment.
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Affiliation(s)
- Chris Mayberry
- School of Animal Biology, The University of Western Australia, Stirling Highway, Crawley 6009, Western Australia, Australia
| | - Peter Mawson
- School of Animal Biology, The University of Western Australia, Stirling Highway, Crawley 6009, Western Australia, Australia; Perth Zoo, 20 Labouchere Road, South Perth 6151, Western Australia, Australia
| | - Shane K Maloney
- School of Anatomy, Physiology, and Human Biology, The University of Western Australia, Stirling Highway, Crawley 6009, Western Australia, Australia
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Lützhøft HCH, Boe K, Fang C, Angelidaki I. Comparison of VFA titration procedures used for monitoring the biogas process. Water Res 2014; 54:262-272. [PMID: 24583519 DOI: 10.1016/j.watres.2014.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 01/27/2014] [Accepted: 02/01/2014] [Indexed: 06/03/2023]
Abstract
Titrimetric determination of volatile fatty acids (VFAs) contents is a common way to monitor a biogas process. However, digested manure from co-digestion biogas plants has a complex matrix with high concentrations of interfering components, resulting in varying results when using different titration procedures. Currently, no standardized procedure is used and it is therefore difficult to compare the performance among plants. The aim of this study was to evaluate four titration procedures (for determination of VFA-levels of digested manure samples) and compare results with gas chromatographic (GC) analysis. Two of the procedures are commonly used in biogas plants and two are discussed in literature. The results showed that the optimal titration results were obtained when 40 mL of four times diluted digested manure was gently stirred (200 rpm). Results from samples with different VFA concentrations (1-11 g/L) showed linear correlation between titration results and GC measurements. However, determination of VFA by titration generally overestimated the VFA contents compared with GC measurements when samples had low VFA concentrations, i.e. around 1 g/L. The accuracy of titration increased when samples had high VFA concentrations, i.e. around 5 g/L. It was further found that the studied ionisable interfering components had lowest effect on titration when the sample had high VFA concentration. In contrast, bicarbonate, phosphate and lactate had significant effect on titration accuracy at low VFA concentration. An extended 5-point titration procedure with pH correction was best to handle interferences from bicarbonate, phosphate and lactate at low VFA concentrations. Contrary, the simplest titration procedure with only two pH end-points showed the highest accuracy among all titration procedures at high VFA concentrations. All in all, if the composition of the digested manure sample is not known, the procedure with only two pH end-points should be the procedure of choice, due to its simplicity and accuracy.
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Affiliation(s)
| | - Kanokwan Boe
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, DK-2800 Kgs. Lyngby, Denmark.
| | - Cheng Fang
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, DK-2800 Kgs. Lyngby, Denmark
| | - Irini Angelidaki
- Department of Environmental Engineering, Technical University of Denmark, Miljøvej 113, DK-2800 Kgs. Lyngby, Denmark.
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Affiliation(s)
- Tinakorn Kanyanee
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence for Innovation in Analytical Science and Technology, Chiang Mai University, Chiang Mai 50200, Thailand.
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Andres SA, Bumpus SB, Wittliff JL. Assessment of phytoestrogen and mycoestrogen recognition by recombinant human estrogen receptor-α using ligand titration arrays. Phytochem Anal 2013; 24:357-366. [PMID: 23401334 DOI: 10.1002/pca.2417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 11/27/2012] [Accepted: 11/30/2012] [Indexed: 06/01/2023]
Abstract
INTRODUCTION Exposure to phytoestrogens and mycoestrogens has emerged as a public health issue due to their potentially endocrine disruption activities resulting from direct interaction with sex-steroid hormone receptors. There is a significant requirement for comprehensive, reproducible methods to determine the extent of estrogen mimicry by compounds encountered in the environment to estimate risk:benefit ratios, particularly in humans. OBJECTIVE To develop a systematic approach for assessing recognition of chemically diverse compounds by human estrogen receptor proteins to aid in their assessment as endocrine disruptor compounds (EDCs). METHODS Recombinant human estrogen receptor-α protein (rhERα) was expressed in Saccharomyces cervisiae as an ubiquitin fusion under control of a CUP1 promoter and partially purified with heparin affinity chromatography in the unliganded state. A novel radio-ligand binding array was developed to evaluate structurally diverse compounds, both naturally occurring and synthetic, for estrogen binding activity and affinity. RESULTS Binding affinities of suspected estrogen mimics for rhERα were calculated over a range of [(3) H]estradiol-17β concentrations using Lundon OneSite® and Compete® software. CONCLUSION β-zearalanol, a mycoestrogen similar to zearalenone used as an ICCVAM validation substance for the in vitro estrogen receptor binding assays (ICCAM report), was employed as a model estrogen mimic to illustrate the approach, methods and calculations using these techniques.
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Affiliation(s)
- Sarah A Andres
- Department of Biochemistry and Molecular Biology, Brown Cancer Center and the Institute for Molecular Diversity and Drug Design, University of Louisville, Louisville, KY 40292, USA
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Abstract
Isothermal titration calorimetry is a highly sensitive technique for the study of molecular interactions. This method has been applied quite extensively to investigate the interaction of proteins with small ligands, other proteins, and nucleic acids as well as with drugs and metal ions. In this chapter, we describe the application of ITC for the investigation of thermodynamics of protein-lipid interaction. A number of parameters such as enthalpy of binding (ΔH), entropy of binding (ΔS), association constant (K (a)), binding stoichiometry (n), and free energy of binding (ΔG) can be obtained from a single calorimetric titration, providing a complete thermodynamic characterization of the interaction. The method is described in detail taking the major protein of the bovine seminal plasma, PDC-109, which exhibits a high preference for interaction with choline-containing lipids, as an example. The method can be applied to investigate the thermodynamics of the interaction of other soluble proteins with lipid membranes.
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Affiliation(s)
- Musti J Swamy
- School of Chemistry, University of Hyderabad, Hyderabad, India.
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Graber ZT, Kooijman EE. Ionization behavior of polyphosphoinositides determined via the preparation of pH titration curves using solid-state 31P NMR. Methods Mol Biol 2013; 1009:129-142. [PMID: 23681530 DOI: 10.1007/978-1-62703-401-2_13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Detailed knowledge of the degree of ionization of lipid titratable groups is important for the evaluation of protein-lipid and lipid-lipid interactions. The degree of ionization is commonly evaluated by acid-base titration, but for lipids localized in a multicomponent membrane interface this is not a suitable technique. For phosphomonoester-containing lipids such as the polyphosphoinositides, phosphatidic acid, and ceramide-1-phosphate, this is more conveniently accomplished by (31)P NMR. Here, we describe a solid-state (31)P NMR procedure to construct pH titration curves to determine the degree of ionization of phosphomonoester groups in polyphosphoinositides. This procedure can also be used, with suitable sample preparation conditions, for other important signaling lipids. Access to a solid-state, i.e., magic angle spinning, capable NMR spectrometer is assumed. The procedures described here are valid for a Bruker instrument, but can be adapted for other spectrometers as needed.
