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Sökning: WFRF:(Emma T) > (2005-2009)

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1.
  • Doornenbal, P., et al. (författare)
  • RISING: Gamma‐ray Spectroscopy with Radioactive Beams at GSI
  • 2007
  • Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 891, s. 99-107
  • Konferensbidrag (refereegranskat)abstract
    • The Rare Isotope Spectroscopic INvestigation at GSI (RISING) project is a major pan‐European collaboration. Its physics aims are the studies of exotic nuclear matter with abnormal proton‐to‐neutron ratios compared with naturally occurring isotopes. RISING combines the FRagment Separator (FRS) which allows relativistic energies and projectile fragmentation reactions with EUROBALL Ge Cluster detectors for γ spectroscopic research. The RISING setup can be used in two different configurations. Either the nuclei of interest are investigated after being stopped or the heavy ions hit a secondary target at relativistic energies and the thereby occurring excitations are studied. For the latter case, MINIBALL Ge detectors and the HECTOR array are used in addition. Example achievements of the Fast Beam setup are presented and compared to various shell model calculations, while for the Stopped Beam setup initial results are shown.
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2.
  • Pietri, S., et al. (författare)
  • First Results from the Stopped Beam Isomer RISING Campaign at GSI
  • 2007
  • Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 38:4, s. 1255-1264
  • Tidskriftsartikel (refereegranskat)abstract
    • The first results from a series of experiments focused on the study of the internal structure of nuclei at the extremes of N:Z ratio using isomer spectroscopy are reported. These experiments represent the first of the Stopped Beam section of the Rare Isotopes Investigations at GSI (RISING) project. Exotic nuclei were synthesized using relativistic projectile fragmentation of similar to 500 -> 1000 MeV/u beams of Ag-107, Pb-208, Xe-136 and Ni-58, or fission of 750 MeV/u U-238 provided by the SIS synchrotron at GSI. A detailed description of the RISING stopped beam set up is given, together with a report of the performance of the associated gamma-ray spectrometer array. Selected results of the first experimental campaign are presented together with a discussion on the use of isomeric spectroscopy to study GeV range nuclear fragmentation. Details on future research plans of this collaboration are also outlined.
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3.
  • Podolyak, Zs., et al. (författare)
  • Isomeric Decay Studies Around 204Pt and 148Tb
  • 2007
  • Ingår i: The European Physical Journal. Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 150, s. 165-168
  • Tidskriftsartikel (refereegranskat)abstract
    • Relativistic energy projectile fragmentation of Pb-208 has been used to produce a range of exotic nuclei. The nuclei of interest were studied by detecting delayed gamma rays following the decay of isomeric states. Experimental information on the excited states of the neutron-rich N = 126 nucleus, Pt-204, following internal decay of two isomeric states, was obtained for the first time. In addition, decays from the previously reported isomeric I=27h and I=(49/2)h states in Tb-148 and Gd-147, respectively, have been observed. These isomeric decays represent the highest spin discrete states observed to date following a projectile fragmentation reaction, and opens further the possibility of doing 'high-spin physics' using this technique.
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4.
  • Regan, P. H., et al. (författare)
  • First Results from the Stopped RISING Campaign at GSI: The Mapping of Isomeric Decays in Highly Exotic Nuclei
  • 2007
  • Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 899, s. 19-22
  • Konferensbidrag (refereegranskat)abstract
    • The first results from the Stopped Beam RISING experimental campaign performed at the GSI laboratory in Darmstadt, Germany, are presented. RISING (Rare ISotope INvestigations at GSI) constitutes a major new experimental program in European nuclear structure physics research aimed at using relativistic‐energy, projectile‐fragmentation reactions to study nuclei with exotic proton‐to‐neutron ratios. This paper introduces the physics aims of the Stopped RISING collaboration and presents some technical details and initial results from experiments using the RISING array to study decays from metastable nuclear states in both proton and neutron‐rich nuclei.
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5.
  • Rudolph, Dirk, et al. (författare)
  • Exciting Isomers from the First Stopped-beam RISING Campaign
  • 2007
  • Ingår i: The European Physical Journal. Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 150, s. 173-176
  • Tidskriftsartikel (refereegranskat)abstract
    • First results are reported from a major new initiative of experiments, which focus on nuclear structure studies at extreme isospin values by means of isomer spectroscopy. The experiments represent the first part of the so-called stopped-beam campaign within the Rare ISotope INvestigations at GSI (RISING) project. Time-correlated gamma decays from individually identified nuclear species have been measured, allowing the clean identification of isomeric decays in a wide range of exotic nuclei both at the proton drip-line and in heavy, neutron-rich systems. An overview of the experimental technique will be given, together with the performance of the new germanium detector array and future research plans for the collaboration.
