| 1. |
- McKenzie, Richard L., et al.
(författare)
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UV Radiation: Balancing Risks and Benefits
- 2009
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 85:1, s. 88-98
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Tidskriftsartikel (refereegranskat)abstract
- We use action spectra published by the International Commission on Illumination to examine diurnal, seasonal and latitudinal variations in erythemally weighted (sunburning) UV-a health risk, and vitamin D-weighted UV-a health benefit. Vitamin D-weighted UV is more strongly dependent on ozone and solar zenith angle. Consequently, its diurnal, seasonal and geographic variability is more pronounced than for erythemally weighted UV. We then investigate relationships between the two quantities. An algorithm is developed and used to relate vitamin D production to the widely used UV index, to help the public to optimize their exposure to UV radiation. In the summer at noon, there should at mid-latitudes be sufficient UV to photosynthesize optimal vitamin D in similar to 1 min for full body exposure, whereas skin damage occurs after similar to 15 min. Further, while it should be possible to photosynthesize vitamin D in the winter at mid-latitudes, the amount of skin that must be exposed is larger than from the hands and face alone. This raises the question of whether the action spectrum for vitamin D production is correct, since studies have reported that production of vitamin D is not possible in the winter at mid-latitudes.
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| 2. |
- Andersson-Engels, Stefan, et al.
(författare)
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Laser-induced Fluorescence In Malignant and Normal Tissue of Rats Injected With Benzoporphyrin Derivative
- 1993
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 57:6, s. 978-983
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced fluorescence was used to characterize the localization of intravenously administered benzoporphyrin derivative-monoacid (BPD-MA) 3 h postinjection in different rat tissue types, including an induced experimental malignant tumor. A comparison of the fluorescence properties and the demarcation potential between the newer sensitizer BPD-MA and four other substances, hematoporphyrin (HP), polyhematoporphyrin ester (PHE), tetrasulfonated phthalocyanine (TSPc) and the commercially available Photofrin earlier investigated, is included. The fluorescence light was induced with a nitrogen laser, emitting at 337 nm. The fluorescence spectrum in the region 380-750 nm was analyzed by a polychromator equipped with a diode array detector. The demarcation potential between tumor and surrounding tissue in terms of fluorescence signal for the tumor model used was 2:1 for BPD-MA. In comparison with the other drugs, HP shows about the same demarcation potential, whereas Photofrin and PHE exhibit about 3 times better and TSPc about 1.5 times better demarcation. By also employing the endogenous tissue fluorescence signature the contrast was enhanced by a factor of about 2 for each of the five drugs.
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| 3. |
- Andreasson, Joakim, 1973, et al.
(författare)
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The gold porphyrin first excited singlet state
- 2002
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Ingår i: Photochemistry and Photobiology. - 0031-8655 .- 1751-1097. ; 76:1, s. 47-50
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Tidskriftsartikel (refereegranskat)abstract
- Gold porphyrins are often used as electron-accepting chromophores in artificial photosynthetic constructs. Because of the heavy atom effect, the gold porphyrin first-excited singlet state undergoes rapid intersystem crossing to form the triplet state. The lowest triplet state can undergo a reduction by electron donation from a nearby porphyrin or another moiety. In addition, it can be involved in triplet-triplet energy transfer interactions with other chromophores. In contrast, little has been known about the short-lived singlet excited state. In this work, ultrafast time-resolved absorption spectroscopy has been used to investigate the singlet excited state of Au(III) 5,15-bis(3,5-di-t-butylphenyl)-2,8,12,18,-tetraethyl-3,7,13,17-tetrameth ylporphyrin in ethanol solution. The excited singlet state is found to form with the laser pulse and decay with a time constant of 240 fs to give the triplet state. The triplet returns to the ground state with a lifetime of 400 ps. The lifetime of the singlet state is comparable with the time constants for energy and photoinduced electron transfer in some model and natural photosynthetic systems. Thus, it is kinetically competent to take part in such processes in suitably designed supermolecular systems.
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| 4. |
- Fragata, M., et al.
(författare)
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Linear Dichroism (250-700 nm) of Chlorophyll a and Pheophytin a Oriented in a Lamellar Phase of Glycerylmonooctanoate / H2O. Characterization of Electronic Transitions
- 1988
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 47:1, s. 133-143
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Tidskriftsartikel (refereegranskat)abstract
- We determined the polarized and isotropic visible/UV absorption spectra of chlorophyll a (Chi a) and pheophytin a (Pheo a) oriented in the lamellar phase of glycerylmonooctanoate/H2O. Resolution into mutually perpendicular X- and Y-polarized absorption spectra of the pigments was achieved assuming that the transition moments of Chi a and Pheo a are located in the plane of the chromophores. The polarized spectra were deconvoluted into harmonic progressions and the resultant assignment of band positions in the long-wavelength region was found to correlate well with independent spectral measurements, such as the polarisation of fluorescence. However, the correlation of the experimentally determined transitions with the results of theoretical calculations is not straightforward. The overall conclusions are of fundamental interest in the determination of orientations of the tetrapyrrole macrocycle in lipid lamellae and pigment-protein structures of photosynthetic membranes.
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| 5. |
- Karlsson, Isabella, 1980, et al.
(författare)
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Investigation of the Sunscreen Octocrylene's Interaction with Amino Acid Analogs in the Presence of UV Radiation
- 2012
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 88:4, s. 904-912
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Tidskriftsartikel (refereegranskat)abstract
- Octocrylene is an organic UV filter, commonly used in sunscreens and cosmetics, which can give rise to both contact and photocontact allergy. Our aim was to investigate octocrylenes interaction with amino acid analogs in the presence of UV radiation to better understand the reason for octocrylenes photoallergenic capacity. The amino acid analogs were photolysed in presence and absence of octocrylene for 1 h in cyclohexane. The rate of degradation was considerably slower for all amino acid analogs when octocrylene was present in the mixture. Benzylamine, the lysine analog, did react with octocrylene during the photolysis and the corresponding amide was formed in an acylation reaction. By varying the benzylamine concentration and keeping the octocrylene concentration fixed the reaction rate was shown to be independent of the amine concentration. The same type of acylation reaction took place when octocrylene alone was photolysed in ethanol in which the ethyl ester was formed from octocrylene and ethanol. Our results suggest that octocrylenes ability to cause photocontact allergy could be due to its photoinduced reactivity toward primary amines and alcohols.
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| 6. |
- Kjellbom, Per, et al.
(författare)
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Cytochrome P-450/420 in plant plasma membranes : a possible component of the blue-light-reducible flavoprotein-cytochrome complex
- 1985
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 42:6, s. 779-783
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Tidskriftsartikel (refereegranskat)abstract
- Carbon monoxide difference spectra and pyridine binding spectra indicate the presence of cytochrome P-450/420 in plasma membranes from cauliflower inflorescences. Mild lithium dodecylsulfate polyacrylamide gel electrophoresis shows only one heme staining band in the plasma membrane fraction at an apparent molecular weight of 93 kiloDalton. This band is suggested to be due to a cytochrome P-450/420 dimer, in view of the known molecular weights of animal cytochromes P-450/420. The plasma membrane-bound cytochrome P-450/420 is probably identical to the blue-light-reducible b-type cytochrome of plant plasma membranes, which has been inferred to have a role in photomorphogenesis.
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| 7. |
- Marchesini, Renato, et al.