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Vermeire J, Naessens E, Vanderstraeten H, Landi A, Iannucci V, Van Nuffel A, Taghon T, Pizzato M, Verhasselt B. Quantification of reverse transcriptase activity by real-time PCR as a fast and accurate method for titration of HIV, lenti- and retroviral vectors. PLoS One 2012; 7:e50859. [PMID: 23227216 PMCID: PMC3515444 DOI: 10.1371/journal.pone.0050859] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 10/29/2012] [Indexed: 11/19/2022] Open
Abstract
Quantification of retroviruses in cell culture supernatants and other biological preparations is required in a diverse spectrum of laboratories and applications. Methods based on antigen detection, such as p24 for HIV, or on genome detection are virus specific and sometimes suffer from a limited dynamic range of detection. In contrast, measurement of reverse transcriptase (RT) activity is a generic method which can be adapted for higher sensitivity using real-time PCR quantification (qPCR-based product-enhanced RT (PERT) assay). We present an evaluation of a modified SYBR Green I-based PERT assay (SG-PERT), using commercially available reagents such as MS2 RNA and ready-to-use qPCR mixes. This assay has a dynamic range of 7 logs, a sensitivity of 10 nU HIV-1 RT and outperforms p24 ELISA for HIV titer determination by lower inter-run variation, lower cost and higher linear range. The SG-PERT values correlate with transducing and infectious units in HIV-based viral vector and replication-competent HIV-1 preparations respectively. This assay can furthermore quantify Moloney Murine Leukemia Virus-derived vectors and can be performed on different instruments, such as Roche Lightcycler® 480 and Applied Biosystems ABI 7300. We consider this test to be an accurate, fast and relatively cheap method for retroviral quantification that is easily implemented for use in routine and research laboratories.
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Affiliation(s)
- Jolien Vermeire
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Evelien Naessens
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Hanne Vanderstraeten
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Alessia Landi
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Veronica Iannucci
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Anouk Van Nuffel
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Tom Taghon
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Massimo Pizzato
- Centre for Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Bruno Verhasselt
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
- * E-mail:
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16
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Papaneophytou CP, Kontopidis GA. Optimization of TNF-α overexpression in Escherichia coli using response surface methodology: Purification of the protein and oligomerization studies. Protein Expr Purif 2012; 86:35-44. [PMID: 22989548 DOI: 10.1016/j.pep.2012.09.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/31/2012] [Accepted: 09/07/2012] [Indexed: 12/29/2022]
Abstract
Tumor necrosis factor-α (TNF-α) is responsible for many autoimmune disorders including rheumatoid arthritis, psoriasis, Chron's disease, stroke, and atherosclerosis. Thus, inhibition of TNF-α is a major challenge in drug discovery. However, a sufficient amount of purified protein is needed for the in vitro screening of potential TNF-α inhibitors. In this work, induction conditions for the production of human TNF-α fusion protein in a soluble form by recombinant Escherichia coli BL21(DE3) pLysS were optimized using response surface methodology based on the central composite design. The induction conditions included cell density prior induction (OD(600nm)), post-induction temperature, IPTG concentration and post-induction time. Statistical analysis of the results revealed that all variables and their interactions had significant impact on production of soluble TNF-α. An 11% increase of TNF-α production was achieved after determination of the optimum induction conditions: OD(600nm) prior induction 0.55, a post induction temperature of 25°C, an IPTG concentration of 1mM and a post-induction time of 4h. We have also studied TNF-α oligomerization, the major property of this protein, and a K(d) value of 0.26nM for protein dimerization was determined. The concentration of where protein trimerization occurred was also detected. However, we failed to determine a reliable K(d) value for protein trimerization probably due to the complexibility of our model.
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Affiliation(s)
- Christos P Papaneophytou
- The Centre for Research and Technology of Thessaly, 3rd km Karditsa-Mitropolis, Karditsa 43100, Greece
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17
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Mercadante S, Gatti A, Porzio G, Lo Presti C, Aielli F, Adile C, Casuccio A. Dosing fentanyl buccal tablet for breakthrough cancer pain: dose titration versus proportional doses. Curr Med Res Opin 2012; 28:963-8. [PMID: 22480130 DOI: 10.1185/03007995.2012.683112] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES The aim of this study was to compare the efficacy and safety of doses of fentanyl buccal tablet (FBT) proportional to doses of opioids used for background analgesia versus dose titration starting with the minimal dose for the management of breakthrough cancer pain (BTcP). METHODS A total of 82 cancer patients with BTcP who were receiving strong opioids in doses of at least 60 mg of oral morphine equivalents and having acceptable background analgesia, were selected for a multicenter unblinded study. Forty-one patients were randomized to receive FBT in doses proportional to the daily opioid doses for four consecutive episodes of BTcP (group P). Forty-one patients underwent dose titration of FBT, with an initial dose of 100 µg, for four consecutive episodes (group T). Pain intensity and symptoms associated with opioid therapy were measured before administering any dose of FBT (T0) and 15 minutes after (T15). RESULTS In all, 80 patients were considered for analysis (39 and 41 patients in group P and T, respectively). Patients were receiving a mean of 126 ± 100 mg of oral morphine equivalents (range 60-480 mg) for background analgesia. A total of 293 episodes of BTcP (144 and 149 in group P and T, respectively) were treated and considered for analysis. No differences were found in the decrease of pain intensity between the two groups. However, in patients receiving doses of oral morphine equivalents of >120 mg/day, a significant number of patients obtained a decrease in pain intensity >50% in group P in comparison with group T (p = 0.040). Also, the need for rescue medication was significantly more frequently reported in group T for the first episode of BTcP (p < 0.0005). No differences in the level of adverse effects were observed between the two groups. No differences in patients' satisfaction were reported. CONCLUSION According to the data obtained in this study, there is no evidence for the use of dose titration in the management of BTcP in opioid-tolerant patients. Indeed, doses proportional to basal opioid regimen for background pain seem to be effective and safe in the majority of patients. Further studies should confirm this data in patients receiving higher doses of opioids, with other rapid-onset opioids, and in other settings.
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18
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Chironi G. [New biomarkers for cardiovascular risk evaluation]. Rev Prat 2012; 62:783-785. [PMID: 22838270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Biomarkers aim at refining risk prediction and at better identifying individuals at high cardiovascular risk. To be recommended in clinical practice, a novel biomarker should be simple to measure, non-invasive, cost-effective, reproducible, and should provide a predictive and discriminative value independently of, and beyond existing risk scores. In addition, it should offer a favourable impact on morbidity, mortality and disability of the disease. Among the hundreds of candidate circulating biomarkers, certain have shown solid statistical associations with the incidence of future events, as is the case for high-sensitivity C-reactive protein. However, contrary to subclinical atherosclerosis assessment, they offer only a modest increase in the predictive value of current scores. To date, the main interest of cardiovascular biomarkers in primary prevention is to better understand pathophysiological mechanisms of atherosclerosis in the research setting.
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Affiliation(s)
- Gilles Chironi
- AP-HP, hôpital européen Georges-Pompidou, centre de médecine préventive cardiovasculaire.
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19
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Li T, Tan XM, Long Q, Chen FL. [Research on TLC identification and anti-coagulant activity quantitatively methods of Scolopendra subspinipes mutilans]. Zhong Yao Cai 2012; 35:686-689. [PMID: 23213726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
OBJECTIVE To improve the quality standard of Scolopendra subspinipes mutilans by researching the methods of the TLC identification and anti-coagulant activity quantitatively. METHODS Identified the free arginine (Arg) and serine (Ser) in scolopendra by TLC, screened the samples preparation process and developed solvent systems; Determined the anti-coagulant activity by method of titration with thrombin and screened the pretreatment methods. RESULTS When medicinal materials was extracted by formic acid and 95% ethanol (1:1) with ultrasonic method and developed by n-butanol-acetic acid-water (12:5:4), the spots of Arg and Ser were well separated. Ultrasonic method was suitable for preparation of the anti-coagulant components in Scolopendra subspinipes mutilans and their anti-coagulant activity was determined by method of titration with thrombin could get a well reproducibility, the anti-thrombin activity of testing sample was (14.00 +/- 1.53) U/g and those of three different batch were (13.00 +/- 0.58) U/g, (17.00 +/- 1.15) U/g, (15.67 +/- 1.53) U/g respectively. CONCLUSION The methods of TLC identification and anti-coagulant activity quantitatively could be used as a basis for improving the quality standard of Scolopendra subspinipes mutilans.
