bluuebunny/crossref_metadata_2025_split huggingface dataset:
ULTRAVIOLET DOSIMETRY IN OUTDOOR MEASUREMENTS BASED ON BACTERIOPHAGE T7 AS A BIOSENSOR
Authors: RONTÓ Gy , Gaspar S. , Gugolya Z. 
Published: January 2008

AbstractA simple method has been worked out for measuring the biologically effective dose (BED) of solar radiation The method uses phage T7 as a biosensor and it includes field measurements of global and direct UV radiation from the sun in the air; it has been applied to underwater measurements as well. Results of field measurements are presented with discussion of the angle‐dependent sensitivity of the biosensor. A model of spectral irradiance based on the measured values is presented. Relevance of the HT7 unit—derived earlier by us from T7 phage inactivation upon UV radiation—as a measure of the BED is also discussed.
POLARIZED SITE‐SELECTION SPECTROSCOPY OF CHLOROPHYLL a IN DETERGENT
Authors: Kwa Stefan L. S. , Voulker Silvia , Tilly Nina T. , Grondelle Rienk van , Dekker Jan P. 
Published: January 2008

AbstractMonomeric chlorophyll a (Chl a) was obtained from the isolated core antenna complex CP47 of photo‐system II after incubation with the detergent triton X‐100 and was studied by low‐temperature polarized light spectroscopy with the aim to obtain model spectra for Chi a in intact photosynthetic complexes. Evidence is presented by circular dichroism and anisotropy measurements that the isolated chlorophyll is monomeric. The absorption bandwidths are relatively large compared to those found in photosynthetic complexes due to inhomogeneous broadening introduced by the detergent. By selective laser excitation at low temperature, considerable narrowing can be achieved. A number of vibrational bands are resolved in the site‐selected, polarized absorption and fluorescence emission spectra. The emission spectrum of Chi a in detergent‐damaged CP47 is compared with that of Chi a in the intact light‐harvesting complex of photosystem II (LHC‐II) from green plants. The spectra are remarkably similar indicating that the low‐temperature thermal emitter in LHC‐II has spectral properties that are very similar to those of monomeric Chl a.
AUTHENTIC in vivo ABSORPTION SPECTRA FOR CHLOROPHYLL IN LEAVES AS DERIVED FROM in situ AND in vitro MEASUREMENTS*
Authors: Richter Thomas , Fukshansky Leonid 
Published: January 2008

AbstractOn the basis of a comprehensive treatment of light propagation in plant tissue the first authentic in vivo absorption spectrum of chlorophyll in a leaf (of Catalpa bignonioides) has been elucidated. An experimental‐theoretical procedure is described, which permits derivation of the authentic chlorophyll spectrum by purifying the in vivo absorption spectrum of a leaf from the distortions of optical origin: multiple scattering and distributional error. The procedure involves measurements of internal and external light fluxes, spatial characterization of tissue layers, cells, chloroplasts and grana stacks. Furthermore, one has to determine the local chlorophyll concentrations. The theories of radiation transfer and absorption statistics make up the theoretical basis of the procedure. The derived authentic chlorophyll spectrum differs both from the in vivo spectrum of the leaf and (although to a smaller degree) from the in vitro spectrum of chlorophyll‐protein complexes extracted from the same leaf.
SPECTRAL AND PHOTOCHEMICAL PROPERTIES OF CURCUMIN
Authors: Chignell Colin F. , Bilskj Piotr , Reszka Krzysztof J. , Motten Ann G. , Sik Robert H. , Dahl Thomas A. 
Published: January 2008

