| 1. |
- Adams, Yvonne, et al.
(författare)
-
3D blood-brain barrier-organoids as a model for Lyme neuroborreliosis highlighting genospecies dependent organotropism
- 2023
-
Ingår i: ISCIENCE. - : CELL PRESS. - 2589-0042. ; 26:1
-
Tidskriftsartikel (refereegranskat)abstract
- Lyme neuroborreliosis (LNB), a tick-borne infection caused by spirochetes within the Borrelia burgdorferi sensu lato (s.L.) complex, is among the most prevalent bacterial central nervous system (CNS) infections in Europe and the US. Here we have screened a panel of low- passage B. burgdorferi s.l. isolates using a novel, human-derived 3D blood-brain barrier (BBB)-organoid model. We show that human-derived BBB-organoids support the entry of Borrelia spirochetes, leading to swelling of the organoids and a loss of their structural integrity. The use of the BBB-organoid model highlights the organotropism between B. burgdorferi s.l. genospecies and their ability to cross the BBB contributing to CNS infection.
|
|
| 2. |
|
|
| 3. |
- Widestrand, Åsa, 1978, et al.
(författare)
-
Increased neurogenesis and astrogenesis from neural progenitor cells grafted in the hippocampus of GFAP-/- Vim-/- mice.
- 2007
-
Ingår i: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 25:10, s. 2619-27
-
Tidskriftsartikel (refereegranskat)abstract
- After neurotrauma, ischemia, or neurodegenerative disease, astrocytes upregulate their expression of the intermediate filament proteins glial fibrillary acidic protein (GFAP), vimentin (Vim), and nestin. This response, reactive gliosis, is attenuated in GFAP(-/-)Vim(-/-) mice, resulting in the promotion of synaptic regeneration after neurotrauma and improved integration of retinal grafts. Here we assessed whether GFAP(-/-)Vim(-/-) astrocytes affect the differentiation of neural progenitor cells. In coculture with GFAP(-/-)Vim(-/-) astrocytes, neural progenitor cells increased neurogenesis by 65% and astrogenesis by 124%. At 35 days after transplantation of neural progenitor cells into the hippocampus, adult GFAP(-/-)Vim(-/-) mice had more transplant-derived neurons and astrocytes than wild-type controls, as well as increased branching of neurite-like processes on transplanted cells. Wnt3 immunoreactivity was readily detected in hippocampal astrocytes in wild-type but not in GFAP(-/-)Vim(-/-) mice. These findings suggest that GFAP(-/-)Vim(-/-) astrocytes allow more neural progenitor cell-derived neurons and astrocytes to survive weeks after transplantation. Thus, reactive gliosis may adversely affect the integration of transplanted neural progenitor cells in the brain. Disclosure of potential conflicts of interest is found at the end of this article.
|
|
| 4. |
- Wilhelmsson, Peter, et al.
(författare)
-
A prospective study on the incidence of Borrelia burgdorferi sensu lato infection after a tick bite in Sweden and On the Åland Islands, Finland (2008-2009)
- 2016
-
Ingår i: Ticks and Tick-borne Diseases. - : Elsevier. - 1877-959X .- 1877-9603. ; 7:1, s. 71-79
-
Tidskriftsartikel (refereegranskat)abstract
- Lyme borreliosis (LB) is a common and increasing tick-borne disease in Europe. The risk of acquiring a Borrelia infection after a tick bite is not fully known. Therefore, we investigated the incidence of Borrelia infection after a bite by a Borrelia-infected tick and if the Borrelia load and/or the duration of tick-feeding influenced the risk of infection. During 2008-2009, ticks and blood samples were collected from 1546 tick-bitten persons from Sweden and the Åland Islands, Finland. Follow-up blood samples were taken 3 months after the tick bite. The duration of tick feeding was microscopically estimated and Borrelia was detected and quantified in ticks by real-time PCR. Anti-Borrelia antibodies were detected in sera using ELISA tests and immunoblot. Five percent (78/1546) of the study participants developed Borrelia infection (LB diagnosis and/or seroconversion) after a tick bite (45% bitten by Borrelia-infected ticks and 55% bitten by uninfected ticks). Of these, 33 developed LB (whereof 9 also seroconverted) while 45 participants seroconverted only. Experience of non-specific symptoms was more frequently reported by Borrelia-infected participants compared to uninfected participants. All who seroconverted removed "their" ticks significantly later than those who did not. The Borrelia load in the ticks did not explain the risk of seroconversion. Regional and sex differences in the Borrelia seroprevalence were found. The risk of developing a Borrelia infection after a bite by a Borrelia-infected tick is small but increases with the duration of tick feeding.
|
|
| 5. |
- Wilhelmsson, Peter, et al.
