| 1. |
- Abdel-Motal, Ussama M., et al.
(författare)
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Major histocompatibility complex class I binding glycopeptides for the estimation of 'empty' class I molecules
- 1995
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Ingår i: Journal of Immunological Methods. - : Elsevier BV. - 0022-1759. ; 188:1, s. 21-31
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Tidskriftsartikel (refereegranskat)abstract
- Different forms of major histocompatibility complex (MHC) class I heavy chains are known to be expressed on the cell surface, including molecules which are functionally 'empty'. Direct peptide binding to cells is obvious during sensitization of target cells in vitro for cytotoxic T lymphocyte killing and 'empty' MHC-I molecules are comparatively abundant on TAP- 1 2 peptide transporter mutant cells. In the present work we have estimated the fraction of 'empty' MHC class I molecules using glycosylated peptides and cellular staining with carbohydrate specific monoclonal antibodies. Synthetic Db and Kb binding peptides were coupled at different positions with different di- or trisaccharides, using different spacing between the carbohydrate and the peptide backbone. Binding of sugar specific mAbs was compared in ELISA and cellular assays. An optimal Db binding glycopeptide was used for comparative staining with anti-Db and anti-carbohydrate monoclonal antibodies to estimate fractions of 'empty' molecules on different T lymphoid cells. On activated normal T cells, a large fraction of Db molecules were found to be 'empty'. The functional cole of such 'empty' MHC class I molecules on T cells is presently unclear. However, on antigen presenting cells they might participate in the antigen presentation process.
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| 2. |
- El-Saadi, Walid, 1984-, et al.
(författare)
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A head-to-head comparison of myocardial strain by fast-strain encoding and feature tracking imaging in acute myocardial infarction
- 2022
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Ingår i: Frontiers in Cardiovascular Medicine. - : Frontiers Media SA. - 2297-055X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundMyocardial infarction (MI) is a major cause of heart failure. Left ventricular adverse remodeling is common post-MI. Several studies have demonstrated a correlation between reduced myocardial strain and the development of adverse remodeling. Cardiac magnetic resonance (CMR) with fast-strain encoding (fast-SENC) or feature tracking (FT) enables rapid assessment of myocardial deformation. The aim of this study was to establish a head-to-head comparison of fast-SENC and FT in post-ST-elevated myocardial infarction (STEMI) patients, with clinical 2D speckle tracking echocardiography (2DEcho) as a reference. MethodsThirty patients treated with primary percutaneous coronary intervention for STEMI were investigated. All participants underwent CMR examination with late gadolinium enhancement, cine-loop steady-state free precession, and fast-SENC imaging using a 1.5T scanner as well as a 2DEcho. Global longitudinal strain (GLS), segmental longitudinal strain (SLS), global circumferential strain (GCS), and segmental circumferential strain (SCS) were assessed along with the MI scar extent. ResultsThe GCS measurements from fast-SENC and FT were nearly identical: the mean difference was 0.01 (2.5)% (95% CI - 0.92 to 0.95). For GLS, fast-SENC values were higher than FT, with a mean difference of 1.8 (1.4)% (95% CI 1.31-2.35). Tests of significance for GLS did not show any differences between the MR methods and 2DEcho. Average strain in the infarct-related artery (IRA) segments compared to the remote myocardium was significantly lower for the left anterior descending artery and right coronary artery culprits but not for the left circumflex artery culprits. Fast-SENC displayed a higher area under the curve for detecting infarcted segments than FT for both SCS and SLS. ConclusionGLS and GCS did not significantly differ between fast-SENC and FT. Both showed acceptable agreement with 2DEcho for longitudinal strain. Segments perfused by the IRA showed significantly reduced strain values compared to the remote myocardium. Fast-SENC presented a higher sensitivity and specificity for detecting infarcted segments than FT.