AbstractCurcumin, bis(4‐hydroxy‐3‐methoxyphenyl)‐l,6‐heptadiene‐3,5‐dione, is a natural yellow‐orange dye derived from the rhizome of Curcuma longa, an East Indian plant. In order to understand the photobiology of curcumin better we have studied the spectral and photochemical properties of both curcumin and 4‐(4‐hydroxy‐3‐methoxy‐phenyl)‐3‐buten‐2‐one (hC, half curcumin) in different solvents. In toluene, the absorption spectrum of curcumin contains some structure, which disappears in more polar solvents, e.g. ethanol, acetonitrile. Curcumin fluorescence is a broad band in acetonitrile (λmax= 524 nm), ethanol (λmax= 549 nm) or micellar solution (λmax= 557 nm) but has some structure in toluene (λmax= 460, 488 nm). The fluorescence quantum yield of curcumin is low in sodium dodecyl sulfate (SDS) solution (φ= 0.011) but higher in acetonitrile (φ= 0.104). Curcumin produced singlet oxygen upon irradiation (φ > 400 nm) in toluene or acetonitrile (Φ= 0.11 for 50 μM curcumin); in acetonitrile curcumin also quenched 1O2 (kq, = 7 × 106 M−1 s−1). Singlet oxygen production was about 10 times lower in alcohols and was hardly detectable when curcumin was solubilized in a D2O micellar solution of Triton X‐100. In SDS micelles containing curcumin no singlet oxygen phosphorescence could be observed. Curcumin photogenerates superoxide in toluene and ethanol, which was detected using the electron paramagnetic resonance/spin‐trapping technique with 5,5‐dimethyl‐pyrroline‐.N‐oxide as a trapping agent. Unidentified carbon‐centered radicals were also detected. These findings indicate that the spectral and photochemical properties of curcumin are strongly influenced by solvent. In biological systems, singlet oxygen, superoxide and products of photodegradation may all participate in curcumin phototoxicity depending on the environment of the dye.
CYTOPROTECTION AGAINST MEROCYANINE 540‐SENSITIZED PHOTOINACTIVATION OF THE Na+,K+‐ADENOSINE TRIPHOSPHATASE IN LEUKEMIA CELLS: GLUTATHIONE AND SELENOPEROXIDASE INVOLVEMENT
Authors: Lin Fubao , Girotti Albert W. 
Published: January 2008

AbstractWhen irradiated with broad‐band visible light in the presence of merocyanine 540 (MC540), murine leukemia L1210 cells grown under selenium‐deficient conditions (Se(‐) cells) accumulated lipid hydroperoxides and lost viability more rapidly than selenium‐satisfied controls (Se(+) cells). These findings suggest that cytoprotection against photoperoxidation and photokilling is mediated at least in part by selenoperoxidase (SePX) action. Similar protection against photoinactivation of an intrinsic membrane enzyme, the Na+,K+‐ATPase, has been observed. Thus, irradiation of MC540‐sensitized Se(‐) cells resulted in an immediate and progressive inactivation of ouabain‐sensitive Na+, K+‐ATPase; by contrast, activity loss in Se(+) cells was preceded by a prominent lag. Enzyme photoinactivation in Se(‐) cells was inhibited by ebselen, an SePX mimetic, confirming that SePX(s) is (are) involved in natural protection. Desferrioxamine treatment (iron sequestration/inactivation) resulted in higher hydroperoxide levels and slower Na+,K+‐ATPase inactivation during MC540/light exposure, whereas ferric‐8‐hydroxyquinoline treatment (iron supplementation) had the opposite effect. Thus, iron appears to play an important role in both of these processes. In contrast, photoinactivation of another intrinsic enzyme in L1210 cells, acetylcholinesterase (AChE), was unaffected by selenium or iron manipulation. On the basis of these findings, we propose that lipid peroxidation plays an important role in the photoinactivation of Na+,K+‐ATPase, but not AChE. This is consistent with the fact that Na+, K+‐ATPase's active site lies within the membrane bilayer, whereas AChE's active site lies outside the bilayer.
EFFECTIVENESS OF PHOTOFRIN II IN ACIWATION OF MACROPHAGES AND in vitro KILLING OF RETINOBLASTOMA CELLS
Authors: Yamamoto Nobuto , Sery Theodore W. , Hoober J. Kenneth , Willett Norman P. , Lindsay Dwight D. 
Published: January 2008

