| 1. |
- Aldén, Anna, et al.
(författare)
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HPLC analysis of carbohydrate deficient transferrin isoforms isolated by the Axis-Shield %CDT method
- 2005
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Ingår i: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981 .- 1873-3492. ; 356:1-2, s. 143-146
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Tidskriftsartikel (refereegranskat)abstract
- Background: Carbohydrate-deficient transferrin (CDT) is elevated during prolonged overconsumption of alcohol and CDT is considered to be the most specific biochemical marker for alcohol overconsumption. However, an accurate method for analysing CDT is necessary because the test is frequently used for example in legal matters. Methods: Patient serum samples were analysed with the Axis-Shield %CDT and eluates were pooled together. Transferrin was purified from the pool by affinity chromatography and further analysed with HPLC to determine the ratios of different transferrin isoforms. Results: In the eluates using the Axis-Shield %CDT method, a substantial amount of trisialo transferrin was found, which is generally not considered a CDT isoform. Conclusions: The fact that trisialo transferrin is present may generate falsely elevated CDT results and it could at least partly explain the discrepancy between results of the Axis-Shield %CDT assay and HPLC in routine analysis. © 2005 Elsevier B.V. All rights reserved.
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| 4. |
- Bergström, Maria, et al.
(författare)
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Cholera toxin inhibitors studied with High-performance liquid affinity chromatography: arobust method to evaluate receptor-ligand interactions
- 2009
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Ingår i: Chemical Biology and Drug Design. - : Wiley. - 1747-0277 .- 1747-0285. ; 73:1, s. 132-141
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Tidskriftsartikel (refereegranskat)abstract
- Anti-adhesion drugs may be an alternative to antibiotics to control infection of micro-organisms. The well-characterized interaction between cholera toxin and the cellular glycolipid GM1 makes it an attractive model for inhibition studies in general. In this report, we demonstrate a high-performance liquid affinity chromatography approach called weak affinity chromatography to evaluate cholera toxin inhibitors. The cholera toxin B-subunit was covalently coupled to porous silica and a (weak) affinity column was produced. The K(D) values of galactose and meta-nitrophenyl alpha-d-galactoside were determined with weak affinity chromatography to be 52 and 1 mm, respectively, which agree well with IC(50) values previously reported. To increase inhibition potency multivalent inhibitors have been developed and the interaction with multivalent glycopolypeptides was also evaluated. The affinity of these compounds was found to correlate with the galactoside content but K(D) values were not obtained because of the inhomogeneous response and slow off-rate from multivalent interactions. Despite the limitations in obtaining direct K(D) values of the multivalent galactopolypeptides, weak affinity chromatography represents an additional and valuable tool in the evaluation of monovalent as well as multivalent cholera toxin inhibitors. It offers multiple advantages, such as a low sample consumption, high reproducibility and short analysis time, which are often not observed in other methods of analysis.
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| 5. |
- Bornberger-Dankvardt, Sten, et al.
(författare)
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Arbetsmiljöarbete i småföretag : samlad kunskap samt behov av forskning och utvecklingsinsatser
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Föreliggande rapport behandlar specifikt behov av och möjligheter för arbetsmiljöarbete i småföretag och är ett delarbete i tema SMARTA. SMARTA – strategier, metoder och arbetssätt för fungerande arbetsmiljöarbete – ingår i Arbetslivsinstitutets temaverksamhet. SMARTA ska bidra till ett hållbart arbetsliv på arbetsplatser där arbetsmiljöarbetet ses som en resurs för både arbetsplatsen och individen. För arbetsplatsen kan det handla om konkurrenskraft, lönsamhet samt attraktivitet och för individen om hälsa, välbefinnande, kreativitet och förnyelseförmåga. SMARTA tar ett helhetsperspektiv på arbetsmiljöarbete inom olika regioner och branscher. Temat sammanställer inledningsvis kunskapsläget och ger exempel på hur arbetsmiljöarbete kan bedrivas och vidareutvecklas. Ambitionen för FoU-projekt i tema SMARTA är att besvara frågor som: • Hur bör arbetsmiljöarbete integreras i organisationers kärnverksamhet? • Hur bör arbetsmiljöarbete bedrivas? • Hur bör interna och externa aktörer agera för att få till stånd ett hållbart och fungerande arbetsmiljöarbete? Rapporten vänder sig till praktiker och forskare som är intresserade av att få en översiktsbild över arbetsmiljösituationen i småföretag och förutsättningar som krävs för fungerande arbetsmiljöarbete.