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6.
  • Adler, Ruth E., et al. (författare)
  • Sediment record from the western Arctic Ocean with an improved Late Quaternary age resolution : HOTRAX core HLY0503-8JPC, Mendeleev Ridge
  • 2009
  • Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 68:02-jan, s. 18-29
  • Tidskriftsartikel (refereegranskat)abstract
    • Sediment core HLY0503-8JPC raised by the HOTRAX'05 expedition from the Mendeleev Ridge was analyzed for multiple lithological, paleontological. and stable-isotopic proxies to reconstruct paleoceanographic conditions in the western Arctic Ocean during the Late Quaternary. The core, extensively sampled in the upper 5 m, reveals pronounced changes in sedimentary environments during the ca. 250 kyr interval encompassing Marine Isotopic Stages (MIS) 1 to 7. An estimated average resolution of 500 yr/sample, at least for the last glacial cycle including the last interglacial, provides more detail than seen in other sedimentary records from the western Arctic Ocean. The age control is provided by C-14 and amino acid racemization measurements on planktonic foraminifers and correlations with the stratigraphy developed for the central Lomonosov Ridge and with glacial events at the Eurasian Arctic margin. Cyclic variations in lithology combined with foraminiferal abundance and stable-isotopic composition indicate profound changes in hydrographic and depositional environments between interglacial-type and glacial-type periods apparently reflecting a combination of 100-kyr and precessional time scales. This periodicity is complicated by abrupt iceberg- and/or meltwater-discharge events with variable (Laurentide vs. Eurasian) provenance. The proxy record from the interval identified as the last interglacial (MIS 5e), which may aid in understanding the future state of the Arctic Ocean, indicates low ice conditions and possibly enhanced stratification of the water column.
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7.
  • Artin, Ingrid, et al. (författare)
  • Effects of carbon dioxide on neurotoxin gene expression in nonproteolytic Clostridium botulinum type E
  • 2008
  • Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 74:8, s. 2391-2397
  • Tidskriftsartikel (refereegranskat)abstract
    • Carbon dioxide is an antimicrobial gas commonly used in modified atmosphere packaging. In the present study, the effects of carbon dioxide on the growth of and neurotoxin production by nonproteolytic Clostridium botulinum type E were studied during the growth cycle. Quantitative reverse transcription-PCR and an enzyme-linked immunosorbent assay were used to quantify expression of the type E botulinum neurotoxin gene (cntE) and the formation of type E neurotoxin. The expression levels of cntE were similar in two strains, with relative expression peaking in the transition between exponential phase and stationary phase. In stationary phase, cntE mRNA expression declined rapidly. The cntE mRNA half-life was calculated to be approximately 9 minutes. Neurotoxin formation occurred in late exponential phase and stationary phase. High carbon dioxide concentrations delayed growth by increasing the lag time and decreasing the maximum growth rate. The effects of carbon dioxide concentration on relative neurotoxin gene expression and neurotoxin formation were significant. Expression of cntE mRNA and the formation of extracellular neurotoxin were twofold higher with a headspace carbon dioxide concentration of 70% (vol/vol) compared to 10% (vol/vol). This finding sheds a new, cautionary light on the potential risks of botulism associated with the use of modified atmosphere packaging. Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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8.
  • Dare, Emma V., et al. (författare)
  • Fibrin Sealants from Fresh or Fresh/Frozen Plasma as Scaffolds for In Vitro Articular Cartilage Regeneration
  • 2009
  • Ingår i: TISSUE ENGINEERING PART A. - : Mary Ann Leibert Inc. - 1937-3341 .- 1937-335X. ; 15:8, s. 2285-2297
  • Tidskriftsartikel (refereegranskat)abstract
    • Our objective was to evaluate human CryoSeal (R) fibrin glue derived from single units of plasma as scaffolds for articular cartilage tissue engineering. Human articular chondrocytes were encapsulated into genipin cross-linked fibrin glue derived from individual units of fresh or frozen plasma using the CryoSeal (R) fibrin sealant (FS) system. The constructs were cultured for up to 7 weeks in vitro under low (5%) or normal (21%) oxygen. Chondrocyte viability was greater than90% within the fibrin gels. Hypoxia induced significant increases in collagen II and Sox9 gene expression and a significant decrease in collagen I. A significant increase in collagen II was detected in fresh plasma-derived cultures, while only collagen I was significantly increased in frozen plasma cultures. Significant increases in total glycosaminoglycan and collagen were detected in the extracellular matrix secreted by the encapsulated chondrocytes. A significant increase in compression modulus was only observed for fresh plasma-derived gels, which is likely explained by a greater amount of collagen type I detected after 7 weeks in frozen compared to fresh plasma gels. Our results indicate that CryoSeal (R) fibrin glue derived from fresh plasma is suitable as a tissue engineering scaffold for human articular chondrocytes, and therefore should be evaluated for autologous articular cartilage regeneration.
