| 1. |
- Akkilic, Namik, et al.
(författare)
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Avidity-Based Affinity Enhancement Using Nanoliposome-Amplified SPR Sensing Enables Low Picomolar Detection of Biologically Active Neuregulin 1
- 2019
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Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 4:12, s. 3166-3174
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Tidskriftsartikel (refereegranskat)abstract
- Biomarkers serve as indicators of disease progression or therapeutic response of an medical intervention, and means for enabling a reliable and sensitive biomarker detection are therefore vital in clinical settings. Most biosensor assays require high-affinity interactions in combination with an enzyme or fluorescent tag to enable detection and frequently employ extensive washing procedures prior to signal readout. Attempts to overcome this limitation by using natural biological partners tend to be demanding, because their very low affinity is frequently not compatible with the need of reaching low limits of detection (LODs), especially for circulating biomarkers that possess short half-lives. To address these challenges, we developed a label-free surface plasmon resonance (SPR) platform for the detection of neuregulin 1 (NRG1) using ErbB4-modified liposomes offering both signal amplification and affinity enhancement via functional multivalent interactions. Through the functional avidity interaction between NRG1 and ErbB4, an LOD of 3.5 picomolar was reached, which is about 60-fold higher than traditional SPR and miniaturized immunoassays. The biosensor displays also an 8-fold higher sensitivity when compared with a single-molecule immunoassay employing the natural binding partner rather than a high-affinity antibody as one of the interaction partners. In fact, the liposome-induced avidity between NRG1 and ErbB4 offered an LOD that was comparable to that obtained using a high-affinity antibody and enabled detection of NRG1 in plasma with a LOD of 36 pM. Employing the liposome-enhanced platform in conjunction with a low-affinity biomarker receptor thus enables the assessment of the functional state of the biomarker at competitive LODs and eliminates the need for high-affinity antibodies.
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| 2. |
- Carlsson, Björn, et al.
(författare)
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Review article: the emerging role of genetics in precision medicine for patients with non-alcoholic steatohepatitis.
- 2020
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Ingår i: Alimentary pharmacology & therapeutics. - : Wiley. - 1365-2036 .- 0269-2813. ; 51:12, s. 1305-1320
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Forskningsöversikt (refereegranskat)abstract
- Non-alcoholic steatohepatitis (NASH) is a severe form of non-alcoholic fatty liver disease (NAFLD) characterised by liver fat accumulation, inflammation and progressive fibrosis. Emerging data indicate that genetic susceptibility increases risks of NAFLD, NASH and NASH-related cirrhosis.To review NASH genetics and discuss the potential for precision medicine approaches to treatment.PubMed search and inclusion of relevant literature.Single-nucleotide polymorphisms in PNPLA3, TM6SF2, GCKR, MBOAT7 and HSD17B13 are clearly associated with NASH development or progression. These genetic variants are common and have moderate-to-large effect sizes for development of NAFLD, NASH and hepatocellular carcinoma (HCC). The genes play roles in lipid remodelling in lipid droplets, hepatic very low-density lipoprotein (VLDL) secretion and de novo lipogenesis. The PNPLA3 I148M variant (rs738409) has large effects, with approximately twofold increased odds of NAFLD and threefold increased odds of NASH and HCC per allele. Obesity interacts with PNPLA3 I148M to elevate liver fat content and increase rates of NASH. Although the isoleucine-to-methionine substitution at amino acid position 148 of the PNPLA3 enzyme inactivates its lipid remodelling activity, the effect of PNPLA3 I148M results from trans-repression of another lipase (ATGL/PNPLA2) by sequestration of a shared cofactor (CGI-58/ABHD5), leading to decreased hepatic lipolysis and VLDL secretion. In homozygous Pnpla3 I148M knock-in rodent models of NAFLD, targeted PNPLA3 mRNA knockdown reduces hepatic steatosis, inflammation and fibrosis.The emerging genetic and molecular understanding of NASH paves the way for novel interventions, including precision medicines that can modulate the activity of specific genes associated with NASH.
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| 3. |
- Knochel, Jane, et al.