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Affiliation(s)
- Tao Li
- Key Laboratory of Chinese Materia Medica Preparation of Guangdong Province, School of Traditional Chinese Medicine, Southern Medical University, Guangzhou 510515, China.
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20
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Meloun M, Ferenčíková Z, Javůrek M. Reliability of dissociation constants and resolution capability of SQUAD(84) and SPECFIT/32 in the regression of multiwavelength spectrophotometric pH-titration data. Spectrochim Acta A Mol Biomol Spectrosc 2012; 86:305-314. [PMID: 22078078 DOI: 10.1016/j.saa.2011.10.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 08/23/2011] [Accepted: 10/17/2011] [Indexed: 05/31/2023]
Abstract
The resolving power of multicomponent spectral analysis and the computation reliability of the stability constants and molar absorptivities determined for five variously protonated anions of physostigmine salicylate by the SQUAD(84) and SPECFIT/32 programs has been examined with the use of simulated and experimental spectra containing overlapping spectral bands. The reliability of the dissociation constants of drug was proven with goodness-of-fit tests and by examining the influence of pre-selected noise level s(inst)(A) in synthetic spectra regarding the precision s(pK) and also accuracy of the estimated dissociation constants. Precision was examined as the linear regression model s(pK)=β(0)+β(1)s(inst)(A). In all cases the intercept β(0) was statistically insignificant. When an instrumental error s(inst)(A) is small and less than 0.5 mAU, the parameters' estimates are nearly the same as the bias ΔpK=pK(a,calc)-pK(a,true) is quite negligible. In all four dissociation constants the bias seems to be quite small even though for pK(a4) it is a little bit higher, i.e., +0.05 for s(inst)(A) about 1.0 mAU. In the interval of s(inst)(A) from 0.1 to 1.0 mAU all four dissociation constants pK(i) are accurate enough. Of the various regression diagnostics considered, the goodness-of-fit is the most efficient criterion of whether the parameters found adequately represent the data. The magnitude of instrumental error s(inst)(A) only slightly affects the shape of a Cattel's scree graph s(k)(A)=f(k) to determine the true number of light-absorbing species in the equilibrium mixture.
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Affiliation(s)
- Milan Meloun
- Department of Analytical Chemistry, University of Pardubice, CZ 532 10 Pardubice, Czech Republic.
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21
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Lee SK, Yeoh HK, Chua ASM, Ngoh GC. Applying the least squares method for the titrimetric determination of the concentration of VFA. Water Sci Technol 2012; 66:620-626. [PMID: 22744694 DOI: 10.2166/wst.2012.216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The titrimetric method is used for on-site measurement of the concentration of volatile fatty acids (VFAs) in anaerobic treatment. In current practice, specific and interpolated pH-volume data points are used to obtain the concentration of VFA by solving simultaneous equations iteratively to convergence (denoted as SEq). Here, the least squares method (LSM) is introduced as an elegant alternative. Known concentrations of VFA (acetic acid and/or propionic acid) ranging from to 200 to 1,000 mg/L were determined using SEq and LSM. Using standard numbers of data points, SEq gave more accurate results compared with LSM. However, results favoured LSM when all data points in the range were included without any interpolation. For model refinement, unit monovalent activity coefficient (f(m) = 1) was found reasonable and arithmetic averages of dissociation constants and molecular weight of 80 mol% acetic acid were recommended in the model for VFA determination of mixtures. An accurate result was obtained with a mixture containing more VFA (butyric acid and valeric acid). In a typical VFA measurement of real anaerobic effluent, a satisfactory result with an error of 14% was achieved. LSM appears to be a promising mathematical model solver for determination of concentration of VFA in the titrimetric method. Validation of LSM in the presence of other electrolytes deserves further exploration.
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Affiliation(s)
- Soo Koon Lee
- Department of Chemical Engineering, University of Malaya, Kuala Lumpur, Malaysia
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22
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Duicu O, Gheorgheosu D, Mirica N, Trancotă S, Cristina D, Firă-Mladinescu O, Muntean D. High-resolution respirometry with multiple substrates titration in permeabilized myocardial fibers. Rev Med Chir Soc Med Nat Iasi 2012; 116:207-213. [PMID: 23077897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The present study was purported to standardize the high-resolution respirometry technique for the analysis of oxidative phosphorylation (OXPHOS) in saponin-skinned cardiac fibers. Preparation of permeabilized myocardial fibers allows the assessment of respiratory function of the entire population of mitochondria in their normal intracellular position. Adult male rat ventricular bundles were permeabilized with saponin (50 microg/ml) and samples (1-3 mg wet weight) were transferred into the Oxygraph-2k (OROBOROS Instr., Austria) chambers containing air saturated incubation buffer in order to measure Complex I (CI) and II (CII) dependent respiration. The following values (expressed in pmol O2 x s(-1) x mg(-1)) were obtained: CI_LEAK, 67.18 +/- 5.12 (CI dependent basal respiration, after glutamate and malate addition); CI_P, 247.37 +/- 49.90 (CI_OXPHOS state after ADP addition); CI_Pc, 252.036 +/- 53.13 (the intactness of the outer mitochondrial membrane assessed after cytochrome c addition); CI+II_P, 342.90 +/- 62.48 (maximum OXPHOS state obtained after succinate addition by activating convergent electron flow from CI+II into the Q junction of the electron transport system (ETS); CII_P, 302.26 +/- 50.16 (CII dependent OXPHOS state obtained after the addition of a CI inhibitor rotenone, with the subsequent entry of electrons from CII only into the Q junction); ETS capacity, 331.11 +/- 62.39 (uncoupled respiration). The standardized technique will allow the systematic characterization of mitochondrial respiratory dysfunction associated with several cardiac pathologies in both animals and humans.
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Affiliation(s)
- Oana Duicu
- Department of Pathophysiology, "Victor Babeş" University of Medicine and Pharmacy Timisoara, Romania
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23
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Mina A, Favaloro EJ, Koutts J. A robust method for testing urinary iodine using a microtitre robotic system. J Trace Elem Med Biol 2011; 25:213-7. [PMID: 21982502 DOI: 10.1016/j.jtemb.2011.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 06/09/2011] [Accepted: 09/09/2011] [Indexed: 11/17/2022]
Abstract
PROJECT Iodine deficiency disorders are due to inadequate thyroid hormone production and 2 billion individuals worldwide are estimated to have insufficient iodine intake. Laboratory assessment methods include urinary iodine (UI) concentration, blood FT3, FT4, TSH and Thyroglobulin. The aim of this study was to set up a robust method for testing urinary iodine using a microtitre robotic system. PROCEDURE The UI method described is based on the Sandell-Kolthoff reaction, which utilizes the catalytic role of iodine in the reduction of ceric ammonium sulphate in the presence of arsenious acid. This method was automated for use on microtitre robotic system. RESULTS The method was compared with the currently employed manual Sandell-Kolthoff reaction method in our laboratory as reference. The two methods correlated well using weighted Deming regression analysis (slope=1.066, intercept=6.5, r=0.994; n=211). Interassay and intraassay variations were similar to the reference method, but cost analysis indicated a large reduction in costs related to increased throughput, and reduced consumables and labour. CONCLUSIONS We have successfully adapted UI testing to an automated method, permitting cheaper, faster and robust screening of large numbers of patients and populations. The described protocol can be used on different microtitre robotic systems permitting up to 372 patient samples per run for 4 microtitre plate systems.