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| 8. |
- Engström, Henrik, 1975-
(författare)
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Development of Flourescence-based Immunosensors for Continous Carbohydrate Monotoring : Applications for Maltose and Glucose
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Weak affinity interaction of monoclonal antibodies and carbohydrate antigens can be detected and quantified by alterations in the antibodies' intrinsic tryptophan fluorescence. These weak/transient binding events have been monitored by total internal reflection fluorescence (TlRF) by facilitating the change in intrinsic tryptophan fluorescence. This immunosensor followed instant changes in the antigen concentration with rapid association- and dissociation rate constants reaching equilibrium in a short time, without the need for regeneration. Furthermore, in a competition assay with extrinsic fluorescence labeling, it was established that Förster/fluorescence resonance energy transfer (FRET) can be applied for weak and transient interactions. By entrapping components in small semipermeable capsules, aconvenient flow system was fabricated allowing on-line measurements of maltose. Quantification of maltose concentration was achievable in the mM-range without need for regeneration.High specificty for maltose was exhibited in crude food-samples with quantification in accordance with batch analysis. Furthermore, a monoclonal antibody was developed for potential use as a glucose immunosensor for diabetes. Its ability to interact with glucose was determined by competitive weak affinity chromatography (WAC) to approximately 19 mM in dissociation constant. This antibody was developed to bind monosaccharides, especially glucose, by utilizing crossreation with a carbohydrate dextran polymer. Selectivity for glucose was greater than for the similar monosaccharides, mannose and galactose. This antibody, or a fragment, in a fluorescence platform is an alternative to monitor glucose in vivo where other glucose-binders might fail.
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| 9. |
- Engström, Henrik, et al.
(författare)
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Evaluation of a glucose sensing antibody using weak affinity chromatography
- 2008
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Ingår i: BMC Biomedical chromotography. - : Wiley. - 0269-3879 .- 1099-0801. ; 22:3, s. 272-277
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Tidskriftsartikel (refereegranskat)abstract
- Continuous monitoring of drug levels and endogenous molecules in biological fluids is a developing research area with many applications. One example is the need to improve life for millions of diabetes mellitus patients by continuously monitoring the glucose level. In order to have a dynamic response, the recognition molecule in a continuous sensor should preferentially have a fast dissociation rate and a dissociation constant in the millimolar range. We have evaluated the monoclonal antibody (mAb) 3F1E8-A2 for its potential to be used in a future glucose sensor application. The mAb was generated from hybridomas by immunizing mice with 10 kDa dextran (an α1,6-glucose polymer) with the aim of obtaining mAbs that can recognize the glucose monomer. The mAb was immobilized to macroporous silica and the interaction with dextran-derived oligosaccharides was evaluated with weak affinity chromatography (WAC). To measure the low affinities between the mAb 3F1E8-A2 and different monosaccharides, a competitive weak affinity chromatography approach was employed. It was found that the mAb had a higher specificity for glucose compared with other monosaccharides and the dissociation constant (Kd) towards glucose was determined as 18.8 ± 2.6 mm.
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| 10. |
- Engström, Henrik, et al.
(författare)
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Towards a FRET-based immunosensor for continuous carbohydrate monitoring
- 2008
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Ingår i: JIM - Journal of Immunological Methods. - : Elsevier BV. - 0022-1759 .- 1872-7905. ; 333:1-2, s. 107-114
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Tidskriftsartikel (refereegranskat)abstract
- In this report we have evaluated the potential of using fluorescence/Förster resonance energy transfer (FRET) in a competitive immunosensor for continuous monitoring of the carbohydrate hapten maltose. The cyanine dyes Cy5 and Cy5.5 were used as a donor–acceptor pair by conjugation to maltose-labeled bovine serum albumin (BSA) and the monoclonal antibody IgG 39.5, giving Cy5–BSA–maltotriitol (3.1/1/18) and Cy5.5–mAb39.5 (2.2/1), respectively. This antibody with weak affinity towards maltose showed full reversibility to both the free maltose and the maltose-labeled conjugate. It allowed us to measure continuously the maltose content by monitoring the FRET signal change over time due to displacement of Cy5–BSA–maltotriitol from Cy5.5–mAb39.5 inside a semipermeable capsule. A near 22% total increase was seen in the fluorescence intensity ratio I670/I700 in the presence of maltose, with a calculated EC50 = 1.87 ± 0.13 mM (R2 = 0.9984) from the sigmoidal dose–response curve at 25 °C. Specificity of the immunosensor was shown with the structural analog to maltose, cellobiose, and it generated no detectable response. A minor drift in the sensor baseline was seen with 0.4% per 24 h, which was in the same magnitude as the signal-to-noise ratio, during the 4 weeks of measurements. The immunosensor was applied to crude samples of oat drinks for direct quantification of the maltose content. Overall, this work demonstrates the potential to use an immunosensor based on weakly binding antibodies and FRET technology for remote and non-invasive carbohydrate monitoring.
