| 1. |
- Aifa, Sami, et al.
(författare)
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Interactions between the juxtamembrane domain of the EGFR and calmodulin measured by surface plasmon resonance
- 2002
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Ingår i: Cellular Signalling. - 0898-6568 .- 1873-3913. ; 14:12, s. 1005-1013
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Tidskriftsartikel (refereegranskat)abstract
- One early response to epidermal growth factor receptor (EGFR) activation is an increase in intracellular calcium. We have used surface plasmon resonance (SPR) to study real-time interactions between the intracellular juxtamembrane (JM) region of EGFR and calmodulin. The EGFR-JM (Met644-Phe688) was expressed as a GST fusion protein and immobilised on a sensor chip surface. Calmodulin specifically interacts with EGFR-JM in a calcium-dependent manner with a high on and high off rate. Chemical modification of EGFR-JM by using arginine-selective phenylglyoxal or deletion of the basic segment Arg645-Arg657 inhibits the interaction. Phosphorylation of EGFR-JM by protein kinase C (PKC) or glutamate substitution of Thr654 inhibits the interaction, suggesting that PKC phosphorylation electrostatically interferes with calmodulin binding to basic arginine residues. Calmodulin binding was also inhibited by suramin. Our results suggest that EGFR-JM is essential for epidermal growth factor (EGF)-mediated calcium-calmodulin signalling and for signal integration between other signalling pathways.
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| 2. |
- Aifa, Sami, et al.
(författare)
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Phosphorylation of Thr654 but not Thr669 within the juxtamembrane domain of the EGF receptor inhibits calmodulin binding
- 2006
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 347:2, s. 381-387
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Tidskriftsartikel (refereegranskat)abstract
- Calcium-calmodulin (CaM) binding to the epidermal growth factor receptor (EGFR) has been shown to both inhibit and stimulate receptor activity. CaM binds to the intracellular juxtamembrane (JM) domain (Met645-Phe688) of EGFR. Protein kinase C (PKC) mediated phosphorylation of Thr654 occurs within this domain. CaM binding to the JM domain inhibits PKC phosphorylation and conversely PKC mediated phosphorylation of Thr654 or Glu substitution of Thr654 inhibits CaM binding. A second threonine residue (Thr669) within the JM domain is phosphorylated by the mitogen-activated protein kinase (MAPK). Previous results have shown that CaM interferes with EGFR-induced MAPK activation. If and how phosphorylation of Thr669 affects CaM-EGFR interaction is however not known.In the present study we have used surface plasmon resonance (BIAcore) to study the influence of Thr669 phosphorylation on real time interactions between the intracellular juxtamembrane (JM) domain of EGFR and CaM. The EGFR-JM was expressed as GST fusion proteins in Escherichia coli and phosphorylation was mimicked by generating Glu substitutions of either Thr654 or Thr669. Purified proteins were coupled to immobilized anti-GST antibodies at the sensor surface and increasing concentration of CaM was applied. When mutating Thr654 to Glu654 no specific CaM binding could be detected. However, neither single substitutions of Thr669 (Gly669 or Glu669) nor double mutants Gly654/Gly669 or Gly654/Glu669 influenced the binding of CaM to the EGFR-JM. This clearly shows that PKC may regulate EGF-mediated CaM signalling through phosphorylation of Thr654 whereas phosphorylation of Thr669 seems to play a CaM independent regulatory role. The role of both residues in the EGFR-calmodulin interaction was also studied in silico. Our modelling work supports a scenario where Thr654 from the JM domain interacts with Glu120 in the calmodulin molecule. Phosphorylation of Thr654 or Glu654 substitution creates a repulsive electrostatic force that would diminish CaM binding to the JM domain. These results are in line with the Biacore experiments showing a weak binding of the CaM to the JM domain with Thr654 mutated to Glu. Furthermore, these results provide a hypothesis to how CaM binding to EGFR might both positively and negatively interfere with EGFR-activity. © 2006 Elsevier Inc. All rights reserved.
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| 3. |
- Arwin, Hans, 1950-, et al.
(författare)
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Enhancement in ellipsometric thin film sensitivity near surface plasmon resonance conditions
- 2008
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlagsgesellschaft. - 1862-6300 .- 1862-6319. ; 205:4, s. 817-820
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Tidskriftsartikel (refereegranskat)abstract
- Ellipsometry used in internal reflection mode exhibits enhanced thin film sensitivity if operated close to surface plasmon resonance conditions. Compared to conventional ellipsometry, the changes in the ellipsometric parameter Δ are several orders of magnitude larger. Here, the origin of this large sensitivity is discussed by analysing thin film approximations of the complex reflectance ratio. It is found that the thickness sensitivity in Δ is proportional to the inverse of the difference between the intrinsic and the radiation-induced damping of the surface plasmons.