Abstract Administration of a small dose (300 ng/mouse) of photofrin II (PII) to mice, followed by 4 days of exposure to only ambient fluorescent light in animal quarters, induced Fc‐receptor‐mediated phagocytic and superoxide‐generating capacities of peritoneal macrophages by five‐ and seven‐fold, respectively. When these mice were kept in the dark for 4 days, no activation of macrophages was observed. These results suggest that macrophage activation is a consequence of photodynamic activation. Much higher doses (> 3000 ng/mouse) suppressed macrophage activity. However, 2 months after administration of 3000 ng PII/mouse, greatly enhanced phagocytic and superoxide‐generating capacities of peritoneal macrophages were observed. In vitro photodynamic activation of macrophages was analyzed after white or red fluorescent light exposure of mouse peritoneal cells (mixture of macrophages and B and T lymphocytes) in media containing PII. A short (10 s) white fluorescent light treatment of peritoneal cells in a medium containing 0.03 ng PII/mL produced the maximal level of phagocytic activity of macrophages. Illumination with the same total fluence of red fluorescent light requires a threefold higher concentration of PII to achieve the same extent of enhanced phagocytic activity of macrophages. Thus, photodynamic activation of macrophages with PII by white fluorescent light was more efficient than by red fluorescent light. Similarly, photodynamic killing of retinoblastoma cells was more efficient with white than red fluorescent light. The concentration of hematoporphyrin (HP) or PII required for direct photodynamic killing of retinoblastoma cells was roughly four orders of magnitude greater than that required for activation of macrophages. These results suggest that effective photodynamic therapy may be achieved with milder treatments that stimulate macrophage activity, an important component of immunopotentiation.
In vivo pH MEASUREMENT AND IMAGING OF TUMOR TISSUE USING A pH‐SENSITIVE FLUORESCENT PROBE (5,6–CARBOXYFLUORESCEIN): INSTRUMENTAL AND EXPERIMENTAL STUDIES
Authors: Mordon Serge , Devoisselle Jean Marie , Maunoury Vincent 
Published: January 2008

Abstract This study evaluated the effectiveness of dual‐wavelength ratio fluorescence imaging using a pH‐dependent indicator (5,6–carboxyfluorescein, 5,6–CF) for in vivo pH mapping of tissue. A prototype version of a highly sensitive fluorescence imaging device consisting of a modified xenon lamp, an image‐intensified camera and a digital imageprocessing system has been developed. 5,6–Carboxyfluorescein was used because its fluorescence emission increases as a function of pH in the physiological (6.0–7.4) pH range. The ratio of fluorescence intensities obtained with the imaging system has been calibrated using aqueous 5,6–CF standards at various pH values. Because the pH of interstitial fluid of malignant tumors tends to be lower than that of normal tissue and can be depressed by glucose administration, experiments were performed on 10 CDF mice bearing lymphoid leukemia P388 grafted subcutaneously. The range of linearity of the calibration curve was obtained between 5.3 and 6.7 with a measured pK, value of 5.93. Consequently the maximum sensitivity was observed in this range. The calculated pH from ratio images was 6.21 ± 0.12 in tumorous tissue. This value was equivalent to those obtained at the same time using microelectrodes (6.2 ± 0.3).These experiments showed that a dose of 5 mg/kg 5,6–CF and an excitation power density of 2.5 mW/cm2 are sufficient to give a fluorescent pH image of tumors. The limitation of 5,6–CF for the in vivo mapping of tissue results from its low pKa and consequent range of sensitivity. The advantages of this imaging technique compared to microelectrodes are that it (1) is noninvasive, (2) displays a two‐dimensional pH image with high resolution (profile distribution of pH in tissue) and (3) can be used to monitor pH over a few hours.
POSSIBLE ROLE OF METALLOTHIONEIN IN THE CELLULARDEFENSE MECHANISM AGAINST UVB IRRADIATION IN NEONATAL HUMAN SKIN FIBROBLASTS
Authors: Kobayashi Shizuko , Hirota Yumiko , Sayato‐Suzuki Junko , Takehana Makoto , Nishimura Hisao , Nishimura Noriko , Tohyama Chiharu 
Published: January 2008