(författare)
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In vivo spectrophotometric evaluation of neoplastic and non-neoplastic skin pigmented lesions--I. Reflectance measurements
- 1991
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 53:1, s. 77-84
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Tidskriftsartikel (refereegranskat)abstract
- Reflectance spectrophotometry from 400 to 800 nm on different cutaneous pigmented lesions, including primary and metastatic malignant melanoma, pigmented nevi, lentigo and seborrhoeic keratosis, has been performed by using an external integrating sphere coupled to a spectrophotometer. Measurements show that reflectance spectra of the different lesions manifest dissimilar patterns, particularly in the near IR region. Comparison of reflectance of nevi with that of malignant melanomas results in a highly significant difference (P less than 10(-6)) between the two samples. Though interpretation of the spectra remains difficult as a result of the complexity of the optical processes of scattering and absorption, our results suggest that a detailed analysis of the reflectance spectrum may give clinically useful information, and could be utilized as an aid in clinical diagnosis of cutaneous pigmented lesions, especially where malignant melanoma is concerned.
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| 8. |
- Nordén, Bengt, 1945, et al.
(författare)
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nteractions between DNA and Psoralenamines Studied with Dichroism Techniques
- 1986
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 44:5, s. 587-594
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of a series of water-soluble mono- and bis-psoralenamines with calf thymus DNA has been studied with flow UV linear dichroism (LD), circular dichroism (CD) and equilibrium techniques. The positive charge of a protonated amino group strongly enhances the DNA affinity compared to that of the parent compound, 8-methoxypsoralen. The orientation of the psoralen when bound to DNA, depends on the position of the amino substituent. With amino substituents in the 5-position (on the‘hydrophobic edge’of psoralen) psoralenamines tend to bind with a considerable tilt relative to the average orientation of the DNA base-pairs. The tilt generally increases with an increased psoralen: base-pair ratio, indicating a more random, nonintercalated binding. With the amino substituents in the 8-position the psoralen binds with its plane parallel to that of the DNA bases as expected for intercalation. The DNA CD supports that these psoralenamines induce a considerable perturbation of the DNA structure, and the CD induced in the psoralen chromophore is in qualitative agreement with intercalation. The study also includes a theoretical and an experimental determination of the UV transition moments of the psoralen chromophore.
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| 9. |
- Steinhoff, Franciska S., et al.
(författare)
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Phlorotannin Production and Lipid Oxidation as a Potential Protective Function Against High Photosynthetically Active and UV Radiation in Gametophytes of Alaria esculenta (Alariales, Phaeophyceae)
- 2012
-
Ingår i: Photochemistry and Photobiology. - : Wiley. - 1751-1097 .- 0031-8655. ; 88:1, s. 46-57
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Tidskriftsartikel (refereegranskat)abstract
- Radiation damage can inter alia result in lipid peroxidation of macroalgal cell membranes. To prevent photo-oxidation within the cells, photoprotective substances such as phlorotannins are synthesized. In the present study, changes in total fatty acids (FA), FA composition and intra/extracellular phlorotannin contents were determined by gas chromatography and the Folin-Ciocalteu method to investigate the photoprotective potential of phlorotannins to prevent lipid peroxidation. Alaria esculenta juveniles (Phaeophyceae) were exposed over 20 days to high/low photosynthetically active radiation (PAR) in combination with UV radiation (UVR) in the treatments: PAB (low/high PAR + UV-B + UV-A), PA (low/high PAR + UV-A) or low/high PAR only. While extracellular phlorotannins increased after 10 days, intracellular phlorotannins increased with exposure time and PA and decreased under PAB. Interactive effects of time:radiation wavebands, time:PAR dose as well as radiation wavebands:PAR dose were observed. Low FA contents were detected in the PA and PAB treatments; interactive effects were observed between time:high PAR and PAB:high PAR. Total FA contents were correlated to extra/intracellular phlorotannin contents. Our results suggest that phlorotannins might play a role in intra/extracellular protection by absorption and oxidation processes. Changes in FA content/composition upon UVR and high PAR might be considered as an adaptive mechanism of the A. esculenta juveniles subjected to variations in solar irradiance.
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| 10. |
- Tjerneld, F., et al.
(författare)
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Interaction Between DNA and 8-Methoxypsoralen Studied by Linear Dichroism
- 1979
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 29:6, s. 1115-1118
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Tidskriftsartikel (refereegranskat)abstract
- High sensitivity linear dichroism on DNA oriented by flow is shown to provide conclusive information about the interaction with 8–methoxypsoralen (8–MOP) both in the dark and by irradiation. 8–MOP forms directly in the dark a weak complex with DNA with a structure consistent with the intercalation model of Lerman. When aqueous DNA-psoralen solutions are UV irradiated (30800 nm). a photoadduct is formed. By comparison with experiments in ice matrix, it is suggested that it is the primarily bound 8–MOP that is responsible for the final product. It is inferred that this product is the 41,5I-photoadduct of 8–MOP. The orientation of the photo adduct on DNA is not consistent with intercalation.
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| 11. |
- Corrie, J, et al.
(författare)
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Photochemistry and thermal decarboxylation of alpha-phosphoryloxy-p-nitrophenylacetates
- 2009
-
Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 85, s. 1089-1096
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Tidskriftsartikel (refereegranskat)abstract
- α-Carboxy-4-nitrobenzyl phosphate 4 and its derived monomethyl phosphate ester 5 were synthesized and purified by anion-exchange chromatography. A gradient of LiCl was necessary for elution of the anion-exchange column to avoid unexpected thermal decarboxylation that occurred during vacuum evaporation when the volatile triethylammonium bicarbonate buffer was used. Photolysis of each compound was accompanied by decarboxylation, and 4 released inorganic phosphate with near-100% stoichiometry. Time-resolved infrared spectroscopy of the photolysis reaction, coupled with density functional theory calculations of vibrational frequencies, enabled us to infer a mechanism for the photolytic pathway, although there was some evidence for a second pathway also being operative. In contrast to the results for 4, photolysis of 5 appeared to release little or no monomethyl phosphate.
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| 12. |
- Durbeej, Bo, et al.
(författare)
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On the formation of cyclobutane pyrimidine dimers in UV-irradiated DNA : why are thymines more reactive?
- 2003
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Ingår i: Photochemistry and Photobiology. - : John Wiley & Sons. - 0031-8655 .- 1751-1097. ; 78:2, s. 159-167
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Tidskriftsartikel (refereegranskat)abstract
- The reaction pathways for thermal and photochemical formation of cyclobutane pyrimidine dimers in DNA are explored using density functional theory techniques. Although it is found that the thermal [2+2] cycloadditions of thymine + thymine (T + T T<>T), cytosine + cytosine (C + C C<>C) and cytosine + thymine (C + T C<>T) all are similarly unfavorable in terms of energy barriers and reaction energies, the excited-state energy curves associated with the corresponding photochemical cycloadditions display differences that – in line with experimental findings – unanimously point to the predominance of T<>T in UV-irradiated DNA. It is shown that the photocycloaddition of thymines is facilitated by the fact that the S1 state of the corresponding reactant complex lies comparatively high in energy. Moreover, at a nuclear configuration coinciding with the ground-state transition structure, the excited-state energy curve displays an absolute minimum only for the T + T system. Finally, the T + T system is also associated with the most favorable excited-state energy barriers and has the smallest S2–S0 energy gap at the ground-state transition structure.
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| 13. |
- Ekelund, Nils, 1956-, et al.
(författare)
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Chromophore rotation in 124-k Dalton Avena sativa phytochrome as measured by light changes in linear dichroism
- 1985
-
Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 41, s. 221-223
-
Tidskriftsartikel (refereegranskat)abstract
- From light‐induced changes in linear dichroism, we have calculated the rotation of the long‐wavelength‐absorbing transition moment that occurs during phototransformation of 124‐kilodalton Avena sativa phytochrome. Phytochrome was purified to homogeneity and immobilized onto Sepharose beads covalently coated with antibodies against A. sativa phytochrome. Changes in linear dichroism were induced by plane‐polarized red or far‐red light and measured by the absorbance differences at 660 and 730 nm using a dual‐wavelength spectrophotometer equipped with polarizing filters in the measuring beams. From such measurements, we calculate a rotation angle of 31o (or 149o) during photoconversion of Pr to Pfr and 30o (or 150o) during photoconversion of Pfr to Pr. These values are similar to the value of 32o (or 148o) reported earlier for the rotation of the transition moment of “large”A. sativa phytochrome (? 120 kilodalton) isolated under conditions that did not preclude post homogenization proteolysis of the 124 kilodalton molecule.
