| 1. |
- van Haarlem, M. P., et al.
(författare)
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LOFAR : The LOw-Frequency ARray
- 2013
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 556, s. 1-53
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Tidskriftsartikel (refereegranskat)abstract
- LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR covers the largely unexplored low-frequency range from 10–240 MHz and provides a number of unique observing capabilities. Spreading out from a core located near the village of Exloo in the northeast of the Netherlands, a total of 40 LOFAR stations are nearing completion. A further five stations have been deployed throughout Germany, and one station has been built in each of France, Sweden, and the UK. Digital beam-forming techniques make the LOFAR system agile and allow for rapid repointing of the telescope as well as the potential for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR achieves unparalleled sensitivity and angular resolution in the low-frequency radio regime. The LOFAR facilities are jointly operated by the International LOFAR Telescope (ILT) foundation, as an observatory open to the global astronomical community. LOFAR is one of the first radio observatories to feature automated processing pipelines to deliver fully calibrated science products to its user community. LOFAR’s new capabilities, techniques and modus operandi make it an important pathfinder for the Square Kilometre Array (SKA). We give an overview of the LOFAR instrument, its major hardware and software components, and the core science objectives that have driven its design. In addition, we present a selection of new results from the commissioning phase of this new radio observatory.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Bood, Mattias, et al.
(författare)
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Pentacyclic adenine: a versatile and exceptionally bright fluorescent DNA base analogue
- 2018
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 9:14, s. 3494-3502
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Tidskriftsartikel (refereegranskat)abstract
- Emissive base analogs are powerful tools for probing nucleic acids at the molecular level. Herein we describe the development and thorough characterization of pentacyclic adenine (pA), a versatile base analog with exceptional fluorescence properties. When incorporated into DNA, pA pairs selectively with thymine without perturbing the B-form structure and is among the brightest nucleobase analogs reported so far. Together with the recently established base analog acceptor qAnitro, pA allows accurate distance and orientation determination via Forster resonance energy transfer (FRET) measurements. The high brightness at emission wavelengths above 400 nm also makes it suitable for fluorescence microscopy, as demonstrated by imaging of single liposomal constructs coated with cholesterolanchored pA-dsDNA, using total internal reflection fluorescence microscopy. Finally, pA is also highly promising for two-photon excitation at 780 nm, with a brightness (5.3 GM) that is unprecedented for a base analog.
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| 6. |
- Füchtbauer, Anders Foller, 1984, et al.
(författare)
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Fluorescent RNA cytosine analogue - an internal probe for detailed structure and dynamics investigations
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The bright fluorescent cytosine analogue tCO stands out among fluorescent bases due to its virtually unquenched fluorescence emission in duplex DNA. However, like most reported base analogues, it has not been thoroughly characterized in RNA. We here report on the first synthesis and RNA-incorporation of tCO, and characterize its base-mimicking and fluorescence properties in RNA. As in DNA, we find a high quantum yield inside RNA duplexes (< Phi(F)> = 0.22) that is virtually unaffected by the neighbouring bases (Phi(F) = 0.20-=0.25), resulting in an average brightness of 1900 M-1 cm(-1). The average fluorescence lifetime in RNA duplexes is 4.3 ns and generally two lifetimes are required to fit the exponential decays. Fluorescence properties in ssRNA are defined by a small increase in average quantum yield (< Phi(F) > = 0.24) compared to dsRNA, with a broader distribution (Phi(F) = 0.17-=0.34) and slightly shorter average lifetimes. Using circular dichroism, we find that the tCO-modified RNA duplexes form regular A-form helices and in UV-melting experiments the stability of the duplexes is only slightly higher than that of the corresponding natural RNA ( = + 2.3 degrees C). These properties make tC(0) a highly interesting fluorescent RNA base analogue for detailed FRET-based structural measurements, as a bright internal label in microscopy, and for fluorescence anisotropy measurements of RNA dynamics.
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| 7. |
- Herlitz, Johan, et al.
(författare)
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Tolerans för betablockad hos äldre
- 1982
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Ingår i: Hypertoni hos äldre. - : Almqvist & Wiksell. ; , s. 101-105
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Hvidsten, D., et al.
(författare)
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The distribution limit of the common tick, Ixodes ricinus, and some associated pathogens in north-western Europe
- 2020
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Ingår i: Ticks and Tick-borne Diseases. - : Elsevier. - 1877-959X .- 1877-9603. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- In north-western Europe, the common tick, Ixodes ricinus, is widely established, its distribution appears to be increasing and the spread of tick-borne diseases is of increasing concern. The project Flatt i Nord (Ticks in northern Norway) commenced in spring 2009 with the intention of studying the ticks distribution and that of its pathogens in northern Norway. Several methods were used: cloth-dragging, collecting from trapped small mammals, and collecting from pets. Since 2010, the occurrence of ticks in the region of northern Norway was determined directly by cloth-dragging 167 times in 109 separate locations between the latitudes of 64 degrees N and 70 degrees N (included seven locations in the northern part of Trondelag County). The northernmost location of a permanent I. ricinus population was found to be Nordoyvagen (66.2204 degrees N, 12.59 degrees E) on the Island of Donna. In a sample of 518 nymphal and adult ticks, the Borrelia prevalence collected close to this distribution limit varied but was low (1-15 %) compared with the locations in Trondelag, south of the study area (15-27 %). Five specimens (1 %) were positive for Rickettsia helvetica. The length of the vegetation growing season (GSL) can be used as an approximate index for the presence of established populations of I. ricinus. The present study suggests that the threshold GSL for tick establishment is about 170 days, because the median GSL from 1991 to 2015 was 174-184 days at sites with permanent tick populations, showing a clear increase compared with the period 1961-1990. This apparent manifestation of climate change could explain the northward extension of the range of I. ricinus.
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| 9. |
- Preus, S., et al.