(författare)
-
A prospective study on the incidence of Borrelia infection after a tick bite in Sweden and on the Åland Islands, Finland (2008-2009)
- 2016
-
Ingår i: Ticks and Tick-borne Diseases. - : Elsevier. - 1877-959X .- 1877-9603. ; 7:1, s. 71-79
-
Tidskriftsartikel (refereegranskat)abstract
- Lyme borreliosis (LB) is a common and increasing tick-borne disease in Europe. The risk of acquiring a Borrelia infection after a tick bite is not fully known. Therefore, we investigated the incidence of Borrelia infection after a tick bite and if the Borrelia load and/or the duration of tick-feeding influenced the risk of infection. During 2008-2009, ticks and blood samples were collected from 1546 tick-bitten persons from Sweden and the Åland Islands, Finland. Follow-up blood samples were taken three months after the tick bite. The duration of tick feeding was microscopically estimated and Borrelia was detected and quantified in ticks by real-time PCR. Anti-Borrelia antibodies were detected in sera using ELISA assays and immunoblot.Even though 28 % of the participants were bitten by a Borrelia-positive tick, only 7.5% (32/428) of them developed a Borrelia infection, half of them LB. All who seroconverted removed “their” ticks significantly later than those who did not. The Borrelia load in the ticks did not explain the risk of seroconversion. Regional as well as gender differences in the Borrelia seroprevalence were found. The risk of developing a Borrelia infection after a bite by a Borrelia-infected tick is small but increases with the duration of tick feeding.
|
|
| 6. |
- Aase, Audun, et al.
(författare)
-
Validate or falsify: Lessons learned from a microscopy method claimed to be useful for detecting Borrelia and Babesia organisms in human blood
- 2016
-
Ingår i: INFECTIOUS DISEASES. - : TAYLOR & FRANCIS LTD. - 2374-4235 .- 2374-4243. ; 48:6, s. 411-419
-
Tidskriftsartikel (refereegranskat)abstract
- Background A modified microscopy protocol (the LM-method) was used to demonstrate what was interpreted as Borrelia spirochetes and later also Babesia sp., in peripheral blood from patients. The method gained much publicity, but was not validated prior to publication, which became the purpose of this study using appropriate scientific methodology, including a control group. Methods Blood from 21 patients previously interpreted as positive for Borrelia and/or Babesia infection by the LM-method and 41 healthy controls without known history of tick bite were collected, blinded and analysed for these pathogens by microscopy in two laboratories by the LM-method and conventional method, respectively, by PCR methods in five laboratories and by serology in one laboratory. Results Microscopy by the LM-method identified structures claimed to be Borrelia- and/or Babesia in 66% of the blood samples of the patient group and in 85% in the healthy control group. Microscopy by the conventional method for Babesia only did not identify Babesia in any samples. PCR analysis detected Borrelia DNA in one sample of the patient group and in eight samples of the control group; whereas Babesia DNA was not detected in any of the blood samples using molecular methods. Conclusions The structures interpreted as Borrelia and Babesia by the LM-method could not be verified by PCR. The method was, thus, falsified. This study underlines the importance of doing proper test validation before new or modified assays are introduced.
|
|
| 7. |
- Aissaoui, Nesrine, 1983, et al.