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Affiliation(s)
- Ashraf Mina
- Department of Endocrinology, Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, Westmead, New Souh Wales, Australia.
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Shehadi IA, Abyzov A, Uzun A, Wei Y, Murga LF, Ilyin V, Ondrechen MJ. ACTIVE SITE PREDICTION FOR COMPARATIVE MODEL STRUCTURES WITH THEMATICS. J Bioinform Comput Biol 2011; 3:127-43. [PMID: 15751116 DOI: 10.1142/s0219720005000916] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2004] [Revised: 06/25/2004] [Accepted: 07/10/2004] [Indexed: 11/18/2022]
Abstract
THEMATICS (Theoretical Microscopic Titration Curves) is a simple, reliable computational predictor of the active sites of enzymes from structure. Our method, based on well-established Finite Difference Poisson–Boltzmann techniques, identifies the ionisable residues with anomalous predicted titration behavior. A cluster of two or more such perturbed residues is a very reliable predictor of the active site. The protein does not have to bear any resemblance in sequence or structure to any previously characterized protein, but the method does require the three-dimensional structure. We now present evidence that THEMATICS can also locate the active site in structures built by comparative modeling from similar structures. Results are given for a total of 21 sets of proteins, including 21 templates and 83 comparative model structures. Detailed results are presented for three sets of orthologous proteins (Triosephosphate isomerase, 6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase, and Aspartate aminotransferase) and for one set of human homologues of Aldose reductase with different functions. THEMATICS correctly locates the active site in the model structures. This suggests that the method can be applicable to a much larger set of proteins for which an experimentally determined structure is unavailable. With a few exceptions, the predicted active sites in the comparative model structures are similar to that of the corresponding template structure.
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Affiliation(s)
- Ihsan A Shehadi
- Department of Chemistry, United Arab Emirates University, Al-Ain, United Arab Emirates.
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25
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Kumar MS, Tamilarasan R, Sreekanth A. 4-Salicylideneamino-3-methyl-1,2,4-triazole-5-thione as a sensor for aniline recognition. Spectrochim Acta A Mol Biomol Spectrosc 2011; 79:370-375. [PMID: 21482181 DOI: 10.1016/j.saa.2011.03.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 03/02/2011] [Accepted: 03/11/2011] [Indexed: 05/30/2023]
Abstract
Tridentate triazole based Schiff base 4-salicylideneamino-3-methyl-1,2,4-triazole-5-thione has been found to selectively detect toxic aromatic amines such as aniline and benzene-1,4-diamine by simple titration techniques like UV-visible, fluorescence spectral studies (PL) and 1H NMR titrations. The Schiff base receptor utilizes, thione sulfur, NH-thione and the phenolic hydroxyl group to form hydrogen bonded adduct of aniline and benzene-1,4-diamine with high binding affinity, followed by a slow removal of the corresponding hydrogens thus providing a promising candidate and an unique receptor for toxic aromatic amines.
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Affiliation(s)
- M Saravana Kumar
- Department of Chemistry, National Institute of Technology - Tiruchirappalli, Tiruchirappalli 620015, Tamilnadu, India
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26
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Omoike A, Brandt B. Interaction between bisphenol A and tannic acid: spectroscopic titration approach. Spectrochim Acta A Mol Biomol Spectrosc 2011; 79:185-190. [PMID: 21435941 DOI: 10.1016/j.saa.2011.02.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 02/03/2011] [Accepted: 02/16/2011] [Indexed: 05/30/2023]
Abstract
The interaction between tannic acid (TA) and bisphenol A (BPA), an endocrine disruptor, was studied by absorption and fluorescence titration techniques. The binding constants and corresponding thermodynamic parameters at different temperatures (294, 296, 298, 300 and 303 K) were determined. The intrinsic fluorescence of BPA was strongly quenched by TA and the quenching mechanism is attributed to static quenching. The thermodynamic data revealed that the formation of TA-BPA complex was exothermic, entropic-driven, and spontaneous. Furthermore, hydrogen and van der Waals interactions seem to be the major driving forces for the formation of the nonfluorescent TA-BPA complex.
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Affiliation(s)
- Anselm Omoike
- Department of Chemistry and Biochemistry, University of Michigan-Flint, Flint, MI 48502-1950, United States.
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Aravinthan V, Hoque MA. Development and calibration of bio-kinetic model for surfactant biodegradation with combined respirometric and titrimetric measurements. Bioresour Technol 2011; 102:5504-5513. [PMID: 20863687 DOI: 10.1016/j.biortech.2010.08.101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 08/25/2010] [Accepted: 08/26/2010] [Indexed: 05/29/2023]
Abstract
Substrate removal mechanism in aerobic activated sludge processes was lately modeled using the simultaneous storage and growth (SSAG) phenomenon. The SSAG model was further refined with titrimetric components and successfully calibrated using both respirometric and titrimetric measurements for common substrate acetate. However, the improved SSAG model calibration was not verified with other organic substrates. Furthermore, very few studies are available in the literature on surfactant bio-kinetics, which generally use off-line experimental measurements with limited model-based interpretation. Therefore, the aim of this paper is to demonstrate its applicability for surfactant biodegradation using on-line measurements. Batch experiments were conducted using sodium dodecyl sulfate (SDS) as a test surfactant. Model calibration was done successfully for three different SDS concentrations using respirometric, titrimetric and combined respirometric-titrimetric measurement approaches. The parameter estimation results from all three stated combinations were statistically evaluated and found to be very close validating the model.
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Affiliation(s)
- V Aravinthan
- Australian Centre for Sustainable Catchments, University of Southern Queensland (USQ), Qld 4350, Australia.
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28
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Zhang X, Zhang D, Lu P, Bai C, Xiao P. Monitoring the nitrification and identifying the endpoint of ammonium oxidation by using a novel system of titrimetry. Water Sci Technol 2011; 64:2246-2252. [PMID: 22156129 DOI: 10.2166/wst.2011.798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Based on the structure of the hybrid respirometer previously developed in our group, a novel implementation for titrimetry was developed, in which two pH electrodes were installed at the inlet and outlet of the measuring cell. The software capable of digital filtering and titration time delay correction was developed in LabVIEW. The hardware and software of the titrimeter and the respirometer were integrated to construct a novel system of respirometry-titrimetry. The system was applied to monitor a batch nitrification process. The obtained profiles of oxygen uptake rate (OUR) and hydrogen ion production rate (HPR) are consistent with each other and agree with the principle of the biological nitrification reaction. According to the OUR and HPR measurements, the oxidized ammonium concentrations were estimated accurately. Furthermore, the endpoint of ammonium oxidation was identified with much higher sensitivity by the HPR measurement. The system could be potentially used for on-line monitoring of biochemical reactions occurring in any kind of bioreactors because its measuring cell is completely independent of the bioreactor.
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Affiliation(s)
- Xin Zhang
- Department of Environmental Science, Chongqing University, Chongqing, China.
