| 1. |
- Benkestock, Kurt, et al.
(författare)
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Influence of droplet size, capillary-cone distance and selected instrumental parameters for the analysis of noncovalent protein-ligand complexes by nano-electrospray ionization mass spectrometry
- 2004
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Ingår i: Journal of Mass Spectrometry. - : Wiley. - 1076-5174 .- 1096-9888. ; 39:9, s. 1059-1067
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested in the literature that nano-electrospray ionization (nano-ESI) mass spectrometry better reflects the equilibrium between complex and free protein in solution than pneumatically assisted electrospray ionization (ESI) in noncovalent interaction studies. However, no systematic studies of the effects of ionization conditions have been performed to support this statement. In the present work, different instrumental and sample-derived parameters affecting the stability of noncovalent complexes during analysis by nano-ESI were investigated. In general, increased values of parameters such as drying gas flow-rate, ion-source temperature, capillary tip voltage and buffer concentration lead to a dissociation of ribonuclease A (RNAse)-cytidine 2'-monophosphate (CMP) and cytidine 5'-triphosphate (CTP) complexes. The size of the electrosprayed droplets was shown to be an important issue. Increasing the capillary to cone distance yielded an increased complex to free protein ratio when a hydrophilic ligand was present and the reverse effect was obtained with a hydrophobic ligand. Important in this regard is the degree of sampling of ions originating from late-generation residue droplets, that is, ions present in the droplet bulk. Sampling of these ions increases with longer capillary-cone distance (flight time). Furthermore, when the sample flow-rate was increased by increasing the capillary internal tip i.d. from 4 to 30 mum, a decreased complex to free protein ratio for the RNAse-CTP system was observed. This behavior was consistent with the change in surface to volume ratio for flow-rates between 2 and 100 nl min(-1). Finally, polarity switching between positive and negative ion modes gave a higher complex to free protein ratio when the ligand and the protein had the same polarity.
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| 2. |
- Christensson, Marta, et al.
(författare)
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Serum sFAS levels are elevated in ANCA-positive vasculitis compared with other autoimmune diseases
- 2002
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Ingår i: Journal of Clinical Immunology. - 0271-9142 .- 1573-2592. ; 22:4, s. 220-227
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Tidskriftsartikel (refereegranskat)abstract
- The role of the Fas/FasL system in ANCA-associated vasculitis is unclear. We therefore assessed levels of soluble Fas (sFas) in sera and Fas expression on mononuclear cells from patients with ANCA-positive vasculitis and compared the results with those found in other rheumatic diseases. Serum levels of sFas were determined by ELISA. The ANCA-positive vasculitis patients studied included 29 at onset, 17 in first remission while on therapy, and 12 in quiescence. For comparison, 10 patients with Sjogren’s syndrome (SS), 14 patients with systemic lupus erythematosus (SLE), 29 patients with rheumatoid arthritis (RA), 7 patients on dialysis (DP), and 26 healthy controls (HC) were studied. In addition, Fas expression in mononuclear cells was examined at the mRNA level using reverse transcriptase (RT)-PCR in 6 vasculitis patients at onset and in first remission. The expression of CD95 on the surface of leukocytes was determined by flow cytometry in 6 vasculitis patients at onset of the disease, in 6 patients in clinical remission, and in 6 HC. Expression of Fas and FasL in renal biopsy specimens was studied using immunohistochemistry. Patients with vasculitis had high sFas levels irrespective of disease phase. Both vasculitis patients and patients with RA and SLE had significantly increased sFas levels compared with healthy controls. All patient groups had sFas levels, which correlated with raised serum creatinine values. However, the sFas levels in vasculitis patients in first remission and in quiescence were increased despite a lower serum creatinine compared with onset. Some of the vasculitis patients showed an increased mRNA expression of Fas in mononuclear cells after treatment, suggesting that Fas production fluctuates with the intensity of the disease. The expression of CD95 on leukocytes was slightly decreased in vasculitis patients compared to healthy controls. No alterations of Fas and FasL expression were seen in renal biopsy specimens. These results show that ANCA-positive vasculitis patients have high sFas levels and that the levels remain elevated even in clinical remission. The findings indicate that perturbations in the Fas/Fas ligand system may play a role in the disease process in ANCA vasculitis.
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| 3. |
- Sundqvist, Anders, et al.
