| 1. |
- Hamaguchi, I, et al.
(författare)
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Lentivirus vector gene expression during ES cell-derived hematopoietic development in vitro
- 2000
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 74:22, s. 84-10778
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Tidskriftsartikel (refereegranskat)abstract
- The murine embryonal stem (ES) cell virus (MESV) can express transgenes from the long terminal repeat (LTR) promoter/enhancer in undifferentiated ES cells, but expression is turned off upon differentiation to embryoid bodies (EBs) and hematopoietic cells in vitro. We examined whether a human immunodeficiency virus type 1-based lentivirus vector pseudotyped with the vesicular stomatitis virus G protein (VSV-G) could transduce ES cells efficiently and express the green fluorescent protein (GFP) transgene from an internal phosphoglycerate kinase (PGK) promoter throughout development to hematopoietic cells in vitro. An oncoretrovirus vector containing the MESV LTR and the GFP gene was used for comparison. Fluorescence-activated cell sorting analysis of transduced CCE ES cells showed 99.8 and 86.7% GPF-expressing ES cells in the VSV-G-pseudotyped lentivirus (multiplicity of infection [MOI] = 59)- and oncoretrovirus (MOI = 590)-transduced cells, respectively. Therefore, VSV-G pseudotyping of lentiviral and oncoretrovirus vectors leads to efficient transduction of ES cells. Lentivirus vector integration was verified in the ES cell colonies by Southern blot analysis. When the transduced ES cells were differentiated in vitro, expression from the oncoretrovirus LTR was severely reduced or extinct in day 6 EBs and ES cell-derived hematopoietic colonies. In contrast, many lentivirus-transduced colonies, expressing the GFP gene in the undifferentiated state, continued to express the transgene throughout in vitro development to EBs at day 6, and many continued to express in cells derived from hematopoietic colonies. This experimental system can be used to analyze lentivirus vector design for optimal expression in hematopoietic cells and for gain-of-function experiments during ES cell development in vitro.
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| 2. |
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| 3. |
- Anugwom, I, et al.
(författare)
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Ionic liquid assisted extraction of nitrogen and sulphur-containing air pollutants from model oil and regeneration of the spent ionic liquid
- 2011
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Ingår i: Journal of Environmental Protection. - : Scientific Research Publishing. - 2152-2197 .- 2152-2219. ; 2:6, s. 796-802
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Tidskriftsartikel (refereegranskat)abstract
- Removal of air pollutants, such as nitrogen and sulphur containing compounds from a model oil (dodecane) was studied. An ionic liquid (1-ethyl-3-methylimidazolium chloride [C2mim] [Cl]) was used as an extractant. Liquid-liquid extraction by using 1-ethyl-3-methylimidazolium chloride [C2mim] [Cl] was found to be a very promising method for the removal of N- and S-compounds. This was evaluated by using a model oil (dodecane) with indole as a neutral nitrogen compound and pyridine as a basic nitrogen compound. Dibenzothiophene (DBT) was used as a sulphur compound. An extraction capacity of up to 90 wt% was achieved for the model oil containing pyridine, while only 76 wt% of indole in the oil was extracted. The extraction capacity of a model sulphur compound DBT was found to be up to 99 wt%. Regeneration of the spent ionic liquid was carried out with toluene back-extraction. A 1:1 toluene-to-IL wt ratio was performed at room temperature. It was observed that, for the spent ionic liquid containing DBT as a model compound more than 85 wt% (corresponding 3852 mg/kg) could be removed from the oil. After the second regeneration cycle, 86 wt% of the DBT was recovered from the ionic liquid to toluene. In the case of indole as the nitrogen containing species, more than 99 wt%, (corresponding to 2993 mg/kg) of the original indole was transferred from the model oil to the ionic liquid. After the first-regeneration cycle of the spent ionic liquid, 54 wt% of the indole–in-IL was transferred to toluene. Thus, both extractions of nitrogen and sulphur model compounds were successfully carried out from model oil and the back-extraction of these compounds from the ionic liquids to toluene demonstrated the proved the concept of the regeneration point of view.