(författare)
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The photoinduced transformation of fluorescent DNA base analogue tC triggers DNA melting
- 2013
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Ingår i: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-9092 .- 1474-905X. ; 12:8, s. 1416-1422
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Tidskriftsartikel (refereegranskat)abstract
- While fluorescent analogues of the canonical nucleobases have proven to be highly valuable in a large number of applications, up until today, fluorescent DNA base analogues remain virtually inapplicable for single-molecule fluorescence experiments which require extremely bright and photostable dyes. Insight into the photodegradation processes of these fluorophores is thus a key step in the continuous development towards dyes with improved performances. Here, we show that the commercially available fluorescent nucleobase analogue tC under intense long-term illumination and in the presence of O-2 is degraded to form a single photoreaction product which we suggest to be the sulfoxide form of tC. The photoproduct is characterized by a blue-shifted absorption and a less intense fluorescence compared to that of tC. Interestingly, when tC is positioned inside double-stranded DNA this photodriven conversion of tC to its photoproduct greatly reduces the duplex stability of the overall double helix in which the probe is positioned. Since tC can be excited selectively at 400 nm, well outside the absorption band of the natural DNA bases, this observation points towards the application of tC as a general light-triggered switch of DNA duplex stability.
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| 10. |
- Aase, Audun, et al.
(författare)
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Validate or falsify: Lessons learned from a microscopy method claimed to be useful for detecting Borrelia and Babesia organisms in human blood
- 2016
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Ingår i: INFECTIOUS DISEASES. - : TAYLOR & FRANCIS LTD. - 2374-4235 .- 2374-4243. ; 48:6, s. 411-419
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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.
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| 11. |
- Andersson, Mathias H., et al.
(författare)
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Epibenthic colonization of concrete and steel pilingsin a cold-temperate embayment : a feld experiment
- 2009
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Ingår i: Helgoland Marine Research. - : Springer Science and Business Media LLC. - 1438-387X .- 1438-3888. ; 63:3, s. 249-260
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Tidskriftsartikel (refereegranskat)abstract
- With large-scale development of offshore wind farms, vertical structures are becoming more common in open water areas. To examine how vertical structures of different materials may be colonized by epibenthic organisms, an experiment was carried out using steel and concrete pilings constructed to resemble those commonly used in wind farm constructions as well as in bridges, jetties and oil platforms. The early recruitment and succession of the epibenthic communities were sampled once a month for the first 5 months and then again after 1 year. Further, the fish assemblages associated with the pillars were sampled and compared to natural areas. The main epibenthic species groups, in terms of coverage, diVered between the two materials at five out of six sampling occasions. Dominant organisms on steel pillars were the barnacle Balanus improvisus,the calcareous tubeworm Pomatoceros triqueter and the tunicate Ciona intestinalis. On the concrete pillars, the hydroid Laomedea sp. and the tunicates Corella parallelogramma and Ascidiella spp. dominated. However, there was no different in coverage at different heights on the pillars or in biomass and species abundance at different directions (north-east or south-west) 5 months after submergence. Fish showed overall higher abundances and species numbers on the pillars (but no difference between steel and concrete)compared to the surrounding soft bottom habitats but not compared to natural vertical rock walls. Two species were attracted to the pillars, indicating a reef effect; Gobiusculus flavescens and Ctenolabrus rupestris. The bottom-dwelling gobies, Pomatoschistus spp., did not show such preferences.
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| 12. |
- Astvaldsdottir, A., et al.
(författare)
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Oral health and dental care of older persons-A systematic map of systematic reviews
- 2018
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Ingår i: Gerodontology. - : Wiley. - 0734-0664 .- 1741-2358. ; 35:4, s. 290-304
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Forskningsöversikt (refereegranskat)abstract
- Objectives: To examine the current knowledge on oral health status and dental care of older persons through a systematic mapping of systematic reviews of low or moderate risk of bias. Background: Geriatric dentistry covers all aspects of oral health and oral care of older persons. Oral health is part of general health and contributes to a person's physical, psychological and social wellbeing. Methods: A literature search was performed in three different databases (PubMed, The Cochrane Library and Cinahl) within 12 domains: Dental caries, periodontitis, Orofacial pain and temporomandibular joint (TMJ) pain, mucosal lesions, oral motor function, dry mouth, halitosis, interaction between oral status and other medical conditions, ability to interrelate and communicate, quality of life, ethics and organisation of dental care for older persons. Systematic reviews were identified and scrutinised, highlighting scientific knowledge and knowledge gaps. Results: We included 32 systematic reviews of which 14 were judged to be of low/moderate risk of bias. Most of the domains lack systematic reviews with low or moderate risk of bias. In two of the domains evidence was identified; in institutionalised people aged 65 or older, effective oral hygiene can prevent pneumonia. Furthermore, there is an evidence of a relationship between malnutrition (protein energy-related malnutrition, PEM) and poor appetite and edentulousness. Conclusions: There is an urgent need for further research and evidence-based knowledge within most domains in geriatric dentistry and in other fields related to oral health and dental care for older persons striving for multi-disciplinary research programmes.
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| 13. |
- Börjesson, Karl, 1982, et al.
(författare)
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Nucleic Acid Base Analog FRET-Pair Facilitating Detailed Structural Measurements in Nucleic Acid Containing Systems
- 2009
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 131:12, s. 4288-4293
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Tidskriftsartikel (refereegranskat)abstract
- We present the first nucleobase analog fluorescence resonance energy transfer (FRET)-pair. The pair consists of tC O , 1,3-diaza-2- oxophenoxazine, as an energy donor and the newly developed tC nitro , 7-nitro-1,3-diaza-2-oxophenothiazine, as an energy acceptor. The FRET-pair successfully monitors distances covering up to more than one turn of the DNA duplex. Importantly, we show that the rigid stacking of the two base analogs, and consequently excellent control of their exact positions and orientations, results in a high control of the orientation factor and hence very distinct FRET changes as the number of bases separating tC O and tCnitro is varied. A set of DNA strands containing the FRET-pair at wisely chosen locations will, thus, make it possible to accurately distinguish distance- from orientation-changes using FRET. In combination with the good nucleobase analog properties, this points toward detailed studies of the inherent dynamics of nucleic acid structures. Moreover, the placement of FRET-pair chromophores inside the base stack will be a great advantage in studies where other (biomacro)molecules interact with the nucleic acid. Lastly, our study gives possibly the first truly solid experimental support to the dependence of energy transfer efficiency on orientation of involved transition dipoles as predicted by the Forster theory. © 2009 American Chemical Society.
