bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE ROLE OF TRANSFERRIN RECEPTOR (CD71) IN PHOTODYNAMIC THERAPY OF ACTIVATED AND MALIGNANT LYMPHOCYTES USING THE HEME PRECURSOR δ‐AMINOLEVULINIC ACID (ALA)
Authors: Rittenhouse‐Diakun K. , Leengoed H. VAN , Morgan J. , Hryhorenko E. , Paszkiewicz G. , Whitaker J. E. , Oseroff A. R. 
Published: January 2008

AbstractEndogenously generated protoporphyrin IX (PpIX) from exogenous ALA can be an effective photosensitizer. PpIX accumulation is inversely dependent on available intracellular iron, which is required for the conversion of PpIX to heme. Iron also is necessary for cell replication. Since iron can be toxic, intracellular iron levels are tightly controlled. Activated and proliferating cells respond to the demand for intracellular iron by upregulating membrane expression of the transferrin receptor (CD71) which is needed for iron uptake. We predicted that activated lymphocytes (CD71 +) would preferentially accumulate PpIX because of their lower intracellular iron levels and because of competition for iron between ALA‐induced heme production and cellular growth processes. Thus, the CD71+ cells could serve as PDT targets. Stimulation of human peripheral blood lymphocytes (PBL) with the mitogens, phytohemagglutinin A, concanavalin A and pokeweed prior to incubation with ALA results in PpIX accumulation correlating with level of activation. Activated lymphocytes expressing high levels of surface CD71 transferrin receptors generated more PpIX than those with low CD71 expression. Incubating activated cells in transferrin depleted medium (thereby decreasing the iron availability) further increased PpIX levels. Malignant, CD71 + T lymphocytes from a patient with cutaneous T‐cell lymphoma (CTCL)/Sezary syndrome also accumulated increased PpIX levels in comparison to norma] lymphocytes. PDT of activated lymphocytes and Sezary cells after ALA incubation demonstrated preferential killing compared to normal, unstimulated PBL. These findings suggest a possible mechanism for the selectivity of ALA PDT for activated CD71+ cells. They also indicate a clinical use for ALA‐PDT in therapy directed towards the malignant lymphocytes in leukemias and lymphomas, and as animmunomodulatory agent.
CHEMILUMINESCENCE and EPR STUDIES ON THE EXCITATION SITE OF FERRIC‐HEME‐OXO COMPLEXES OF NATURAL and MODEL HEME SYSTEMS
Authors: Liu Yang , Nohl Hans 
Published: January 2008

Abstract—Chemiluminescence was detected both in the reaction system of H2O2 plus heme proteins such as methemo‐ and metmyoglobin and ferric‐protoheme complexes used as a model system. The intensity of chemiluminescence was found to be mediated by ligand binding to the sixth coordination site of the ferric‐protoheme compounds, e.g. chemiluminescence was not observed with the bisimidazole ferric‐protoheme complex. On the other hand the pentacoordinated histidine ferric‐protoheme complex exhibited strong light emission. Comparative studies with various ligand‐heme compounds elucidated that light emission was inversely correlated with the binding strength of the respective ligand at the sixth coordination site.The basic reaction mechanism causing the establishment of an excited state was studied by monitoring chemiluminescence and EPR signal formation of ligand‐modified heme proteins in the presence of different electron donors. External electron donors such as Trolox C, TMPD and ascorbic acid affected a strong reduction in the development of chemiluminescence suggesting the essential involvement of an inner‐molecular electron transfer process. Our results allow the conclusion that chemiluminescence is generated from the decay of an excited state of oxo‐heme compounds established as a result of a one electron transfer step from a ligand group to heme iron.
EFFECT OF IRON(III) ON CHEMILUMINESCENCE FROM THE NEUTRALIZATION REACTION OF NITRIC ACID and POTASSIUM HYDROXIDE
Authors: Fujiwara Terufumi , Sakai Hiroyuki , Kumamaru Takahiro 
Published: January 2008

