| 1. |
- Gomez-Pinilla, Pedro J., et al.
(författare)
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Effect of melatonin on age associated changes in guinea pig bladder function
- 2007
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Ingår i: Journal of Urology. - : Ovid Technologies (Wolters Kluwer Health). - 1527-3792 .- 0022-5347. ; 177:4, s. 1558-1561
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The incidence of urinary incontinence increases with age but the cause and effect relationship between aging and altered bladder function is poorly understood. It was suggested that melatonin can ameliorate negative effects induced by aging by its free radical scavenging activity and its ability to decrease oxidative stress. We investigated the changes in bladder function evoked by aging and the possible benefits of melatonin treatment on age related bladder disturbances. Materials and Methods: Bladder function was assessed using cystometry in conscious, freely moving female guinea pigs. Animals were grouped according to age as young adults (4 months old) and senescents (18 to 20 months old). A group of senescent animals were treated with 2.5 mg kg(-1) day(-1) melatonin for 21 days. Results: Aging led to increased detrusor activity, as demonstrated by short micturition intervals, decreased bladder capacity and spontaneous contractions during the filling phase. During the voiding phase aged animals showed lower micturition pressures than young adults. Melatonin counteracted the cystometric changes in senescent animals and restored micturition parameters to those of young adults. Conclusions: These results show that in guinea pigs aging induces detrusor overactivity. Melatonin treatment improved age induced changes in bladder function. If similar effects can be demonstrated in humans, melatonin treatment may be a new approach to decrease the impact of age related bladder disorders.
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| 2. |
- Gomez-Pinilla, Pedro J, et al.
(författare)
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Melatonin restores impaired contractility in aged guinea pig urinary bladder
- 2008
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Ingår i: Journal of Pineal Research. - : Blackwell Publishing Ltd. - 1600-079X .- 0742-3098. ; 44:4, s. 416-425
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Tidskriftsartikel (refereegranskat)abstract
- Urinary bladder disturbances are frequent in the elderly population but the responsible mechanisms are poorly understood. This study evaluates the effects of aging on detrusor myogenic contractile responses and the impact of melatonin treatment. The contractility of bladder strips from adult, aged and melatonin-treated guinea pigs was evaluated by isometric tension recordings. Cytoplasmatic calcium concentration ([Ca2+](i)) was estimated by epifluorescence microscopy of fura-2-loaded isolated detrusor smooth muscle cells, and the levels of protein expression and phosphorylation were quantitated by Western blotting. Aging impairs the contractile response of detrusor strips to cholinergic and purinergic agonists and to membrane depolarization. The impaired contractility correlates with increased [Ca2+](i) in response to the stimuli, suggesting a reduced Ca(2+)sensitivity. Indeed, the agonist-induced contractions in adult strips were sensitive to blockade with Y27362, an inhibitor of Rho kinase (ROCK) and GF109203X, an inhibitor of protein kinase C (PKC), but these inhibitors had negligible effects in aged strips. The reduced Ca2+ sensitivity in aged tissues correlated with lower levels of RhoA, ROCK, PKC and the two effectors CPI-17 and MYPT1, and with the absence of CPI-17 and MYPT1 phosphorylation in response to agonists. Interestingly, melatonin treatment restored impaired contractility via normalization of Ca2+ handling and Ca2+ sensitizations pathways. Moreover, the indoleamine restored age-induced changes in oxidative stress and mitochondrial polarity. These results suggest that melatonin might be a novel therapeutic tool to palliate aging-related urinary bladder contractile impairment.
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| 3. |
- Alarcon, Hugo, et al.