(författare)
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Transcription-dependent degradation controls the stability of the SREBP family of transcription factors
- 2003
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 100:24, s. 13833-13838
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Tidskriftsartikel (refereegranskat)abstract
- Cholesterol metabolism is tightly controlled by members of the sterol regulatory element-binding protein (SREBP) family of transcription factors. Here we demonstrate that the ubiquitination and degradation of SREBPs depend on their transcriptional activity. Mutations in the transactivation or DNA-binding domains of SREBPs inhibit their transcriptional activity and stabilize the proteins. The transcriptional activity and degradation of these mutants are restored when fused to heterologous transactivation or DNA-binding domains. When SREBP1a was fused to the DBD of Gal4, the ubiquitination and degradation of the fusion protein depended on coexpression of a promoter-reporter gene containing Gal4-binding sites. In addition, disruption of the interaction between WT SREBP and endogenous p300/CBP resulted in inhibition of SREBP-dependent transcription and stabilization of SREBP. Chemical inhibitors of transcription reduced the degradation of transcriptionally active SREBP1a, whereas they had no effect on the stability of transcriptionally inactive mutants, demonstrating that transcriptional activation plays an important role in the degradation of SREBPs. Thus, transcription-dependent degradation of SREBP constitutes a feedback mechanism to regulate the expression of genes involved in cholesterol metabolism and may represent a general mechanism to regulate the duration of transcriptional responses.
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| 4. |
- Sundqvist, Jan-Olov, et al.
(författare)
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Proceedings from Workshop on System Studies of Integrated Solid Waste Management in Stockholm 2 - 3 April 2001
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This international workshop was held to discuss results and experience from system studies of waste management system and methodological questions and issues based on case studies. The workshop gathered more than 40 participants. These proceedings document more than 20 presentations as well as six discussion sessions. An overall aim of the workshop was to draw some general conclusions from the presented studies concerning - waste strategies that generally seem to be favourable or not favourable - methodological approaches and assumptions that can govern the results - lack of knowledge.Considering the environmental aspects, the presented studies indicated that the waste hierarchy seems to be valid: * Paper and plastic: Material recycling < Incineration < Landfilling * Biodegradable waste: Incineration » Anaerobic digestion < Composting < Landfilling A number of key aspects that can influence the results were identified: * Avoided products (heat, electricity, material, fertiliser produced from waste). * Efficiency in power plants, heating plants etc. and also recycling plants. * Emissions and impacts from recycling plants - Landfilling models, e.g. time frames.* Final sinks: there should be a distinction between temporary sinks (landfills) and final sinks - Local conditions and local impacts are often neglected. * Electricity production * Choice of alternatives to compare can have an influence on the conclusions drawn. - Stakeholders' influence. * Linear modelling. * Data gaps. Especially data on toxic substances where identified as an important data gap
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| 5. |
- Sundqvist, Jan-Olov, et al.
(författare)
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Syntes av systemanalyser av avfallshantering
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I föreliggande studie har gjorts en genomgång av de systemstudier som genomförts i Energimyndighetens forskningsprogram Energi från Avfall. De olika studierna har i de flesta fall visat upp ett likartat resultat. I de flesta fall är resultaten samstämmiga när samma frågeställningar besvarats. I de fall då olika resultat visas upp, beror det på att man valt olika systemgränser så att det egentligen är olika saker man beräknar. Skillnader kan också uppstå på grund av reella eller antagna skillnader i omgivande system, exempelvis vad gäller fjärrvärmesystem och konkurrerande energikällor. Ur de genomgångna studierna har ett antal generella slutsatser kunna dragits, bl.a.: * Deponering av avfall som kan förbrännas, rötas, komposteras eller materialåtervinnas är i allmänhet i sämre alternativ än andra behandlingsformer ur både ett miljömässigt och ekonomiskt perspektiv * Rötning och förbränning (av nedbrytbart avfall från hushållen) är svåra att jämföra. Ingendera är miljömässigt entydigt bättre än det andra. * Kompostering (strängkompostering) av lättnedbrytbart avfall har nästan inga miljömässiga fördelar gentemot förbränning. * Materialåtervinning är generellt miljömässigt bättre än förbränning i de fall som studerats. * Transporter av avfall, sedan det väl är insamlat, är av begränsad energimässig, miljömässig och ekonomisk betydelse. Hushållens transporter (med personbil) kan påverka resultatet
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