Abstract—Low levels (around 90 μM) of iron(III) caused an increase in chemiluminescence (CL) from the neutralization reaction involving nitric acid and potassium hydroxide without use of any luminescent reagent. When oxygen was excluded from the reaction, a significant decrease in the CL emission was observed. This suggests that molecular oxygen present in the solutions may play an important role in the process of the iron‐catalyzed CL induced by the neutralization reaction, which liberates a sufficient energy. Other experimental parameters like the influence of several other metal ions, counteranions and acid media were also examined. The results showed that the observed CL enhancement by iron(III) proved to become most remarkable under sporadical conditions alone, and the presence of small amounts (less than 0.20 mM) of sulfate ion increase the catalytic activity of iron(III). A possible mechanism involving transient formation of iron–radical complexes upon neutralization and subsequent reaction of the complexes with molecular oxygen is considered for the present CL reaction.
THE ACTION SPECTRA FOR UV‐INDUCED SUPPRESSION OF MLR and MECLR SHOW THAT IMMUNOSUPPRESSION IS MEDIATED BY DNA DAMAGE
Authors: Hurks H. M. H. , Out‐Luiting C. , Vermeer B. J. , Claas F. H. J. , Mommaas A. M. 
Published: January 2008

Abstract—‐Ultraviolet‐B (UVB,280–320 nm) radiation can promote the induction of skin cancer by two mechanisms: damage of epidermal DNA and suppression of the immune system, allowing the developing tumor to escape immune surveillance. The mixed lymphocyte reaction (MLR) and the mixed epidermal cell lymphocyte reaction (MECLR) are commonly used methods to study the immunosuppressive effects of UVB radiation. To obtain a better understanding of the mechanism by which UVB radiation decreases the alloactivating capacity of in vitro‐irradiated cells, action spectra for the MLR and MECLR were determined. Suspensions of peripheral blood mononuclear cells or epidermal cells were irradiated with monochromatic light of 254, 297, 302 or 312 nm and used as stimulator cells in the MLR or MECLR. Using dose‐response curves for each wavelength, the action spectra were calculated. Both MLR and MECLR action spectra had a maximum at 254 nm and a relative sensitivity at 312 nm that was a thousand times lower than at 254 nm. Strikingly, the action spectra corresponded very closely to the action spectra that were found by Matsunaga et al. (Photochem. Photobiol. 54,403–410, 1991) for the induction of thymine dimers and (6‐4)photoproducts in irradiated calf thymus DNA solutions, strongly suggesting that the UV‐induced abrogation of the MLR and MECLR responses is mediated by UV‐induced DNA damage. Furthermore, the action spectra for the MLR and MECLR were similar, suggesting that they share a common mechanism for UV‐induced suppression.
In vitro DEMONSTRATION OF A FUNDAMENTAL DIFFERENCE IN THE PROLIFERATION OF MURINE and HUMAN BONE MARROW and LYMPHOCYTES FOLLOWING ULTRAVIOLET IRRADIATION: RELEVANCE TO BONE MARROW TRANSPLANTATION
Authors: Hudson J. G. , Pullens R. , Godwin V. , Preece A. W. , Pamphilon D. H. 
Published: January 2008

Abstract—Exposure of rodent allogeneic donor marrow and splenocyte grafts to ultraviolet radiation (UVR) has been shown to permit durable engraftment at doses that abolish graft‐versus‐host disease (GVHD) and graft rejection. We have compared both murine and human alloreactive and mitogen‐induced lymphoid responses and bone marrow proliferation in mixed lymphocyte culture (MLC), phy‐tohemagglutinin (PHA)‐induced proliferation and colony‐forming unit‐granulocyte/macrophage (CFU‐GM) assays using germicidal UVC (200–290nm), broadband and narrowband UVB (290–320nm) and UVA (320^100 nm) sources. Our data show a wavelength and dose‐dependent reduction in lymphoid proliferation in the mouse with CFU‐GM survival of50–75% of control at doses required to abolish allogeneic lymphocyte responses for all lamps. In contrast, human lymphocyte responses are more resistant to UVC with CFU‐GM proliferation reduced to zero when allostimulation is abolished. Mito‐gen‐induced lymphoid responses show a similar wavelength‐dependent sensitivity. Abolition of response in MLC using UV‐irradiated stimulator cells was less sensitive than proliferation with UV‐irradiated responder cells at all wavelengths in both species. With all sources, murine CFU‐GM proliferation is less susceptible to UVR than human marrow at doses required to abolish lymphoid responses.
THE DEVELOPMENT OF PERSONAL DOSIMETERS FOR USE IN THE VISIBLE AND ULTRAVIOLET WAVELENGTH REGIONS
Authors: Duncan D. D. , Schneider W. , West K. J. , Kirkpatrick S. J. , West S. K. 
Published: January 2008

Abstract—We have designed, developed, and field evaluated a two‐part personal dosimeter for estimating ocular exposure to visible and ultraviolet radiation. The detector head is compact enough to be mounted on the bow of eyeglass frames, and the recorder is small enough to be carried in a shirt pocket. The detector head consists of a silicon photodiode with filter (Schott glass GG400) and diffuser for visible light measurements and a polysulphone film badge for ultraviolet‐B (UVB, 290–320 nm) measurements. The measurements correspond well to those obtained using ambient monitors and should be useful for studies of ocular UVB exposure.
INCREASED UV EXPOSURE IN FINLAND IN 1993
Authors: Jokela Kari , Leszczynski Kirsti , Visuri Reijo , Ylianttila Lasse 
Published: January 2008

Abstract—Exceptionally low total ozone, up to 40% below the normal level, was measured over Northern Europe during winter and spring in 1992 and 1993. In 1993 the depletion persisted up to the end of May, resulting in a significant increase of biologically effective UV radiation. The increases were significantly smaller in 1992 and 1994 than in 1993. The UV exposure of the Finnish population was evaluated through measurements and theoretical calculations. The increase in measured erythemal (International Lighting Commission) UV falling onto horizontal surfaces on clear days was determined relative to model calculations for an average ozone amount. The increase was on average 10% from April to May 1993, and the maximal measured increase was 34%. Theoretical calculations for both erythemal and carcinogenic (Skin Cancer Utrecht‐Philadelphia) UV indicated that in 1993 the theoretical annual increase to a vertical (cylinder) surface ranged from 8 to 13% in Finland. The reflection of UV from snow considerably increases facial UV doses in Northern Finland.
Picosecond Fluorescence of Merocyanines Derived from Photochromic Spironaphthoxazines
Authors: Monti Sandra , Malatesta Vincenzo , Bortolus Pietro , Magde Douglas 
Published: January 2008

AbstractThe emission of the merocyanines derived from the photochromic 1, 3, 3‐trimethylspiro[indoline‐2,3′[3H]naphth[2,1‐b][1, 4]oxazine] 1, the 4, 5‐dimethyl‐substituted compound 2 and the 6′‐piperidino‐substituted derivative 3, in solution with acetonitrile or ethanol, was studied by means of a time‐correlated single photon counting system with ca 10 ps time resolution. The signal decays were described by a sum of two or three exponential components with τ1=10–60 ps, τ2= 0.5–1ns, τ3=1–2 ns, corresponding to the contribution of different fluorescing merocyanine isomers. The most intense emission, the shortest lived one, is characterized by extremely low quantum yields (<10−6). The effect of the addition of LiClO4 to acetonitrile solutions of 2 is in agreement with the formation of ground‐state complexes with particular open isomers.
The Use of UV Radiation to Control the Architecture of Salvia splendens Plants. II. Relationships between PAR Levels and UV Radiation in the Photoregulation of Stem Elongation
Authors: Bertram Lise , Lercari Bartolomeo 
Published: January 2008

AbstractThe effects of UV irradiation on stem elongation of Salvia splendens plants preadapted to two and grown under four different irradiances of visible light, were studied using linear voltage differential transducers. The levels of radiant energy during the experimental phase showed a temporary and opposite effect during the day‐time and the night‐time: increasing levels of photosynthetically active radiation (PAR)† reduced stem growth during the day and enhanced elongation growth during the night. It appears, therefore, that similar final stem elongation in plants grown under very different PAR levels is the result of the algebraic sum of different and sometimes opposite effects of PAR on stem growth. Except for the controls, the plants received one UV treatment from Philips TL 12 40 W fluorescent tubes either in the middle of the light period or at the beginning of the dark period. The results show that the preadapting PAR conditions changed the sensitivity of the plants to both UV and to the following PAR conditions. The sensitivity of S. splendens to UV radiation is inversely correlated to the PAR levels before and during the UV treatments. Furthermore the presence of active photosynthetic and photomorphogenic systems, i. e. the presence of visible light during the UV treatment, decreases the sensitivity of the plants to UV radiation. Depending on PAR levels, the UV treatments given during the night induced a temporary inhibition of growth followed by a promotion of stem elongation.
Serine Conjugates of Chlorophyll and Bacteriochlorophyll: Photocytotoxicity in vitro and Tissue Distribution in Mice Bearing Melanoma Tumors
Authors: Rosenbach‐Belkin V. , Chen L. , Fiedor L. , Tregub I. , Pavlotsky F. , Brumfeld V. , Salomon Y. , Scherz A. 
Published: January 2008