Abstract –The role of metallothionein (MT) in protecting skin cells against UVB irradiation was investigated. Fibroblast strains from normal adult (HS‐K) and neonatal (NB1RGB) human skins as well as keratinocyte strains from human skin (SV40‐HSK) and newborn Balb/c mouse skin (Pam 212) were exposed to UVB irradiation.The sensitivity of HS‐K and NB1RGB cells to UVB irradiation was similar; those of SV40‐HSK and Pam 212 cells were two‐ and six‐fold as sensitive to UVB irradiation as HS‐K cells, respectively. The HS‐K cells contained the greatest cellular reduced form of glutathione (GSH) levels compared to the three other skin cells: the levels were 13‐, 7‐ and 6‐fold of those in NB1RGB, SV40‐HSK and Pam 212 cells, respectively. These results indicated that the sensitivity of skin cells to UVB irradiation was not always associated with their endogenous GSH levels. In particular, despite the fact that NB1 RGB cells contained a relatively small amount of GSH, they were less sensitive to UVB irradiation.NB1RGB cells contained 4–30 times more MT than those in other skin cells examined. The sulfhydryl residues of MT molecules in the NB1RGB cells were estimated to be mostly unoccupied by metals, suggesting they act in a similar way to those of GSH. Moreover, NB1RGB cells in which the MT content was elevated by dexamethasone (1 μg/mL) or Zn2+ (7 μg/mL) treatment were more resistant to UVB irradiation than nontreated ones.These results suggest that, at least in neonatal human skin fibroblasts, MT may play a role in protection against UVB irradiation.
CHEMIEXCITATION IN THE PEROXIDATIVE METABOLISM OF N‐ METHYLCARBAZOLE: MECHANISTIC IMPLICATIONS
Authors: Melo Mariza Pires DE , Cilento Giuseppe 
Published: January 2008

Abstract –The peroxidative metabolism of TV‐methylcarbazole emits light independently of the presence of oxygen. It is likely that two chemiexcited transients are formed by electron transfer to the activated peroxidase, the cation radical by one electron transfer and a cation biradical by two electron transfer consistent with the failure to observe horseradish peroxidase‐II in the steady state of the reaction. In the spectral range investigated (390–700 nm) the observed emission (570–700 nm) is ascribed to the biradical, as the latter is equivalent to an excited state of the postulated iminium cation.While lipoxygenase has no effect upon JV‐methylcarbazole, it markedly enhances the emission if peroxidase is present. This effect requires oxygen and is ascribed to an excited product formed by lipoxygenase acting upon an intermediate hydroperoxide of the aerobic process promoted by peroxidase.
PHOTOINACTIVATION (365 NM) OF VACCINIA AND HERPES SIMPLEX VIRUSES INDUCED BY A NEW BUILT‐IN DNA PHOTOSENSITIZER: 4‐THIOTHYMIDINE
Authors: Domi Arban , Siromachkova Martchela , Fourrey Jean‐Louis , Favre Alain , Beaud Georges 
Published: January 2008

AbstractThe thymidine analogue 4‐thiothymidine (s4T) strongly absorbs light at wavelengths in the UVA range (Λmax 335 nm) and we have examined the photoinactivation of vaccinia and herpes simplex viruses grown in the presence of this nucleoside. The cells used in this study (Vero, mouse 1D‐TK+) were able to grow at the same rate when cultured in the presence of 2 mM s4T or 2 mM thymidine, albeit at a slower rate than control cells. Consistent with this finding, viruses grown in the presence of1–4 mM s4T were obtained in reduced yield but retained full infectivity. Both viruses were specifically inactivated by irradiation with 365 nm light and their photosensitivity, as measured by the initial slope of the inactivation curve, increased in parallel with the concentration of s4T added to the culture medium. More than 90% of vaccinia virus grown in the presence of 4 mM s4T was inactivated. Organomercurial agarose chromatography of sheared DNA isolated from vaccinia virus grown in the presence of 2 mM s4T showed that approximately 2.5% of DNA fragments were specifically retained, as compared to 0.2% for control DNA. This value corresponds to at least one s4T residue incorporated per 30 000 nucleotides of vaccinia virus DNA. In fact, it is likely that this ratio is actually approximately 10 times higher because of the incomplete retention of control thiolated oligodeoxynucleotides. The incorporation of s4T into vaccinia virus DNA was required for photoinactivation as (1) the expression of a viral or cellular thymidine kinase was required to confer photosensitivity, and (2) virus plaque reduction assays revealed that maximal photosensitivity coincided with the first rounds of viral DNA replication. The photo‐inactivated virus was unable to induce detectable synthesis of several early proteins after infection of cells. These data show that s4T is incorporated into the DNA of vaccinia virus grown in the presence of the analogue and then behaves as a built‐in UVA light photosensitizer.
ON THE INDUCTION OF PROTECTIVE RESPONSES IN Salmonella typhimurium STRAIN TA1535/pSK1002 BY UVA (365 nm)
Authors: Rahman Md. S. , Bose Biplab , Chatterjee S. N. 
Published: January 2008