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| 4. |
- Arwin, Hans, 1950-, et al.
(författare)
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Total internal reflection ellipsometry : principles and applications
- 2004
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Ingår i: Applied Optics. - 0003-6935 .- 1539-4522. ; 43:15, s. 3028-3036
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Tidskriftsartikel (refereegranskat)abstract
- A concept for a measurement technique based on ellipsometry in conditions of total internal reflection is presented. When combined with surface plasmon resonance (SPR) effects, this technique becomes powerful for monitoring and analyzing adsorption and desorption on thin semitransparent metal films as well as for analyzing the semitransparent films themselves. We call this technique total internal reflection ellipsometry (TIRE). The theory of ellipsometry under total internal reflection combined with SPR is discussed for some simple cases. For more advanced cases and to prove the concept, simulations are performed with the Fresnel formalism. The use of TIRE is exemplified by applications in protein adsorption, corrosion monitoring, and adsorption from opaque liquids on metal surfaces. Simulations and experiments show greatly enhanced thin-film sensitivity compared with ordinary ellipsometry.
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| 5. |
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| 6. |
- Bruun, Jarle, et al.
(författare)
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Regulator of Chromosome Condensation 2 Identifies High-Risk Patients within Both Major Phenotypes of Colorectal Cancer
- 2015
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Ingår i: Clinical Cancer Research. - : AMER ASSOC CANCER RESEARCH. - 1078-0432 .- 1557-3265. ; 21:16, s. 3759-3770
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Colorectal cancer has high incidence and mortality worldwide. Patients with microsatellite instable (MSI) tumors have significantly better prognosis than patients with microsatellite stable (MSS) tumors. Considerable variation in disease outcome remains a challenge within each subgroup, and our purpose was to identify biomarkers that improve prediction of colorectal cancer prognosis. Experimental Design: Mutation analyses of 42 MSI target genes were performed in two independent MSI tumor series (n = 209). Markers that were significantly associated with prognosis in the test series were assessed in the validation series, followed by functional and genetic explorations. The clinical potential was further investigated by immunohistochemistry in a population-based colorectal cancer series (n = 903). Results: We identified the cell-cycle gene regulator of chromosome condensation 2 (RCC2) as a cancer biomarker. We found a mutation in the 50 UTR region of RCC2 that in univariate and multivariate analyses was significantly associated with improved outcome in the MSI group. This mutation caused reduction of protein expression in dual luciferase gene reporter assays. siRNA knockdown in MSI colon cancer cells (HCT15) caused reduced cell proliferation, cell-cycle arrest, and increased apoptosis. Massive parallel sequencing revealed few RCC2 mutations in MSS tumors. However, weak RCC2 protein expression was significantly associated with poor prognosis, independent of clinical highrisk parameters, and stratifies clinically important patient subgroups with MSS tumors, including elderly patients (greater than 75 years), stage II patients, and those with rectal cancer. Conclusions: Impaired RCC2 affects functional and clinical endpoints of colorectal cancer. High-risk patients with either MSI or MSS tumors can be identified with cost-effective routine RCC2 assays. (C) 2015 AACR.
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| 7. |
- Charalampopoulos, Dimitrios, et al.
(författare)
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Exploring Variation in Glycemic Control Across and Within Eight High-Income Countries: A Cross-sectional Analysis of 64,666 Children and Adolescents With Type 1 Diabetes
- 2018
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Ingår i: Diabetes Care. - : AMER DIABETES ASSOC. - 0149-5992 .- 1935-5548. ; 41:6, s. 1180-1187
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE International studies on childhood type 1 diabetes (T1D) have focused on whole-country mean HbA(1c) levels, thereby concealing potential variations within countries. We aimed to explore the variations in HbA(1c) across and within eight high-income countries to best inform international benchmarking and policy recommendations. RESEARCH DESIGN AND METHODS Data were collected between 2013 and 2014 from 64,666 children with T1D who were amp;lt; 18 years of age across 528 centers in Germany, Austria, England, Wales, U.S., Sweden, Denmark, and Norway. We used fixed-and random-effects models adjusted for age, sex, diabetes duration, and minority status to describe differences between center means and to calculate the proportion of total variation in HbA(1c) levels that is attributable to between-center differences (intraclass correlation [ICC]). We also explored the association between within-center variation and childrens glycemic control. RESULTS Sweden had the lowest mean HbA(1c) (59mmol/mol [7.6%]) and together with Norway and Denmark showed the lowest between-center variations (ICC amp;lt;= 4%). Germany and Austria had the next lowest mean HbA(1c) (61-62 mmol/mol [7.7-7.8%]) but showed the largest center variations (ICC similar to 15%). Centers in England, Wales, and the U.S. showed low-to-moderate variation around high mean values. In pooled analysis, differences between counties remained significant after adjustment for children characteristics and center effects (P value amp;lt; 0.001). Across all countries, children attending centers with more variable glycemic results had higher HbA(1c) levels (5.6mmol/mol [0.5%] per 5mmol/mol [0.5%] increase in center SD of HbA(1c) values of all children attending a specific center). CONCLUSIONS A tsimilar average levels of HbA(1c), countries display different levels of center variation. The distribution of glycemic achievement within countries should be considered in developing informed policies that drive quality improvement.