(författare)
-
FRET enhancement close to gold nanoparticles positioned in DNA origami constructs
- 2017
-
Ingår i: Nanoscale. - Cambridge, United Kingdom : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 9:2, s. 673-683
-
Tidskriftsartikel (refereegranskat)abstract
- Here we investigate the energy transfer rates of a Förster resonance energy transfer (FRET) pair positioned in close proximity to a 5 nm gold nanoparticle (AuNP) on a DNA origami construct. We study the distance dependence of the FRET rate by varying the location of the donor molecule, D, relative to the AuNP while maintaining a fixed location of the acceptor molecule, A. The presence of the AuNP induces an alteration in the spontaneous emission of the donor (including radiative and non-radiative rates) which is strongly dependent on the distance between the donor and AuNP surface. Simultaneously, the energy transfer rates are enhanced at shorter D-A (and D-AuNP) distances. Overall, in addition to the direct influence of the acceptor and AuNP on the donor decay there is also a significant increase in decay rate not explained by the sum of the two interactions. This leads to enhanced energy transfer between donor and acceptor in the presence of a 5 nm AuNP. We also demonstrate that the transfer rate in the three "particle" geometry (D + A + AuNP) depends approximately linearly on the transfer rate in the donor-AuNP system, suggesting the possibility to control FRET process with electric field induced by 5 nm AuNPs close to the donor fluorophore. It is concluded that DNA origami is a very versatile platform for studying interactions between molecules and plasmonic nanoparticles in general and FRET enhancement in particular.
|
|
| 8. |
- Andersson, Peter, et al.
(författare)
-
Texter som inte räknas? : Om digitala läs- och skrivaktiviteter bland barn och unga
- 2010
-
Ingår i: Utbildning och lärande. - Skövde : Avdelningen barns, ungas och vuxnas lärande vid Högskolan i Skövde. - 1653-0594. ; 4:1, s. 14-33
-
Tidskriftsartikel (refereegranskat)abstract
- In the age of the Internet and a changing semiotic landscape, reading and writing become increasingly complex activities in school. ICT have to be considered as a partner in the daily pedagogies. Digital media and new forms of communication are of great interest for literacy researches, particularly within the area of research that has come to be called New literacies. This article presents the results of a survey in which we asked 320 pupils about their use of information technology as part of daily literacy activities in and outside school. The study is inspired by an American study among young adolescents in New York (Agee & Altarriba 2009), but based on a wider range of ages: between 10-16 years. Our results show some significant differences in the pupils’ literacy activities based on factors such as gender, age, and attitudes towards reading and writing. Of particular interest is one group that distinguishes itself by having a negative attitude to reading and writing even though spending much time on digital literacies in and outside school.
|
|
| 9. |
- Aspelin, Peter, et al.
(författare)
-
Ultrasound examination of soft tissue injury of the lower limb in athletes
- 1992
-
Ingår i: The American journal of sports medicine. - : SAGE Publications. - 1552-3365 .- 0363-5465. ; 20:5, s. 601-603
-
Tidskriftsartikel (refereegranskat)abstract
- We performed ultrasonography on 32 athletes complaining of intense pain in a swollen and tender thigh or calf after a contusion or stretching trauma. The ultrasonogram was used to visualize the presence and size of a suspected hematoma. The findings included the following: 7 patients with a circumscribed, anechoic lesion compatible with a liquefied hematoma; 10 patients with a circumscribed lesion of mixed echogenicity compatible with areas of liquefied hematoma, coagulated blood, and edema; and 15 patients with a diffuse change in echogenicity of the whole muscle. The circumscribed liquefied, and mixed hematoma were more common after contusion trauma, while the diffuse type was more common after injury caused by stretching. Ultrasonography is useful in localizing the hematoma and in characterizing the different types. Differentiation is important in diagnosis and choice of treatment.
|
|
| 10. |
- Bijelovic, Stojanka, et al.
