| 1. |
- Izumrudov, Vladimir, et al.
(författare)
-
Factors Controlling Phase Separation in Water-Salt Solutions of DNA and Polycations.
- 2003
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 19:11, s. 4733-4739
-
Tidskriftsartikel (refereegranskat)abstract
- Factors affecting phase separation in water-salt solutions of polyelectrolyte complexes (PECs), formed by DNA and integral or pendant polycations with a quaternary amino group in every monomer unit, have been studied. When no salt was added, quantitative DNA precipitation occurred at a stoichiometric charge ratio, = [+]/[-] 1. In DNA mixtures with poly(N,N'-dimethyldiallylammonium chloride) (PDMDAAC, a pendant polycation), insoluble PECs formed in the range 0.7 < < 2. This suggests the formation of soluble, negatively charged PECs at 0 < < 0.7 and soluble, positively charged PECs at > 2. For different aliphatic ionene bromides (integral polycations), the range of corresponding to insoluble PECs was significantly broader, mainly due to the poor ability of the ionenes to form soluble, positively charged PECs. The range was also relatively broad for poly(N-ethyl-4-vinylpyridinium bromide) (a pendant polycation) and became broader with decreasing degree of polymerization of the polycation. The formation of insoluble PECs was favored by the addition of salt (NaCl), and the effect was more pronounced when decreasing the relative content of the solubilizing component, i.e., the nucleic acid at < 1 and the polycation at > 1. At moderate ionic strength, 0.12 M < [NaCl] < 0.6 M, quantitative precipitation of DNA was attained by addition of PDMAAC in the whole region studied: 1 < < 4.5. The data obtained strongly suggest that phase separation in solutions of DNA-containing PECs follows general rules revealed by studying PECs formed by flexible vinyl polyanions. However, the high rigidity of the DNA double helix appears to be responsible for the key feature revealed in the phase diagrams, i.e., significant broadening of the region for insoluble PECs at the expense of the region in which soluble DNA-containing PECs are formed. This feature may severely limit the application of DNA-containing PECs in medicine and biology but could be beneficial in the development of simple and effective procedures for DNA separation in biotechnology.
|
|
| 2. |
- Wahlund, Per-Olof, et al.
(författare)
-
Phase Separations in Water-Salt Solutions of Polyelectrolyte Complexes Formed by RNA and Polycations: Comparison with DNA Complexes.
- 2003
-
Ingår i: Macromolecular Bioscience. - : Wiley. - 1616-5195 .- 1616-5187. ; 3:8, s. 404-411
-
Tidskriftsartikel (refereegranskat)abstract
- Formation of insoluble polyelectrolyte complexes (PECs) between RNA and polycations was followed by measuring the residual RNA absorbance in the solution after separation of the precipitate. The polycations studied were poly(N,N-dimethyldiallylammonium) chloride (pendant type) and 2,5-ionene bromide (integral type) with quaternary amino groups in every monomer unit. The data obtained were compared with the results of analogous studies of DNA-containing PECs. This study is a part of a project aimed at the specific separation of plasmid DNA from RNA, a major problem in the preparative isolation of plasmid DNA. We thus deliberately chose a heterogenous RNA sample as it represents the RNA present in a real cell extract. In contrast to the exhaustive precipitation of DNA observed at certain values, a significant part of RNA was nonprecipitated at any = [+]/[-], that is, at any ratio of positively charged quaternary amino groups and negatively charged phosphate groups. The addition of sodium chloride increased the nonprecipitated fraction of RNA. DNA, on the other hand, was completely precipitated by both polycations at > 0.7. The less effective precipitation of RNA was probably due to the presence of a considerable fraction of short-chained molecules, incapable of forming a sufficient cooperative system of salt bonds with the polycation. This assumption was supported by a separate experiment, in which the precipitation behavior of RNA fractions of different molecular masses was investigated. The same tendency, while less pronounced, was also ascertained for PECs formed by polycations with DNA fractions of different molecular masses. The possibility of using the revealed differences between DNA and RNA behavior for effective precipitation procedure useful in bioseparation is discussed. The difference in the precipitation behavior of nucleic acids of different molecular masses means there is a possibility for developing an enzymatic assay for DNAase and RNAase activity.
|
|
| 3. |
- Wahlund, Per-Olof, et al.