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| 4. |
- Anugwom, I, et al.
(författare)
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Selective Extraction of Hemicelluloses from Spruce using Switchable Ionic Liquids
- 2012
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Ingår i: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 87:3, s. 2005-2011
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Tidskriftsartikel (refereegranskat)abstract
- Switchable Ionic Liquids (SILs) made from alcohols, either hexanol or butanol, and CO2 together with an amidine (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)) were investigated as dissolution/fractionation solvents for wood material. Both native spruce (Picea abies), and pre-extracted spruce were treated with either butanol SIL (SIL1) or hexanol SIL (SIL 2) for 5 days at 55 °C under normal pressure. The SILs were formed by bubbling CO2 through an equimolar mixture of either 1-hexanol or 1-butanol and DBU. The viscosity of the mixture increased from 7.1 mPas to 2980 mPas for SIL 2 and 5.1 to 1600 mPas for SIL 1. Melting points of the SILs 1 and 2 were at 8 and 14 °C, respectively. After the treatment time (5 days), the undissolved fraction contained 38 wt % less hemicelluloses compared to native spruce. There was an increase in the glucose content of the milled spruce treated with both SILs, since the milling step reduced the cellulose crystallinity of the wood and facilitated an easier SIL access into the wood. The solvents were very neutral in terms of lignin removal. Consequently, only about 2% of the lignin was removed from native wood. Moreover, a priori removal of the wood extractives did not influence the lignin removal. Highlights► Switchable Ionic Liquids made from, either hexanol or butanol, and CO2 together with an amidine (DBU) were studies as dissolution/fractionation solvents for spruce wood. ► After the treatment undissolved fraction contained 38 wt-% less hemicelluloses. ► We conclude that Switchable ionic liquids are effective solvent for fractionation of wood material, and they are easily recycled and can be reused.
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| 5. |
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| 6. |
- Dey, Lankeswar, et al.
(författare)
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Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare : Improved Orbital Parameters
- 2018
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 866:1
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Tidskriftsartikel (refereegranskat)abstract
- Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole (BBH) central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects of certain hereditary contributions to GW emission are required to predict impact flare timings of OJ 287. We develop an approach that incorporates this effect into the BBH model for OJ 287. This allows us to demonstrate an excellent agreement between the observed impact flare timings and those predicted from ten orbital cycles of the BBH central engine model. The deduced rate of orbital period decay is nine orders of magnitude higher than the observed rate in PSR 1913+16, demonstrating again the relativistic nature of OJ 287's central engine. Finally, we argue that precise timing of the predicted 2019 impact flare should allow a test of the celebrated black hole no-hair theorem at the 10% level.
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| 7. |
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| 8. |
- Huerta, I., et al.
(författare)
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Effect of low hydrogen to palladium molar ratios in the direct synthesis of H2O2 in water in a trickle bed reactor
- 2015
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 248, s. 91-100
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Tidskriftsartikel (refereegranskat)abstract
- Application of a trickle bed reactor (TBR) renders a very compact solution to carry out direct synthesis of hydrogen peroxide in water over a carbon supported palladium. The laboratory scale reactor was filled with silica particles (50-70 mesh) physically mixed with 37.5 to 75 mg of 5%Pd/C particles. The reaction conditions applied were 15 degrees C, 15-28 barg, 0.5 to 6 mL min(-1) of liquid and 4.0-4.5 mL min(-1) of gas flowrate (86.7/11/2.23 mol% of CO2/O-2/H-2). Thus, we demonstrated that the ratio between H-2 and Pd is one of the key factors to achieve optimized, higher yields of hydrogen peroxide. Consequently, low H-2 concentrations lead to low productivities. One of the least studied parameters, addressed here, is the ratio between the bed filling (SiO2) and the catalyst; i.e. the active catalytic species dilution effect. In short, it was found that when the amount of Pd was reduced below 0.094 mg Pd cm(-3) SiO2 the highest productivity of H2O2 could be achieved. The selectivity obtained were between 5.3 and 38.0%, respectively, corresponding to turn-over-frequencies (TOF) ranging from 65 to 921 mmol H2O2 gPd(-1) h(-1). (C) 2014 Elsevier B.V. All rights reserved.