(författare)
-
Wear-resistant magnetic thin film material based on a Ti1−xFexC1−y nanocomposite alloy
- 2010
-
Ingår i: Physical Review B Condensed Matter. - : The American Physical Society. - 0163-1829 .- 1095-3795. ; 81:1, s. 014405-
-
Tidskriftsartikel (refereegranskat)abstract
- In this study we report on the film growth and characterization of thin films deposited on amorphous quartz. The experimental studies have been complemented by first-principles density-functional theory metastable Ti-Fe-C film changes. With increasing annealing time, there is a depletion of iron close to the surface of the film, while regions enriched in iron are simultaneously formed deeper into the film. Both the magnetic ordering temperature and the saturation magnetization changes significantly upon annealing. The DFT calculations show that the critical temperature and the magnetic moment both increase with increasing Fe and C-vacancy concentration. The formation of the metastable iron-rich Ti-Fe-C compound is reflected in the strong increase in the magnetic ordering temperature. Eventually, after enough annealing time nanocrystalline -Fe starts to precipitate, the amount and size of which can be controlled by the annealing procedure; after 20 min of annealing, the experimental results indicate a nanocrystalline iron-film embedded in a wear-resistant TiC compound. This conclusion is further supported by transmission electron microscopy studies on epitaxial Ti-Fe-C films deposited on single-crystalline MgO substrates where, upon annealing, an iron film embedded in TiC is formed. Our results suggest that annealing of metastable Ti-Fe-C films can be used as an efficient way of creating a wear-resistant magnetic thin film material. approximately 50-nm-thick Ti-Fe-CDFT calculations. Upon annealing of as-prepared films, the composition of the10 min, nanocrystalline -Fe starts to precipitate, the amount and size of which can be controlled by the annealing procedure; after 20 min of annealing, the experimental results indicate a nanocrystalline iron-film embedded in a wear-resistant TiC compound. This conclusion is further supported by transmission electron microscopy studies on epitaxial Ti-Fe-C films deposited on single-crystalline MgO substrates where, upon annealing, an iron film embedded in TiC is formed. Our results suggest that annealing of metastable Ti-Fe-C films can be used as an efficient way of creating a wear-resistant magnetic thin film material.
|
|
| 11. |
|
|
| 12. |
- Börjesson, Karl, 1982, et al.
(författare)
-
Characterization and use of tricyclic fluorescent nucleic acid base analogues
- 2008
-
Ingår i: Nucleic acids symposium series (2004). - 1746-8272. ; :52, s. 3-4
-
Tidskriftsartikel (refereegranskat)abstract
- The two recently developed nucleic acid probe molecules tC and tC(O) both have unique properties compared to other molecules in the family of fluorescent base analogues.(1-5) These tricyclic base analogues both form very stable base pairs with guanine and give minimal perturbations to the native structure of DNA.(2) We have found that tC(O) is the brightest fluorescent base analogue reported(4) and that tC also is very bright and has a fluorescence quantum yield that is virtually insensitive to its surrounding microenvironment within the nucleic acid(3). These base analogues have so far been used in FRET-studies of a DNA-polymerase system(6) and in initial anisotropy-studies of DNA-containing systems(4).
|
|
| 13. |
- Börjesson, Karl, 1982, et al.
(författare)
-
Nucleic acid structure and sequence probing using fluorescent base analogue tCo
- 2009
-
Ingår i: Biophysical Chemistry. - : Elsevier BV. - 1873-4200 .- 0301-4622. ; 139:1, s. 24-28
-
Tidskriftsartikel (refereegranskat)abstract
- The fluorescent cytosine analog tC(o) is on average the brightest probe of its kind and, moreover, it introduces minimal perturbations to the normal secondary structure of DNA. Here several ways of how tC(o), with an advantage, can be used as a local fluorescent probe in nucleic acid systems are presented. Most importantly, we show that tCo is an excellent probe for the detection of individual melting processes of complex nucleic acid structures containing a large number of separate secondary structure motifs. Since conventional UV-melting investigations merely monitor the global melting process of the whole nucleic acid structure, e.g. multi-hairpin systems in RNA/DNA, and thus is incapable of estimating individual melting transitions of such systems, tC(o) represents a new method of characterization. Furthermore, we find that tCo may be used to detect bulges and loops in nucleic acids as well as to distinguish a matched base-pair from several of the mismatched.
|
|
| 14. |
|
|
| 15. |
- Carlströmer Berthén, Nellie, et al.
(författare)
-
The AxBioTick Study: Borrelia Species and Tick-Borne Encephalitis Virus in Ticks, and Clinical Responses in Tick-Bitten Individuals on the Aland Islands, Finland
- 2023
-
Ingår i: Microorganisms. - : MDPI. - 2076-2607. ; 11:5
-
Tidskriftsartikel (refereegranskat)abstract
- The AxBioTick Study: Borrelia Species and Tick-Borne Encephalitis Virus in Ticks, and Clinical Responses in Tick-Bitten Individuals on the Aland Islands, Finlandby Nellie Carlströmer Berthén 1,2,*,† , Eszter Tompa 3,† , Susanne Olausson 1,2, Clara Nyberg 1, Dag Nyman 1,2, Malin Ringbom 1,4, Linda Perander 1,4, Joel Svärd 3, Per-Eric Lindgren 3,5, Pia Forsberg 3, Peter Wilhelmsson 3,5,‡, Johanna Sjöwall 3,6,‡ and Marika Nordberg 1,4,‡ 1Borrelia Research Group of the Aland Islands, 22100 Mariehamn, The Aland Islands, Finland2Bimelix AB, 22100 Mariehamn, The Aland Islands, Finland3Department of Biomedical and Clinical Sciences, Division of Inflammation and Infection, Linkoping University, 581 83 Linkoping, Sweden4The Aland Islands Healthcare Services, 22100 Mariehamn, The Aland Islands, Finland5Clinical Microbiology, Laboratory Medicine, County Hospital Ryhov, 551 85 Jonkoping, Sweden6Department of Infectious Diseases, Vrinnevi Hospital, 603 79 Norrkoping, Sweden*Author to whom correspondence should be addressed.†These authors contributed equally to the study.‡These authors contributed equally to the study.Microorganisms 2023, 11(5), 1100; https://doi.org/10.3390/microorganisms11051100Received: 30 March 2023 / Revised: 17 April 2023 / Accepted: 19 April 2023 / Published: 22 April 2023(This article belongs to the Special Issue Research on Ticks and Tick-Borne Pathogens)Download Browse Figures Versions NotesArticle Views585 AbstractThe AxBioTick study was initiated to investigate the prevalence of ticks and tick-borne pathogens and their impact on antibody and clinical responses in tick-bitten individuals on the Aland Islands. This geographical area is hyperendemic for both Lyme borreliosis (LB) and Tick-borne encephalitis (TBE). Blood samples and ticks were collected from 100 tick-bitten volunteers. A total of 425 ticks was collected, all determined to Ixodes ricinus using molecular tools. Of them 20% contained Borrelia species, of which B. garinii and B. afzelii were most common. None contained the TBE virus (TBEV). Blood samples were drawn in conjunction with the tick bite, and eight weeks later. Sera were analyzed for Borrelia- and TBEV-specific antibodies using an ELISA and a semiquantitative antibody assay. In total 14% seroconverted in Borrelia C6IgG1, 3% in TBEV IgG, and 2% in TBEV IgM. Five participants developed clinical manifestations of LB. The high seroprevalence of both Borrelia (57%) and TBEV (52%) antibodies are likely attributed to the endemic status of the corresponding infections as well as the TBE vaccination program. Despite the similar prevalence of Borrelia spp. detected in ticks in other parts of Europe, the infection rate in this population is high. The AxBioTick study is continuing to investigate more participants and ticks for co-infections, and to characterize the dermal immune response following a tick bite.
|
|
| 16. |
- Chiappa, Giulia, et al.
(författare)
-
A Novel High Discriminatory Protocol for the Detection of Borrelia afzelii, Borrelia burgdorferi Sensu Stricto and Borrelia garinii in Ticks
- 2022
-
Ingår i: Pathogens. - : MDPI. - 2076-0817. ; 11:11
-
Tidskriftsartikel (refereegranskat)abstract
- Bacteria of the Borrelia burgdorferi sensu lato complex are the causative agents of Lyme borreliosis (LB). Even if the conventional diagnosis of LB does not rely on the species itself, an accurate species identification within the complex will provide a deepened epidemiological scenario, a better diagnosis leading to a more targeted therapeutic approach, as well as promote the general publics awareness. A comparative genomics approach based on the 210 Borrelia spp. genomes available in 2019 were used to set up three species-specific PCR protocols, able to detect and provide species typing of Borrelia afzelii, Borrelia burgdorferi sensu stricto (s.s.) and Borrelia garinii, the three most common and important human pathogenic Lyme Borrelia species in Europe. The species-specificity of these protocols was confirmed on previously identified B. afzelii, B. burgdorferi s.s. and B. garinii specimens detected in Ixodes ricinus samples. In addition, the protocols were validated on 120 DNA samples from ticks collected in Sweden, showing 88% accuracy, 100% precision, 72% sensitivity and 100% specificity. The proposed approach represents an innovative tool in epidemiological studies focused on B. burgdorferi s.l. occurrence in ticks, and future studies could suggest its helpfulness in routine diagnostic tests for health care.
|
|
| 17. |
- Cronhjort, Samuel, et al.
(författare)
-
The Tick-Borne Diseases STING study : Real-time PCR analysis of three emerging tick-borne pathogens in ticks that have bitten humans in different regions of Sweden and the Aland islands, Finland
- 2019
-
Ingår i: Infection Ecology & Epidemiology. - : Taylor & Francis. - 2000-8686 .- 2000-8686. ; 9:1
-
Tidskriftsartikel (refereegranskat)abstract
- A milder climate has during the last decade contributed to an increased density and spreading of ixodid ticks, thus enhancing their role as emerging vectors for pathogenic microorganisms in northern Europe. It remains unclear if they contribute to the occurrence of infections caused by the bacteria Bartonella spp., Francisella tularensis subspecies holarctica and the parasite Toxoplasma gondii in Sweden and on the Åland islands, Finland. In this study, we want to improve understanding of the tick-borne transmission of these pathogens. Volunteers were recruited at primary healthcare centers. Ticks and blood samples were acquired from participants recruited in 2008 and 2009. Health questionnaires were completed, and medical records were acquired where applicable. Feeding time was estimated and screening of pathogens in the ticks was performed through real-time PCR. Ticks (n = 1849) were of mixed developmental stages: 76 larvae, 1295 nymphs, 426 adults and 52 undetermined. All analyzed ticks were considered negative for these pathogens since the CT-values were all below the detection limit for Bartonella spp. (1663 ticks), Francisella spp. (1849 ticks) and Toxoplasma gondii (1813 ticks). We assume that infections with these pathogens are caused by other transmission pathways within these regions of Sweden and the Åland islands, Finland.
|
|
| 18. |
- Dessau, Ram B, et al.
(författare)
-
Study of a Cohort of 1,886 Persons To Determine Changes in Antibody Reactivity to Borrelia burgdorferi 3 Months after a Tick Bite
- 2015
-
Ingår i: Clinical and Vaccine Immunology. - 1556-6811 .- 1556-679X. ; 22:7, s. 823-827
-
Tidskriftsartikel (refereegranskat)abstract
- Lyme borreliosis is a tick-borne disease caused by the bacterium Borrelia burgdorferi. The most frequent clinical manifestation is a rash called erythema migrans. Changes in antibody reactivity to B. burgdorferi 3 months after a tick bite are measured using enzyme-linked immunosorbent assays (ELISAs). One assay is based on native purified flagellum antigen (IgG), and the other assay is based on a recombinant antigen called C6 (IgG or IgM). Paired samples were taken at the time of a tick bite and 3 months later from 1,886 persons in Sweden and the Åland Islands, Finland. The seroconversion or relative change is defined by dividing the measurement units from the second sample by those from the first sample. The threshold for the minimum level of significant change was defined at the 2.5% level to represent the random error level. The thresholds were a 2.7-fold rise for the flagellar IgG assay and a 1.8-fold rise for the C6 assay. Of 1,886 persons, 102/101 (5.4%) had a significant rise in antibody reactivity in the flagellar assay or the C6 assay. Among 40 cases with a diagnosis of Lyme borreliosis, the sensitivities corresponding to a rise in antibodies were 33% and 50% for the flagellar antigen and the C6 antigen, respectively. Graphical methods to display the antibody response and to choose thresholds for a rise in relative antibody reactivity are shown and discussed. In conclusion, 5.4% of people with tick bites showed a rise in Borrelia-specific antibodies above the 2.5% threshold in either ELISA but only 40 (2.1%) developed clinical Lyme borreliosis.
|
|
| 19. |
- Dierckx, Anke, 1986, et al.