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| 8. |
- Frankelius, Per, 1966-, et al.
(författare)
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Agricultural Innovation and the Role of Institutions : Lessons from the Game of Drones
- 2019
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Ingår i: Journal of Agricultural and Environmental Ethics. - : Springer. - 1187-7863 .- 1573-322X. ; 32:5-6, s. 681-707
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Tidskriftsartikel (refereegranskat)abstract
- In 2015, observers argued that the fourth agricultural revolution had been initiated. This article focuses on one part of this high-tech revolution: the origin, development, applications, and user value of unmanned aerial systems (UAS). Institutional changes connected to the UAS innovation are analyzed, based on a Swedish case study. The methods included autoethnography. The theoretical frame was composed by four perspectives: innovation, institutions, sustainability, and ethics. UAS can help farmers cut costs and produce higher quantity with better quality, and also has environmental benefits. However, this promising innovation was exposed to institutional forces and suddenly became subordinated the Act of Camera Surveillance. This study illuminates how legislative institutions can inhibit responsible innovation. The study shows that different ethical perspectives can collide with each other.
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| 9. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Surface plasmon resonance detection of blood coagulation and platelet adhesion under venous and arterial shear conditions.
- 2007
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Ingår i: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 23:2, s. 261-8
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Tidskriftsartikel (refereegranskat)abstract
- A surface plasmon resonance (SPR) based flow chamber device was designed for real time detection of blood coagulation and platelet adhesion in platelet rich plasma (PRP) and whole blood. The system allowed the detection of surface interactions throughout the 6mm length of the flow chamber. After deposition of thromboplastin onto a section of the sensor surface near the inlet of the flow chamber, coagulation was detected downstream of this position corresponding to a SPR signal of 7 to 8 mRIU (7 to 8 ng/mm2). A nonmodified control surface induced coagulation 3.5 times slower. Platelet adhesion to gold and fibrinogen coated surfaces in the magnitude of 1.25 and 1.66 mRIU was also shown with platelets in buffer, respectively. SPR responses obtained with PRP and whole blood on surfaces that were methylated or coated with von Willebrand factor (vWF), fibrinogen, or collagen, coincided well with platelet adhesion as observed with fluorescence microscopy in parallel experiments. The present SPR detection equipped flow chamber system is a promising tool for studies on coagulation events and blood cell adhesion under physiological flow conditions, and allows monitoring of short-range surface processes in whole blood.
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| 10. |
- Hansson, Kenny, 1972-, et al.
(författare)
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Surface plasmon resonance (SPR) analysis of coagulation in whole blood with application in prothrombin time assay
- 1999
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 14:8-9, s. 671-682
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Tidskriftsartikel (refereegranskat)abstract
- It is previously shown that surface plasmon resonance (SPR) can be used to study blood plasma coagulation. This work explores the use of this technique for the analysis of tissue factor induced coagulation, i.e. prothrombin time (PT) analysis, of whole blood and plasma. The reference method was nephelometry. The prothrombin time analysis by SPR was performed by mixing two volumes of blood/plasma, one volume of thromboplastin, and one volume of CaCl2 solution directly on a sensor surface. The measurements show good agreement between nephelometry and SPR plasma analysis and also between SPR plasma and whole blood analysis. The effect of anticoagulant treatment on the clotting times was significant both quantitatively and qualitatively. The impact on the SPR signal of different physiological events in the coagulation process is discussed, and tentative interpretations of the sensorgram features are given. The major advantage of the SPR method compared to nephelometry is the possibility to perform analysis on whole blood instead of plasma. In conclusion, SPR is a promising method for whole blood coagulation analysis.
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