(författare)
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A Markov model of fibrosis development in nonalcoholic fatty liver disease predicts fibrosis progression in clinical cohorts
- 2023
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Ingår i: CPT. - : WILEY. - 2163-8306. ; 12:12, s. 2038-2049
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Tidskriftsartikel (refereegranskat)abstract
- Disease progression in nonalcoholic steatohepatitis (NASH) is highly heterogenous and remains poorly understood. Fibrosis stage is currently the best predictor for development of end-stage liver disease and mortality. Better understanding and quantifying the impact of factors affecting NASH and fibrosis is essential to inform a clinical study design. We developed a population Markov model to describe the transition probability between fibrosis stages and mortality using a unique clinical nonalcoholic fatty liver disease cohort with serial biopsies over 3 decades. We evaluated covariate effects on all model parameters and performed clinical trial simulations to predict the fibrosis progression rate for external clinical cohorts. All parameters were estimated with good precision. Age and diagnosis of type 2 diabetes (T2D) were found to be significant predictors in the model. Increase in hepatic steatosis between visits was the most important predictor for progression of fibrosis. Fibrosis progression rate (FPR) was twofold higher for fibrosis stages 0 and 1 (F0-1) compared to fibrosis stage 2 and 3 (F2-3). A twofold increase in FPR was observed for T2D. A two-point steatosis worsening increased the FPR 11-fold. Predicted fibrosis progression was in good agreement with data from external clinical cohorts. Our fibrosis progression model shows that patient selection, particularly initial fibrosis stage distribution, can significantly impact fibrosis progression and as such the window for assessing drug efficacy in clinical trials. Our work highlights the increase in hepatic steatosis as the most important factor in increasing FPR, emphasizing the importance of well-defined lifestyle advise for reducing variability in NASH progression during clinical trials.
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| 4. |
- Liljeblad, Mathias, et al.
(författare)
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A Lectin Immunosensor Technique for Determination of α1-Acid Glycoprotein Fucosylation
- 2001
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 288:2, s. 216-224
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Tidskriftsartikel (refereegranskat)abstract
- The fucosylation of α1-acid glycoprotein (AGP), an acute-phase protein, is known to change in association with inflammatory diseases. Thus, fucosylation of AGP could be a potential diagnostic or prognostic marker. The change in fucosylation has previously been investigated using crossed affinoimmunoelectrophoresis, high-pH anion-exchange chromatography, and lectin ELISA. This study describes a surface plasmon resonance-based affinity biosensor assay for quantification of the fucosylation of AGP. Diluted EDTA plasma or serum was injected directly in a BIACORE 2000 biosensor. AGP was captured on the sensor surface using immobilized antibodies and a fucose-binding lectin from Aleuria aurentia was then used for the detection of fucosylation. The feature of the biosensor makes it possible to determine both the amount of bound AGP and the amount of bound lectin. Using a calibration curve it was possible to obtain a fucosylation ratio that was independent of AGP concentration. The assay was validated against a lectin ELISA and used to follow inflammation in patients with severe burns.
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| 5. |
- Liljeblad, Mathias, et al.
(författare)
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Analysis of agalacto-IgG in rheumatoid arthritis using surface plasmon resonance
- 2000
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Ingår i: Glycoconjugate Journal. - 0282-0080 .- 1573-4986. ; 17:5, s. 323-329
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Tidskriftsartikel (refereegranskat)abstract
- It is well established that IgG from rheumatoid arthritis (RA) patients are less galactosylated than IgG from normal individuals. Determination of agalacto-IgG may therefore aid in diagnosis and treatment of RA. The decrease in galactosylation of IgG leads to an increase in terminal N-acetylglucosamine residues, which can be detected using a specific lectin from Psathyrella velutina. In the present study IgG from RA and control serum was purified using affinity chromatography. The samples were then, after reduction, analyzed on a BIOCORE® 2000 system with immobilized Psathyrella velutina lectin. Using this technique it was possible to discriminate between IgG from RA patients and IgG from control individuals with respect to its content of IgG with terminal N-acetylglucosamine. The affinity biosensor technique makes it possible to detect binding without labeling or using secondary antibodies.
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| 6. |
- Liljeblad, Mathias, et al.