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9.
  • Dare, Emma V., et al. (författare)
  • Genipin Cross-Linked Fibrin Hydrogels for in vitro Human Articular Cartilage Tissue-Engineered Regeneration
  • 2009
  • Ingår i: Cells Tissues Organs. - : Karger. - 1422-6405 .- 1422-6421. ; 190:6, s. 313-325
  • Tidskriftsartikel (refereegranskat)abstract
    • Our objective was to examine the potential of a genipin cross-linked human fibrin hydrogel system as a scaffold for articular cartilage tissue engineering. Human articular chondrocytes were incorporated into modified human fibrin gels and evaluated for mechanical properties, cell viability, gene expression, extracellular matrix production and subcutaneous biodegradation. Genipin, a naturally occurring compound used in the treatment of inflammation, was used as a cross-linker. Genipin cross-linking did not significantly affect cell viability, but significantly increased the dynamic compression and shear moduli of the hydrogel. The ratio of the change in collagen II versus collagen I expression increased more than 8-fold over 5 weeks as detected with real-time RT-PCR. Accumulation of collagen II and aggrecan in hydrogel extracellular matrix was observed after 5 weeks in cell culture. Overall, our results indicate that genipin appeared to inhibit the inflammatory reaction observed 3 weeks after subcutaneous implantation of the fibrin into rats. Therefore, genipin cross-linked fibrin hydrogels can be used as cell-compatible tissue engineering scaffolds for articular cartilage regeneration, for utility in autologous treatments that eliminate the risk of tissue rejection and viral infection.
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10.
  • Engelmark, Malin T., et al. (författare)
  • Identification of susceptibility loci for cervical carcinoma by genome scan of affected sib-pairs
  • 2006
  • Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 15:22, s. 3351-3360
  • Tidskriftsartikel (refereegranskat)abstract
    • Cervical cancer is caused by a combination of environmental and genetic risk factors. Infection by oncogenic types of human papillomavirus is recognized as the major environmental risk factor and epidemiological studies indicate that host genetic factors predispose to disease development. A number of genetic susceptibility factors have been proposed, but with exception of the human leukocyte antigen CHLA, class II, have not shown consistent results among studies. We have performed the first genomewide linkage scan using 278 affected sib-pairs to identify loci involved in susceptibility to cervical cancer. A two-step qualitative non-parametric linkage analysis using 387 microsatellites with an average spacing of 10.5 cM revealed excess allelic sharing at nine regions on eight chromosomes. These regions were further analysed with 125 markers to increase the map density to 1.28 cM. Nominal significant linkage was found for three of the nine loci [9q32 (maximum lod-score, MLS) =1.95, P < 0.002), 12q24 (MLS=1.25, P < 0.015) and 16q24 (MLS=1.35, P < 0.012)]. These three regions have previously been connected to human cancers that share characteristics with cervical carcinoma, such as esophageal cancer and Hodgkin's lymphoma. A number of candidate genes involved in defence against viral infections, immune response and tumour suppression are found in these regions. One such gene is the thymic stromal co-transporter (TSCOT). Analyses of TSCOT single nucleotide polymorphisms further strengthen the linkage to this region (MLS=2.40, P < 0.001). We propose that the 9q32 region contains susceptibility locus for cervical cancer and that TSCOT is a candidate gene potentially involved in the genetic predisposition to this disease.
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11.