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| 14. |
- Dierckx, Anke, 1986, et al.
(författare)
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Quadracyclic Adenine: A Non-Perturbing Fluorescent Adenine Analogue
- 2012
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Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 18:19, s. 5987-5997
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescent-base analogues (FBAs) comprise a group of increasingly important molecules for the investigation of nucleic acid structure and dynamics as well as of interactions between nucleic acids and other molecules. Here, we report on the synthesis, detailed spectroscopic characterisation and base-pairing properties of a new environment-sensitive fluorescent adenine analogue, quadracyclic adenine (qA). After developing an efficient route of synthesis for the phosphoramidite of qA it was incorporated into DNA in high yield by using standard solid-phase synthesis procedures. In DNA qA serves as an adenine analogue that preserves the B-form and, in contrast to most currently available FBAs, maintains or even increases the stability of the duplex. We demonstrate that, unlike fluorescent adenine analogues, such as the most commonly used one, 2-aminopurine, and the recently developed triazole adenine, qA shows highly specific base-pairing with thymine. Moreover, qA has an absorption band outside the absorption of the natural nucleobases (>300 nm) and can thus be selectively excited. Upon excitation the qA monomer displays a fluorescence quantum yield of 6.8?% with an emission maximum at 456 nm. More importantly, upon incorporation into DNA the fluorescence of qA is significantly less quenched than most FBAs. This results in quantum yields that in some sequences reach values that are up to fourfold higher than maximum values reported for 2-aminopurine. To facilitate future utilisation of qA in biochemical and biophysical studies we investigated its fluorescence properties in greater detail and resolved its absorption band outside the DNA absorption region into distinct transition dipole moments. In conclusion, the unique combination of properties of qA make it a promising alternative to current fluorescent adenine analogues for future detailed studies of nucleic acid-containing systems.
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| 15. |
- Dueñas, S., et al.
(författare)
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Experimental investigation of the electrical properties of atomic layer deposited hafnium-rich silicate films on n-type silicon
- 2006
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 100:9, s. 094107-
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Tidskriftsartikel (refereegranskat)abstract
- This work examines the structural and electrical properties of HfSixOy film based metal-insulator-semiconductor capacitors by means of x-ray diffraction, x-ray photoelectron spectroscopy, capacitance-voltage (C-V), deep level transient spectroscopy, and conductance transient (G-t) techniques. Hafnium-rich silicate films were atomic layer deposited onto HF-etched or SiO2 covered silicon. Although as-deposited samples exhibit high interfacial state and disorder-induced gap state densities, a postdeposition thermal annealing in vacuum under N2 flow for 1 min at temperatures between 600 and 730 °C clearly improves the interface quality. Marked crystallization and phase separation occurred at 800 °C, increasing the structural heterogeneity and defect density in the dielectric oxide layers.
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| 16. |
- Dumat, Blaise, 1984, et al.
(författare)
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Second-Generation Fluorescent Quadracyclic Adenine Analogues: Environment-Responsive Probes with Enhanced Brightness
- 2015
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 21:10, s. 4039-4048
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescent base analogues comprise a group of increasingly important molecules for the investigation of nucleic acid structure, dynamics, and interactions with other molecules. Herein, we report on the quantum chemical calculation aided design, synthesis, and characterization of four new putative quadracyclic adenine analogues. The compounds were efficiently synthesized from a common intermediate through a two-step pathway with the Suzuki-Miyaura coupling as the key step. Two of the compounds, qAN1 and qAN4, display brightnesses (εΦF) of 1700 and 2300, respectively, in water and behave as wavelength-ratiometric pH probes under acidic conditions. The other two, qAN2 and qAN3, display lower brightnesses but exhibit polarity-sensitive dual-band emissions that could prove useful to investigate DNA structural changes induced by DNA-protein or -drug interactions. The four qANs are very promising microenvironment-sensitive fluorescent adenine analogues that display considerable brightness for such compounds. Polarity and pH probes: 2-Aminopurine has long been the standard for fluorescent base analogues. Four new fluorescent probes suitable for the replacement of adenine in nucleic acids are presented. Based on their high structural similarity to their parent compound, quadracyclic adenine, they have the potential to be excellent A analogues. Their improved photophysical properties also suggest that they could be significantly brighter than 2-aminopurine inside nucleic acid systems (see figure; ΦF: fluorescence quantum yield).
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| 17. |
- Eskeland, Sveinung, et al.
(författare)
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Assessing the clinical and bacteriological outcomes of vaccination with recombinant Asp14 and OmpA against A. phagocytophilum in sheep
- 2019
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Ingår i: Veterinary Immunology and Immunopathology. - : ELSEVIER. - 0165-2427 .- 1873-2534. ; 218
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Tidskriftsartikel (refereegranskat)abstract
- Anaplasma phagocytophilum is a tick borne bacterium, causing disease in sheep and other mammals, including humans. The bacterium has great economic and animal welfare implications for sheep husbandry in Northern Europe. With the prospect of a warmer and more humid climate, the vector availability will likely increase, resulting in a higher prevalence of A. phagocytophilum. The current preventive measures, as pyrethroids acting on ticks or long acting antibiotics controlling bacterial infection, are suboptimal for prevention of the disease in sheep. Recently, the increased awareness on antibiotic- and pyrethorid resistance, is driving the search for a new prophylactic approach in sheep against A. phagocytophilum. Previous studies have used an attenuated vaccine, which gave insufficient protection from challenge with live bacteria. Other studies have focused on bacterial membrane surface proteins like Asp14 and OmpA. An animal study using homologous proteins to Asp14 and OmpA of A. marginate, showed no protective effect in heifers. In the current study, recombinant proteins of Asp14 (rAsp14) and OmpA (rOmpA) of A. phagocytophilum were produced and prepared as a vaccine for sheep. Ten lambs were vaccinated twice with an adjuvant emulsified with rAsp14 or rOmpA, three weeks apart and challenged with a live strain of A. phagocytophilum (GenBank acc.nr M73220) on day 42. The control group consisted of five lambs injected twice with PBS and adjuvant. Hematology, real time qPCR, immunodiagnostics and flow cytometric analyses of peripheral blood mononuclear cells were performed. Vaccinated lambs responded with clinical signs of A.phagocytophilum infection after challenge and bacterial load in the vaccinated group was not reduced compared to the control group. rAsp14 vaccinated lambs generated an antibody response against the vaccine, but a clear specificity for rAsp14 could not be established. rOmpA-vaccinated lambs developed a strong specific antibody response on days 28 after vaccination and 14 days post-challenge. Immunofluorescent staining and flow cytometric analysis of peripheral blood mononuclear monocytes revealed no difference between the three groups, but the percentage of CD4, CD8(+), gamma delta TcR+, lambda-Light chain(+), CD11b(+), CD14(+) and MHC II+ cells, within the groups changed during the study, most likely due to the adjuvant or challenge with the bacterium. Although an antigen specific antibody response could be detected against rOmpA and possibly rAsp14, the vaccines seemed to be ineffective in reducing clinical signs and bacterial load caused by A. phagocytophilum. This is the first animal study with recombinant Asp14 and OmpA aimed at obtaining clinical protection against A. phagocytophilum in sheep.