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| 14. |
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| 15. |
- Nessvi, Sofia, et al.
(författare)
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Association of 25-Hydroxyvitamin D(3) Levels in Adult New Zealanders with Ethnicity, Skin Color and Self-Reported Skin Sensitivity to Sun Exposure
- 2011
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Ingår i: Photochemistry and Photobiology. - : Wiley-Blackwell. - 0031-8655 .- 1751-1097. ; 87:5, s. 1173-1178
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Tidskriftsartikel (refereegranskat)abstract
- The study aim was to determine the contribution of ethnicity, objectively measured skin color and skin reaction-to-sun exposure to variations in 25-hydroxyvitamin D(3) [25(OH)D(3)]. A multiethnic sample (European, Maori, Pacific and Asian) of 503 adult volunteers aged 18-85 years, recruited from Auckland and Dunedin in New Zealand, answered a questionnaire on sun exposure and self-defined ethnicity. Skin color was measured using a spectrophotometer and the Individual Typology Angle (ITA) calculated. A blood sample was collected 4 weeks later to measure 25(OH)D(3). 25(OH)D(3) was associated with ethnicity, but not self-reported skin reaction-to-sun exposure. Amongst the ethnic groups, Asians had the lowest mean 25(OH)D level (37.0 nmol L(-1)) and Europeans with lighter colored skin had the highest (57.9 nmol L(-1)). An association also was seen between 25(OH)D(3) and skin color, with an increase of 2-3 nmol L(-1) per 10 degrees increase in ITA value, indicating higher 25(OH)D(3) with lighter skin color; but much of this association disappeared after adjusting for ethnicity. In contrast, ethnicity remained associated with 25(OH)D(3) after adjusting for ITA skin color and skin reaction-to-sun exposure. These results indicate that self-defined ethnicity was a major determinant of variations in serum 25(OH)D(3), while objective measures of skin color explained relatively little additional variation.
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| 16. |
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| 17. |
- Svahn, Carina, et al.
(författare)
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Photosynthetic activity in marine and brackish water strains of Fucus vesiculosus and Fucus radicans (Phaeophyceae) at different light qualities
- 2012
-
Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 88:6, s. 1455-1460
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the effects of different light qualities on the photosynthetic capacity of the brown algae Fucus vesiculosus, from the Norwegian Sea, and Fucus radicans and F. vesiculosus, from the Bothnian Sea. The electron transport rates (ETR) obtained for F. vesiculosus from the Norwegian Sea showed significantly higher levels of light saturation compared with both species of algae from the Bothnian Sea. The maximum of ETR values for the Norwegian Sea strain showed no significant changes due to varying light quality compared with the initial values. For F. vesiculosus, from the Bothnian Sea, treatment with blue light showed an effect after 1 week of 30 and 90 μmol photons m -2 s -1 (P < 0.01), and for F. radicans from the Bothnian Sea, at the irradiance of 90 μmol photons m -2 s -1 and 1 week (P < 0.01). After 1 week in the Bothnian Sea species and after 2 weeks in F. vesiculosus from the Norwegian Sea, the photosynthetic efficiency (α) was significantly higher regardless of light quality and irradiance compared with the initial values. Variation in light quality and irradiance had minor effects on the F v:F m values of the three algal strains studied. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.
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| 18. |
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| 19. |
- von Beckerath, Mathias, 1966-, et al.
(författare)
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The influence of UV exposure on 5-aminolevulinic acid-induced protoporphyrin IX production in skin
- 2001
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Ingår i: Photochemistry and Photobiology. - 0031-8655 .- 1751-1097. ; 74:6, s. 825-828
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Tidskriftsartikel (refereegranskat)abstract
- The skin of nude mice was exposed to erythemogenic doses of UV radiation, which resulted in erythema with edema. An ointment containing 5-aminolevulinic acid (ALA) was topically applied on mouse and human skin. Differences in the kinetics of protoporphyrin accumulation were investigated in normal and UV-exposed skin. At 24 and 48 h after UV exposure, skin produced significantly less protoporphyrin IX (PpIX) than skin unexposed to UV. Human skin on body sites frequently exposed to solar radiation (the lower arm) also produced less PpIX than skin exposed more rarely to the sun (the upper arm). It is concluded that UV radiation introduces persisting changes in the skin, relevant to its capability of producing PpIX from ALA. The observed differences in ALA-induced PpIX fluorescence may be the result of altered penetration of ALA through the stratum corneum or altered metabolizing ability of normal and UV-exposed skin (or both).
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| 20. |
- DaCosta, R. S., et al.
(författare)
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Molecular fluorescence excitation-emission matrices relevant to tissue spectroscopy
- 2003
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Ingår i: Photochemistry and Photobiology. - 0031-8655 .- 1751-1097. ; 78:4, s. 384-392
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Tidskriftsartikel (refereegranskat)abstract
- In vivo and ex vivo studies of fluorescence from endogenous and exogenous molecules in tissues and cells are common for applications such as detection or characterization of early disease. A systematic determination of the excitation-emission matrices (EEM) of known and putative endogenous fluorophores and a number of exogenous fluorescent photodynamic therapy drugs has been performed in solution. The excitation wavelength range was 250-520 nm, with fluorescence emission spectra collected in the range 260-750 nm. In addition, EEM of intact normal and adenomatous human colon tissues are presented as an example of the relationship to the EEM of constituent fluorophores and illustrating the effects of tissue chromophore absorption. As a means to make this large quantity of spectral data generally available, an interactive database has been developed. This currently includes EEM and also absorption spectra of 35 different endogenous and exogenous fluorophores and chromophores and six photosensitizing agents. It is intended to maintain and extend this database in the public domain, accessible through the Photochemistry and Photobiology website (http://www.aspjournal.com/).
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| 21. |
- Bhalerao, RP, et al.
(författare)
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The structure of phycobilisomes in mutants of synechococcus sp strain pcc-7942 devoid of specific linker polypeptides
- 1995
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Ingår i: Photochemistry and Photobiology. - 0031-8655 .- 1751-1097. ; 61:3, s. 298-302
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Tidskriftsartikel (refereegranskat)abstract
- The effect of elimination of the 30, 33 and 9 kDa phycobilisome rod-linker polypeptides on rod length was examined by electron microscopy of phycobilisomes isolated from wild-type Synechococcus sp. strain PCC 7942 and from genetically engineered mutants with lesions in the genes encoding the rod-linker polypeptides. The maximum rod length in the absence of the 33 kDa linker polypeptide was two phycocyanin hexamers, whereas rods with up to five hexamers were found in the mutant strain lacking the 30 kDa linker polypeptide. Elimination of the 9 kDa linker polypeptide did not have a significant effect on rod length. Finally, mutants lacking either the 30 or 33 kDa rod-associated linker polypeptides had an increased number of rods that terminated with a phycocyanin trimer. These observations are discussed with respect to the role of the linker polypeptides in the biosynthesis of the rod substructure.
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| 22. |
- Ekelund, Nils, 1956-, et al.
(författare)
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Chromophore rotation in 124-k Dalton Avena sativa phytochrome as measured by light changes in linear dichroism
- 1985
-
Ingår i: Photochemistry and Photobiology. - 0031-8655 .- 1751-1097. ; 41, s. 221-223
-
Tidskriftsartikel (refereegranskat)abstract
- From light-induced changes in linear dichroism, the rotation of the long-wavelength-absorbing transition moment that occurs during phototransformation of 124-kilodalton (kD) A. sativa phytochrome was calculated Phytochrome was purified to homogeneity and immobilized onto Sepharose beads covalently coated with antibodies against A. sativa phytochrome. Changes in linear dichroism were induced by plane-polarized red or far-red light and measured by the absorbance differences at 660 and 730 nm using a dual-wavelength spectrophotometer equipped with polarizing filters in the measuring beams. From such measurements, a rotation angle of 31° (or 149°) was calculated during photoconversion of Pr to Pfr and 30° (or 150°) during photoconversion of Pfr to Pr. These values are similar to the value of 32° (or 148°) reported earlier for the rotation of the transition moment of "large" A. sativa phytochrome (~120 kD) isolated under conditions that did not preclude post-homogenization proteolysis of the 124 kD mol.