  • Falck, Emma, et al. (författare)
  • Interaction of fusidic acid with lipid membranes: Implications to the mechanism of antibiotic activity
  • 2006
  • Ingår i: Biophysical Journal. - : Elsevier BV. - 1542-0086 .- 0006-3495. ; 91:5, s. 1787-1799
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied the effects of cholesterol and steroid-based antibiotic fusidic acid (FA) on the behavior of lipid bilayers using a variety of experimental techniques together with atomic-scale molecular dynamics simulations. Capillary electrophoretic measurements showed that FA was incorporated into fluid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membranes. Differential scanning calorimetry in turn showed that FA only slightly altered the thermodynamic properties of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers, whereas cholesterol abolished all endotherms when the mole fraction of cholesterol (X-chol) was > 0.20. Fluorescence spectroscopy was then used to further characterize the influence of these two steroids on DPPC large unilamellar vesicles. In the case of FA, our result strongly suggested that FA was organized into lateral microdomains with increased water penetration into the membrane. For cholesterol/DPPC mixtures, fluorescence spectroscopy results were compatible with the formation of the liquid-ordered phase. A comparison of FA and cholesterol-induced effects on DPPC bilayers through atomistic molecular dynamics simulations showed that both FA and cholesterol tend to order neighboring lipid chains. However, the ordering effect of FA was slightly weaker than that of cholesterol, and especially for deprotonated FA the difference was significant. Summarizing, our results show that FA is readily incorporated into the lipid bilayer where it is likely to be enriched into lateral microdomains. These domains could facilitate the association of elongation actor-G into lipid rafts in living bacteria, enhancing markedly the antibiotic efficacy of FA.
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12.
  • Gabrysch, Markus, et al. (författare)
  • Formation of secondary electron cascades in single-crystalline plasma-deposited diamond upon exposure to femtosecond x-ray pulses
  • 2008
  • Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Secondary electron cascades were measured in high purity single-crystalline chemical vapor deposition (CVD) diamond, following exposure to ultrashort hard x-ray pulses (140 fs full width at half maximum, 8.9 keV energy) from the Sub-Picosecond Pulse Source at the Stanford Linear Accelerator Center. We report measurements of the pair creation energy and of drift mobility of carriers in two CVD diamond crystals. This was done for the first time using femtosecond x-ray excitation. Values for the average pair creation energy were found to be 12.17 +/- 0.57 and 11.81 +/- 0.59 eV for the two crystals, respectively. These values are in good agreement with recent theoretical predictions. The average drift mobility of carriers, obtained by the best fit to device simulations, was mu(h)= 2750 cm(2)/V s for holes and was mu(e)= 2760 cm(2) / V s for electrons. These mobility values represent lower bounds for charge mobilities due to possible polarization of the samples. The results demonstrate outstanding electric properties and the enormous potential of diamond in ultrafast x-ray detectors.
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13.
  • Geisler-Lee, Jane, et al. (författare)
  • Poplar carbohydrate-active enzymes. Gene identification and expression analyses.
  • 2006
  • Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 140:3, s. 946-62
  • Tidskriftsartikel (refereegranskat)abstract
    • Over 1,600 genes encoding carbohydrate-active enzymes (CAZymes) in the Populus trichocarpa (Torr. & Gray) genome were identified based on sequence homology, annotated, and grouped into families of glycosyltransferases, glycoside hydrolases, carbohydrate esterases, polysaccharide lyases, and expansins. Poplar (Populus spp.) had approximately 1.6 times more CAZyme genes than Arabidopsis (Arabidopsis thaliana). Whereas most families were proportionally increased, xylan and pectin-related families were underrepresented and the GT1 family of secondary metabolite-glycosylating enzymes was overrepresented in poplar. CAZyme gene expression in poplar was analyzed using a collection of 100,000 expressed sequence tags from 17 different tissues and compared to microarray data for poplar and Arabidopsis. Expression of genes involved in pectin and hemicellulose metabolism was detected in all tissues, indicating a constant maintenance of transcripts encoding enzymes remodeling the cell wall matrix. The most abundant transcripts encoded sucrose synthases that were specifically expressed in wood-forming tissues along with cellulose synthase and homologs of KORRIGAN and ELP1. Woody tissues were the richest source of various other CAZyme transcripts, demonstrating the importance of this group of enzymes for xylogenesis. In contrast, there was little expression of genes related to starch metabolism during wood formation, consistent with the preferential flux of carbon to cell wall biosynthesis. Seasonally dormant meristems of poplar showed a high prevalence of transcripts related to starch metabolism and surprisingly retained transcripts of some cell wall synthesis enzymes. The data showed profound changes in CAZyme transcriptomes in different poplar tissues and pointed to some key differences in CAZyme genes and their regulation between herbaceous and woody plants.
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14.
  • Hawke, Emma, et al. (författare)
  • The effects of sex and repeated-sprints on muscle protein signalling
  • 2009
  • Ingår i: Book of Abstracts of the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 2009. Sport Sciences: Nature, Nuture and Culture. - European College of Sport Science. ; , s. 351-352
  • Konferensbidrag (refereegranskat)
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15.
  • Holtz, Emma, et al. (författare)
  • The role of processing parameters on energy efficiency during microwave convective drying of porous materials
  • 2009
  • Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 27:2, s. 173-185
  • Tidskriftsartikel (refereegranskat)abstract
    • A small-scale microwave convective dryer was built to study the effects of microwave power level, air temperature, and air velocity on drying kinetics, temperature development, and specific energy consumption (MJ/ kg evaporated water) using statistical designs. Increased microwave power had a large significant effect on moisture loss and temperature development and it reduced specific energy consumption. Increased air temperature and air velocity increased specific energy consumption, as their effect on drying kinetics was smaller in the system used. Low air temperature slowed the drying process, without affecting the relationship between average sample temperature and average moisture content during drying.
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16.
  • Jansson, Anna M., et al. (författare)
  • Structure of the methyltransferase domain from the Modoc virus, a flavivirus with no known vector
  • 2009
  • Ingår i: Acta Crystallographica Section D. - 0907-4449 .- 1399-0047. ; 65, s. 796-803
  • Tidskriftsartikel (refereegranskat)abstract
    • The Modoc virus (MODV) is a flavivirus with no known vector (NKV). Evolutionary studies have shown that the viruses in the MODV group have evolved in association with mammals (bats, rodents) without transmission by an arthropod vector. MODV methyltransferase is the first enzyme from this evolutionary branch to be structurally characterized. The high-resolution structure of the methyltransferase domain of the MODV NS5 protein (MTase(MODV)) was determined. The protein structure was solved in the apo form and in complex with its cofactor S-adenosyl-l-methionine (SAM). Although it belongs to a separate evolutionary branch, MTase(MODV) shares structural characteristics with flaviviral MTases from the other branches. Its capping machinery is a relatively new target in flaviviral drug development and the observed structural conservation between the three flaviviral branches indicates that it may be possible to identify a drug that targets a range of flaviviruses. The structural conservation also supports the choice of MODV as a possible model for flavivirus studies.
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17.
  • Johansson, Emma, et al. (författare)
  • Gamma-ray Spectroscopy of the Doubly Magic Nucleus 56Ni
  • 2006
  • Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 27:2, s. 157-165
  • Tidskriftsartikel (refereegranskat)abstract
    • The doubly magic N = Z nucleus Ni-56 has been investigated with two fusion-evaporation reactions; Ca-40(Si-28, 3 alpha)Ni-56 at a beam energy of 122MeV and Si-28(S-32, 2p2n)Ni-56 at 130MeV. To detect gamma-rays in coincidence with evaporated particles the Ge-detector array Gammasphere was used in conjunction with the charged-particle detector system, Microball and a 1 pi neutron detector array. Results include a significantly extended level scheme of Ni-56, which is compared to large-scale shell model calculations in the fp shell. The experimental and theoretical results agree to a large extent, with one notable exception; the theoretical model fails to predict the proper sequence of the yrast and yrare 8(+) states.
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18.
  • Jonsson Rudsander, Ulla, et al. (författare)
  • Comparative NMR analysis of cellooligosaccharide hydrolysis by GH9 bacterial and plant endo-1,4-ss-glucanases
  • 2008
  • Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 47:18, s. 5235-5241
  • Tidskriftsartikel (refereegranskat)abstract
    • H-1 NMR spectroscopy has been used to analyze the product profiles arising from the hydrolysis of cellooligosaccharides by family GH9 cellulases. The product profiles obtained with the wild type and several active site mutants of a bacterial processive endoglucanase, Tf Cel9A, were compared with those obtained by a randomly acting plant endoglucanase, PttCe19A. PttCe19A is an orthologue of the Arabidopsis endocellulase, Korrigan, which is required for efficient cellulose biosynthesis. As expected, poplar PttCe19A was shown to catalyze the degradation of cellooligosaccharides by inversion of the configuration of the anomeric carbon. The product analyses showed that the number of interactions between the glucose units of the substrate and the aromatic residues in the enzyme active sites determines the point of cleavage in both enzymes.
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19.