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| 9. |
- Lê, A D, et al.
(författare)
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Neurobiological processes in alcohol addiction.
- 2001
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Ingår i: Alcoholism, clinical and experimental research. - 0145-6008. ; 25:5 Suppl ISBRA
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Forskningsöversikt (refereegranskat)abstract
- This article represents the proceedings of a symposium at the ISBRA Meeting in Yokohama, Japan. The chairs were A. D. Lê and K. Kiianmaa. The presentations were (1) Alcohol reward and aversion, by C. L. Cunningham; (2) The role of sensitization of neuronal mechanisms in ethanol self-administration, by J. A. Engel, M. Ericson, and B. Söderpalm; (3) Alcohol self-administration in dependent animals: Neurobiological mechanisms, by G. F. Koob, A. J. Roberts, and F. Weiss; (4) Stress and relapse to alcohol, by A. D. Lê; (5) Alcohol-preferring AA and alcohol-avoiding ANA rats differ in locomotor activation induced by repeated morphine injections, by P. Hyytiä, S. Janhunen, J. Mikkola, P. Bäckström, and K. Kiianmaa; and (6) Initial sensitivity and acute functional tolerance to the hypnotic effects of ethanol in mice genetically selected for mild and severe ethanol withdrawal convulsions, by I. Ponomarev and J. C. Crabbe.
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| 10. |
- Mikkola, H, et al.
(författare)
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Lentivirus gene transfer in murine hematopoietic progenitor cells is compromised by a delay in proviral integration and results in transduction mosaicism and heterogeneous gene expression in progeny cells
- 2000
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 74:24, s. 8-11911
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Tidskriftsartikel (refereegranskat)abstract
- Human immunodeficiency virus type 1-based lentivirus vectors containing the green fluorescent protein (GFP) gene were used to transduce murine Lin(-) c-kit(+) Sca1(+) primitive hematopoietic progenitor cells. Following transduction, the cells were plated into hematopoietic progenitor cell assays in methylcellulose and the colonies were scored for GFP positivity. After incubation for 20 h, lentivirus vectors transduced 27.3% +/- 6.7% of the colonies derived from unstimulated target cells, but transduction was more efficient when the cells were supported with stem cell factor (SCF) alone (42. 0% +/- 5.5%) or SCF, interleukin-3 (IL-3), and IL-6 (53.3 +/- 1.8%) during transduction. The, vesicular stomatitis virus glycoprotein-pseudotyped MGIN oncoretrovirus control vector required IL-3, IL-6, and SCF for significant transduction (39.3 +/- 9.4%). Interestingly, only a portion of the progeny cells within the lentivirus-transduced methylcellulose colonies expressed GFP, in contrast to the homogeneous expression in oncoretrovirus-transduced colonies. Secondary plating of the primary GFP(+) lentivirus vector-transduced colonies revealed vector PCR(+) GFP(+) (42%), vector PCR(-) GFP(-) (46%), and vector PCR(+) GFP(-) (13%) secondary colonies, indicating true genetic mosaicism with respect to the viral genome in the progeny cells. The degree of vector mosaicism in individual colonies could be reduced by extending the culture time after transduction and before plating into the clonal progenitor cell assay, indicating a delay in the lentiviral integration process. Furthermore, supplementation with exogenous deoxynucleoside triphosphates during transduction decreased mosaicism within the colonies. Although cytokine stimulation during transduction correlates with higher transduction efficiency, rapid cell division after transduction may result in loss of the viral genome in the progeny cells. Therefore, optimal transduction may require activation without promoting intense cell proliferation prior to vector integration.
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