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| 18. |
- Fang, C.M., et al.
(författare)
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General trend of the mechanical properties of the ternary carbides M3SiC2 (M=transition metal)
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:5, s. 054106-
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Tidskriftsartikel (refereegranskat)abstract
- We present results from first-principles calculations of ternary transition metal carbides in the M3SiC2 series (where M=early transition metal). We predict structural and mechanical properties of these new MN+1AXN phases. The bulk modulus of the ternary carbides, M3SiC2, are in the calculations found to be proportional to the bulk modulus of the corresponding binary carbides, MC. We have analyzed this behavior using a simple, nearest-neighbor bond model, as well as from first-principles total energy calculations and have found that it is caused by a considerably weaker M-Si bond compared to the M-C bond.
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| 19. |
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| 20. |
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| 21. |
- Fisher, Rachel S., et al.
(författare)
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Pulse-shaped two-photon excitation of a fluorescent base analogue approaches single-molecule sensitivity
- 2018
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 20:45, s. 28487-28498
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescent nucleobase analogues (FBAs) have many desirable features in comparison to extrinsic fluorescent labels, but they are yet to find application in ultrasensitive detection. Many of the disadvantages of FBAs arise from their short excitation wavelengths (often in the ultraviolet), making two-photon excitation a potentially attractive approach. Pentacyclic adenine (pA) is a recently developed FBA that has an exceptionally high two-photon brightness. We have studied the two-photon-excited fluorescence properties of pA and how they are affected by incorporation in DNA. We find that pA is more photostable under two-photon excitation than via resonant absorption. When incorporated in an oligonucleotide, pA has a high two-photon cross section and emission quantum yield, varying with sequence context, resulting in the highest reported brightness for such a probe. The use of a two-photon microscope with ultrafast excitation and pulse shaping has allowed the detection of pA-containing oligonucleotides in solution with a limit of detection of ∼5 molecules, demonstrating that practical single-molecule detection of FBAs is now within reach.
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| 22. |
- Freeman, N.S., et al.
(författare)
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Chromophoric Nucleoside Analogues: Synthesis and Characterization of 6-Aminouracil-Based Nucleodyes
- 2016
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 81:11, s. 4530-4539
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Tidskriftsartikel (refereegranskat)abstract
- Nucleodyes, visibly colored chromophoric nucleoside analogues, are reported. Design criteria are outlined and the syntheses of cytidine and uridine azo dye analogues derived from 6-aminouracil are described. Structural analysis shows that the nucleodyes are sound structural analogues of their native nucleoside counterparts, and photophysical studies demonstrate that the nucleodyes are sensitive to microenvironmental changes. Quantum chemical calculations are presented as a valuable complementary tool for the design of strongly absorbing nucleodyes, which overlap with the emission of known fluorophores. Förster critical distance (R0) calculations determine that the nucleodyes make good FRET pairs with both 2-aminopurine (2AP) and pyrrolocytosine (PyC). Additionally, unique tautomerization features exhibited by 5-(4-nitrophenylazo)-6-oxocytidine (8) are visualized by an extraordinary crystal structure.
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| 23. |
- Granberg, S, et al.
(författare)
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The effects of oral estriol on the endometrium in postmenopausal women
- 2002
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Ingår i: Maturitas. - 0378-5122 .- 1873-4111. ; 42:2, s. 149-156
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To study the long-term effects of oral estriol tablets on the endometrium of postmenopausal women by TVS and histology. Method: This was a cross sectional, parallel-group, multicenter trial of 241 postmenopausal women, out of whom 125 were treated with oral estriol and 116 were untreated controls. Endometrial histology using Pipelle biopsies and/or dilatation and curettage (D&C) was taken, endometrial thickness was assessed by use of transvaginal ultrasound (TVS), and the relation between endometrial thickness and histology was calculated. Results: No statistically significant differences between the two groups were found in endometrial histology. There were found more polyps in the oral estriol group (14.0%) as compared with the control group (2.9%). The mean endometrial thickness in the oral estriol group was 3.0 mm compared with a mean value of 2.4 mm in the control group: P=0.01. Conclusions: No clinically relevant difference was found between the endometrium status (assessed by histology and TVS) of postmenopausal women on long-term oral estriol therapy and untreated controls. This trial supports the endometrial safety of maintenance treatment with oral estriol tablets. However, there are signs, not statistically significant, that may be associated with more endometrial polyps in postmenopausal women than if therapy is not given and that TVS is a useful instrument for the diagnosis. ⌐ 2002 Elsevier Science Ireland Ltd. All rights reserved.
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| 24. |
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| 25. |
- Herlitz, Johan, et al.