(författare)
-
Polyelectrolyte complexes as a tool for purification of plasmid DNA background and development
- 2004
-
Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 807:1, s. 121-127
-
Tidskriftsartikel (refereegranskat)abstract
- The demand for highly purified plasmids in gene therapy and plasmid-based vaccines requires large-scale production of pharmaceutical-grade plasmid. Plasmid DNA was selectively precipitated from a clarified alkaline lysate using the polycation poly(N,N'-dimethyldiallylammonium) chloride which formed insoluble polyelectrolyte complex (PEC) with the plasmid DNA. Soluble PECs of DNA with polycations have earlier been used for cell transformation, but now the focus has been on insoluble PECs. Both DNA and RNA form stable PECs with synthetic polycations. However, it was possible to find a range of salt concentration where plasmid DNA was quantitatively precipitated whereas RNA remained in solution. The precipitated plasmid DNA was resolubilised at high salt concentration and the polycation was removed by gel-filtration. (C) 2004 Elsevier B.V. All rights reserved.
|
|
| 4. |
- Wahlund, Per-Olof, et al.
(författare)
-
Precipitation by polycation as capture step in purification of plasmid DNA from a clarified lysate
- 2004
-
Ingår i: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 87:5, s. 675-684
-
Tidskriftsartikel (refereegranskat)abstract
- The demand for highly purified plasmids in gene therapy and plasmid-based vaccines requires large-scale production of pharmaceutical-grade plasmid. Large-scale purification of plasmid DNA from bacterial cell culture normally includes one or several chromatographic steps. Prechromatographic steps include precipitation with solvents, salts, and polymers combined with enzymatic degradation of nucleic acids. No method alone has so far been able to selectively capture plasmid DNA directly from a clarified alkaline lysate. We present a method for selective precipitation of plasmid DNA from a clarified alkaline lysate using polycation poly(N,N'-dimethyldiallylammonium) chloride (PDMDAAC). The specific interaction between the polycation and the plasmid DNA resulted in the formation of a stoichiometric insoluble complex. Efficient removal of contaminants such as RNA, by far the major contaminant in a clarified lysate, and proteins as well as 20-fold plasmid concentration has been obtained with about 80% recovery. The method utilizes a inexpensive, commercially available polymer and thus provides a capture step suitable for large-scale production. (C) 2004 Wiley Periodicals, Inc.
|
|
| 5. |
- Andre, M., et al.
(författare)
-
Multi-spacecraft observations of broadband waves near the lower hybrid frequency at the Earthward edge of the magnetopause
- 2001
-
Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 19:12-okt, s. 1471-1481
-
Tidskriftsartikel (refereegranskat)abstract
- Broadband waves around the lower hybrid frequency (around 10 Hz) near the magnetopause are studied, using the four Cluster satellites. These waves are common at the Earthward edge of the boundary layer, consistent with earlier observations, and can have amplitudes at least up to 5 mV/m. These waves are similar on all four Cluster satellites, i.e. they are likely to be distributed over large areas of the boundary. The strongest electric fields occur during a few seconds, i.e. over distances of a few hundred km in the frame of the moving magnetopause, a scale length comparable to the ion gyroradius. The strongest magnetic oscillations in the same frequency range are typically found in the boundary layer, and across the magnetopause. During an event studied in detail, the magnetopause velocity is consistent with a large-scale depression wave, i.e. an inward bulge of magnetosheath plasma, moving tailward along the nominal magnetopause boundary. Preliminary investigations indicate that a rather flat front side of the large-scale wave is associated with a rather static small-scale electric field, while a more turbulent backside of the large-scale wave is associated with small-scale time varying electric field wave packets.
|
|
| 6. |
|
|
| 7. |
- Blomberg, Lars, et al.
(författare)
-
Electric Field Diagnostics in the Jovian System : Brief Scientific Case and Instrumentation Overview
- 2006
-
Ingår i: Proceedings of the 6th IAA International Conference on Low-Cost Planetary Missions. ; , s. 335-340
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Jovian plasma environment exhibits a variety of plasma flow interactions with magnetised as well as unmagnetised bodies, making it a good venue for furthering our understanding of solar wind - magnetosphere / ionosphere interactions. On an overall scale the solar wind interacts with the Jovian magnetosphere, much like at Earth but with vastly different temporal and spatial scales. Inside the Jovian magnetosphere the co-rotating plasma interacts with the inner moons. The latter interaction is slower and more stable than the corresponding interaction between the solar wind and the planets, and can thus provide additional information on the principles of the interaction mechanisms. Because of the wealth of expected low-frequency waves, as well as the predicted quasi-static electric fields and plasma drifts in the interaction regions between different parts of the Jovian system, a most valuable component in future payloads would be a double-probe electric field instrument. Recent developments in low-mass instrumentation facilitate electric field measurements on spinning planetary spacecraft, which we here exemplify.
|
|
| 8. |
- Carlsson, Alexandra Dimitrijevic, et al.