(författare)
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Modification of nanostructured TiO2 electrodes by electrochemical Al3+ insertion : Effects on dye-sensitized solar cell performance
- 2007
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:35, s. 13267-13274
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured TiO2 films were modified by insertion with aluminum ions using an electrochemical process. After heat treatment these films were found suitable as electrodes in dye-sensitized solar cells. By means of a catechol adsorption test, as well as photoelectron spectroscopy (PES), it was demonstrated that the density of Ti atoms at the metal oxide/electrolyte interface is reduced after Al modification. There is, however, not a complete coverage of aluminum oxide onto the TiO2, but the results rather suggest either the formation of a mixed Al-Ti oxide surface layer or formation of a partial aluminum oxide coating. No new phase could, however, be detected. In solar cells incorporating Al-modified TiO2 electrodes, both electron lifetimes and electron transport times were increased. At high concentrations of inserted aluminum ions, the quantum efficiency for electron injection was significantly decreased. Results are discussed at the hand of different models: A multiple trapping model, which can explain slower kinetics by the creation of additional traps during Al insertion, and a surface layer model, which can explain the reduced recombination rate, as well as the reduced injection efficiency, by the formation of a blocking layer.
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| 4. |
- Dunér, Gunnar, et al.
(författare)
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Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films
- 2008
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 24:14, s. 7559-7564
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerization method enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highly sensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposed to buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and the extent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resulting responses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereas higher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfaces also proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansion and contraction. Using ellipsometry, copolymer layers were estimated to be similar to 220 nm in a collapsed state and similar to 340 nm in the expanded state, effectively increasing the thickness of the film by 55%.
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| 5. |
- Fredin, Kristofer, et al.
(författare)
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Using a molten organic conducting material to infiltrate a nanoporous semiconductor film and its use in solid-state dye-sensitized solar cells
- 2009
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Ingår i: Synthetic metals. - : Elsevier BV. - 0379-6779 .- 1879-3290. ; 159:1-2, s. 166-170
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We describe a method to fill thin films of nanoporous TiO2 with solid organic hole-conducting materials and demonstrate the procedure specifically for use in the preparation of dye-sensitized solar cells. Cross-sections of the films were investigated by scanning electron microscopy and it was observed that a hot molten organic material fills pores that are 10 mu m below the surface of the film. We characterized the incident photon to current conversion efficiency properties of the solid TiO2/organic dye/organic hole-conductor heterojunctions and the spectra show that the dye is still active after the melting process.
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| 6. |
- Hedlund, Maria
(författare)
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Demokratiska genvägar : Expertinflytande i den svenska lagstiftningsprocessen om medicinsk genteknik
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation is about expert influence and democracy and focuses on how political decision-making about issues highly dependent on qualified scientific expertise should come about in order to be democratic. The primary purpose of the study is to evaluate, from a democratic perspective, the Swedish legislative process concerned with medical gene technology ? an archetypal case where the decision-making processes involve a marked level of expertise. It is argued that a democratic decision-making process should be characterized by openness and transparency and the possibility for a variety of standpoints to be visible and open to debate. This democratic norm is valid for all decision-making processes and the crucial question is whether a decision-making process highly dependent on qualified scientific expertise would have difficulties meeting such posed democratic criteria. The author makes a systematic empirical and normative analysis of the decision-making process in question, which is anatomised and evaluated against the democratic norm. The overall result of the study is that scientific experts have been able to define the problems on the political agenda and, thereby, had influenced the process as a whole. However, this has not constrained a variety of standpoints to be visible, but views expressed about the experts? problem definitions have prompted more frequent responses from the political decision-makers than other views, which only occasionally have been responded to. The Swedish legislative process concerned with medical gene technology has thereby partly deviated from democratic ideals.
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| 7. |
- Hedlund, Maria, et al.