AbstractExposure to UVA (365 nm) led to growth delay, loss of viability and inhibition of 3H‐thymidine incorporation into the cells of Salmonella typhimurium strain TA1535 containing multiple copies of a plasmid pSK1002 carrying a umuC‐'lacZ fusion gene. Ultraviolet‐A induced umu gene expression, as monitored by the estimation of β‐galactosidase, in a linear fluence‐dependent manner. The induction of umu gene expression increased with the increase of postirradiation incubation period of the cells in the LB‐ampicillin (LB A) medium at 37° C and leveled off from 2 h onward. The induction of gene expression depended on concomitant protein synthesis and represented the induction of the SOS response in the particular S. typhimurium cells used. The exposure to low fluences (sublethal) of UVA also led to the induction of an adaptive response in the same bacterial cells, which made them resistant to subsequent challenge by a much higher fluence of the same radiation. The adaptive response, as monitored by the assays of viability and β‐galactosidase units, increased with the period of exposure to sublethal fluences of UVA, attained a maximum at the UVA exposure of 4.5 kj/m2 (15 min) and thereafter gradually decreased with further increase of UVA exposure period. Modulation studies involving D2O, LBA growth medium, different scavengers of free radicals and quenchers of activated oxygen species indicated the involvement of both hydroxyl free radicals and singlet oxygen in the UVA‐induced umu gene expression.
A COMPARATIVE STUDY OF THE VISIBLE LIGHT PHOTOCHEMISTRY OF GILVOCARCINS V and M
Authors: Alegria Antonio E. , Zayas Luis , Guevara Norberto 
Published: January 2008

Abstract—Quantum yields for the formation of superoxide ions, O2−1, and singlet oxygen, 1O2, were determined during the photolyses of gilvocarcin M (GM) in air‐saturated dry dimethylsulfoxide (DMSO) and in 45:55 (vol/vol) DMSO‐water mixtures. The quantum yield for the photoreduction of methyl viologen by GM in nitrogen‐saturated dry DMSO was also determined. These values are not different, within experimental error, from those corresponding to gilvocarcin V (GV). Because GV is a strong photocytotoxic agent and GM is not, these results imply that Type I and Type II mechanisms are not important pathways in the cytotoxicity of GV.
THE USE OF EXOGENOUS FLUORESCENT PROBES FOR TEMPERATURE MEASUREMENTS IN SINGLE LIVING CELLS
Authors: Chapman C. F. , Liu Y. , Sonek G. J. , Tromberg B. J. 
Published: January 2008