(författare)
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Development of congestive heart failure after treatment with metoprolol in acute myocardial infarction
- 1984
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Ingår i: British Heart Journal. - : BMJ Group. - 0007-0769. ; 51:5, s. 539-544
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Tidskriftsartikel (refereegranskat)abstract
- In a double blind study of metoprolol in the treatment of suspected acute myocardial infarction 698 patients (study group) received metoprolol and 697 a placebo (control group). Metoprolol was given in an intravenous dose of 15 mg as soon as possible after admission to hospital followed by 50 g by mouth four times a day for two days and thereafter 100 mg twice a day for three months. A placebo was similarly given. Congestive heart failure occurred in a similar percentage of patients in both the study (27%) and the control groups (30%). Its severity was estimated by calculating the total dose of frusemide given during the first four days in hospital. Less frusemide was given to patients treated with metoprolol compared with those given a placebo in the total series. An appreciably lower total dose of frusemide was given to patients included in the trial less than or equal to 12 hours after the onset of pain and treated with metoprolol compared with a placebo, while no difference was seen among patients treated later. The initial heart rate, systolic blood pressure, and infarct site affected the results.
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| 26. |
- Herlitz, Johan, et al.
(författare)
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Effect of metoprolol on chest pain in acute myocardial
- 1984
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Ingår i: British Heart Journal. - : BMJ Group. - 0007-0769. ; 51:4, s. 438-444
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Tidskriftsartikel (refereegranskat)abstract
- A total of 1395 patients aged 40 to 74 years were included in a double blind trial with the beta 1 selective blocker metoprolol in suspected acute myocardial infarction. Metoprolol was given intravenously (15 mg) as soon as possible after admission to hospital followed by 200 mg daily for three months. A placebo was given in the same manner. The severity of chest pain in the acute phase was calculated by recording the number of injections of analgesics given and the time from the start of blind treatment to the time when the last analgesic was given (duration of pain). The patients receiving metoprolol were given a lower mean number of injections of analgesics during the first four days and after randomisation than those receiving a placebo. The estimated duration of pain was shorter in the metoprolol group than in the placebo group. These effects were related to the initial heart rate, the initial systolic blood pressure, and the final site of the infarct as determined electrocardiographically. Thus metoprolol given in the acute phase of suspected or definite myocardial infarction appears to reduce the severity of chest pain.
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| 27. |
- Herlitz, Johan, et al.
(författare)
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Effect of metoprolol on indirect signs of the size and severity of acute myocardial infarction
- 1983
-
Ingår i: American Journal of Cardiology. - : Elsevier Excerpta Medica, Inc.. - 0002-9149 .- 1879-1913. ; 51:8, s. 1282-1288
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Tidskriftsartikel (refereegranskat)abstract
- In a double-blind randomized trial, 1,395 patients with suspected acute myocardial infarction (MI) were investigated to evaluate the possibility of limiting indirect signs of the size and severity of acute MI with the beta1-selective adrenoceptor antagonist metoprolol. Metoprolol (15 mg) was given intravenously and followed by oral administration for 3 months (200 mg daily). Placebo was given in the same way. The size of the MI was estimated by heat-stable lactate dehydrogenase (LD[EC 1.1.1.27]) analyses and precordial electrocardiographic mapping. Lower maximal enzyme activities compared with placebo were seen in the metoprolol group (11.1 ± 0.5 μkat · liter−1)when the patient was treated within 12 hours of the onset of pain (13.3 ± 0.6 μkat · liter−1; n = 936; p = 0.009). When treatment was started later than 12 hours, no difference was found between the 2 groups. Enzyme analyses were performed in all but 20 patients (n = 1,375). Precordial mapping with 24 chest electrodes was performed in patients with anterior wall MI. The final total R-wave amplitude was higher and the final total Q-wave amplitude lower in the metoprolol group than in the placebo group. Patients treated with metoprolol ≤12 hours also showed a decreased need for furosemide, a shortened hospital stay, and a significantly reduced 1-year mortality compared with the placebo group, whereas no difference was observed among patients treated later on. After 3 months, however, there was a similar reduction in mortality among patients in whom therapy was started 12 hours and >12 hours after the onset of pain. The results support the hypothesis that intravenous metoprolol followed by oral treatment early in the course of suspected myocardial infarction can limit infarct size and improve longterm prognosis.
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| 28. |
- Herlitz, Johan, et al.
(författare)
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Effects of work and acute beta-receptor blockade on myocardial noradrenaline release in congestive cardiomyopathy
- 1979
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Ingår i: Clinical Cardiology. - : John Wiley & Sons, Inc. - 0160-9289 .- 1932-8737. ; 2:6, s. 424-430
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Tidskriftsartikel (refereegranskat)abstract
- Systemic hemodynamic changes and noradrenaline concentrations in coronary sinus blood were studied at rest and during work before and after acute beta-receptor blockade. Patients with congestive cardiomyopathy were compared to patients with primary valvular diseases and to healthy subjects. Noradrenaline concentrations were higher in coronary sinus blood than in arterial blood and increased after beta blockade and during work. Noradrenaline concentrations were more increased in patients with more pronounced myocardial failure and did not seem to separate patients with congestive cardiomyopathy from those with valvular disease. Patients with congestive cardiomyopathy showed a good hemodynamic tolerance toward acute beta blockade.
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| 29. |
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| 30. |
- Herlitz, Johan, et al.
(författare)
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Göteborg Metoprolol Trial : mortality and causes of death
- 1984
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Ingår i: American Journal of Cardiology. - : Excerpta Medica, Inc.. - 0002-9149 .- 1879-1913. ; 53:13, s. 9-14
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Tidskriftsartikel (refereegranskat)abstract
- During the 3-month blind treatment period there were 40 deaths in the metoprolol group compared with 62 deaths in the placebo group (p = 0.024). During the first year (after 3 months the 2 groups were treated similarly) there were 64 deaths in the metoprolol group vs 93 in the placebo group (p = 0.017) and during 2 years 92 patients died in the metoprolol group vs 120 in the placebo group (p = 0.043). The relative incidence of different causes of death did not differ significantly between the 2 treatment groups, indicating that metoprolol reduced all causes of death to the same extent as its effect on overall mortality.
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| 31. |
- Herlitz, Johan, et al.