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Abstract
Baculovirus expression vector system (BEVS) is well known as a feasible and safe technology to produce recombinant (re-)proteins in a eukaryotic milieu of insect cells. However, its proven power in gene delivery and gene therapy is still poorly recognized. The basis of BEVS lies in large enveloped DNA viruses derived from insects, the prototype virus being Autographa californica multiple nucleopolyhedrovirus (AcMNPV). Infection of insect cell culture with a virus encoding a desired transgene under powerful baculovirus promoter leads to re-protein production in high quantities. Although the replication of AcMNPV is highly insect specific in nature, it can penetrate and transduce a wide range of cells of other origin. Efficient transduction requires only virus arming with an expression cassette active in the cells under investigation. The inherent safety, ease and speed of virus generation in high quantities, low cytotoxicity and extreme transgene capacity and tropism provides many advantages for gene delivery over the other viral vectors typically derived from human pathogens.
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Affiliation(s)
- Kari J Airenne
- Department of Molecular Medicine, A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland.
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Abstract
Adeno-associated virus (AAV) vectors have evolved over the past decade as a particularly useful gene -vector for in vivo applications. In contrast to oncoretro- and lentiviral vectors, this vector stays essentially episomal after gene transfer, making it safer because of the absence of insertional mutagenesis. AAV's non-pathogenicity is a further advantage. For decades, this vector could only be produced at a small scale for research purposes and, eventually, used at very small doses for clinical studies, because only transfection methods were available, which have limited scalability. However, since the development of scalable production methods, this bottleneck is resolved and, from a technical point of view, large quantities of AAV vectors can be produced, opening the possibility of using AAV vectors for whole body treatments in gene therapy trials. This chapter presents the basic principles of small- and large-scale production procedures as well as detailed procedure of small-scale production, purification, and analytical protocols for AAV vectors. In Chapter 10, the reader will find a large-scale production method based on the use of the insect cell/baculovirus system.
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Fang L, Cai P, Li P, Wu H, Liang W, Rong X, Chen W, Huang Q. Microcalorimetric and potentiometric titration studies on the adsorption of copper by P. putida and B. thuringiensis and their composites with minerals. J Hazard Mater 2010; 181:1031-1038. [PMID: 20576350 DOI: 10.1016/j.jhazmat.2010.05.118] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 04/22/2010] [Accepted: 05/26/2010] [Indexed: 05/29/2023]
Abstract
In order to have a better understanding of the interactions of heavy metals with bacteria and minerals in soil and associated environments, isothermal titration calorimetry (ITC), potentiometric titration and equilibrium sorption experiments were conducted to investigate the adsorption behavior of Cu(II) by Bacillus thuringiensis, Pseudomonas putida and their composites with minerals. The interaction of montmorillonite with bacteria increased the reactive sites and resulted in greater adsorption for Cu(II) on their composites, while decreased adsorption sites and capacities for Cu(II) were observed on goethite-bacteria composites. A gram-positive bacterium B. thuringiensis played a more important role than a gram-negative bacterium P. putida in determining the properties of the bacteria-minerals interfaces. The enthalpy changes (DeltaH(ads)) from endothermic (6.14 kJ mol(-1)) to slightly exothermic (-0.78 kJ mol(-1)) suggested that Cu(II) is complexed with the anionic oxygen ligands on the surface of bacteria-mineral composites. Large entropies (32.96-58.89 J mol(-1) K(-1)) of Cu(II) adsorption onto bacteria-mineral composites demonstrated the formation of inner-sphere complexes in the presence of bacteria. The thermodynamic data implied that Cu(II) mainly bound to the carboxyl and phosphoryl groups as inner-sphere complexes on bacteria and mineral-bacteria composites.
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Affiliation(s)
- Linchuan Fang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
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32
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Janot N, Reiller PE, Korshin GV, Benedetti MF. Using spectrophotometric titrations to characterize humic acid reactivity at environmental concentrations. Environ Sci Technol 2010; 44:6782-6788. [PMID: 20698549 DOI: 10.1021/es1012142] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Potentiometric titration is a common method to characterize dissolved organic matter (DOM) reactivity. Because of the sensitivity of pH electrodes, it is necessary to work with very high DOM (>1 g/L) concentrations that are unrealistic compared to those found in natural waters (0.1 to 100 mg/L). To obtain proton binding data for concentrations closer to environmental values, spectroscopic titration methodology is a viable alternative to traditional potentiometric titrations. Spectrophotometric titrations and UV-visible spectra of a diluted solution of purified Aldrich humic acid (5 mgDOC/L) are used to estimate changes in proton binding moieties as function of pH and ionic strength after calculation of differential absorbance spectra variations. After electrostatic correction of spectrophotometric data, there is a linear operational correlation between spectrophotometric and potentiometric data which can be used as a transfer function between the two properties. Spectrophotometric titrations are then used to determine the changes of humic acid protonation after adsorption onto alpha-alumina.
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Affiliation(s)
- Noémie Janot
- Laboratoire de Géochimie des Eaux, Universite Paris Diderot, IPGP, UMR CNRS 7154, Case Postale 7052, 75025 Paris, Cedex 13, France
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Zhang X, Zhang DJ, Zhang WG, Lu PL. [Monitoring the stoichiometric relation of ammonium oxidation with the titrimetry of hydrogen ion variation]. Huan Jing Ke Xue 2010; 31:1590-1595. [PMID: 20825030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A set of automatically titrimetric system to monitor the hydrogen ion variation during biological wastewater treatment process in a batch bioreactor was developed, which consists of a batch bioreactor, data auto-acquisition and preservation unit, and titrant autodosing unit. The accuracy of measurement for the system was evaluated by measuring the stoichiometric ratio of hydrogen ion production amount to ammonium consumption amount of ammonium oxidation in an activated sludge system. The ratios measured in a 1L bioreactor with NH4+ -N concentrations of 1.67, 3.33, 8.33, 16. 66 and 30.00 mg/L as N respectively were very close to the theoretical value, and the relative errors were among 2.09%-6.34%. However, the relative errors in bioreactors of 1, 2, 3 and 4 L with NH4+ -N concentration of 16.66 mg/L as N were among 2.09%- -18.57%, and increased significantly with accretion of the volume of bioreactor. The buffers of bicarbonate and the ammonium, especially the titrimetric dynamic effects in a larger bioreactor are the primarily factors resulting in errors. This study provides an important approach for monitoring hydrogen ion variation in the process of biological wastewater treatment by titrimetry.
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Affiliation(s)
- Xin Zhang
- Department of Environmental Science, Chongqing University, Chongqing 400030, China.
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Nurisso A, Blanchard B, Audfray A, Rydner L, Oscarson S, Varrot A, Imberty A. Role of water molecules in structure and energetics of Pseudomonas aeruginosa lectin I interacting with disaccharides. J Biol Chem 2010; 285:20316-27. [PMID: 20410292 PMCID: PMC2888444 DOI: 10.1074/jbc.m110.108340] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 04/11/2010] [Indexed: 11/06/2022] Open
Abstract
Calcium-dependent lectin I from Pseudomonas aeruginosa (PA-IL) binds specifically to oligosaccharides presenting an alpha-galactose residue at their nonreducing end, such as the disaccharides alphaGal1-2betaGalOMe, alphaGal1-3betaGalOMe, and alphaGal1-4betaGalOMe. This provides a unique model for studying the effect of the glycosidic linkage of the ligands on structure and thermodynamics of the complexes by means of experimental and theoretical tools. The structural features of PA-IL in complex with the three disaccharides were established by docking and molecular dynamics simulations and compared with those observed in available crystal structures, including PA-IL.alphaGal1-2betaGalOMe complex, which was solved at 2.4 A resolution and reported herein. The role of a structural bridge water molecule in the binding site of PA-IL was also elucidated through molecular dynamics simulations and free energy calculations. This water molecule establishes three very stable hydrogen bonds with O6 of nonreducing galactose, oxygen from Pro-51 main chain, and nitrogen from Gln-53 main chain of the lectin binding site. Binding free energies for PA-IL in complex with the three disaccharides were investigated, and the results were compared with the experimental data determined by titration microcalorimetry. When the bridge water molecule was included in the free energy calculations, the simulations predicted the correct binding affinity trends with the 1-2-linked disaccharide presenting three times stronger affinity ligand than the other two. These results highlight the role of the water molecule in the binding site of PA-IL and indicate that it should be taken into account when designing glycoderivatives active against P. aeruginosa adhesion.
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Affiliation(s)
- Alessandra Nurisso
- From the Centre de Rechèrche sur les Macromolécules Végétales-CNRS (affiliated with Université Joseph Fourier and Institut de Chimie Moléculaire de Grenoble), BP 53, 38041 Grenoble Cedex 9, France and
| | - Bertrand Blanchard
- From the Centre de Rechèrche sur les Macromolécules Végétales-CNRS (affiliated with Université Joseph Fourier and Institut de Chimie Moléculaire de Grenoble), BP 53, 38041 Grenoble Cedex 9, France and
| | - Aymeric Audfray
- From the Centre de Rechèrche sur les Macromolécules Végétales-CNRS (affiliated with Université Joseph Fourier and Institut de Chimie Moléculaire de Grenoble), BP 53, 38041 Grenoble Cedex 9, France and
| | - Lina Rydner
- the Centre for Synthesis and Chemical Biology, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Stefan Oscarson
- the Centre for Synthesis and Chemical Biology, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Annabelle Varrot
- From the Centre de Rechèrche sur les Macromolécules Végétales-CNRS (affiliated with Université Joseph Fourier and Institut de Chimie Moléculaire de Grenoble), BP 53, 38041 Grenoble Cedex 9, France and
| | - Anne Imberty
- From the Centre de Rechèrche sur les Macromolécules Végétales-CNRS (affiliated with Université Joseph Fourier and Institut de Chimie Moléculaire de Grenoble), BP 53, 38041 Grenoble Cedex 9, France and
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Elbagerma MA, Azimi G, Edwards HGM, Alajtal AI, Scowen IJ. In situ monitoring of pH titration by Raman spectroscopy. Spectrochim Acta A Mol Biomol Spectrosc 2010; 75:1403-1410. [PMID: 20299276 DOI: 10.1016/j.saa.2010.01.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 01/24/2010] [Accepted: 01/27/2010] [Indexed: 05/29/2023]
Abstract
Molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman technique was chosen because it allows the identification of compounds in different states, and it can give information about the molecular geometry from the analysis of the vibrational spectra. The effect of pH on organic compounds can give information about the ionisation of molecule species. In this study the ionisation steps of salicylic acid and paracetamol have been studied by means of potentiometry coupled with Raman spectroscopy at 30.0 degrees C in a solution of ionic strength 0.96moldm(-3) (KNO(3)) and 0.04moldm(-3) (HNO(3)). The protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the three different species in the Raman spectra of aqueous salicylic acid have been identified satisfactorily, characterised, and determined by numeric treatment of the data using a multiwavelength curve-fitting program and confirmed with the observed spectral information.
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Affiliation(s)
- M A Elbagerma
- Raman Spectroscopy Group, University Analytical Centre, Division of Chemical and Forensic Sciences, University of Bradford, West Yorkshire BD7 1DP, UK
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Hoque MA, Aravinthan V, Pradhan NM. Calibration of biokinetic model for acetate biodegradation using combined respirometric and titrimetric measurements. Bioresour Technol 2010; 101:1426-1434. [PMID: 19656672 DOI: 10.1016/j.biortech.2009.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 07/07/2009] [Accepted: 07/07/2009] [Indexed: 05/28/2023]
Abstract
Simultaneous storage and growth model has recently gained increased acceptance among researchers that can better interpret the processes occurring in activated sludge processes during aerobic biodegradation of organic carbon. The model underwent further improvement and was successfully calibrated using respirometric measurements, acetate being a test substrate. However, model based interpretation of titrimetry needs to be verified for proper validation of this model since pH and dissolved oxygen dynamics occur simultaneously in a batch reactor. Hence, in this paper, it is aimed to modify the existing model by introducing stoichiometric parameters involved in titrimetry in each step of the growth and storage phases along with the consideration of non-linear carbon dioxide transfer rate in liquid phase. The model calibration was done for three different acetate concentrations using titrimetric, respirometric and combined respirometric-titrimetric measurements. The parameter estimation results from all three combinations were found to be very close that supports the validity of the model.
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Affiliation(s)
- M A Hoque
- Australian Centre for Sustainable Catchments, University of Southern Queensland (USQ), Qld-4350, Australia
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Abstract
Good quality data on iodine concentrations in urine and salt samples are indispensable for the efficient management of national salt iodisation programmes and for evaluating iodine interventions. Most of the analytical methods for urinary iodine concentration are based on the manual spectrophotometric measurement of Sandell-Kolthoff reduction reaction catalysed by iodine using different oxidising reagents in the initial digestion step. Other analytical methods include semi-quantitative methods, a microplate method, automated methods; and the technologically advanced methods include the inductively coupled plasma mass-spectrometer method. Iodine in salt is determined quantitatively by the titration method, colorimetrically by the WYD iodine checker or by a technologically advanced potentiometric method. Worldwide, titration is the method of choice because of its accuracy, ease of operation and low cost. Rapid test kits are suitable for qualitative use in situations where iodised salt need to be distinguished from non-iodised salt, preferably with titration back-up.
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Affiliation(s)
- Pieter L Jooste
- Nutritional Intervention Research Unit, Medical Research Council, Tygerberg 7505, Cape Town, South Africa.
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Jonnalagadda SB, Gengan P. Titrimetric and photometric methods for determination of hypochlorite in commercial bleaches. J Environ Sci Health A Tox Hazard Subst Environ Eng 2010; 45:917-922. [PMID: 20446147 DOI: 10.1080/10934521003772295] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Two methods, simple titration and photometric methods for determination of hypochlorite are developed, based its reaction with hydrogen peroxide and titration of the residual peroxide by acidic permanganate. In the titration method, the residual hydrogen peroxide is estimated by titration with standard permanganate solution to estimate the hypochlorite concentration. The photometric method is devised to measure the concentration of remaining permanganate, after the reaction with residual hydrogen peroxide. It employs 4 ranges of calibration curves to enable the determination of hypochlorite accurately. The new photometric method measures hypochlorite in the range 1.90 x 10(-3) to 1.90 x 10(-2) M, with high accuracy and with low variance. The concentrations of hypochlorite in diverse commercial bleach samples and in seawater which is enriched with hypochlorite were estimated using the proposed method and compared with the arsenite method. The statistical analysis validates the superiority of the proposed method.
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Abstract
Biophysical measurements of multidrug transporters in vitro can often be of limited relevance to the natural in vivo behavior. In particular, the properties of transporters when removed from their native bilayer and solubilized in detergents or lipids can differ significantly from their in vivo properties, reducing the value of in vitro measurements for the design of antagonists to the transporters. This problem can be addressed by studying the transport protein in liposomes in which the properties of the liposome bilayer are altered through systematic changes in lipid composition. Isothermal titration calorimetry can be used to determine the properties of the lipid-reconstituted protein in bilayers of different lipid compositions as well as to quantify the percentage recovery of functional protein in different lipids. Both these measurements lead to an accurate analysis of substrate binding activity. The approach is illustrated here for the small multidrug transport protein, EmrE from Escherichia coli. The percentage of functional EmrE successfully reconstituted into liposome depends on lipid composition. Differences in ligand binding and subtle differences in the secondary structure also occur in different lipid compositions.
