| 1. |
- Andersson, Ingegärd, et al.
(författare)
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Speciation in the aqueous H+/H2VO4–/H2O2/phosphate system
- 2005
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Ingår i: DALTON TRANSACTIONS. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 22, s. 3658-66
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Tidskriftsartikel (refereegranskat)abstract
- The speciation in the aqueous H+/H2VO4- /phosphate (dihydrogen phosphate, P) and H+/H2VO4/H2O2/P systems has been determined in the physiological medium of 0.150 M Na(Cl) at 25 degrees C. A combination of multinuclear NMR integral and chemical shift (Bruker AMX500) as well as potentiometric data (glass electrode) have been collected and treated simultaneously by the computer program LAKE. The pK(a)-values for phosphoric acid have been determined by potentiometric and P-31 NMR chemical shift data, and have been found to be 1.85 +/- 0.02, 6.69 +/- 0.02 and 11.58 +/- 0.07. The errors given are 3 sigma. Altogether nine vanadate phosphate species have been found in the ternary H+/H2VO4-/P- system in the PH region 1-11, with the following compositions: VP, VP2 and V14P. Equilibrium is very slow in acidic solutions, requiring more than 3 months for the formation of V14P species. On the other hand, less than 15 min are needed for equilibration at neutral and alkaline pH. In the H+/H2VO4-/H2O2/P- system, four new species have been found in addition to all binary and ternary complexes. They are of VXP and VX2P compositions, where X denotes the peroxo ligand. V-51 and P-31 NMR chemical shifts, compositions and formation constants are given, and equilibrium conditions are illustrated in distribution diagrams as well as the fit of the model to the experimental data. Biological and medical relevance of the species is also discussed and physiological conditions are modelled.
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| 2. |
- González Baró, Ana, et al.
(författare)
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Speciation in the aqueous peroxovanadate-maltol and (peroxo)vanadate-uridine systems
- 2008
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 8, s. 1095-102
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Tidskriftsartikel (refereegranskat)abstract
- The speciation in the aqueous H+/H2VO4-/H2O2/maltol (Ma), H+/H2VO4-/uridine (Ur) and H+/H2VO4-/H2O2/Ur systems was determined in the physiological medium of 0.150 M Na(Cl) at 25 °C. A combination of quantitative 51V NMR (Bruker AMX500) and potentiometric data (glass electrode) was collected and treated simultaneously by the computer program LAKE. In the quaternary maltol system, the two species VXMa2- and VX2Ma2- (where X denotes the peroxo ligand) were found in the pH region 5-10, in addition to all binary and ternary complexes. Their formation was fast. In the ternary uridine (H+/H2VO4-/Ur) subsystem, altogether three vanadate-uridine (V-Ur) species were found in the pH region 4-10, with compositions VUr2-, V2Ur22- and V2Ur23-. Equilibrium was fast except in weakly acidic solutions when slowly decomposing decavanadates formed. In the quaternary H+/H2VO4-/H2O2/Ur system, five additional species were found at pH > 7. They were of VXUr and VX2Ur compositions. Their formation was fast. Formation constants, compositions and 51V NMR chemical shifts are given for all the species found in the systems, and equilibrium conditions are illustrated in distribution diagrams as well as the fit of the model to the experimental data. Biological and medical relevance of the species (in the treatment of diabetes) are also discussed, with pseudo-physiological conditions modelled.
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| 3. |
- Gorzsás, András, et al.
(författare)
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On the Fate of Vanadate in Human Blood
- 2006
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Ingår i: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-0682. ; 18, s. 3559-65
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Tidskriftsartikel (refereegranskat)abstract
- The cover picture shows a symbolic representation of the fate of vanadate in human blood. Since the transition metal vanadium is named after Vanadis, the Nordic goddess of beauty, she is represented by the famous Venus de Milo sculpted in metal. Her cloth is decorated with the functional groups of the ligands that can form a complex (dress) with the metal while travelling in the blood vessels, the latter being symbolised by the caverns in the background. The water in the caves represents the aqueous solutions in which speciation studies have been carried out in the group of Professor Lage Pettersson. Further references to these studies are found as cave paintings on the walls: a distribution diagram and a set of 51V NMR spectra. The studies have been carried out in the framework of the COST D21/009 working group. The geographical locations of the research groups within this working group are shown by illuminated dots on the map of Europe in the background. The goal of the studies was to better understand the ability of vanadium to lower blood glucose levels (represented by the sugar cubes washed ashore on the left) and thus its potential as an orally applicable drug against diabetes. A Microreview, covering the results of the above mentioned speciation studies dealing with the fate of vanadate in human blood, is represented by A. Gorzsás, I. Andersson, and L. Pettersson on p. 3559 ff. The digital artwork for this cover was created by András Gorzsás.
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| 4. |
- Gorzsás, András, et al.
(författare)
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Speciation in Aqueous Vanadate – Ligand and Peroxovanadate – Ligand systems
- 2009
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Ingår i: Journal of Inorganic Biochemistry. - : Elsevier BV. - 0162-0134 .- 1873-3344. ; 103:4, s. 517-526
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Tidskriftsartikel (refereegranskat)abstract
- In the present focused review, the speciation studies of aqueous vanadate-ligand (L) and peroxovanadate-L systems are addressed. The paper focuses solely on the systems studied at our department in the context of potential insulin-enhancing effects, including the following ligands: imidazole, alanylhistidine, alanylserine, lactate, picolinate, citrate, phosphate, maltol, and uridine. We summarise the results of detailed and thorough potentiometric (glass electrode) and 51V NMR (Bruker AMX-500 MHz) spectroscopic studies, performed at 25 °C in 0.150 M Na(Cl), a medium representing human blood. The importance of experimental conditions is discussed and illustrated. A detailed overview of our methodology, based on combining potentiometric and 51V integral and chemical shift data by means of the computer program LAKE, is also given. We list the important steps of equilibrium analysis and the kinds of information available from different sets of NMR spectra. The ligand picolinate is chosen to exemplify our working method, but conclusions are drawn from all systems, reviewing trends and common features. An overview of all systems is given in two tables, including e.g. types and number of species formed. Previously unpublished modelling results at physiological conditions are also shown for all peroxovanadate-ligand systems.
