ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01828.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01829.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract—Transcutaneous photodynamic therapy (PDT), utilizing benzoporphyrin derivative monoacid ring A (BPD, ver‐teporfin) and whole‐body light exposure, was assessed for its capacity to modify the course of adoptively transferred experimental autoimmune encephalomyelitis (EAE) in PL mice. Using a novel cell culture technique to facilitate the induction of this neurodegenerative condition, disease signs commenced 3–4 weeks after the transfer of myelin basic protein (MBP)‐reactive lymph node or spleen cells to naive syngeneic recipients. Mice administered MBP‐sensitized lymph node cells preincu‐bated with BPD followed by whole‐body 690 nm light irradiation (15 J/cm2) did not display symptoms of EAE. Although almost all animals given MBP‐sensitized spleen cells developed EAE, mice given BPD (1 mg/kg) and the light treatment 24, 48 or 120 h after spleen cell transfer exhibited significantly less severe disease symptoms than control animals. Mice given the photodynamic treatment 24 h after spleen cell transfer also exhibited a significantly later disease onset than the control animals. Treatment of mice with PDT 24 h prior to spleen cell transfer did not influence subsequent disease severity but modestly delayed its onset. In the absence of directed light, BPD did not influence the development of EAE. Spinal cord tissues were evaluated for the presence of T cell receptor (TCR) Vα4 mRNA transcripts that specifically encode for the TCR ot‐chain of MBP‐reactive T cells of PL mice. Using the polymerase chain reaction, Va4 TCR mRNA transcripts were present in spinal cord samples prepared from almost all control mice but in only about one‐half of spinal cord samples prepared from mice treated with PDT 24 h after spleen cell transfer. These observations indicated that PDT had limited the expansion of MBP‐specific Vot4+ T cells within the central nervous system. Transcutaneous PDT represents a new technique with which to approach the treat

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01830.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract—Local photodynamic therapy may have potential in preventing myointimal hyperplasia after angioplasty. In this study, the effect of photodynamic therapy was evaluated in an experimental model of restenosis. Standardized unidirectional arterial injury with a directional atherectomy catheter was performed in porcine arteries. Animals were randomly allocated to four groups: group 1, unidirectional injury only; group 2, injury followed by local delivery of photosensitizer; group 3, injury followed by local exposure to monochromatic light; and group 4, where injury was followed by local drug delivery of photosensitizer and subsequent exposure to light (photodynamic therapy). Seven, 14 or 21 days after treatment, all experimental vessels were excised, fixed and processed for histology. An inflammatory and myoproliferative response was observed after injury in vessels from groups 1, 2 and 3. In group 4, after injury followed by photodynamic therapy, the myoproliferative response was significantly reduced. Thus, in this study, tissue hyperplasia after unidirectional injury was effectively suppressed by photodynamic therap

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01831.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract—The enzyme DNA photolyase mediates the repair of pyrimidine dimers. This repair step, a net retro [2+2] reaction, proceeds through either the cation or anion radical of the pyrimidine dimer. In order to understand how electron transfer makes the repair process possible, its energetics have been examined by photothermal beam deflection calorimetry, fluorescence quenching and quantum yield studies. The enthalpy for the cleavage reaction ofcis‐syn1,3‐dimethylthymine dimer itself was found to be ‐19 kcal/mol. In addition, from the redox potentials, the enthalpies for the cleavage reactions of the dimer cation radical and the anion radical were determined to be ‐19 kcal/mol and ‐28 kcal/mol, r

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01832.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract—The photoreaction of 2‐methyl‐l,4‐naphthoquinone (MQ, menadione) with DNA and polynucleotides in argon‐saturated aqueous solution (pH 7) was studied. Results from laser flash photolysis experiments indicate that triplet quinone reacts with DNA and polyA but not detectably with polyU by one‐electron oxidation of the bases of the nucleic acid with formation of the radical anion of the quinone. Irradiation of argon‐saturated solutions containing MQ and DNA or polynucleotides (polyU, polyA, polyG or polyC) with 334 nm light leads to an increase in molecular weight for single‐stranded DNA, polyA and to a much less extent for polyU. This finding indicates crosslink formation with quantum yields in the ra