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| 23. |
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| 24. |
- Henych, Jiri, et al.
(författare)
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In Situ FTIR Spectroscopy Study of the Photodegradation of Acetaldehyde and azo Dye Photobleaching on Bismuth-Modified TiO2
- 2015
-
Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 91:1, s. 48-58
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Tidskriftsartikel (refereegranskat)abstract
- The photocatalytic properties of bismuth-modified titania were studied by photobleaching of two aqueous azo dyes solutions (Reactive Black 5 and Acid Orange 7), and by photoinduced decomposition (PID) of acetaldehyde using in situ FTIR spectroscopy. Low bismuth doping concentrations up to 3 at.% is shown to lead to an increased photobleaching rate of both azo dyes solutions. Too high Bi dopant concentrations lead to less developed crystallite nanoparticles and exhibit weaker adsorption capacity. Bismuth doping altered the adsorption kinetics of acetaldehyde resulting in different surface products, and a modified photocatalytic reaction pathway was inferred.
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| 25. |
- Karonen, Maarit, et al.
(författare)
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A Tandem Mass Spectrometric Method for Singlet Oxygen Measurement
- 2014
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 90:5, s. 965-971
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Tidskriftsartikel (refereegranskat)abstract
- Singlet oxygen, a harmful reactive oxygen species, can be quantified with the substance 2,2,6,6-tetramethylpiperidine (TEMP) that reacts with singlet oxygen, forming a stable nitroxyl radical (TEMPO). TEMPO has earlier been quantified with electron paramagnetic resonance (EPR) spectroscopy. In this study, we designed an ultra-high-performance liquid chromatographictandem mass spectrometric (UHPLC-ESI-MS/MS) quantification method for TEMPO and showed that the method based on multiple reaction monitoring (MRM) can be used for the measurements of singlet oxygen from both nonbiological and biological samples. Results obtained with both UHPLC-ESI-MS/MS and EPR methods suggest that plant thylakoid membranes produce 3.7x10(-7) molecules of singlet oxygen per chlorophyll molecule in a second when illuminated with the photosynthetic photon flux density of 2000molm(-2)s(-1).
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| 26. |
- McGivney, Eric, et al.
(författare)
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Effects of UV-C and Vacuum-UV TiO2 Advanced Oxidation Processes on the Acute Mortality of Microalgae
- 2015
-
Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 91:5, s. 1142-1149
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Tidskriftsartikel (refereegranskat)abstract
- Advanced oxidation processes/technologies (AOT) that combine a semiconductor, such as titanium dioxide (TiO2), with a UV source have been used to eliminate microorganisms in various water treatment applications. To facilitate the applicability of this technique, the gain in efficiency from the semiconductor compared to the UV source alone with respect to different target organisms requires evaluation. The primary objective of this study was to determine the effects of TiO2 and UV wavelength on a freshwater alga, Pseudokirchneriella subcapitata and a marine alga, Tetraselmis suecica. For each species, dose-response experiments were conducted to determine the median lethal dose (LC50) of the following treatments: UV light emitted with a peak of 254nm, UV light emitted with a peak of 254nm in the presence of TiO2 and UV light emitted with a peak of 254 and 185nm in the presence of TiO2. In both species, the presence of TiO2 significantly increased mortality. Across all three treatments, P.subcapitata was more sensitive than T.suecica; moreover, the addition of the 185nm wavelength significantly increased cell mortality in P.subcapitata but not in T.suecica.
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| 27. |
- Navizet, Isabelle, et al.
(författare)
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Are the Bio- and Chemiluminescence States of the Firefly Oxyluciferin the Same as the Fluorescence State?
- 2013
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Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 89:2, s. 319-325
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Tidskriftsartikel (refereegranskat)abstract
- A usual strategy in both experimental and theoretical studies on bio- and chemiluminescence is to analyze the fluorescent properties of the bio- and chemiluminescence reaction product. Recent findings in a coelenteramide and Cypridina oxyluciferin model arise a concern on the validity of this procedure, showing that the light emitters in each of these luminescent processes might differ. Here, the thermal decomposition path of the firefly dioxetanone and the light emission states of the Firefly oxyluciferin responsible for the bio-, chemiluminescence, and fluorescence of the molecule are characterized using ab initio quantum chemistry and hybrid quantum chemistry/molecular mechanics methods to determine if the scenario found in the coelenteramide and Cypridina oxyluciferin study does also apply to the Firefly bioluminescent systems. The results point out to a unique emission state in the bio-, chemiluminescence, and fluorescence phenomena of the Firefly oxyluciferin and, therefore, using fluorescence properties of this system is reasonable.
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| 28. |
- Pagels, Peter, et al.
(författare)
-
Suberythemal Sun Exposures at Swedish Schools Depend on Sky Views of the Outdoor Environments - Possible Implications for Pupils' Health
- 2016
-
Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655 .- 1751-1097. ; 92:1, s. 201-207
-
Tidskriftsartikel (refereegranskat)abstract
- More scheduled outdoor stay is increasingly advocated for school children. This study measured 2(nd), 5(th) and 8(th) graders' erythemal UV-exposure in September, March and May at four Swedish schools. We related those exposures, as fractions of total available ambient radiation, to the schools outdoor environments differing in amount of shade, vegetation, and peripheral city-scape quantified as percentage of free sky view calculated from fish-eye photographs. Exposures correlated with the sky views (with exceptions in May) and were suberythemal. The exposures were also below the threshold limit of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for hazard evaluation of UVR but were potentially enough for adequate vitamin D formation according to a cited model calculation - as illustrated in the results and discussed. The school environments, typical in southern and middle Sweden, offer enough shade to protect children from overexposure during seasons with potentially harmful solar UV radiation. Pupils' outdoor stay may be extended during September and March. In May extended outdoor stay of the youngest pupils requires a more UVR-protective environment.
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| 29. |
- Sandstrom, S, et al.
(författare)
-
CP43 ', the isiA gene product, functions as an excitation energy dissipator in the cyanobacterium Synechococcus sp PCC 7942
- 2001
-
Ingår i: Photochemistry and Photobiology. - 0031-8655 .- 1751-1097. ; 74:3, s. 431-437
-
Tidskriftsartikel (refereegranskat)abstract
- Under conditions of iron deficiency certain cyanobacteria induce a chlorophyll (Chl)-binding protein, CP43 ', which is encoded by the isiA gene. We have previously suggested that CP43' functions as a nonradiative dissipator of light energy. To further substantiate its functional role an isiA overexpression construct was introduced into the genome of a cyanobacterium Synechococcus sp. PCC 7942 (giving isiA(oe) cells). The presence of functional CP43' in isiA(oe) cells was confirmed by Western blot as well as by the presence of a characteristic blueshift of the red Chi a absorption peak and a notable increase in the 77 K fluorescence peak at 685 nm. Compared to wildtype cells isiA(oe) cells, with induced CP43', had both smaller functional antenna size and decreased yields of room temperature Chi fluorescence at various light irradiances. These observations strongly suggest that isiA(oe) cells, with induced CP43', have an increased capacity for dissipating light energy as heat. In agreement with this hypothesis isiA(oe) cells were also more resistant to photoinhibition of photosynthesis than wild-type cells. Based on these results we have further strengthened the hypothesis that CP43 ' functions as a nonradiative dissipator of light energy, thus protecting photosystem II from excessive excitation under iron-deficient conditions.