Abstract—The fluorescent membrane probes 7‐nitrobenz‐2‐oxa‐1,3‐diazo1‐4‐y1 (NBD) and 6‐dodeca‐noy1‐2‐dimethylamino‐naphthalene (laurdan) have been studied for use as optical thermometers in living cells. The thermal sensitivity of NBD is primarily a consequence of rapid, heat‐induced electronic changes, which increase the observed fluorescence decay rate. As a result, fluorescence intensity and lifetime variations of membrane‐bound NBD‐conjugated phospholipids and fatty acids can be directly correlated with cellular temperature. In contrast, laurdan fluorescence undergoes a dramatic temperature‐dependent Stokes shift as the membrane undergoes a gel‐to‐liquid‐crystalline phase transition. This facilitates the use of fluorescence spectra to record the indirect effect of microenvironmental changes, which occur during bilayer heating. Microscope and suspension measurements of cells and phospholipid vesicles are compared for both probes using steady‐state and fluorescence lifetime (suspension only) data. Our results show that NBD fluorescence lifetime recordings can provide reasonable temperature resolution (approximately 2°C) over a broad temperature range. Laurdan's microenvironmental sensitivity permits better temperature resolution (0.1‐1°C) at the expense of a more limited dynamic range that is determined solely by bilayer properties. The temperature sensitivity of NBD is based on rapid intramolecular rotations and vibrations, while laurdan relies on a slower, multistep mechanism involving bilayer rearrangement, water penetration and intermolecular processes. Because of these differences in time scale, NBD appears to be more suitable for monitoring ultrafast phenomena, such as the impact of short‐pulse microirradiation on single cells.
CHARACTERISTICS OF THE CHEMILUMINESCENCE FROM THE BLOOD PLASMA OF A NORMAL HUMAN POPULATION
Authors: Matich A. J. , Th.Bury R. N. , Jordan T. W. 
Published: January 2008

Abstract—Oxygen‐dependent chemiluminescence was detected from human blood plasma. The intensity of the chemiluminescence increased about three‐fold under oxygenation and decreased almost to the background (zero) level under a nitrogen atmosphere. The blood plasma from a sample (n = 100) of donors was tested to determine the variability of several properties of the chemiluminescence in a normal population. No statistically significant difference in blood plasma chemiluminescence between genders was found, but there was a slight increase in luminescence intensity with age. However, the results were found to be dependent on a number of other factors, such as diet, smoking and the length of time between the donor's last meal and the sampling of the blood. Some of the trends in the results coincide with similar trends in the plasma lipoprotein levels and thus support the suggestion that the chemiluminescence arises from the decomposition of lipid hydroperoxides. These factors must all, therefore, be taken into account when using chemiluminescence as an indicator of illness.
LIPOSOME FUSION AND LIPID EXCHANGE ON ULTRAVIOLET IRRADIATION OF LIPOSOMES CONTAINING A PHOTOCHROMIC PHOSPHOLIPID
Authors: Morgan C. G. , Yianni Y. P. , Sandhu S. S. , Mitchell A. C. 
Published: January 2008

Abstract—A photochromic phospholipid, 1,2‐bis[4‐(4‐n‐butylphenylazo)phenylbutyroyl]phosphatidyl‐choline (Bis‐Azo PC) has been incorporated into liposomes of gel‐ and liquid‐crystalline‐phase phospholipids. Liposomes of gel‐phase phospholipid are stable in the presence of the trans photostationary state Bis‐Az.o PC and can encapsulate fluorescent marker dye. On photoisomerization to the cis photostationary state, trapped marker is rapidly released. Liposomes containing Bis‐Azo PC can rapidly fuse together after UV isomerization, this process continuing in the dark. Exposure to white light causes reversion of Bis‐Azo PC to the trans form and halts dye leakage and vesicle fusion. Both unilamellar and multilamellar liposomes are able to fuse together on UV exposure. On UV photolysis, liposomes containing Bis‐Azo PC do not fuse with a large excess of unlabeled liposomes, but transfer of Bis‐Azo PC can be demonstrated spectrophotometrically. Vesicles of pure gel‐phase lipid containing trapped marker dye but initially no Bis‐Azo PC become leaky as a result of this lipid transfer. Liposomes composed of liquid‐crystalline‐phase phosphatidylcholine‐containing Bis‐Azo PC neither leak trapped marker nor fuse together on photolysis, nor do liquid‐crystalline‐phase liposomes fuse with gel‐phase liposomes under these conditions. These results are discussed together with some possible applications of liposome photodestabilization.