(författare)
-
Characterization of photophysical and base-mimicking properties of a novel fluorescent adenine analogue in DNA
- 2011
-
Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 39:10, s. 4513-4524
-
Tidskriftsartikel (refereegranskat)abstract
- To increase the diversity of fluorescent base analogues with improved properties, we here present the straightforward click-chemistry-based synthesis of a novel fluorescent adenine-analogue triazole adenine (A(T)) and its photophysical characterization inside DNA. A(T) shows promising properties compared to the widely used adenine analogue 2-aminopurine. Quantum yields reach > 20% and > 5% in single- and double-stranded DNA, respectively, and show dependence on neighbouring bases. Moreover, A(T) shows only a minor destabilization of DNA duplexes, comparable to 2-aminopurine, and circular dichroism investigations suggest that A(T) only causes minimal structural perturbations to normal B-DNA. Furthermore, we find that A(T) shows favourable base-pairing properties with thymine and more surprisingly also with normal adenine. In conclusion, A(T) shows strong potential as a new fluorescent adenine analogue for monitoring changes within its microenvironment in DNA.
|
|
| 20. |
|
|
| 21. |
- Eklund, Per, et al.
(författare)
-
Structural, electrical, and mechanical properties of nc-TiC/a-SiC nanocomposite thin films
- 2005
-
Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 23:6, s. 2486-2495
-
Tidskriftsartikel (refereegranskat)abstract
- We have synthesized Ti–Si–C nanocomposite thin films by dc magnetron sputtering from a Ti3SiC2 compound target in an Ar discharge on Si(100), Al2O3(0001), and Al substrates at temperatures from room temperature to 300 °C. Electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy showed that the films consisted of nanocrystalline (nc-) TiC and amorphous (a-) SiC, with the possible presence of a small amount of noncarbidic C. The growth mode was columnar, yielding a nodular film-surface morphology. Mechanically, the films exhibited a remarkable ductile behavior. Their nanoindentation hardness and E-modulus values were 20 and 290 GPa, respectively. The electrical resistivity was 330 µ cm for optimal Ar pressure (4 mTorr) and substrate temperature (300 °C). The resulting nc-TiC/a-SiC films performed well as electrical contact material. These films' electrical-contact resistance against Ag was remarkably low, 6 µ at a contact force of 800 N compared to 3.2 µ for Ag against Ag. The chemical stability of the nc-TiC/a-SiC films was excellent, as shown by a Battelle flowing mixed corrosive-gas test, with no N, Cl, or S contaminants entering the bulk of the films.
|
|
| 22. |
|
|
| 23. |
- Eliassen, Knut Eirik, et al.
(författare)
-
Tick-transmitted co-infections among erythema migrans patients in a general practice setting in Norway : a clinical and laboratory follow-up study
- 2021
-
Ingår i: BMC Infectious Diseases. - : BMC. - 1471-2334. ; 21:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background Erythema migrans (EM) is the most common manifestation of Lyme borreliosis. Here, we examined EM patients in Norwegian general practice to find the proportion exposed to tick-transmitted microorganisms other than Borrelia, and the impact of co-infection on the clinical manifestations and disease duration. Methods Skin biopsies from 139/188 EM patients were analyzed using PCR for Neoehrlichia mikurensis, Rickettsia spp., Anaplasma phagocytophilum and Babesia spp. Follow-up sera from 135/188 patients were analyzed for spotted fever group (SFG) Rickettsia, A. phagocytophilum and Babesia microti antibodies, and tested with PCR if positive. Day 0 sera from patients with fever (8/188) or EM duration of >= 21 days (69/188) were analyzed, using PCR, for A. phagocytophilum, Rickettsia spp., Babesia spp. and N. mikurensis. Day 14 sera were tested for TBEV IgG. Results We detected no microorganisms in the skin biopsies nor in the sera of patients with fever or prolonged EM duration. Serological signs of exposure against SFG Rickettsia and A. phagocytophilum were detected in 11/135 and 8/135, respectively. Three patients exhibited both SFG Rickettsia and A. phagocytophilum antibodies, albeit negative PCR. No antibodies were detected against B. microti. 2/187 had TBEV antibodies without prior immunization. There was no significant increase in clinical symptoms or disease duration in patients with possible co-infection. Conclusions Co-infection with N. mikurensis, A. phagocytophilum, SFG Rickettsia, Babesia spp. and TBEV is uncommon in Norwegian EM patients. Despite detecting antibodies against SFG Rickettsia and A. phagocytophilum in some patients, no clinical implications could be demonstrated.