AbstractChlorophyll (Chl) and bacteriochlorophyll (Bchl) have been made water soluble by transesterfication with serine (Ser) at the propionyl residue and tested as potential reagents for photodynamic therapy (PDT). Photocytotoxicity of the conjugates Chl‐Ser and Bchl‐Ser in M2R mouse melanoma was tested in cell cultures. Tissue uptake and clearance of the photosensitizers in CD1 nude and C57B1 mice implanted with M2R tumors are described. Photocytotoxicity in cell cultures was determined microscopically and by [3H]thymidine incorporation. The LD50 values in vitro were 0.05‐0.1 μM for both sensitizers while that of the commercially available hematoporphyrin derivative (HPD, Photosan) was over 100 times higher for the same light intensity (45 mW/cm2). Pigment concentrations were determined fluorometrically in acetone extracts of the tissues of interest at different times after intraperitoneal injection of 20 mg pigment/kg body weight. The distribution pattern of Chl‐Ser in the different tissues resembled that reported for Photofrin, chlorin and bacteriochlorin derivatives. Clearance from normal tissues was essentially completed within 16 h for Bchl‐Ser and 72 h for Chl‐Ser with mean half‐lives (t1/2) of about 2 and 7 h, respectively. In contrast, the clearance rates of these pigments and their metabolites from melanoma tumor tissue were significantly longer: t1/2= 20 h for Chl‐Ser and 15 h for Bchl‐Ser and metabolites. The clearance rates showed biphasic or single exponential decay patterns in normal tissues and in tumors, respectively. Cumulatively the high phototoxicity, simple mode of delivery and fast tissue clearance rates reported here suggest that polar conjugates of Chl and Bchl promise to be highly effective PDT reagents.
The Origin of Magnetic Field Dependent Recombination in Alkylcobalamin Radical Pairs
Authors: Natarajan Ettaya , Grissom Charles B. 
Published: January 2008

AbstractMagnetic field effect studies of alkylcobalamin photolysis provide evidence for the formation of a reactive radical pair that is born in the singlet spin state. The radical pair recombination process that is responsible for the magnetic field dependence of the continuous‐wave (CW) quantum yield is limited to the diffusive radical pair. Although the geminate radical pair of adenosylcob(III)alamin also undergoes magnetic field dependent recombination (A. M. Chagovetz and C. B. Grissom, J. Am. Chem. Soc. 115, 12152–12157, 1993), this process does not account for the magnetic field dependence of the CW quantum yield that is only observed in viscous solvents. Glycerol and ethylene glycol increase the microviscosity of the solution and thereby increase the lifetime of the spin‐correlated diffusive radical pair. This enables magnetic field dependent recombination among spin‐correlated diffusive radical pairs in the solvent cage. Magnetic field dependent recombination is not observed in the presence of nonviscosigenic alcohols such as isopropanol, thereby indicating the importance of the increased microviscosity of the medium. Paramagnetic radical scavengers that trap alkyl radicals that escape the solvent cage do not diminish the magnetic field effect on the CW quantum yield, thereby ruling out radical pair recombination among randomly diffusing radical pairs, as well as excluding the involvement of solvent‐derived radicals. Magnetic field dependent recombination among alkylcobalamin radical pairs has been simulated by a semiclassical model of radical pair dynamics and recombination. These calculations support the existence of a singlet radical pair precursor.
Formation of Cyclobutane Thymine Dimers from UVA Photosensitization of Pyridopsoralen Monoadducted DNA
Authors: Guillo Lidia Andreu , Beylot Bénédicte , Vigny Paul , Spassky Annick 
Published: January 2008

AbstractThe present report provides evidence that thymine dimerization can be UVA photosensitized at a tetranucleotide, 5′‐TATT‐3′, by a 7‐methyl‐pyrido(3, 4‐c)psoralen monoadduct in DNA. The efficiency of the photoprocess depends on the tetranucleotide flanking sequences. These results demonstrate that one DNA lesion can originate the contiguous formation of a second type of lesion and emphasize the sequence‐specific response to interaction of drugs with DNA. Results are related to the sensitivity of DNA to 1, 10‐phenanthroline‐cuprous ion complex nucleolytic activity and discussed in terms of the major role of local deformability of DNA in interaction with ligands.
Determination of Fluorescence Polarization and Absorption Anisotropy in Molecular Complexes Having Threefold Rotational Symmetry
Authors: Demidov Andrey A. , Andrews David L. 
Published: January 2008