  • Nikinmaa, Mikko, et al. (författare)
  • Population origin, development and temperature of development affect the amounts of HSP70, HSP90 and the putative hypoxia-inducible factor in the tadpoles of the common frog Rana temporaria
  • 2008
  • Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 211:12, s. 1999-2004
  • Tidskriftsartikel (refereegranskat)abstract
    • We raised Rana temporaria tadpoles from three different populations from southern, mid and northern Sweden (the total north-to-south distance between populations is approximately 1500 km) at two temperatures, and measured the differences in HSP70, HSP90 and putative HIF-1 alpha levels (Rana temporaria HIF-1 alpha was sequenced in the present study) with immunoblotting. The levels of the studied proteins increased with developmental stage. Also, the levels increased with latitude at the lower but not at the higher developmental temperature. This shows that there is a clear difference between the populations at the molecular level but that this difference can be modified by the environmental conditions experienced during development. The proteins analyzed may be involved in the regulation of developmental processes. If this is the case, the tadpoles from the northernmost population have the most advanced complement of regulatory proteins at developmental stages approaching metamorphosis.
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20.
  • Parikh, Hemang, et al. (författare)
  • TXNIP regulates peripheral glucose metabolism in humans
  • 2007
  • Ingår i: PLoS Medicine. - : Public Library of Science (PLoS). - 1549-1676. ; 4:5, s. 868-879
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Type 2 diabetes mellitus ( T2DM) is characterized by defects in insulin secretion and action. Impaired glucose uptake in skeletal muscle is believed to be one of the earliest features in the natural history of T2DM, although underlying mechanisms remain obscure. Methods and Findings We combined human insulin/glucose clamp physiological studies with genome-wide expression profiling to identify thioredoxin interacting protein ( TXNIP) as a gene whose expression is powerfully suppressed by insulin yet stimulated by glucose. In healthy individuals, its expression was inversely correlated to total body measures of glucose uptake. Forced expression of TXNIP in cultured adipocytes significantly reduced glucose uptake, while silencing with RNA interference in adipocytes and in skeletal muscle enhanced glucose uptake, confirming that the gene product is also a regulator of glucose uptake. TXNIP expression is consistently elevated in the muscle of prediabetics and diabetics, although in a panel of 4,450 Scandinavian individuals, we found no evidence for association between common genetic variation in the TXNIP gene and T2DM. Conclusions TXNIP regulates both insulin-dependent and insulin- independent pathways of glucose uptake in human skeletal muscle. Combined with recent studies that have implicated TXNIP in pancreatic beta-cell glucose toxicity, our data suggest that TXNIP might play a key role in defective glucose homeostasis preceding overt T2DM.
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21.
  • Patra, Michael, et al. (författare)
  • Long-range interactions and parallel scalability in molecular simulations
  • 2007
  • Ingår i: Computer Physics Communications. - : Elsevier BV. - 0010-4655. ; 176:1, s. 14-22
  • Tidskriftsartikel (refereegranskat)abstract
    • Typical biomolecular systems such as cellular membranes, DNA, and protein complexes are highly charged. Thus, efficient and accurate treatment of electrostatic interactions is of great importance in computational modeling of such systems. We have employed the GROMACS simulation package to perform extensive benchmarking of different commonly used electrostatic schemes on a range of computer architectures (Pentium-4, IBM Power 4, and Apple/IBM G5) for single processor and parallel performance up to 8 nodes-we have also tested the scalability on four different networks, namely Infiniband, GigaBit Ethernet, Fast Ethernet, and nearly uniform memory architecture, i.e. communication between CPUs is possible by directly reading from or writing to other CPUs' local memory. It turns out that the particle-mesh Ewald method (PME) performs surprisingly well and offers competitive performance unless parallel runs on PC hardware with older network infrastructure are needed. Lipid bilayers of sizes 128, 512 and 2048 lipid molecules were used as the test systems representing typical cases encountered in biomolecular simulations. Our results enable an accurate prediction of computational speed on most current computing systems, both for serial and parallel runs. These results should be helpful in, for example, choosing the most suitable configuration for a small departmental computer cluster.
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22.