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Affiliation(s)
- David Miller
- Department of Biochemistry, University of Bristol, UK
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Abstract
Oligomerization is a frequently encountered physical characteristic of biological molecules that occurs for a wide number of transcription factors, ion channels, oxygen-carrying macromolecules such as hemocyanin and enzymes. On the other hand, unwanted protein oligomerization can lead to the formation of pathogenic structures related with Alzheimer and other diseases. Self-assembly is also a well-described phenomenon within peroxiredoxins, a family of thiol peroxidases. Peroxiredoxin hyperaggregate formation is the key mechanism that triggers the switch between Prx activity as peroxidase and chaperone. The oligomerization process is fundamental for understanding the multiple peroxiredoxin function. The chapter gives a detailed description of typical 2-Cys Peroxiredoxin oligomerization using isothermal titration calorimetry (ITC) and provides a recipe for studying the thermodynamic parameters of peroxiredoxin assembly, that is, association and dissociation constant, enthalpy, entropy, and the Gibbs free energy of the process.
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Franzini VP, Moraes MD, Neto JAG. Direct determination of phosphite in fertilizers by amperometric titration. J Agric Food Chem 2009; 57:372-374. [PMID: 19117396 DOI: 10.1021/jf803107x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Amperometric titration using two Pt microelectrodes for the determination of phosphite in fertilizers based on the oxidation of analyte by iodine is proposed. The influence of pH, buffer composition, temperature, and foreign species on the end point and titration time was investigated. For titrations carried out at 70 degrees C using the pH 6.8 phosphate buffer, samples containing ca. 0.4% (m/v) P(2)O(5) could be titrated with 0.050 mol L(-1) iodine titrant, and the end point determined by extrapolating the linear portions of the plot to their intersection coincided with the end point identified by spectrophotometry. Accuracy was checked for phosphite determination in five fertilizer samples. Results were in agreement at the 95% confidence level (paired t test) with spectrophotometry. Recoveries of phosphite added to fertilizer samples ranged from 97% to 102% regardless of the amount of spiking in several determinations. The relative standard deviation (n = 10) was 1.0% for a diluted sample containing 0.050 mol L(-1) Na(2)HPO(3).
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Affiliation(s)
- Vanessa P Franzini
- Analytical Chemistry Department, São Paulo State University, Araraquara, Brazil
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42
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Qin Q, Mi ZM, Zhao YS, Feng XP, Zeng HX. [A discussion on the concentration assay for hemihydrate gypsum in plaster of paris bandage-viscose form]. Zhongguo Yi Liao Qi Xie Za Zhi 2009; 33:62-63. [PMID: 19459355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This essay is to present an improvement on the concentration assay for hemihydrate gypsum in plaster of Paris bandage-Viscose form.
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Affiliation(s)
- Qing Qin
- Hebei Province, medical equipment and medicine packaging materials laboratory Hebei, Shijiazhuang, 050061.
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Salonen K, Leisola M, Eerikäinen T. Developing a multipoint titration method with a variable dose implementation for anaerobic digestion monitoring. Water Sci Technol 2009; 59:2395-2403. [PMID: 19542645 DOI: 10.2166/wst.2009.275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Determination of metabolites from an anaerobic digester with an acid base titration is considered as superior method for many reasons. This paper describes a practical at line compatible multipoint titration method. The titration procedure was improved by speed and data quality. A simple and novel control algorithm for estimating a variable titrant dose was derived for this purpose. This non-linear PI-controller like algorithm does not require any preliminary information from sample. Performance of this controller is superior compared to traditional linear PI-controllers. In addition, simplification for presenting polyprotic acids as a sum of multiple monoprotic acids is introduced along with a mathematical error examination. A method for inclusion of the ionic strength effect with stepwise iteration is shown. The titration model is presented with matrix notations enabling simple computation of all concentration estimates. All methods and algorithms are illustrated in the experimental part. A linear correlation better than 0.999 was obtained for both acetate and phosphate used as model compounds with slopes of 0.98 and 1.00 and average standard deviations of 0.6% and 0.8%, respectively. Furthermore, insensitivity of the presented method for overlapping buffer capacity curves was shown.
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Affiliation(s)
- K Salonen
- Department of Biotechnology and Chemical Technology, Helsinki University of Technology, Kemistintie 1, Espoo FI-02150, Finland.
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Bratskaya S, Golikov A, Lutsenko T, Nesterova O, Dudarchik V. Charge characteristics of humic and fulvic acids: comparative analysis by colloid titration and potentiometric titration with continuous pK-distribution function model. Chemosphere 2008; 73:557-563. [PMID: 18657293 DOI: 10.1016/j.chemosphere.2008.06.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 05/14/2008] [Accepted: 06/05/2008] [Indexed: 05/26/2023]
Abstract
Charge characteristics of humic and fulvic acids of a different origin (inshore soils, peat, marine sediments, and soil (lysimetric) waters) were evaluated by means of two alternative methods - colloid titration and potentiometric titration. In order to elucidate possible limitations of the colloid titration as an express method of analysis of low content of humic substances we monitored changes in acid-base properties and charge densities of humic substances with soil depth, fractionation, and origin. We have shown that both factors - strength of acidic groups and molecular weight distribution in humic and fulvic acids - can affect the reliability of colloid titration. Due to deviations from 1:1 stoichiometry in interactions of humic substances with polymeric cationic titrant, the colloid titration can underestimate total acidity (charge density) of humic substances with domination of weak acidic functional groups (pK>6) and high content of the fractions with molecular weight below 1kDa.
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Affiliation(s)
- S Bratskaya
- Institute of Chemistry FEBRAS, 159, Prospect 100-letiya Vladivostoka, Vladivostok 690022, Russia.
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Abstract
During the past decade, isothermal titration calorimetry (ITC) has developed from a specialist method for understanding molecular interactions and other biological processes within cells to a more robust, widely used method. Nowadays, ITC is used to investigate all types of protein interactions, including protein-protein interactions, protein-DNA/RNA interactions, protein-small molecule interactions and enzyme kinetics; it provides a direct route to the complete thermodynamic characterization of protein interactions. This review concentrates on the new applications of ITC in protein folding and misfolding, its traditional application in protein interactions, and an overview of what can be achieved in the field of protein science using this method and what developments are likely to occur in the near future. Also, this review discusses some new developments of ITC method in protein science, such as the reverse titration of ITC and the displacement method of ITC.
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Affiliation(s)
- Yi Liang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
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Fiocchi N, Ficara E, Bonelli S, Canziani R, Ciappelloni F, Mariani S, Pirani M, Ratini P, Mazouni D, Harmand J. Automatic set-point titration for monitoring nitrification in SBRs. Water Sci Technol 2008; 58:331-336. [PMID: 18701782 DOI: 10.2166/wst.2008.387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nitrification is usually the bottleneck of biological nitrogen removal processes. In SBRs systems, it is not often enough to monitor dissolved oxygen, pH and ORP to spot problems which may occur in nitrification processes. Therefore, automated supervision systems should be designed to include the possibility of monitoring the activity of nitrifying populations. Though the applicability of set-point titration for monitoring biological processes has been widely demonstrated in the literature, the possibility of an automated procedure is still at its early stage of industrial development. In this work, the use of an at-line automated titrator named TITAAN (TITrimetric Automated ANalyser) is presented. The completely automated sensor enables us to track nitrification rate trend with time in an SBR, detecting the causes leading to slower specific nitrification rates. It was also possible to perform early detection of toxic compounds in the influent by assessing their effect on the nitrifying biomass. Nitrifications rates were determined with average errors+/-10% (on 26 tests), never exceeding 20% as compared with UV-spectrophotometric determinations.