(författare)
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Göteborg Metoprolol Trial : design, patient characteristics and conduct
- 1984
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Ingår i: American Journal of Cardiology. - : Excerpta Medica, Inc.. - 0002-9149 .- 1879-1913. ; 53:13, s. 3D-8D
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Tidskriftsartikel (refereegranskat)abstract
- The Göteborg Metoprolol Trial was a double-blind, placebo-controlled, stratified trial aimed at evaluating the effect of the beta 1-selective blocker, metoprolol, in suspected acute myocardial infarction and during 2 years of follow-up. The primary end-point was 3-month mortality (blind treatment period). Secondary end-points were 2-year mortality, indirect signs of infarct size, chest pain, arrhythmias and tolerability. The entry criteria were fulfilled in 2,802 patients, 1,395 of whom were included in the trial. Treatment started as soon as possible after arrival in hospital with intravenous administration followed by oral treatment for 3 months. All patients were randomized 48 hours or less after estimated onset of infarction and 69% were randomized at 12 hours or less. The blind treatment had to be withdrawn in 19% of all randomized patients before the end of the 3-month follow-up.
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| 32. |
- Hjalmarson, Å, et al.
(författare)
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Effect on mortality of metoprolol in acute myocardial infarction
- 1981
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Ingår i: The Lancet. - : The Lancet Publishing Group. - 0140-6736 .- 1474-547X. ; 318:8251, s. 823-827
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Tidskriftsartikel (refereegranskat)abstract
- The effect of metoprolol on mortality was compared with that of placebo in a double-blind randomised trial in patients with definite or suspected acute myocardial infarction. Treatment with metoprolol or placebo started as soon as possible after the patient's arrival in hospital and was continued for 90 days. Metoprolol was given as a 15 mg intravenous dose followed by oral administration of 100 mg twice daily. 1395 patients (697 on placebo and 698 on metoprolol) were included in the trial. Definite acute myocardial infarction developed in 809 and probable infarction in 162. Patients were allocated to various risk groups and within each group patients were randomly assigned to treatment with metoprolol or placebo. There were 62 deaths in the placebo group (8·9%) and 40 deaths in the metoprolol group (5·7%), a reduction of 36% (p<0·03). Mortality rates are given according to the treatment group to which the patients were initially randomly allocated.
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| 33. |
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| 34. |
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| 35. |
- Jaenson, Thomas G.T. 1948-, et al.
(författare)
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Coinfection of Babesia and Borrelia in the Tick Ixodes ricinus-A Neglected Public Health Issue in Europe?
- 2024
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Ingår i: Pathogens. - : MDPI. - 2076-0817. ; 13:1
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Forskningsöversikt (refereegranskat)abstract
- Ixodes ricinus nymphs and adults removed from humans, and larvae and nymphs from birds, have been analysed for infection with Babesia species and Borrelia species previously in separately published studies. Here, we use the same data set to explore the coinfection pattern of Babesia and Borrelia species in the ticks. We also provide an overview of the ecology and potential public health importance in Sweden of I. ricinus infected both with zoonotic Babesia and Borrelia species. Among 1952 nymphs and adult ticks removed from humans, 3.1% were PCR-positive for Babesia spp. Of these Babesia-positive ticks, 43% were simultaneously Borrelia-positive. Among 1046 immatures of I. ricinus removed from birds, 2.5% were Babesia-positive, of which 38% were coinfected with Borrelia species. This study shows that in I. ricinus infesting humans or birds in Sweden, potentially zoonotic Babesia protozoa sometimes co-occur with human-pathogenic Borrelia spp. Diagnostic tests for Babesia spp. infection are rarely performed in Europe, and the medical significance of this pathogen in Europe could be underestimated.
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| 36. |
- Kutti, Jack, et al.
(författare)
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Plasma concentrations of platelet-specific proteins in young female acute myocardial infarction survivors and their age-matched female controls.
- 1983
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Ingår i: European heart journal. - 0195-668X. ; 4:5, s. 300-5
-
Tidskriftsartikel (refereegranskat)abstract
- The steady state plasma concentrations of the two platelet-specific proteins beta-thromboglobulin (BTG) and platelet factor 4 (PF4) were determined in two groups of females: 36 acute myocardial infarction (AMI) survivors, and 38 age-matched control subjects. For the AMI patients the mean BTG and PF4 values were 57 +/- 4 and 14.1 +/- 1.7 ng/ml, respectively. These two means significantly exceeded the corresponding means for the controls, 40 +/- 2 and 10.3 +/- 0.6 ng/ml, respectively. Similar results have recently been reported by other workers who investigated patients with coronary artery disease; however, in no previous study were the values for BTG and PF4 related to those obtained for control subjects matched with respect to sex and age. The present results therefore further support the concept that increased platelet activation and secretion is taking place in steady state patients who previously have sustained an AMI.
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| 37. |
- Kutti, Jack, et al.
(författare)
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The relation between platelet reactivity and coronary angiographic findings in young female survivors of acute myocardial infarction.
- 1986
-
Ingår i: Thrombosis and haemostasis. - 0340-6245. ; 56:2, s. 207-10
-
Tidskriftsartikel (refereegranskat)abstract
- In 31 women who had survived their first acute myocardial infarction (MI) studies of platelet reactivity were related to coronary angiographic findings. The results were compared to those obtained from 38 age-matched control women. According to the cardioangiographic findings the group of MI was subdivided into: 9 patients with 1-vessel disease (VD), 10 patients with 2-VD, and 5 patients with 3-VD; 7 subjects did not reveal significant coronary stenosis. When each of these 4 subgroups of MI-patients were compared with the control material significant difference with respect to PF4 was found only for subjects with 1-VD (20.0 +/- 4.8 vs. 10.3 +/- 0.6 ng/ml). As regards BTG the difference was significant for 1-VD and 2-VD patients (69 +/- 12 and 59 +/- 3, respectively vs. 40 +/- 2 ng/ml). The cumulative frequency for secondary aggregation differed only as regards 1-VD patients (78 vs 40%).
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| 38. |
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| 39. |
- Larsen, Anders Foller, 1984, et al.