|
|
| 24. |
- Engerstam, Sviatlana, 1974-
(författare)
-
Housing Market Dynamics
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dynamics of housing markets constitute a complex phenomenon. The body of research is vast and includes thousands of studies done on the national and international level. Empirical evidence indicates that housing markets differ in local institutional arrangements and that these might affect the ways they develop over time. To analyze housing market dynamics in various institutional environments and to increase our understanding of them is the main objective of this thesis.The scope of research includes analysis of relevant theories and empirical models that might explain development of house prices over the long run. Given that prices affect housing construction, this thesis also aims to deepen understanding of the impact of the relationship between new construction and underlying fundamentals, together with various institutional arrangements that might differ between countries. In particular, they include bank lending policies, valuation methods for mortgage purposes, different regulatory measures like rent control, as well as land and building policies.The Swedish apartment market was chosen for empirical analysis. The analysis is carried out by a combination of qualitative and quantitative methodology and applies several research methods, such as systematic literature review, and panel data analysis with application of advanced econometric techniques like Dynamic Ordinary Least Squares, Fixed and Random Effects and Seemingly Unrelated Regressions. Four studies are carried out using these methodologies.The results indicate that the interest rate, disposable income and population growth seem to be major determinants of house prices according to studies found in the empirical literature (Paper 1). The study also classifies house price determinants in relation to the size of their elasticities. However, fundamental factors cannot always provide an explanation for the deviations in house price dynamics in different countries, whereas the institutional environment might do so (Paper 2). The analysis demonstrates that land prices and building policies, along with a number of market fundamentals, affect the average size of an apartment in new residential construction (Paper 3). In the presence of rent control, the rent or price level does not contribute by adding new units to the total housing stock. In addition, the displacement effect occurs primarily in the market’s rental sector and not in the tenant-owned apartments segment (Paper 4).This research contributes to a better understanding of housing markets dynamics and suggests policy implications that might reduce the risks for housing bubbles and improve the socio-economic development of the society over the long run.
|
|
| 25. |
- Engman, Cecilia, 1974, et al.
(författare)
-
DNA adopts normal B-form upon incorporation of highly fluorescent DNA base analogue tC: NMR structure and UV-Vis spectroscopy characterization
- 2004
-
Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 32:17, s. 5087-95
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of the highly fluorescent tricyclic cytosine base analogue (tC) on duplex DNA conformation is investigated. The duplex properties are characterized by absorbance and circular dichroism (CD) for all combinations of neighbouring bases to tC, and an NMR structure is determined for one tC-containing sequence. For the oligonucleotides with one tC incorporated instead of cytosine, the melting temperature is increased on average by 2.7 degrees C above that for the unmodified ones. CD spectra are practically identical for modified and unmodified sequences, indicating an unperturbed B-DNA conformation. The NMR structure determination of the self-complementary sequence 5'-CTC(tC)ACGTGGAG shows a DNA conformation consistent with B-form for the whole duplex. The root-mean-square distance for the nucleotides of the eight central base pairs between the 10 structures with lowest CYANA target functions and a mean structure is 0.45 +/- 0.17 A. The NMR data confirm correct base pairing for tC by the observation of both intrastrand and interstrand imino proton NOEs. Altogether, this suggests that tC works well as a cytosine analogue, i.e. it is situated in the base stack, forming hydrogen bonds with G in the complementary strand, without distorting the DNA backbone conformation. This first example of an artificial, highly fluorescent DNA base that does not perturb the DNA conformation could have valuable applications for the study of the structure and dynamics of nucleic acid systems.
|
|