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| 30. |
- Simpson, Madeline J., et al.
(författare)
-
Impact of Dye-Protein Interaction and Silver Nanoparticles on Rose Bengal Photophysical Behavior and Protein Photocrosslinking
- 2013
-
Ingår i: Photochemistry and Photobiology. - : Wiley-Blackwell. - 0031-8655 .- 1751-1097. ; 89:6, s. 1433-1441
-
Tidskriftsartikel (refereegranskat)abstract
- The role of recombinant Type-I human collagen in the free form or forming AgNP@collagen on the photophysical and photochemical behavior of rose Bengal was analyzed. The formation of dye aggregates on the protein surface was experimentally observed and corroborated by docking calculations. The formation of such aggregates is believed to change the main oxidative mechanism from Type-II (singlet oxygen) to Type-I (free radical) photosensitization. Remarkably, the presence of AgNP in the form of AgNP@collagen altered the dynamics of dye triplet deactivation, effectively preventing the dye degradation and reducing the extent of protein crosslinked. Both crosslinked rHC and AgNP@collagen were able to support fibroblasts proliferation, but only the material containing silver was resistant to S. epidermidis infection.
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| 31. |
- Wester, Ulf, et al.
(författare)
-
Solar Ultraviolet Radiation Exposure Proxy-estimated by Sky View Fish-eye Photography-Potentials and Limitations from an Exploratory Correlation Study
- 2019
-
Ingår i: Photochemistry and Photobiology. - : Wiley-Blackwell. - 0031-8655 .- 1751-1097. ; 95:2, s. 656-661
-
Tidskriftsartikel (refereegranskat)abstract
- Potentials and limitations of sky view fish-eye photography and calculation of the percentage of free sky (sky view factor, SVF) as a proxy to estimate solar ultraviolet radiation (UVR) exposure in shade settings are investigated using controlled situations. SVF and measured solar UVR exposure correlated at high mid-latitude (56.65 degrees N) near autumnal equinox in September. The correlation was enhanced by splitting the sky view images into a south- and a north-half and weighting the south-half higher to account for the direct sun. Sky view images from eight different settings with SVF-values 98.3% - 14.9% were compared to exposure measurements by polysulphone film dosimeter badges in the horizontal zenith-, vertical-south-, east-, west- and north-directions and their combinations. The sky view images were un-split and un-weighted or split and the semi-skies given south/north weights (3.0/1.0) or a higher weight ratio (3.5/0.5). Of all tested combinations split sky view SVFs weighted 3.0/1.0 and compared to horizontal (zenith-oriented) dosimeters yielded the highest correlation (R-2 = 0.96). The weight ratio (3.5/0.5) yielded the 2(nd) highest correlation (R-2 = 0.90) both compared to measured horizontal exposure and compared to the horizontal exposure averaged with the vertical-south-oriented exposure. SVF from sky view fish-eye photography may estimate solar UVR exposure in shade settings.
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| 32. |
- Lindskog, Magnus, et al.
(författare)
-
Glycaemic control in end-of-life care : fundamental or futile?
- 2014
-
Ingår i: Current Opinion in Supportive and Palliative Care. - 1751-4258 .- 1751-4266. ; 8:4, s. 378-382
-
Forskningsöversikt (refereegranskat)abstract
- Purpose of review Diabetes mellitus is one of the most common comorbidities in palliative care. Yet, the optimal handling of diabetes mellitus in dying patients is debated. This review aims to discuss comprehensively the scientific basis as of today for diabetes mellitus management decisions in end-of-life (EOL) care. Recent findings Glycaemic control provides prognostic information in EOL care of diabetes mellitus patients. Original data on how to manage dying patients with type 2 diabetes mellitus are scarce. Findings in elderly type 2 diabetes mellitus patients and expert opinions support that glycaemic control should be relaxed in dying patients with type 2 diabetes mellitus, in the absence of risk factors for true insulin dependence, to avoid symptomatic hypoglycaemia. For terminal but conscious type 1 diabetes mellitus patients, regular blood glucose measurements and continued insulin therapy is the mainstay, with some discrepancy in preferred management between palliative care physicians and diabetes consultants. No randomized controlled trials are available. Improvement is clearly needed with regard to communication about diabetes mellitus in EOL and documentation of decisions. Corticosteroid-induced diabetes mellitus is a significant problem in palliative care, but predictors exist. Summary In the absence of large observational studies or randomized controlled trials, the current body of knowledge is based on expert opinions, surveys and retrospective studies. Nevertheless, some clinically meaningful recommendations can be made. Prospective studies need to be performed in order to improve our understanding about diabetes mellitus management in EOL. The palliative care community has a joint responsibility to address these questions.
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| 33. |
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| 34. |
- Emilsson, Össur Ingi
(författare)
-
The burden and impact of chronic cough in severe disease
- 2022
-
Ingår i: CURRENT OPINION IN SUPPORTIVE AND PALLIATIVE CARE. - : Lippincott Williams & Wilkins. - 1751-4258 .- 1751-4266. ; 16:4, s. 183-187
-
Forskningsöversikt (refereegranskat)abstract
- Purpose of review: Chronic cough is common in severe diseases, such as COPD, interstitial lung disease, lung cancer and heart failure, and has a negative effect on quality of life. In spite of this, patients with cough sometimes feel their cough is neglected by healthcare workers. This review aims to briefly describe cough mechanisms, highlight the burden chronic cough can be for the individual, and the clinical impact of chronic cough.Recent findings: Chronic cough is likely caused by different mechanisms in different diseases, which may have therapeutic implications. Chronic cough, in general, has a significant negative effect on quality of life, both with and without a severe comorbid disease. It can lead to social isolation, recurrent depressive episodes, lower work ability, and even conditions such as urinary incontinence. Cough may also be predictive of more frequent exacerbations among patients with COPD, and more rapid lung function decline in idiopathic pulmonary fibrosis. Cough is sometimes reported by patients to be underappreciated by healthcare.Summary: Chronic cough has a significant negative impact on quality of life, irrespective of diagnosis. Some differences are seen between patients with and without severe disease. Healthcare workers need to pay specific attention to cough, especially patients with severe disease.
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| 35. |
- Posthuma, Rein, et al.