  • Rodushkin, Ilya, et al. (författare)
  • Authentication of Kalix (NE Sweden) vendace caviar using inductively coupled plasma-based analytical techniques : evaluation of different approaches
  • 2007
  • Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 583:2, s. 310-318
  • Tidskriftsartikel (refereegranskat)abstract
    • Different analytical approaches for origin differentiation between vendace and whitefish caviars from brackish- and freshwaters were tested using inductively coupled plasma double focusing sector field mass spectrometry (ICP-SFMS) and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). These approaches involve identifying differences in elemental concentrations or sample-specific isotopic composition (Sr and Os) variations. Concentrations of 72 elements were determined by ICP-SFMS following microwave-assisted digestion in vendace and whitefish caviar samples from Sweden (from both brackish and freshwater), Finland and USA, as well as in unprocessed vendace roe and salt used in caviar production. This data set allows identification of elements whose contents in caviar can be affected by salt addition as well as by contamination during production and packaging. Long-term method reproducibility was assessed for all analytes based on replicate caviar preparations/analyses and variations in element concentrations in caviar from different harvests were evaluated. The greatest utility for differentiation was demonstrated for elements with varying concentrations between brackish and freshwaters (e.g. As, Br, Sr). Elemental ratios, specifically Sr/Ca, Sr/Mg and Sr/Ba, are especially useful for authentication of vendace caviar processed from brackish water roe, due to the significant differences between caviar from different sources, limited between-harvest variations and relatively high concentrations in samples, allowing precise determination by modern analytical instrumentation. Variations in the 87Sr/86Sr ratio for vendace caviar from different harvests (on the order of 0.05-0.1%) is at least 10-fold less than differences between caviar processed from brackish and freshwater roe. Hence, Sr isotope ratio measurements (either by ICP-SFMS or by MC-ICP-MS) have great potential for origin differentiation. On the contrary, it was impossible to differentiate between Swedish caviar processed from brackish water roe and Finnish freshwater caviar based solely on 187Os/188Os ratios.
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23.
  • Smith, Emma, et al. (författare)
  • Inhibition of EBF function by active Notch signaling reveals a novel regulatory pathway in early B-cell development
  • 2005
  • Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 106:6, s. 1995-2001
  • Tidskriftsartikel (refereegranskat)abstract
    • The Notch signaling pathway is involved in several lineage commitment and differentiation events. One of these is fate determination of the common lymphoid progenitor, promoting T-cell development at the expense of B-cell differentiation. It has been suggested that this process relies on Notchs ability to inhibit E proteins, which are crucial for early B-cell development. Here, we report that Notch signaling also modulates the function of the transcription factor, early B-cell factor (EBF). Transient transfection of intracellular Notch1 (Notch1-IC) into a pre-B cell line resulted in the down-regulation of EBF-regulated promoters and diminished the capacity of EBF to activate these promoters in an epithelial cell line. This correlated with a reduction in the ability of EBF to bind DNA. Ligand-induced stimulation of endogenous Notch receptors with Delta4 mimicked the activity of Notch1-IC toward EBF. These data suggest that Notch signaling may affect B- versus T-lineage commitment by the targeting of both EBF and E2A.
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24.
  • Sparr, Emma, et al. (författare)
  • Molecular organization in striated domains induced by transmembrane alpha-helical peptides in dipalmitoyl phosphatidylcholine bilayers
  • 2005
  • Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 44:1, s. 2-10
  • Tidskriftsartikel (refereegranskat)abstract
    • Transmembrane (TM) alpha-helical peptides with neutral flanking residues such as tryptophan form highly ordered striated domains when incorporated in gel-state 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers and inspected by atomic force microscopy (AFM) (1). In this study, we analyze the molecular organization of these striated domains using AFM, photo-cross-linking, fluorescence spectroscopy, nuclear magnetic resonance (NMR), and X-ray diffraction techniques on different functionalized TM peptides. The results demonstrate that the striated domains consist of linear arrays of single TM peptides with a dominantly antiparallel organization in which the peptides interact with each other and with lipids. The peptide arrays are regularly spaced by +/-8.5 nm and are separated by somewhat perturbed gel-state lipids with hexagonally organized acyl chains, which have lost their tilt. This system provides an example of how domains of peptides and lipids can be formed in membranes as a result of a combination of specific peptide-peptide and peptide-lipid interactions.
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25.
  • Sparr, Emma, et al. (författare)
  • Self-association of transmembrane alpha-helices in model membranes - Importance of helix orientation and role of hydrophobic mismatch
  • 2005
  • Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 280:47, s. 39324-39331
  • Tidskriftsartikel (refereegranskat)abstract
    • Interactions between transmembrane helices play a key role in almost all cellular processes involving membrane proteins. We have investigated helix-helix interactions in lipid bilayers with synthetic tryptophan-flanked peptides that mimic the membrane spanning parts of membrane proteins. The peptides were functionalized with pyrene to allow the self-association of the helices to be monitored by pyrene fluorescence and Trp-pyrene fluorescence resonance energy transfer (FRET). Specific labeling of peptides at either their N or C terminus has shown that helix-helix association occurs almost exclusively between antiparallel helices. Furthermore, computer modeling suggested that antiparallel association arises primarily from the electrostatic interactions between alpha-helix backbone atoms. We propose that such interactions may provide a force for the preferentially antiparallel association of helices in polytopic membrane proteins. Helix-helix association was also found to depend on the lipid environment. In bilayers of dioleoylphosphatidylcholine, in which the hydrophobic length of the peptides approximately matched the bilayer thickness, association between the helices was found to require peptide/lipid ratios exceeding 1/25. Self-association of the helices was promoted by either increasing or decreasing the bilayer thickness, and by adding cholesterol. These results indicate that helix-helix association in membrane proteins can be promoted by unfavorable protein-lipid interactions.