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| 5. |
- Gorzsás, András, 1975-
(författare)
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Vanadate and Peroxovanadate Complexes of Biomedical Relevance : A speciation approach with focus on diabetes
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diabetes mellitus is one of the most threatening epidemics of modern times with rapidly increasing incidence. Vanadium and peroxovanadium compounds have been shown to exert insulin–like actions and, in contrast to insulin, are orally applicable. However, problems with side–effects and toxicity remain. The exact mechanism(s) by which these compounds act are not yet fully known. Thus, a better understanding of the aqueous chemistry of vanadates and peroxovanadates in the presence of various (bio)ligands is needed. The present thesis summarises six papers dealing mainly with aqueous speciation in different vanadate – and peroxovanadate – ligand systems of biological and medical relevance. Altogether, five ligands have been studied, including important blood constituents (lactate, citrate and phosphate), a potential drug candidate (picolinic acid), and a dipeptide (alanyl serine) to model the interaction of (peroxo)vanadate in the active site of enzymes. Since all five ligands have been studied both with vanadates and peroxovanadates, the number of systems described in the present work is eleven, including the vanadate – citrate – lactate mixed ligand system. The pH–independent formation constants have been determined for 33 ternary vanadate – ligand, 41 quaternary peroxovanadate – ligand and two vanadate – mixed ligand species in addition to the pKa values of all five ligands. These constants have been used to model physiological conditions, and the biomedical relevance of the different species is discussed. The studies have been performed at 25 ºC in the physiological medium of 0.150 M Na(Cl), i.e. the ionic strength of human blood. No buffers have been used, and wide pH–ranges have usually been covered. The applied experimental techniques comprise mostly 51V NMR and potentiometry, but 31P, 13C, 1H and 14N NMR as well as EPR and ESI–MS have also been used to gain additional information. Multimethod data have been treated by the least–squares program LAKE and modelling has been carried out by the software package WinSGW. Whenever possible, solution structures of the species have been proposed. In addition, simple biological tests have been carried out to determine the stability of the formed peroxovanadate complexes in the presence of human catalase. A brief comparison is given of the different vanadate – ligand and peroxovanadate – ligand systems with emphasis on observed trends and general features.
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| 6. |
- Stenlund, Hans, et al.
(författare)
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Orthogonal Projections to Latent Structures Discriminant Analysis Modeling on in Situ FT-IR Spectral Imaging of Liver Tissue for Identifying Sources of Variability.
- 2008
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 80:18, s. 6898-906
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the orthogonal projections to latent structures discriminant analysis (OPLS-DA) method was used to assess the in situ chemical composition of two different cell types in mouse liver samples, hepatocytes and erythrocytes. High spatial resolution FT-IR microspectroscopy equipped with a focal plan array (FPA) detector is capable of simultaneously recording over 4000 spectra from 64 x 64 pixels with a maximum spatial resolution of about 5 mum x 5 mum, which allows for the differentiation of individual cells. The main benefit with OPLS-DA lies in the ability to separate predictive variation (between cell type) from variation that is uncorrelated to cell type in order to facilitate understanding of different sources of variation. OPLS-DA was able to differentiate between chemical properties and physical properties (e.g., edge effects). OPLS-DA model interpretation of the chemical features that separated the two cell types clearly highlighted proteins and lipids/bile acids. The modeled variation that was uncorrelated to cell type made up a larger portion of the total variation and displayed strong variability in the amide I region. This could be traced back to a gradient in the high intensity (high-density) areas vs the low intensity areas (close to empty areas) that as a result of normalization had an adverse effect on FT-IR spectral profiles. This highlights that OPLS-DA provides an effective solution to identify different sources of variability, both predictive and uncorrelated, and also facilitates understanding of any sampling, experimental, or preprocessing issues.
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| 7. |
- Ubeda-Tomas, Susana, et al.
(författare)
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Genomic-assisted identification of genes involved in secondary growth in Arabidopsis utilising transcript profiling of poplar wood-forming tissues
- 2007
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 129:2, s. 415-428
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of secondary growth in plants, relatively few genes regulating this process have been identified to date. By using data from detailed transcript profiling of the poplar wood-forming tissues, 150 genes that are differentially expressed within the zone of secondary growth were identified. In order to determine the possible function of these poplar genes, potential Arabidopsis thaliana orthologs were identified and gene knockout lines analysed. Three selection filters were used to identify the most likely orthologous genes using poplar and Arabidopsis sequence comparisons, expression profiling in secondary thickened Arabidopsis hypocotyls and global expression analysis of Arabidopsis tissues. Three genes encoding AtCSLA2 (At5g22740), the AtGUT1 GT47 glycosyltransferase (At1g27440) and a protein with no proposed function AtUNKA (At4g27435) were selected for further detailed analysis of their role in secondary growth in Arabidopsis. The presented genome-based approach using both poplar and Arabidopsis systems provides powerful means towards assigning biological functions to enzymes with poorly understood biochemical activity, such as AtCSLA2 and AtGUT1, as well as for proteins with no known function.
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