(författare)
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Effects of water in the Surface Adsorption of Dye molecules at Nanostructured TiO2
- 2006
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Ingår i: 16th International Conference on Photochemical Conversion and Storage of Solar Energy (IPS-16).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The dye-sensitized solar cell is a promising new alternative to conventional solar cells. However these molecular solar cells may suffer from long term stability problems. Some of these problems are believed to be linked to the presence of water. Recently, dyes possessing long hydrophobic chains have been introduced, as an effort to come to terms with problems related to water [1]. In this study the Ru-dyes N3, N719 and 520DN (an analog containing hydrophobic chains) bound to TiO2, have after being exposed to water, been investigated by photoelectron spectroscopy (PES). PES was used to understand on a molecular level, how the introduction of water influences the molecular and electronic structure of these dye sensitized surfaces.In general, the surface sensitized with 520DN does not give signs of any major changes after being subjected to water. The investigation therefore found that the hydrophobic chains in the dye surface with 520DN effectively protect the molecular structure of the surface. However the surfaces of N3 and N719 do show large changes after exposing the surface to water. More specifically, it has been found that the outermost molecular orbitals (HOMO), which are vital for the function of the solar cell, are affected by water by shifting towards higher binding energies.Also, changes in the thiocyanate group can be found in the N3 and N719 dyes after being exposed to water. Specifically, the sulphur S2p energy levels have a substantially larger amount of a second spin-orbit split peak after being exposed to water. The nitrogen N1s peak relating to the thiocyanate group also changes shape. Moreover, in the case of N719, the counter ion TBA+ is not present on the dye sensitized surface after being subjected to water.Finally, the amount of dye on the TiO2 surfaces is also important for the efficiency of the solar cell. It was found that the coverage of N3 and N719 dye decreases when exposed to water, but the coverage of the 520DN dye remains the same.
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| 8. |
- Jensen, Lasse Dahl, et al.
(författare)
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Nitric oxide permits hypoxia-induced lymphatic perfusion by controlling arterial-lymphatic conduits in zebrafish and glass catfish
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:43, s. 18408-18413
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Tidskriftsartikel (refereegranskat)abstract
- The blood and lymphatic vasculatures are structurally and functionally coupled in controlling tissue perfusion, extracellular interstitial fluids, and immune surveillance. Little is known, however, about the molecular mechanisms that underlie the regulation of bloodlymphatic vessel connections and lymphatic perfusion. Here we show in the adult zebrafish and glass catfish (Kryptopterus bicirrhis) that blood-lymphatic conduits directly connect arterial vessels to the lymphatic system. Under hypoxic conditions, arterial-lymphatic conduits (ALCs) became highly dilated and linearized by NO-induced vascular relaxation, which led to blood perfusion into the lymphatic system. NO blockage almost completely abrogated hypoxia-induced ALC relaxation and lymphatic perfusion. These findings uncover mechanisms underlying hypoxia-induced oxygen compensation by perfusion of existing lymphatics in fish. Our results might also imply that the hypoxia-induced NO pathway contributes to development of progression of pathologies, including promotion of lymphatic metastasis by modulating arterial-lymphatic conduits, in the mammalian system.
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| 9. |
- Johansen, Kari, et al.
(författare)
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Norovirus strains belonging to the GII.4 genotype dominate as a cause of nosocomial outbreaks of viral gastroenteritis in Sweden 1997-2005 - Arrival of new variants is associated with large nation-wide epidemics
- 2008
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Ingår i: Journal of Clinical Virology. - : Elsevier BV. - 1386-6532 .- 1873-5967. ; 42:2, s. 129-134
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Tidskriftsartikel (refereegranskat)abstract
- Background: In recent years an increase of the incidence of nosocomial outbreaks caused by noroviruses has been observed throughout Sweden, with high peaks noted in the winter seasons 2002/2003 and 2004/2005, respectively. Objectives: To phylogenetically characterize norovirus strains causing nosocomial outbreaks from 1997 to 2005 and estimate the impact of norovirus-like disease on the Swedish health care system during the peak season 2002/2003 when a new variant of norovirus occurred. Study design: Stool samples from 115 randomly selected nosocomial outbreaks occurring during 1997-2005 throughout Sweden were studied by RT-PCR and sequencing. In addition, to investigate the impact on the health-care system, a questionnaire was distributed to infection control units (n = 90) serving all Swedish hospitals, nursing homes and other health-care institutions during the largest epidemic of nosocomial outbreaks. Results: Sequencing of 279 nucleotides of the norovirus RNA polymerase gene in stools containing norovirus RNA showed that strains belonging to the GII.4 genotype dominated. Each of the two large epidemics was due to a new variant within this cluster. The questionnaire revealed that 30,000-35,000 episodes of nosocomial norovirus-like infections occurred in 80 of 82 major Swedish hospitals affected in 2002/2003. Conclusion: New norovirus variants within the cluster GGII.4 may have a major impact on the health-care system. (c) 2008 Elsevier B.V. All rights reserved.
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| 10. |
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