(författare)
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Analysis of glycoproteins in cell culture supernatants using a lectin immunosensor technique
- 2002
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 17:10, s. 883-891
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Tidskriftsartikel (refereegranskat)abstract
- A method based on a surface plasmon resonance technique for detection of changes in concentration and glycosylation of proteins in cell culture supernatant is described. The method was used to analyze α1-acid glycoprotein (AGP) produced by a human hepatoma cell line (HepG2). Cell culture supernatant was injected to a BIACORE 2000 instrument and AGP was captured on the sensor chip by immobilized antibodies. The captured glycoprotein was then analyzed for content of carbohydrate epitopes using three different lectins, Aleuria aurantia lectin (AAL), Sambucus nigra agglutinin (SNA), and Triticum vulgaris agglutinin (wheat germ agglutinin, WGA). The method was used to analyze changes in concentration and glycosylation of AGP produced by HepG2 cells grown with or without three different cytokines, interleukin-1β (IL-1β), interleukin-6 (IL-6), and transforming growth factor β-1 (TGFβ1). Using the described method it was shown that when HepG2 cells were grown in the presence of IL-6 both AGP concentration and fucosylation increased. When HepG2 cells instead were grown in the presence of TGFβ1 AGP fucosylation increased whereas AGP concentration decreased.
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| 7. |
- Liljeblad, Mathias, et al.
(författare)
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Detection of low-molecular-weight heparin oligosaccharides (Fragmin™) using surface plasmon resonance
- 1998
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Ingår i: Journal of Molecular Recognition. - : John Wiley and Sons. - 0952-3499 .- 1099-1352. ; 11:1-6, s. 191-193
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Tidskriftsartikel (refereegranskat)abstract
- During the last decades there has been a growing realization of the central biological role that oligosaccharides and oligosaccharide–protein interactions play. One of the most striking examples is the use of heparin and low-molecular-weight heparin oligosaccharides (Fragmin™) to modify blood coagulation. Several monoclonal antibodies directed against glycosaminoglycan structures have been produced. However, their clinical use is limited by the difficulty of detection systems for oligosaccharides. In the present study we used a monoclonal antibody directed against heparin oligosaccharides prepared by partial nitrous acid deamination of heparin. Using a biosensor (BIAcore™), purified antibody was immobilized on sensor surfaces and binding of oligosaccharide was measured by surface plasmon resonance. Using this technique, it was possible to quantitate low-molecular-weight heparin oligosaccharides in nanomolar concentrations.
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| 8. |
- Liljeblad, Mathias
(författare)
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Shedding light on glycosylation : Analysis of complex carbohydrates using an affinity biosensor
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective during the work described in this thesis has been to develop assays for stodies of complex carbohydrates in a clinical context. Complex carbohydrates, such as free or protein linked oligosaccharides, have been shown to have important biological functions. Furthermore, certain diseases have been associated with changes in oligosaccharide composition. We wanted to explore the potential of affinity biosensors to analyze such changes, since disease-specific carbohydrate stroctores might be useful in the diagnosis and prognosis of diseases.Throughout this work a surface plasmon based affinity biosensor instrument has been used. The instrmnent detects changes in refractive index close to a sensor surface. By immobilization of, e.g., an antibody at the sensor surface, the change in refractive index caused by antigen binding can be followed over time. The change in refractive index is proportional to the mass of bound antigen. This detection technique was used in the present work to quantitate free oligosaccharides as well as the presence of certain carbohydrate stroctores on glycoproteins.Two different types of assays for analysis of complex carbohydrates were developed. The first type of assay was a single step assay, where a carbohydrate-binding protein was immobilized at the sensor surface. Changes in response due to binding of free oligosaccharides or glycoproteins in samples were then used to quantitate the content of specific carbohydrate structores. The second type of assay was a sandwich assay, where antibodies directed to the glycoprotein to be stodied were immobilized at the sensor surface. This allowed the glycoprotein to be captored at the sensor surface from crude samples such as diluted blood plasma. The glycosylation of the captored glycoprotein was then analyzed by injection of a lectin over the sensor surface. The relative amount of the carbohydrate stroctore recognized by the lectin was determined by calculating a ratio between sensor responses for bound lectin and captored glycoprotein.The single step assay was used to quantitate Fragmin ® concentration, a low molecular weight heparin used as an anticoagulant. The single step assay was further used to analyze immunoglobulin G from rheumatoid arthritis patients and control individuals for oligosaccharide chains deficient in galactose, a carbohydrate structure associated with this disease. The sandwich type assay was used to follow changes in fucosylation of an acute-phase protein, α1-acid glycoprotein, in plasma from patients with severe burns. The same assay was also used to stndy the effect of cytokines on secretion and glycosylation of α1-acid glycoprotein from a human hepatoma cell line (HepG2).
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