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| 3. |
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| 4. |
- Hedenström, Mattias, 1976-
(författare)
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NMR as a tool in drug research : Structure elucidation of peptidomimetics and pilicide-chaperone complexes
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the last decades NMR spectroscopy has become an invaluable tool both in academic research and in the pharmaceutical industry. This thesis describes applications of NMR spectroscopy in biomedicinal research for structure elucidation of biologically active peptides and peptidomimetics as well as in studies of ligand-protein interactions. The first part of this thesis describes the theory and methodology of structure calculations of peptides using experimental restraints derived from NMR spectroscopy. This methodology has been applied to novel mimetics of the peptide hormones desmopressin and Leu-enkephalin. The results of these studies highlight the complicating issue of conformational exchange often encountered in structural determination of peptides and how careful analysis of experimental data as well as optimization of experimental conditions can enable structure determinations in such instances. Although the mimetics of both desmopressin and Leu-enkephalin were found to adopt the wanted conformations, they exhibited no or very poor biological activity. These results demonstrate the difficulties in designing peptidomimetics without detailed structural information of the receptors. A stereoselective synthetic route towards XxxΨ[CH2O]Ala pseudodipeptides is also presented. Such pseudodipeptides can be used as isosteric amide bond replacements in peptides in order to increase their resistance towards proteolytic degradation. The second part of this thesis describes the study of the interaction between compounds that inhibit pilius assembly, pilicides, and periplasmic chaperones from uropathogenic Escherichia coli. Periplasmic chaperones are key components in assembly of pili, i.e. hair-like protein complexes located on the surface of Escherichia coli that cause urinary tract infections. Detailed knowledge about this interaction is important in understanding how pilicides can inhibit pilus assembly by binding to chaperones. Relaxation-edited NMR experiments were used to confirm the affinity of the pilicides for the chaperones and chemical shift mapping was used to study the pilicide-chaperone interaction surface. These studies show that at least two interaction sites are present on the chaperone surface and consequently that two different mechanisms resulting in inhibition of pilus assembly may exist.
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| 5. |
- Kihlberg, Steve, et al.
(författare)
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Arbete och Hälsa
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En ergonomisk och teknisk utvärdering genomfördes av en förändring av produktionssystemet i ett elektronikföretag som innebar en ökad automatisering. Själva förändringsprocessen utvärderades också.Automatiseringen av den manuella monteringen och transporten minskade exponeringstiden för manuell montering på systemnivå samt ökade produktiviteten. För den kvarstående manuella monteringen ökade dock repetitiviteten och ensidigheten. Montörerna upplevde också att den psykiska arbetsbelastningen var större i det nya systemet jämfört med det gamla. De ansåg också att de manuella monteringsstationerna som helhet var dåliga arbetsuppgifter.I den studerade förändringsprocessen var bristen på kontinuitet i arbetsledning ett av avdelningens huvudproblem. Arbetsledaren fick också sätta sin prägel på hur produktionsmålen skulle uppfyllas och hur arbetsförhållandena skulle utformas. Därigenom blev det arbetsledaren och inte den handlingsplan med arbetsrotation som en arbetsorganisationsgrupp utformade som avgjorde hur arbetsorganisationen utformades.
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| 6. |
- Kihlberg, Steve, et al.
(författare)
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Ett produktionssystem under förändring - ergonomisk och teknisk utvärdering
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En ergonomisk och teknisk utvärdering genomfördes av en förändring av produktionssystemet i ett elektronikföretag som innebar en ökad automatisering. Själva förändringsprocessen utvärderades också. Automatiseringen av den manuella monteringen och transporten minskade exponeringstiden för manuell montering på systemnivå samt ökade produktiviteten. För den kvarstående manuella monteringen ökade dock repetitiviteten och ensidigheten. Montörerna upplevde också att den psykiska arbetsbelastningen var större i det nya systemet jämfört med det gamla. De ansåg också att de manuella monteringsstationerna som helhet var dåliga arbetsuppgifter. I den studerade förändringsprocessen var bristen på kontinuitet i arbetsledning ett av avdelningens huvudproblem. Arbetsledaren fick också sätta sin prägel på hur produktionsmålen skulle uppfyllas och hur arbetsförhållandena skulle utformas. Därigenom blev det arbetsledaren och inte den handlingsplan med arbetsrotation som en arbetsorganisationsgrupp utformade som avgjorde hur arbetsorganisationen utformades.
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| 7. |
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| 8. |
- Al-Smadi, Derar, 1983-, et al.
(författare)
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Chemical and Biochemical Approaches for the Synthesis of Substituted Dihydroxybutanones and Di-, and Tri-Hydroxypentanones
- 2019
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 84:11, s. 6982-6991
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Tidskriftsartikel (refereegranskat)abstract
- Polyhydroxylated compounds are building blocks for the synthesis of carbohydrates and other natural products. Their synthesis is mainly achieved by different synthetic versions of aldol-coupling reactions, catalyzed either by organocatalysts, enzymes or metal-organic catalysts. We have investigated the formation of 1,4-substituted 2,3-dihydroxybutan-1-one derivatives from para- and meta-substituted phenylacetaldehydes by three distinctly different strategies. The first involved a direct aldol reaction with hydroxyacetone, dihydroxyacetone or 2-hydroxyacetophenone, catalyzed by the cinchona derivative cinchonine. The second was reductive cross-coupling with methyl or phenyl glyoxal promoted by SmI2 resulting in either 5-substituted 3,4-dihydroxypentan-2-ones or 1,4 bis-phenyl substituted butanones, respectively. Finally, in the third case, aldolase catalysis was employed for synthesis of the corresponding 1,3,4-trihydroxylated pentan-2-one derivatives. The organocatalytic route with cinchonine generated distereomerically enriched syn products (de = 60−99 %), with moderate enantiomeric excesses (ee = 43−56%), but did not produce aldols with either hydroxyacetone or dihydroxyacetone as donor ketones. The SmI2-promoted reductive cross-coupling generated product mixtures with diastereomeric and enantiomeric ratios close to unity. This route allowed for the production of both 1-methyl- and 1-phenylsubstituted 2,3-dihydroxybutanones, at yields between 40−60%. Finally, the biocatalytic approach resulted in enantiopure syn (3R,4S) 1,3,4-trihydroxypentan-2-ones.