(författare)
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Development of bright fluorescent quadracyclic adenine analogues: TDDFT-calculation supported rational design
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- Fluorescent base analogues (FBAs) comprise a family of increasingly important molecules for the investigation of nucleic acid structure and dynamics. We recently reported the quantum chemical calculation supported development of four microenvironment sensitive analogues of the quadracyclic adenine (qA) scaffold, the qANs, with highly promising absorptive and fluorescence properties that were very well predicted by TDDFT calculations. Herein, we report on the efficient synthesis, experimental and theoretical characterization of nine novel quadracyclic adenine derivatives. The brightest derivative, 2-CNqA, displays a 13-fold increased brightness (epsilon Phi(F) = 4500) compared with the parent compound qA and has the additional benefit of being a virtually microenvironment-insensitive fluorophore, making it a suitable candidate for nucleic acid incorporation and use in quantitative FRET and anisotropy experiments. TDDFT calculations, conducted on the nine novel qAs a posteriori, successfully describe the relative fluorescence quantum yield and brightness of all qA derivatives. This observation suggests that the TDDFT-based rational design strategy may be employed for the development of bright fluorophores built up from a common scaffold to reduce the otherwise costly and time-consuming screening process usually required to obtain useful and bright FBAs.
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| 40. |
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| 41. |
- Lindgren, Malin, et al.
(författare)
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Fondue and transglutaminase in the Drosophila larval clot
- 2008
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Ingår i: Journal of insect physiology. - : Elsevier BV. - 0022-1910 .- 1879-1611. ; 54:3, s. 586-592
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Tidskriftsartikel (refereegranskat)abstract
- Hemolymph coagulation is vital for larval hemostasis and important in immunity, yet the molecular basis of coagulation is not well understood in insects. Of the larval clotting factors identified in Drosophila, Fondue is not conserved in other insects, but is notable for its effects on the clot's physical properties, a possible function in the cuticle, and for being a substrate of transglutaminase. Transglutaminase is the only mammalian clotting factor found in Drosophila, and as it acts in coagulation in other invertebrates, it is also likely to be important in clotting in Drosophila. Here we describe a Fondue-GFP fusion construct that labels the cuticle and clot, and show that chemical inhibition and RNAi knockdown of the Drosophila transglutaminase gene affect clot properties and composition in ways similar to knockdown of the fon gene. Thus, Fondue appears to be incorporated into the cuticle and is a key transglutaminase substrate in the clot. This is also the first direct functional confirmation that transglutaminase acts in coagulation in Drosophila.
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| 42. |
- Lindh, T, et al.
(författare)
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Tooth-implant supported fixed prostheses : A retrospective multicenter study
- 2001
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Ingår i: International Journal of Prosthodontics. - 0893-2174 .- 1139-9791. ; 14:4, s. 321-328
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this retrospective multicenter study on implants combined with natural teeth was to investigate the implant survival rate and loss of marginal bone, as well as indications and complications pertinent to this form of implant therapy. Materials and Methods: The study comprised 185 implants in 111 patients from six different clinics in Sweden. Gathering of data, which were taken from patient records, followed a strict protocol. The registrations included indications for treatment, failure of implants, radiographs from baseline and follow-up, and information on complications. Results: The cumulative implant survival was found to be 95.4% (standard error 4.5%) up to 3 years of follow-up. The marginal bone level at baseline was lower in the maxilla compared with the mandible (P = .015), but any further loss did not differ between the jaws. The most severe complication other than loss of osseointegration (6/185) or periimplant infections (4/183) was intrusion of the abutment teeth, which occurred in 5% of the cases. In all instances, the intrusion was seen in constructions with nonrigid forms of connection between the implants and teeth. Conclusion: The tooth-implant supported prosthesis using the Branemark system is in the short term an equally predictable treatment as the completely implant-supported prosthesis concerning implant survival and loss of marginal bone. When combining implants and teeth, a rigid form of connection should be used to prevent tooth intrusion.
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| 43. |
- Liu, Z. W., et al.
(författare)
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Beneficial Effects of GFAP/Vimentin Reactive Astrocytes for Axonal Remodeling and Motor Behavioral Recovery in Mice after Stroke
- 2014
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Ingår i: Glia. - : Wiley. - 0894-1491. ; 62:12, s. 2022-2033
-
Tidskriftsartikel (refereegranskat)abstract
- The functional role of reactive astrocytes after stroke is controversial. To elucidate whether reactive astrocytes contribute to neurological recovery, we compared behavioral outcome, axonal remodeling of the corticospinal tract (CST), and the spatio-temporal change of chondroitin sulfate proteoglycan (CSPG) expression between wild-type (WT) and glial fibrillary acidic protein/vimentin double knockout (GFAP(-/-)Vim(-/-)) mice subjected to Rose Bengal induced cerebral cortical photothrombotic stroke in the right forelimb motor area. A foot-fault test and a single pellet reaching test were performed prior to and on day 3 after stroke, and weekly thereafter to monitor functional deficit and recovery. Biotinylated dextran amine (BDA) was injected into the left motor cortex to anterogradely label the CST axons. Compared with WT mice, the motor functional recovery and BDA-positive CST axonal length in the denervated side of the cervical gray matter were significantly reduced in GFAP(-/-)Vim(-/-) mice (n=10/group, P<0.01). Immunohistological data showed that in GFAP(-/-)Vim(-/-) mice, in which astrocytic reactivity is attenuated, CSPG expression was significantly increased in the lesion remote areas in both hemispheres, but decreased in the ischemic lesion boundary zone, compared with WT mice (n=12/group, P<0.001). Our data suggest that attenuated astrocytic reactivity impairs or delays neurological recovery by reducing CST axonal remodeling in the denervated spinal cord. Thus, manipulation of astrocytic reactivity post stroke may represent a therapeutic target for neurorestorative strategies. GLIA 2014;62:2022-2033 Post stroke, GFAP/Vimentin knockout mice with attenuated gliosis have reduced or slower neurological recovery and corticospinal remodeling, and increased chondroitin sulfate proteoglycan expression, suggesting that reactive astrocytes promote recovery.