(författare)
-
Recent advances in bronchoscopic lung volume reduction for severe COPD patients
- 2023
-
Ingår i: CURRENT OPINION IN SUPPORTIVE AND PALLIATIVE CARE. - 1751-4258 .- 1751-4266. ; 17:4, s. 296-300
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose of review Bronchoscopic lung volume reduction (BLVR) is a novel and effective treatment for a specific phenotype of chronic obstructive pulmonary disease (COPD) characterized by advanced emphysema with static lung hyperinflation and severe breathlessness. This review aims to provide an overview of the recent advances made in BLVR.For achieving optimal outcomes with BLVR, patient selection and target lobe identification is crucial. BLVR has recently also been established to improve pulmonary function, exercise capacity and quality of life in COPD patients falling outside the standard treatment criteria, including patients with moderate hyperinflation, chronic hypercapnic failure or with very low diffusion capacity. In a cluster analysis, target lobe characteristics like emphysema destruction, air trapping and perfusion were found to be important discriminators between responders and non-responders. A potential survival benefit has been demonstrated in BLVR-treated patients when compared to non-treated patients. Long-term outcomes showed sustained outcomes of BLVR; however, effects decline over time, probably due to disease progression.BLVR using one-way endobronchial valves has become a guideline treatment offered in specialized intervention centres for a specific subgroup of COPD patients. Recent studies further characterize responders, describe extrapulmonary effects of BLVR and show positive long-term outcomes and a potential survival benefit.R. Posthuma is supported by the Lung Foundation Netherlands, grant number: 5.1.17.171.0.There are no conflicts of interest.Patients with chronic obstructive pulmonary disease (COPD) suffer from respiratory symptoms and reduced quality of life due to destruction and/or inflammation of the airways and alveoli, leading to airflow limitation1. Despite pharmacological and non-pharmacological therapies, patients with advanced COPD often remain highly symptomatic with debilitating breathlessness and reduced exercise capacity. In the last decade, bronchoscopic lung volume reduction (BLVR) emerged as an effective intervention in a carefully selected subgroup of COPD patients characterized by severe emphysema, static lung hyperinflation and breathlessness. In Patel et al.'s2 systematic review and meta-analysis, consistent results on improving pulmonary function, exercise capacity and health-related quality of life were demonstrated. Different techniques exist to reduce hyperinflation bronchoscopically, and while vapour ablation, sealants and coils are available and being researched, the currently most widely implemented are one-way endobronchial valves (EBVs), which have progressed from experimental therapy to standard of care1,3. BLVR is still a relatively novel technique in full development and has only recently been upgraded to the highest level of evidence in the Global Initiative for Chronic Obstructive Lung Disease 2023 report1.In this narrative review, we present the most recent developments in BLVR using EBV, focussing on primary research describing patient selection, (long-term) outcomes and extrapulmonary effects.Purpose of review Bronchoscopic lung volume reduction (BLVR) is a novel and effective treatment for a specific phenotype of chronic obstructive pulmonary disease (COPD) characterized by advanced emphysema with static lung hyperinflation and severe breathlessness. This review aims to provide an overview of the recent advances made in BLVR.For achieving optimal outcomes with BLVR, patient selection and target lobe identification is crucial. BLVR has recently also been established to improve pulmonary function, exercise capacity and quality of life in COPD patients falling outside the standard treatment criteria, including patients with moderate hyperinflation, chronic hypercapnic failure or with very low diffusion capacity. In a cluster analysis, target lobe characteristics like emphysema destruction, air trapping and perfusion were found to be important discriminators between responders and non-responders. A potential survival benefit has been demonstrated in BLVR-treated patients when compared to non-treated patients. Long-term outcomes showed sustained outcomes of BLVR; however, effects decline over time, probably due to disease progression.BLVR using one-way endobronchial valves has become a guideline treatment offered in specialized intervention centres for a specific subgroup of COPD patients. Recent studies further characterize responders, describe extrapulmonary effects of BLVR and show positive long-term outcomes and a potential survival benefit.R. Posthuma is supported by the Lung Foundation Netherlands, grant number: 5.1.17.171.0.There are no conflicts of interest.Patients with chronic obstructive pulmonary disease (COPD) suffer from respiratory symptoms and reduced quality of life due to destruction and/or inflammation of the airways and alveoli, leading to airflow limitation1. Despite pharmacological and non-pharmacological therapies, patients with advanced COPD often remain highly symptomatic with debilitating breathlessness and reduced exercise capacity. In the last decade, bronchoscopic lung volume reduction (BLVR) emerged as an effective intervention in a carefully selected subgroup of COPD patients characterized by severe emphysema, static lung hyperinflation and breathlessness. In Patel et al.'s2 systematic review and meta-analysis, consistent results on improving pulmonary function, exercise capacity and health-related quality of life were demonstrated. Different techniques exist to reduce hyperinflation bronchoscopically, and while vapour ablation, sealants and coils are available and being researched, the currently most widely implemented are one-way endobronchial valves (EBVs), which have progressed from experimental therapy to standard of care1,3. BLVR is still a relatively novel technique in full development and has only recently been upgraded to the highest level of evidence in the Global Initiative for Chronic Obstructive Lung Disease 2023 report1.In this narrative review, we present the most recent developments in BLVR using EBV, focussing on primary research describing patient selection, (long-term) outcomes and extrapulmonary effects.Purpose of review Bronchoscopic lung volume reduction (BLVR) is a novel and effective treatment for a specific phenotype of chronic obstructive pulmonary disease (COPD) characterized by advanced emphysema with static lung hyperinflation and severe breathlessness. This review aims to provide an overview of the recent advances made in BLVR.For achieving optimal outcomes with BLVR, patient selection and target lobe identification is crucial. BLVR has recently also been established to improve pulmonary function, exercise capacity and quality of life in COPD patients falling outside the standard treatment criteria, including patients with moderate hyperinflation, chronic hypercapnic failure or with very low diffusion capacity. In a cluster analysis, target lobe characteristics like emphysema destruction, air trapping and perfusion were found to be important discriminators between responders and non-responders. A potential survival benefit has been demonstrated in BLVR-treated patients when compared to non-treated patients. Long-term outcomes showed sustained outcomes of BLVR; however, effects decline over time, probably due to disease progression.BLVR using one-way endobronchial valves has become a guideline treatment offered in specialized intervention centres for a specific subgroup of COPD patients. Recent studies further characterize responders, describe extrapulmonary effects of BLVR and show positive long-term outcomes and a potential survival benefit.R. Posthuma is supported by the Lung Foundation Netherlands, grant number: 5.1.17.171.0.There are no conflicts of interest.Patients with chronic obstructive pulmonary disease (COPD) suffer from respiratory symptoms and reduced quality of life due to destruction and/or inflammation of the airways and alveoli, leading to airflow limitation1. Despite pharmacological and non-pharmacological therapies, patients with advanced COPD often remain highly symptomatic with debilitating breathlessness and reduced exercise capacity. In the last decade, bronchoscopic lung volume reduction (BLVR) emerged as an effective intervention in a carefully selected subgroup of COPD patients characterized by severe emphysema, static lung hyperinflation and breathlessness. In Patel et al.'s2 systematic review and meta-analysis, consistent results on improving pulmonary function, exercise capacity and health-related quality of life were demonstrated. Different techniques exist to reduce hyperinflation bronchoscopically, and while vapour ablation, sealants and coils are available and being researched, the currently most widely implemented are one-way endobronchial valves (EBVs), which have progressed from experimental therapy to standard of care1,3. BLVR is still a relatively novel technique in full development and has only recently been upgraded to the highest level of evidence in the Global Initiative for Chronic Obstructive Lung Disease 2023 report1.In this narrative review, we present the most recent developments in BLVR using EBV, focussing on primary research describing patient selection, (long-term) outcomes and extrapulmonary effects.Purpose of review Bronchoscopic lung volume reduction (BLVR) is a novel and effective treatment for a specific phenotype of chronic obstructive pulmonary disease (COPD) characterized by advanced emphysema with static lung hyperinflation and severe breathlessness. This review aims to provide an overview of the recent advances made in BLVR.For achieving optimal outcomes with BLVR, patient selection and target lobe identification is crucial. BLVR has recently also been established to improve pulmonary function, exercise capacity and quality of life in COPD patients falling outside the standard treatment criteria, including patients wit
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| 36. |
- Billsten, Helena, et al.
(författare)
-
Photophysical Properties of Xanthophylls in Carotenoproteins from Human Retina.
- 2003
-
Ingår i: Photochemistry and Photobiology. - 0031-8655. ; 78:2, s. 138-145
-
Tidskriftsartikel (refereegranskat)abstract
- The macula of the human retina contains high amounts of the xanthophyll carotenoids lutein and zeaxanthin [a mixture of (3R,3′R)-zeaxanthin and (3R,3′S-meso)-zeaxanthin]. Recently, it was shown that the uptake and the stabilization of zeaxanthin and lutein into the retina are likely to be mediated by specific xanthophyll-binding proteins (XBP). Here, we have used femtosecond pump–probe spectroscopy to study the dynamics of the S1 state of these xanthophylls in xanthophyll-enriched and native XBP. The results from the native XBP and the enriched XBP were then compared with those for carotenoids in organic solvents and in detergent micelles. Steady-state and transient absorption spectra show that the incorporation of xanthophylls into the protein causes a redshift of the spectra, which is stronger for lutein than for zeaxanthin. The transient absorption spectra further indicate that a part of the xanthophylls remains unbound in the xanthophyll-enriched XBP. The transient absorption spectra of the native XBP prove the presence of both xanthophylls in native XBP. Although the S1 lifetime of lutein does not exhibit any changes when measured in solution, micelles or XBP, we have observed the influence of the environment on the S1 lifetime of meso-zeaxanthin, which has a longer (12 ps) lifetime in XBP than in solution (9 ps). The most pronounced effect was found for vibrational relaxation in the S1 state, which is significantly slower for xanthophylls in XBP compared with micelles and solution. This effect is more pronounced for meso-zeaxanthin, suggesting a specific site of binding of this carotenoid to XBP.
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| 37. |
- Johansson, Jonas, et al.
(författare)
-
Time-Resolved Studies of Light Propagation in Crassula and Phaseolus Leaves
- 1999
-
Ingår i: Photochemistry and Photobiology. - 0031-8655. ; 69:2, s. 242-247
-
Tidskriftsartikel (refereegranskat)abstract
- Time-resolved transmittance was used to extract in vivo optical properties of leaves of green plants experimentally. In time-resolved transmittance measurements an ultrashort light pulse is directed onto the surface of the object and the transmitted light is measured with a time resolution in the range of picoseconds. A table-top terawatt laser was used to generate 200 fs light pulses at 790 nm with a repetition rate of 10 Hz. The light pulses were focused through a cuvette filled with water to produce white light pulses and optical filters were placed in the beam path to select the wavelength of the light focused onto the leaf surface. The time profiles of the light transmitted through the leaves was recorded with a streak camera having a time resolution of about 2.5 ps. Results from Crassula falcata and Phaseolus vulgaris studied at 550, 670 and 740 nm are reported. The three selected wavelength regions represent medium, high and a low absorption of light, respectively. A library of curves was generated using Monte Carlo simulation, and the absorption and scattering coefficients were extracted by comparison of experimental curves with this library. Our results suggest that in the case of the thin (200 μm) Phaseolus leaves and certainly in the case of the thick (4 mm) Crassula leaves, light scattering plays an important role in light transport through the leaf and should also affect light flux in these leaves.
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| 38. |
- Andersson-Engels, Stefan, et al.
(författare)
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Fluorescence Imaging and Point Measurements of Tissue - Applications To the Demarcation of Malignant-tumors and Atherosclerotic Lesions From Normal Tissue
- 1991
-
Ingår i: Photochemistry and Photobiology. - 0031-8655. ; 53:6, s. 807-814
-
Tidskriftsartikel (refereegranskat)abstract
- The possibilities of using laser-induced fluorescence for tissue diagnostics are discussed. The tissue types investigated are malignant tumors and atherosclerotic lesions. Studies with natural autofluorescence as well as with fluorescent tumor markers are included in this paper. Fluorescence emission and decay data are presented for some tissue chromophores contributing to tissue autofluorescence. Optical spectroscopic characteristics of fluorescent malignant tumor markers are analyzed and instrumental designs for clinical applications are discussed. Images recorded with a multicolor fluorescence imaging system developed in Lund are presented.
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| 39. |
- Andersson, PA, et al.
(författare)
-
Photophysical characterization of natural cis-carotenoids
- 2001
-
Ingår i: PHOTOCHEMISTRY AND PHOTOBIOLOGY. - 0031-8655. ; 74:4, s. 549-57
-
Tidskriftsartikel (refereegranskat)abstract
- By means of steady-state fluorescence spectroscopy we explore the photophysics of two lowest lying singlet excited states in two natural 15-cis-carotenoids, namely phytoene and phytofluene, possessing three and five conjugated double bonds (N), respectively. The results are interpreted in relation to the photophysics of all-trans-carotenoids with varying N. The fluorescence of phytofluene is more Stokes-shifted relative to that of phytoene, and is ascribed to the forbidden S-1 --> S-0 transition, with its first excited singlet state (S-1) lying 3340 cm(-1) below the dipole allowed second excited singlet state (S-2), at 77 K. For phytoene the S-2 and S-1 potential surfaces are closer in energy, probably giving rise to the mixed S-2 and S-1 fluorescence characteristics. The origin of phytoene fluorescence is discussed and is suggested to be due to the S-1 --> S-0 transition; with the S-1 state located 1100 cm(-1) below S-2 at 77 K. The dependence of the fluorescence quantum yield on temperature and viscosity shows that large amplitude molecular motions are involved in the radiationless relaxation process of phytoene. The transition dipole moment of absorption and emission are parallel in phytoene and nonparallel in phytofluene.
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| 40. |
- Björn, Lars Olof
(författare)
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Light-induced linear dichroism in photoreversibly photochromic sensor pigments 1. Theory
- 1981
-
Ingår i: Photochemistry and Photobiology. - 0031-8655. ; 33:5, s. 707-711
-
Tidskriftsartikel (refereegranskat)abstract
- With a photoreversibly photochromic regulator pigment such as phytochrome, linear action dichroism could theoretically be obtained after photoselection even if the molecules are initially randomly oriented. If randomly oriented Pr (red-absorbing phytochrome) (plant photoregulators) molecules are partially converted to Pfr (far-red absorbing phytochrome) molecules by plane-polarized red light, those molecules will preferentially be converted which have their red transition moments nearly parallel to the electric vector of the red light. The effect of subsequent plane-polarized far-red light will depend on the plane of polarization. A general theory is developed for how this can be used to determine whether or not the transition moment changes direction during conversion. The pigment need not be isolated, since only physiological reactions (such as germination or chromatic adaptation) are measured.
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| 41. |
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| 42. |
- Björn, Lars Olof, et al.
(författare)
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Quantifying light and ultraviolet radiation in plant biology
- 1996
-
Ingår i: Photochemistry and Photobiology. - 0031-8655. ; 64:3, s. 403-406
-
Tidskriftsartikel (refereegranskat)abstract
- Fluence rate and irradiance, two parameters used to quantify light and ultraviolet radiation, do not have a constant relation under natural fight conditions, A method is described for measuring fluence rate, the preferred parameter, using meters intended for irradiance measurements. Values measured under natural light conditions are compared to a daylight model.
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| 43. |
- Björn, Lars Olof, et al.
(författare)
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Studies on energy dissipation in phycobilisomes using the Kennard-Stepanov relation between absoption and fluorescence emission spectra
- 1986
-
Ingår i: Photochemistry and Photobiology. - 0031-8655. ; 44:4, s. 535-542
-
Tidskriftsartikel (refereegranskat)abstract
- Absorption and fluorescence emission spectra were measured at room temperature (ca. 22.degree.C) for solutions of phycocyanin-1, phycocyanin-2, and allophycocyanin from Phormidium luridum, and also for phycobilisome preparations from various blue-green algae (Anabaena variabilis, Nostoc muscorum strain A, Nostoc sp. strain Mac. Phormidium luridum). Kennard-Stepanov (KS) temperatures (T) were computed using the Kennard-Stepanov relationship F(.lambda.) = b A (.lambda.) (.lambda.-5 exp(-hc/.lambda.kT), where F(.lambda.) stands for fluorescence (energy per wavelength interval) as a function of wavelength (.lambda.), A(.lambda.) is absorbance as a function of wavelength, b a proportionality factor, and h, c and k are Planck's constant, the velocity of light and Boltzmann's constant, respectively. In most cases experimental data followed the expected relationship, but at low ionic strength allophycocyanin gave a clearly biphasic KS plot, i.e. In .lambda.5 F(.lambda.)/A(.lambda.) vs l /.lambda.. This could be due to the presence of both monomers and trimers in the sample at low ionic strength. For purified allophycocyanin and phycocyanins (PC-1 and PC-2) as well as phycobilisomes from Phormidium luridum, the KS temperatures were only slightly (insignificantly) elevated above the sample temperature. Thus, after absorption of a photon, vibrational and configurational equilibration is essentially completed before emission of the fluorescence photon takes place. For phycobilisomes from Anabaena variabilis and the two Nostoc species the KS temperatures were moderately elevated. Since there was no correlation between radiation temperature and excitation wavelength, the elevation is not due to excess (undissipated) vibrational energy, but rather to incomplete configurational equilibration.
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| 44. |
- Danielsen, Patricia L, et al.
(författare)
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Acute Ultraviolet Radiation Perturbs Epithelialization but not the Biomechanical Strength of Full-thickness Cutaneous Wounds.
- 2016
-
Ingår i: Photochemistry and Photobiology. - : Wiley. - 0031-8655. ; 92:1, s. 187-192
-
Tidskriftsartikel (refereegranskat)abstract
- We hypothesized that priming of the skin with ultraviolet radiation (UVR) before being injured would enhance wound healing. Four groups, each comprising 20 immunocompetent hairless mice, were exposed to simulated solar irradiation in escalating UVR doses; 0 SED (standard erythema dose) = control, 1 SED, 3 SED and 5 SED. Twenty-four h after UV irradiation, inflammation was quantified by skin reflectance (erythema) and myeloperoxidase (MPO) tissue levels, and two 6-mm full-thickness excisional wounds and one 3-cm incisional wound were inflicted. Epidermal hyperplasia was assessed by quantitative histology. Five days after wounding, wound coverage by neoepithelium and wound width of the excisional wounds was quantified in hematoxylin-eosin sections, and breaking strength was measured in strips from incisional wounds. Erythema (P < 0.001), MPO levels (P < 0.0005) and epidermal cell layers (P < 0.001) increased dose-dependently by UV exposure of dorsal skin. In the excisional wounds, epithelial coverage decreased (P = 0.024) by increasing the UVR dose while there was no significant difference (P = 0.765) in wound MPO levels. Neither wound width (P = 0.850) nor breaking strength (P = 0.320) differed among the groups. Solar-simulated UVR 24 h before wounding impaired epithelialization but was not detrimental for surgical wound healing. This article is protected by copyright. All rights reserved.
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| 45. |
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| 46. |
- Sundqvist, C, et al.
(författare)
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Light-induced linear dichroism in photoreversibly photochromic sensor pigments 2. Chromophore rotation in immobilized phytochrome
- 1983
-
Ingår i: Photochemistry and Photobiology. - 0031-8655. ; 37:1, s. 69-75
-
Tidskriftsartikel (refereegranskat)abstract
- Large phytochrome ((P) from Avena sativa) immobilized via anti-phytochrome immunoglobulin bound to Sepharose beads was irradiated to saturation with unpolarized far-red (fr) light. The apparent absorbance level was recorded in a dual wavelength spectrophotometer with both measuring beams set to either 600 or 730 nm and polarized perpendicular to each other. The sample was then irradiated with red (r) polarized light. The apparent change in absorbance obtained after this irradiation indicated that purified phytochrome could show linear dichroism. From the absorbance values obtained it was computed that the direction of the long-wavelength transition moment changes by either 32.degree. or 148.degree., when phytochrome is transformed from P1r to Pfr. Considering the model of Hahn and Song (1981), the latter value appears more likely. In light of these results, the conclusions drawn from in vivo experiments on action dichroism in Dryopteris, Adiantum (Kadota et al.,1982) and Mougeoutia, which point to a 90.degree. rotation should be reconsidered.
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| 47. |
- Svensson, Jenny, et al.
(författare)
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Tumor selectivity at short times following systemic administration of a liposomal temoporfin formulation in a murine tumor model
- 2007
-
Ingår i: Photochemistry and Photobiology. - 0031-8655. ; 83:5, s. 1211-1219
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Tidskriftsartikel (refereegranskat)abstract
- Meso-tetra(hydroxyphenyl)chlorin (mTHPC) (INN: Temoporfin) is one of the most potent photodynamically active substances in clinical use. Treatment protocols for Temoporfin-mediated photodynamic therapy often rely on drug-light intervals of several days in order for the photosensitizer to accumulate within the target tissue, though tumor selectivity is limited. Here, the mTHPC localization was studied at 2-8 h following systemic administration of a liposomal Temoporfin formulation (0.15 mg kg(-1) b.w.) in HT29 human colon adermcarcinoma in NMRI nu/nu mice. Photosensitizer distribution within tumor and internal organs was investigated by means of high performance liquid chromatography following chemical extraction, as well as in situ fluorescence imaging and point-monitoring fluorescence spectroscopy. For tumor tissue, the Temoporfin concentrations at 4 h (0.16 +/- 0.024 ng mg(-1)) and 8 h (0.18 +/- 0.064 ng mg(-1)) were significantly higher than at 2 It (0.08 +/- 0.026 ng mg(-1)). The average tumor-to-muscle and the tumor-to-skin selectivity were 6.6 and 2, respectively, and did not vary significantly with time after photosensitizer injection. In plasma, the Temoporfin concentration was low (0.07 +/- 0.07 ng mg(-1)) and showed no significant variation with time. Our results indicate a rapid biodistribution and clearance from the bloodstream. Within the same type of organ, data from both fluorescence methods generally exhibited a significant correlation with the extraction results.
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| 48. |
- Ahmadi, Zainab, et al.
(författare)
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Palliative oxygen for chronic breathlessness : What new evidence?
- 2017
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Ingår i: Current Opinion in Supportive and Palliative Care. - 1751-4258. ; 11:3, s. 159-164
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Forskningsöversikt (refereegranskat)abstract
- Purpose of review Supplemental oxygen improves survival in patients with chronic obstructive pulmonary disease (COPD) and severe hypoxaemia, but the effect of oxygen therapy in mild or moderate hypoxaemia to reduce symptomatic chronic breathlessness remains unclear. This review provides an overview of recent evidence about the role of oxygen therapy for the relief of chronic breathlessness in advanced illness. Recent findings In COPD, a recent Cochrane review strengthens earlier findings regarding the positive effect of supplemental oxygen compared with air during exercise test in the training setting. The novel analysis of effect of oxygen therapy on quality of life (QoL) showed no clear effect. Short-burst oxygen therapy given before exercise had no effect and should not be used. Summary Supplemental oxygen during exercise has been shown to reduce breathlessness in patients with COPD who have no or mild hypoxaemia, but it is not clear whether the reduction in breathlessness shown in the laboratory setting translates into a clinically important benefit. Further studies are needed to establish this.
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| 49. |
- Ahmadi, Zainab
(författare)
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The burden of chronic breathlessness across the population
- 2018
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Ingår i: Current Opinion in Supportive and Palliative Care. - 1751-4258. ; 12:3, s. 214-218
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Forskningsöversikt (refereegranskat)abstract
- Purpose of review Chronic breathlessness is a common and distressing symptom globally. It is associated with major adverse health outcomes. This review provides an overview of new evidence about the prevalence of chronic breathlessness in the population. Recent findings A literature search was conducted using MEDLINE database including studies on prevalence of chronic breathlessness and its impact on the community published between 2016 and 2018. Identified studies were divided into four themes: breathlessness in relation to sex, BMI, quality of life and age (the elderly). In the general population, breathlessness was twice as common in women as in men related to their smaller absolute lung volumes. Obesity was to be found an independent risk factor for chronic breathlessness. A strong association between chronic breathlessness and poor physical and mental health-related quality of life was found across all adult age groups. Among elderly people, breathlessness predicted activity of daily living decline over 5 years. Summary Interesting large population-based studies published recently have shed light on the association between chronic breathlessness and sex, obesity, quality of life and increasing age.
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| 50. |
- Ekström, Magnus, et al.
(författare)
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Editorial : Breathing problems in focus
- 2021
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Ingår i: Current Opinion in Supportive and Palliative Care. - 1751-4266. ; 15:4, s. 197-198
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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