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Affiliation(s)
- N Fiocchi
- Politecnico di Milano, DIIAR Sezione Ambientale, Piazza L. da Vinci 32, 20133, Milano, Italy.
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Meloun M, Bordovská S, Galla L. The thermodynamic dissociation constants of four non-steroidal anti-inflammatory drugs by the least-squares nonlinear regression of multiwavelength spectrophotometric pH-titration data. J Pharm Biomed Anal 2007; 45:552-64. [PMID: 17825517 DOI: 10.1016/j.jpba.2007.07.029] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 07/23/2007] [Accepted: 07/29/2007] [Indexed: 02/05/2023]
Abstract
The mixed dissociation constants of four non-steroidal anti-inflammatory drugs (NSAIDs) ibuprofen, diclofenac sodium, flurbiprofen and ketoprofen at various ionic strengths I of range 0.003-0.155, and at temperatures of 25 degrees C and 37 degrees C, were determined with the use of two different multiwavelength and multivariate treatments of spectral data, SPECFIT/32 and SQUAD(84) nonlinear regression analyses and INDICES factor analysis. The factor analysis in the INDICES program predicts the correct number of components, and even the presence of minor ones, when the data quality is high and the instrumental error is known. The thermodynamic dissociation constant pK(a)(T) was estimated by nonlinear regression of (pK(a), I) data at 25 degrees C and 37 degrees C. Goodness-of-fit tests for various regression diagnostics enabled the reliability of the parameter estimates found to be proven. PALLAS, MARVIN, SPARC, ACD/pK(a) and Pharma Algorithms predict pK(a) being based on the structural formulae of drug compounds in agreement with the experimental value. The best agreement seems to be between the ACD/pK(a) program and experimentally found values and with SPARC. PALLAS and MARVIN predicted pK(a,pred) values with larger bias errors in comparison with the experimental value for all four drugs.
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Affiliation(s)
- Milan Meloun
- Department of Analytical Chemistry, University of Pardubice, CZ 532 10 Pardubice, Czech Republic.
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Mbao V, Berkvens D, Dorny P, Van den Bossche P, Marcotty T. Comparison of the survival on ice of thawed Theileria parva sporozoites of different stocks cryoprotected by glycerol or sucrose. Onderstepoort J Vet Res 2007; 74:9-15. [PMID: 17708148 DOI: 10.4102/ojvr.v74i1.134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Stabilates of Theileria parva sporozoites are mostly delivered in liquid nitrogen tanks to the East Coast fever immunization points. Using an in vitro titration model, we assessed the loss of infectivity of several stabilates when they are stored in ice baths for up to 24 h. Comparisons, with respect to rates of loss of infectivity, were made between T. parva stocks (Chitongo and Katete), cryoprotectants (sucrose and glycerol) and method of assessment (in vivo and in vitro techniques). Chitongo and Katete stabilates showed similar loss dynamics. The losses were 1-4% (depending on parasite stock) and 3% per hour of storage for glycerol and sucrose stabilates respectively, and the loss rates were not significantly different. The results suggest that Chitongo stabilates and sucrose cryoprotected suspensions can be delivered on ice as is done for Katete. A graphical relationship of in vitro effective dose at 50% infectivity (ED50) and in vivo protection rate was made. The relationship showed a 35% loss of protection for a relatively low corresponding increase of ED50 from 0.006 to 0.007 tick equivalent.
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Affiliation(s)
- V Mbao
- Department of Animal Health, Institute of Tropical Medicine, Nationalestraat 155, B-2000 Antwerp, Belgium
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Jin JP, Chong SM, Hossain MM. Microtiter plate monoclonal antibody epitope analysis of Ca2+- and Mg2+-induced conformational changes in troponin C. Arch Biochem Biophys 2007; 466:1-7. [PMID: 17761138 PMCID: PMC2064003 DOI: 10.1016/j.abb.2007.07.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 07/15/2007] [Accepted: 07/16/2007] [Indexed: 11/30/2022]
Abstract
Spectroscopic methods such as circular dichroism and Förster resonance energy transfer are current approaches for monitoring protein conformational changes. Those analyses require special equipment and expertise. The need for fluorescence labeling of the protein may interfere with the native structure. We have developed a microtiter plate-based monoclonal antibody (mAb) epitope analysis to detect protein conformational changes in a high throughput manner. This method is based on the concept that the affinity of the antigen-binding site of an antibody for the specific antigenic epitope will change when the 3-D structure of the epitope changes. The effectiveness of this approach was demonstrated in the present study on troponin C (TnC), an allosteric protein in the Ca(2+) regulatory system of striated muscle. Using TnC purified by a highly effective rapid procedure and mAbs developed against epitopes in the N- and C-domains of TnC enzyme-linked immunosorbant assay (ELISA) clearly detected Ca(2+)-induced conformational changes in both the N-terminal regulatory domain and the C-terminal structural domain of TnC. On the other hand, Mg(2+)-binding to the C-domain of TnC resulted in a long-range effect on the N-domain conformation, indicating a functional significance of Ca(2+)-Mg(2+) exchange at the C-domain metal ion-binding sites. In addition to further understanding of the structure-function relationship of TnC, the data demonstrate that the mAb epitope analysis provides a simple high throughput method for monitoring 3-D structural changes in native proteins under physiological condition and has broad applications in protein structure-function relationship studies.
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Affiliation(s)
- Jian-Ping Jin
- Section of Molecular Cardiology, Evanston Northwestern Healthcare and Northwestern University, Feinberg School of Medicine, 2650 Ridge Avenue, Evanston, IL 60201, USA.
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Lang W, Meier N. Calculation of the pH and the titratable acidity in clinically used infusion solutions. Comput Methods Programs Biomed 2007; 87:160-9. [PMID: 17597251 DOI: 10.1016/j.cmpb.2007.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Revised: 05/10/2007] [Accepted: 05/11/2007] [Indexed: 05/16/2023]
Abstract
Clinically used infusion solutions are complex aqueous mixtures composed of a variety of different salts, acids, and non-electrolytes, and are characterized by composition, initial pH, and titratable acidity (TA). By rigorous treatment as a multi-composed acid-base system, pH and TA were calculated from proton dissociation equilibria, mass balance equations and electroneutrality condition. Nine were arbitrarily chosen as model solutions in which pH and TA were experimentally determined. From composition, and based on a set of apparent acidity constants (pK values) at 37 degrees C and total ionic strength 0.155 mol/l, pH was calculated by iteration. In the model solutions, measured pH was in the range 5-7, and the difference between calculated and experimental values was+/-0.064. Good agreement was also found between calculated and measured TA: in the range 0-55 mmol/l the mean difference was+/-2.07 mmol/l, if calculated from measured pH, and +/-0.95 mmol/l, if calculated from calculated pH.
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Affiliation(s)
- Werner Lang
- Institute of Physiology and Pathophysiology, Johannes Gutenberg University Mainz, Saarstrasse 21, D-55099 Mainz, Germany.
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