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| 9. |
- Al-Smadi, Derar, 1983-, et al.
(författare)
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Synthesis of substrates for aldolase-catalyzed reactions : A comparison of methods for the synthesis of substituted phenylacetaldehydes
- 2018
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Ingår i: Synlett. - : Georg Thieme Verlag KG. - 0936-5214 .- 1437-2096. ; 29:9, s. 1187-1190
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Tidskriftsartikel (refereegranskat)abstract
- Methods for the synthesis of phenylacetaldehydes (oxidation, one-carbon chain extension) were compared by using the synthesis of 4-methoxyphenylacetaldehyde as a model example. Oxidations of 4-methoxyphenylethanol with activated DMSO (Swern oxidation) or manganese dioxide gave unsatisfactory results; whereas oxidation with 2-iodoxybenzoic add (IBX) produced 4-methoxyphenylacetaldehyde in reasonable (75%) yield. However, Wittig-type one-carbon chain extension with methoxymethylene-triphenylphosphine followed by hydrolysis gave an excellent (81% overall) yield of 4-methoxyphenylacetaldehyde from 4-methoxybenzaldehyde (a cheap starting material). This approach was subsequently used to synthesise a set of 10 substituted phenylacetaldehydes in good to excellent yields.
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| 10. |
- Andersson, Charlotta, et al.
(författare)
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Phase-contrast MRI volume flow - a comparison of breath held and navigator based acquisitions
- 2016
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Ingår i: BMC Medical Imaging. - : BioMed Central. - 1471-2342 .- 1471-2342. ; 16:26
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Tidskriftsartikel (refereegranskat)abstract
- Background: Magnetic Resonance Imaging (MRI) 2D phase-contrast flow measurement has been regarded as the gold standard in blood flow measurements and can be performed with free breathing or breath held techniques. We hypothesized that the accuracy of flow measurements obtained with segmented phase-contrast during breath holding, and in particular higher number of k-space segments, would be non-inferior compared to navigator phase-contrast. Volumes obtained from anatomic segmentation of cine MRI and Doppler echocardiography were used for additional reference. Methods: Forty patients, five women and 35 men, mean age 65 years (range 53-80), were randomly selected and consented to the study. All underwent EKG-gated cardiac MRI including breath hold cine, navigator based free-breathing phase-contrast MRI and breath hold phase-contrast MRI using k-space segmentation factors 3 and 5, as well as transthoracic echocardiography within 2 days. Results: In navigator based free-breathing phase-contrast flow, mean stroke volume and cardiac output were 79.7 +/- 17.1 ml and 5071 +/- 1192 ml/min, respectively. The duration of the acquisition was 50 +/- 6 s. With k-space segmentation factor 3, the corresponding values were 77.7 ml +/- 17.5 ml and 4979 +/- 1211 ml/min (p = 0.15 vs navigator). The duration of the breath hold was 17 +/- 2 s. K-space segmentation factor 5 gave mean stroke volume 77.9 +/- 16.4 ml, cardiac output 5142 +/- 1197 ml/min (p = 0.33 vs navigator), and breath hold time 11 +/- 1 s. Anatomical segmentation of cine gave mean stroke volume and cardiac output 91.2 +/- 20.8 ml and 5963 +/- 1452 ml/min, respectively. Echocardiography was reliable in 20 of the 40 patients. The mean diameter of the left ventricular outflow tract was 20.7 +/- 1.5 mm, stroke volume 78.3 ml +/- 15.2 ml and cardiac output 5164 +/- 1249 ml/min. Conclusions: In forty consecutive patients with coronary heart disease, breath holding and segmented k-space sampling techniques for phase-contrast flow produced stroke volumes and cardiac outputs similar to those obtained with free-breathing navigator based phase-contrast MRI, using less time. The values obtained agreed fairly well with Doppler echocardiography while there was a larger difference when compared with anatomical volume determinations using SSFP (steady state free precession) cine MRI.
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