(författare)
-
Orofacial pain in juvenile idiopathic arthritis is associated with stress as well as psychosocial and functional limitations
- 2019
-
Ingår i: Pediatric Rheumatology. - : BioMed Central (BMC). - 1546-0096. ; 17:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background The aim of this study was to investigate relations between psychosocial factors, signs and symptoms of orofacial pain and jaw dysfunction in patients with juvenile idiopathic arthritis (JIA). Methods Forty-five patients with JIA (median age 12 years) and 16 healthy matched controls (median age 13 years) were examined according to the diagnostic criteria for temporomandibular disorders (DC/TMD). The subjects answered the DC/TMD questionnaires regarding psychosocial factors (pain intensity, pain-related disability, depression, stress, catastrophizing, pain locations and jaw function). Results JIA patients with orofacial pain had higher degree of stress, depression, catastrophizing and jaw dysfunction compared to subjects without. In turn, these factors were associated with orofacial pain intensity. Also, patients with orofacial pain had higher systemic inflammatory activity. Conclusions Orofacial pain in patients with JIA is associated with stress, psychological distress, jaw dysfunction and loss of daily living activities. Pain intensity seems to be the major pain aspect related to these factors. In addition, systemic inflammatory activity appears to be an important factor contributing to orofacial pain in JIA.
|
|
| 9. |
- Dimitrijevic Carlsson, Alexandra, 1966-, et al.
(författare)
-
Increase in stress contributes to impaired jaw function in juvenile idiopathic arthritis : a two-year prospective study
- 2024
-
Ingår i: Pediatric Rheumatology. - : BioMed Central (BMC). - 1546-0096. ; 22:1
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundStress in patients with Juvenile Idiopathic Arthritis (JIA) has been found to be associated with orofacial pain, psychological distress, jaw dysfunction and loss of daily activities in a cross-sectional study. The aim of this study was to investigate the relations between stress and change of stress over time versus changes in orofacial pain, psychosocial factors and jaw function over a two-year period in patients with JIA.MethodsThis is a two-year prospective follow-up study involving 40 JIA patients. At baseline (2015) the median age was 12 years and at two-year follow up (2018) 14 years. The JIA patients were examined clinically and with questionnaires at baseline and follow-up with the diagnostic criteria for temporomandibular disorders (DC/TMD) and completed the same set of DC/TMD questionnaires regarding orofacial pain symptoms and psychosocial factors.ResultsChange in stress was associated with change in catastrophizing, psychological distress as well as limitation in general function and jaw function.ConclusionsThis study emphasizes the importance of maintaining a low stress level in patients with JIA since an increase in stress level over a two-year period seems to impair jaw function as well as psychological distress and catastrophizing.
|
|
| 10. |
- Dimitrijevic Carlsson, Alexandra, 1966-, et al.
(författare)
-
Juvenile idiopathic arthritis and the temporomandibular joint : a case-control study of magnetic resonance imaging findings in relation to clinical and psychosocial factors
- 2023
-
Ingår i: European Journal of Paediatric Dentistry. - : Società Italiana di Odontoiatria Infantile. - 1591-996X .- 2035-648X. ; 24:1, s. 69-76
-
Tidskriftsartikel (refereegranskat)abstract
- AimIn juvenile idiopathic arthritis (JIA), the temporomandibular joint (TMJ) is a particularly challenging joint to assess both clinically and with imaging. The aim of this article is to investigate TMJ magnetic resonance imaging (MRI) findings in relation to clinical and psychosocial factors in patients with JIA and healthy individuals related to TMJ arthritis in JIA.Material and methods In total, 45 patients (6–16 years) with JIA and 16 healthy age- and sex-matched controls were examined according to the diagnostic criteria for temporomandibular disorders (DC/TMD). The subjects answered questionnaires about psychosocial factors (pain intensity, pain-related disability, depression, stress, catastrophising, pain locations, and jaw function) and underwent bilateral MRI of the TMJ.ResultsThere were no significant differences between JIA patients and healthy individuals in any of the TMJ MRI findings. Moderate/severe changes among JIA patients were found only for effusion, synovial thickening, condylar flattening, and erosion, with no moderate/severe changes in healthy individuals. In JIA patients, orofacial pain intensity was related to TMJ bone marrow oedema, and pain in jaw muscles during jaw function was related to TMJ bone marrow oedema and erosion. There were no significant correlations between psychosocial aspects and MRI findings.ConclusionsThis study indicates a substantial overlap of TMJ MRI findings in both the inflammatory domain and the damage domain between JIA patients and healthy individuals. In JIA patients, the inflammatory MRI sign of bone marrow oedema seems to influence orofacial pain intensity.
|
|