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| 44. |
- Lundberg, Erik, 1981, et al.
(författare)
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Addressable molecular node assembly - high information density DNA nanostructures
- 2008
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Ingår i: Nucleic acids symposium series (2004). - 1746-8272. ; :52, s. 683-684
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Tidskriftsartikel (refereegranskat)abstract
- The inherent self-assembly properties of DNA make it ideal in nanotechnology. We present a fully addressable DNA nanostructure with the smallest possible unit cell, a hexagon with a side-length of only 3.4 nm.(2,3) Using novel three-way oligonucleotides, where each side has a unique double-stranded DNA sequence that can be assigned a specific address, we will build a non-repetitive two-dimensional grid.
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| 45. |
- Magnuson, Martin, et al.
(författare)
-
Electronic structure and chemical bonding in Ti2AlC investigated by soft x-ray emission spectroscopy
- 2006
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:195108
-
Tidskriftsartikel (refereegranskat)abstract
- Theelectronic structure of the nanolaminated transition metal carbide Ti2AlC hasbeen investigated by bulk-sensitive soft x-ray emission spectroscopy. The measuredTi L, C K, and Al L emission spectra arecompared with calculated spectra using ab initio density-functional theory includingdipole matrix elements. The detailed investigation of the electronic structureand chemical bonding provides increased understanding of the physical propertiesof this type of nanolaminates. Three different types of bondregions are identified: The relatively weak Ti 3d–Al 3p bond1 eV below the Fermi level and the Ti 3d–C 2pand Ti 3d–C 2s bonds which are stronger and deeperin energy are observed around 2.5 and 10 eV below theFermi level, respectively. A strongly modified spectral shape of the3s final states in comparison to pure Al is detectedfor the intercalated Al monolayers indirectly reflecting the Ti 3d–Al3p hybridization. The differences between the electronic and crystal structuresof Ti2AlC, Ti3AlC2, and TiC are discussed in relation tothe number of Al layers per Ti layer in thetwo former systems and the corresponding change of the unusualmaterials properties.
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| 46. |
- Olander, Angelica, et al.
(författare)
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An Exploration of Swedish Adolescents’ Experiences of Mobile Apps for Physical Activity
- 2024
-
Ingår i: Psychological topics. - : University of Rijeka, Faculty of Humanities and Social Sciences. - 1849-0395 .- 1332-0742. ; 33:1, s. 91-114
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Tidskriftsartikel (refereegranskat)abstract
- Recent reports on children and adolescents’ physical activity indicate that approximately 80% do not meet the World Health Organisation’s recommended levels of physical activity. Childhood is a critical period of development; as such, it is important to prioritize health promotion in this phase of one’s life. Use of gamification in mobile apps has been shown to positively influence physical activity levels in children and adolescents. Inclusion of behaviour change techniques (BCTs) has been noted to increase the effect of health promoting interventions. Previous research highlights that children and adolescents find the BCTs of goal setting/planning, feedback, reward, self-monitoring, social comparison, and social support to be of interest. The aim of this study was to explore Swedish adolescents’ experience with physical activity and apps with a focus on the influence of BCTs. Three focus group interviews were undertaken with a total of 18 participants (11-15 years of age). The data were explored using reflective thematic analysis. In addition to the BCTs identified in previous research, participants in the present study indicated they were positive about mobile apps providing instruction on how to perform a behaviour, demonstration of the behaviour, and the influence of removal of reward. Other attractive features of physical activities apps included developing a streak, competition, and provision of an adequate level of challenge. The present study contributes to a deeper understanding of how BCTs and other features can be implemented in physical activity apps, where individualization and renewal appear to be more important than the actual content features. These findings are important for future work to create interventions that increase the level of physical activity among adolescents both in Sweden and other countries.
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| 47. |
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| 48. |
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| 49. |
- Preus, S., et al.
(författare)
-
Advances in Quantitative FRET-Based Methods for Studying Nucleic Acids
- 2012
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Ingår i: ChemBioChem. - : Wiley. - 1439-7633 .- 1439-4227. ; 13:14, s. 1990-2001
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Tidskriftsartikel (refereegranskat)abstract
- Förster resonance energy transfer (FRET) is a powerful tool for monitoring molecular distances and interactions at the nanoscale level. The strong dependence of transfer efficiency on probe separation makes FRET perfectly suited for on/off experiments. To use FRET to obtain quantitative distances and three-dimensional structures, however, is more challenging. This review summarises recent studies and technological advances that have improved FRET as a quantitative molecular ruler in nucleic acid systems, both at the ensemble and at the single-molecule levels.
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| 50. |
- Preus, S., et al.
(författare)
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Characterization of Nucleobase Analogue FRET Acceptor tC(nitro)
- 2010
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 114:2, s. 1050-1056
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Tidskriftsartikel (refereegranskat)abstract
- The fluorescent nucleobase analogues of the tricyclic cytosine (tC) family, tC and tC(O), possess high fluorescence quantum yields and single fluorescence lifetimes, even after incorporation into double-stranded DNA, which make these base analogues particularly useful as fluorescence resonance energy transfer (FRET) probes. Recently, we reported the first all-nucleobase FRET pair consisting of tC(O) as the donor and the novel tC(nitro) as the acceptor. The rigid and well-defined position of this FRET pair inside the DNA double helix, and consequently excellent control of the orientation factor in the FRET efficiency, are very promising features for future studies of nucleic acid structures. Here, we provide the necessary spectroscopic and photophysical characterization Of tC(nitro) needed in order to utilize this probe as a FRET acceptor in nucleic acids. The lowest energy absorption band from 375 to 525 nm is shown to be the result of a single in-plane polarized electronic transition oriented similar to 27 degrees from the molecular long axis, This band overlaps the emission bands of both tC and tC(O), and the Forster characteristics of these donor-acceptor pairs are calculated for double-stranded DNA scenarios. In addition, the UV-vis absorption of tC(nitro) is monitored in a broad pH range and the neutral form is found to be totally predominant under physiological conditions with a pK(a) of 11.1. The structure and electronic spectrum Of tC(nitro) is further characterized by density functional theory calculations.
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