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26.
  • Sviestins, Emma, et al. (författare)
  • Speed adaptation for a robot walking with a human
  • 2007
  • Ingår i: HRI 2007 - Proceedings of the 2007 ACM/IEEE Conference on Human-Robot Interaction - Robot as Team Member. - New York, NY, USA : ACM. - 1595936173 - 9781595936172 ; , s. 349-356
  • Konferensbidrag (refereegranskat)abstract
    • We have taken steps towards developing a method that enables an interactive humanoid robot to adapt its speed to a walking human that it is moving together with. This is difficult because the human is simultaneously adapting to the robot. From a case study in human-human walking interaction we established a hypothesis about how to read a human's speed preference based on a relationship between humans' walking speed and their relative position in the direction of walking. We conducted two experiments to verify this hypothesis: one with two humans walking together, and one with a human subject walking with a humanoid robot, Robovie-IV. For 11 out of 15 subjects who walked with the robot, the results were consistent with the speed-position relationship of the hypothesis. We also conducted a preferred speed estimation experiment for six of the subjects. All of them were satisfied with one or more of the speeds that our algorithm estimated and four of them answered one of the speeds as the best one if the algorithm was allowed to give three options. In the paper, we also discuss the difficulties and possibilities that we learned from this preliminary trial.
  •  
27.
  • Szatmari, Peter, et al. (författare)
  • Mapping autism risk loci using genetic linkage and chromosomal rearrangements.
  • 2007
  • Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 39:3, s. 319-328
  • Tidskriftsartikel (refereegranskat)abstract
    • Autism spectrum disorders (ASDs) are common, heritable neurodevelopmental conditions. The genetic architecture of ASDs is complex, requiring large samples to overcome heterogeneity. Here we broaden coverage and sample size relative to other studies of ASDs by using Affymetrix 10K SNP arrays and 1,168 families with at least two affected individuals, performing the largest linkage scan to date while also analyzing copy number variation in these families. Linkage and copy number variation analyses implicate chromosome 11p12-p13 and neurexins, respectively, among other candidate loci. Neurexins team with previously implicated neuroligins for glutamatergic synaptogenesis, highlighting glutamate-related genes as promising candidates for contributing to ASDs.
  •  
28.
  • Takahashi Schmidt, Junko, et al. (författare)
  • KORRIGAN1 and its Aspen Homolog PttCel9A1 Decrease Cellulose Crystallinity in Arabidopsis Stems
  • 2009
  • Ingår i: Plant and Cell Physiology. - : Oxford University Press (OUP). - 0032-0781 .- 1471-9053. ; 50:6, s. 1099-1115
  • Tidskriftsartikel (refereegranskat)abstract
    • KORRIGAN1 (KOR1) is a membrane-bound cellulase implicated in cellulose biosynthesis. PttCel9A1 from hybrid aspen (Populus tremula L. tremuloides Michx.) has high sequence similarity to KOR1 and we demonstrate here that it complements kor1-1 mutants, indicating that it is a KOR1 ortholog. We investigated the function of PttCel9A1/KOR1 in Arabidopsis secondary growth using transgenic lines expressing 35S::PttCel9A1 and the KOR1 mutant line irx2-2. The presence of elevated levels of PttCel9A1/KOR1 in secondary walls of 35S::PttCel9A1 lines was confirmed by in muro visualization of cellulase activity. Compared with the wild type, 35S::PttCel9A1 lines had higher trifluoroacetic acid (TFA)-hydrolyzable glucan contents, similar Updegraff cellulose contents and lower cellulose crystallinity indices, as determined by C-13 solid-state nuclear magnetic resonance (NMR) spectroscopy. irx2-2 mutants had wild-type TFA-hydrolyzable glucan contents, but reduced Updegraff cellulose contents and higher than wild-type cellulose crystallinity indices. The data support the hypothesis that PttCel9A1/KOR1 activity is present in cell walls, where it facilitates cellulose biosynthesis in a way that increases the amount of non-crystalline cellulose.
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29.
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