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| 12. |
- Johansson, Reine, et al.
(författare)
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Thermostable carbohydrate-binding modules in affinity chromatography
- 2006
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Ingår i: Journal of Molecular Recognition. - : Wiley. - 0952-3499 .- 1099-1352. ; 19:4, s. 275-281
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Konferensbidrag (refereegranskat)abstract
- Affinity chromatography is routinely used mostly on a preparative scale to isolate different biomolecules such as proteins and carbohydrates. To this end a variety of proteins is in common use as ligands. To extend the arsenal of binders intended for separation of carbohydrates, we have explored the use of carbohydratebinding modules (CBM) in affinity chromatography. The thermostable protein CBM4-2 and two variants (X-6 and A-6) thereof, selected from a newly constructed combinatorial library, were chosen for this study. The CBM4-2 predominantly binds to xylans but also crossreacts with glucose-based olligomers. The two CBM-variants X-6 and A-6 had been selected for binding to xylan and Avicel (a mixture of amorphous and microcrystalline cellulose), respectively. To assess the ability of these proteins to separate carbohydrates, they were immobilized to macroporous microparticulate silica and analyses were conducted at temperatures ranging from 25 to 65 degrees C. With the given set of CBM-variants, we were able to separate cello- and xylo-oligomers under isocratic conditions. The affinities of the CBMs for their targets were weak (in the mM-mu M range) and by adjusting the column temperature we could optimize peak resolution and chromatographic retention times. The access to thermostable CBM-variants with diverse affinities and selectivities holds promise to be an efficient tool in the field of affinity chromatography for the separation of carbohydrates. Copyright (c) 2006 John Wiley & Sons Ltd.
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| 14. |
- Mandenius, Carl-Fredrik, 1954-, et al.
(författare)
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Monitoring of influenza virus hemagglutinin in process samples using weak affinity ligands and surface plasmon resonance
- 2008
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 623, s. 66-75
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Tidskriftsartikel (refereegranskat)abstract
- Surface plasmon resonance (SPR) was used to screen the interaction between a variety of affinity ligands and hemagglutinin (HA) from human influenza virus, with the aim of identifying low affinity ligands useful for the development of a rapid bioanalytical sensor. Three sialic acid-based structures and four lectins were evaluated as sensor ligands. The sialic acid-based ligands included a natural sialic acid-containing glycoprotein, human α1-acid glycoprotein (α1-AGP), and two synthetic 6′-sialyllactose-conjugates, with varying degree of substitution. The interaction of HA with the four lectin-based ligands, concanavalin A (Con A), wheat germ agglutinin (WGA), Maackia amurensis lectin (MAL), and Sambucus nigra agglutinin (SNA), showed a wide variation of affinity strengths. Affinity and kinetics data were estimated. Strong affinities were observed for Con A, WGA, α1-AGP, and a 6′-sialyllactose-conjugate with a high substitution degree, and low affinities were observed for MAL and a 6′-sialyllactose-conjugate with low substitution. The main objective, to identify a low affinity ligand which could be used for on-line monitoring and product quantification, was met by a 6′-sialyllactose–ovalbumin conjugate that had 0.6 mol ligand per mol carrier protein. The apparent affinity of this ligand was estimated to be 1.5 ± 0.03 μM (KD) on the SPR surface. Vaccine process samples containing HA were analyzed in the range 10–100 μg HA mL−1 and correlated with single-radial immunodiffusion. The coefficient of variation on the same chip was between 0.010 and 0.091.
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