Abstract— The current work concerns investigation of the polarization properties of complex molecular ensembles exhibiting threefold (C3) rotational symmetry, particularly with regard to the interplay between their structure and dynamics of internal energy transfer. We assume that the molecules or chromophores in such complexes possess strongly overlapped spectra both for absorption and fluorescence. Such trimeric structures are widely found in biological preparations, as for example the trimer of C‐phycocyanin (C‐PC). Higher order aggregates, e.g. hex‐amers and three‐hexamer rods, are also investigated and compared with the trimer case. The theory addresses both steady‐state and 8‐pulse excitation and establishes some links between them. Monochromophoric, bichro‐mophoric and trichromophoric molecular complexes are individually examined.For steady‐state excitation, analytical formulas are reported for the degree of fluorescence polarization and absorption anisotropy. It is shown that the polarization is dependent on the chromophore inclination relative to the symmetry axis, the relative efficiencies of absorption and fluorescence by chromophores of different spectral types, and the rates of energy equilibration. To assess the validity of the theory, it has been applied to C‐PC aggregates. Here it was found that different C‐PC aggregates provide practically identical polarization response. For S‐pulse excitation we give analytical formulas for determination of the fluorescence depolarization, and also the depolarization associated with absorption recovery, both for a monochromophoric trimer and some particular cases of bichromophoric trimer. More complicated systems are analyzed by computer modeling. Thus it transpires that the initial polarization anisotropy r(t = 0) takes the value 0.4 for all considered aggregates; the long‐time limit r(t →∞) has about the same value as is associated with steady‐state excitation. We also show that with steady‐state excitation the degree of fluorescence polarization is practically equal for various C3 aggregates of C‐PC, and that the major factor determining the polarization is the chromophore orientation relative to the symmetry axis.
Overexpression of Medaka (Oryzias latipes) Photolyase Gene in Medaka Cultured Cells and Early Embryos
Authors: Funayama Tomoo , Mitani Hiroshi , Shima Akihiro 
Published: January 2008

ABSTRACTTo study the role and the regulation of the photolyase gene in the Medaka (small teleost), we constructed a eu‐karyotic expression plasmid of the Medaka photolyase gene and introduced it into Medaka cells in vitro and in viva The expression plasmid contains a cytomegalovirus enhancer and a thymidine kinase promoter to overex‐press the photolyase gene of the Medaka. First, we trans‐fected this construct into cultured Medaka cells and established several lines of transfectant. Every transfectant showed enhanced ability of pyrimidine dimer repair in the presence of fluorescent light. In the transfectant that showed the most enhanced ability of photorepair, the augmented transcription of photolyase gene was observed compared with that of progenitor OL32 cells. In this transfectant, we also observed an enhanced rate of UV survival with 20 min of fluorescent light treatment after irradiation with a 400 J/m2 UV sunlamp. Next, the expression construct was microinjected into the embryos of the Medaka at the one cell stage. Compared with the nontreated counterparts, the overexpression of a photolyase gene was detected in the microinjected embryos, but we failed to detect a significant increase in photo‐reactivability of death at the midblastula stage.
Formation of Fluorescent and Nonfluorescent Difluoroboron Complexes in the Reaction of BF3Etherate with 21H,24H‐Bilin‐1,19‐dione Derivatives
Authors: Borle Francois , Fehr Felix , Nesvadba Petr , Gossauer Albert 
Published: January 2008

ABSTRACTOn reaction with BF3 etherate, in the presence of base, bile pigments of the biliverdin and 2,3‐dihydrobiliverdin type form two kinds of difluoroboron chelates. In one of them, which displays intensive photoluminescence, the boron atom is complexed through the nitrogen atoms of the dipyrrin moiety of the ligand molecule. In the second type of chelates, which have been characterized in the present work for the first time, the boron atom is complexed through the nitrogen atoms of the pyrrole and one of the terminal lactam rings. These BF2 complexes are devoid of manifest fluorescence. Their 1H‐NMR spectra show clear through‐space 1H‐19T spin‐spin couplings that served for structure elucidation. Bile pigment analogs, in which the pyrrolic HN group has been replaced by N‐CH3 or by divalent heteroatoms, such as an O or S atom, form only the latter type of BF2 chelates.