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01833.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract—The photophysics of purinic compounds (purine, 6‐meth‐ylpurine, 6‐aminopurine [adenine], 6‐chloropurine, 6‐methoxypurine) and theophylline in acetonitrile solution were studied by pulsed laser‐induced optoacoustic spectroscopy (LIOAS) exciting at 266 nm. The effect of O2, Xe and MnCl2on the photophysical behavior of these compounds was studied; as well, the formation quantum yield of purine and 6‐methylpurine triplet states were determined, with φT= 0.88 ± 0.03 for both compounds. Multiphotonic and depletion processes were observed at high laser fluences. In order to explain this behavior, theoretical UV‐visible absorption electronic spectra from both the S0and S1state have been calculated for purines and theophylline by using the semiempirical PM3

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01834.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract—Steady‐state and multifrequency phase fluorometry were used to characterize the conformational state and conformational dynamics of recombinant tick anticoagulant peptide (Ornithodorus moubata) (TAP). The TAP contains two tryptophan residues at positions 11 and 37. The fluorescence emission varies sigmoidally as a function of pH with a pKaof 6.01 ± 0.07. This pH dependency suggests that tryptophan fluorescence is quenched by His43 at low pH. This is confirmed by modification of the his‐tidine with diethylpyrocarbonate. At pH 9 the fluorescence decay is well described by a sum of three exponentials (0.52,1.9 and 5.4 ns), which decrease all three at pH 4 (0.25, 1.61 and 4.4 ns). From the reactivity of the fluorescence lifetimes towardN‐bromosuccinimide and from the calculation of the accessibility we can attribute the long lifetime to Trpll, the short one to Trp37 and the middle one to both. The anisotropy decay was resolved into two components of 3.85 ns and 0.27 ns at pH 4 and 4.5 ns and 0.6 ns at pH 9. The long anisotropy decay time corresponds to the rotational correlation time of the protein, the short one to local mobility of the tryptophan

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01835.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract—Spectral measurements of UV irradiance at the Fraunhofer Institute at Garmisch‐Partenkirchen, Germany, are intercompared with data from two different Robert‐son‐Berger‐type meters. More than 21000 spectra gathered during 20 months of continuous operation were used for this analysis, sampling a large variety of atmospheric conditions. At low solar zenith angles the agreement (± 10%) was quite satisfactory, whereas at high solar zenith angles the broadband instruments gave systematically lower readings than the erythemally weighted spectral data. The deviation of the spectral response of the broadband instruments from the Commission Internationale de 1'Eclairage (CIE) erythema function and the cosine error provide an explanation of the observed differences that are similar for both broadband meters. Model calculations agree quite well with the observations, if an accurate measurement of the broadband spectral response is available. An analytical fit curve was established for the ratio between broadband and weighted spectral data, as a function of solar zenith angle, enabling quick and easy checks of the stability of the spectrora‐diometric system. The relative standard deviation of the data from the fit function was only2–3% in the case of cloudless sky conditions and 5% for all sky conditions, including all types of systematic and instr

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01836.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract—Dimerization of uracil monomers in a polycrystalline state by UV radiation changes the absorption characteristics of a thin layer of the material. The change in optical density, measured by spectrophotometry in the250–400 nm range, as a function of the exposure time is evaluated in terms of the biologically effective UV dose. A statistical evaluation of a great number of uracil dosimeters irradiated with a TL01 lamp from Philips establishes the possibility of evaluating the biologically effective UV dose using a uracil dosimeter. Nonlinear regression procedures were introduced to correct the absorption spectra for contributions due to light scattering and to determine the optical density values required to calculate the UV dose expressed in HUunits. Comparison of cumulative daily doses and long‐term monitoring measured by the uracil thin‐layer dosimeter and a phage T7 dosimeter are given, which allow the determination of conversion factors between various biological dosimeters under different irradiation con

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1996.tb01837.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY