bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
PRODUCTS OF PSORALEN PHOTOOXIDATION POSSESS IMMUNOMODULATIVE AND ANTILEUKEMIC EFFECTS*
Authors: POTAPENKO A. YA. , KYAGOVA A. A. , BEZDETNAYA L. N. , LYSENKO E. P. , Chernyakhovskaya I. Yu. , Bekhalo V. A. , Nagurskaya E. V. , Nesterenko V. A. , Korotky N. G. , Akhtyamov S. N. , Lanshchikova T. M.
Published: January 2008

Abstract It has been proposed that the therapeutic effect of PUVA (psoralens + UVA radiation) is connected to its immunomodulative properties, and that the molecular basis of such properties is the oxygen‐independent pho‐toaddition of psoralens to DNA. We have investigated effects of preliminary photooxidized psoralens (POP) on the delayed‐type hypersensitivity reaction (DTH) to sheep red blood cells and on growth of grafted T‐cell lymphoma EL‐4 in mice. We have shown that intravenous injection of POP at low concentrations activated, and at high concentrations suppressed, DTH. The POP products are thermolabile. They preserved their immunosuppressive activity for 3 days at room temperature and lost it in several min at 58°C. Incubation of POP in the presence of Fe2+ during 2 h before intravenous injection leads to complete loss of its immunomodulative activity, suggesting a peroxidic nature of POP products. The POP‐inhibited growth of grafted T‐cell lymphoma independent of the mode of POP application in mice (intravenous or subcutaneous injections, oral or nasal administration). Our data suggest that photooxidative reactions of psoralens, in addition to oxygen‐independent photoaddition to DNA, form the basis for biological activity of these drugs.
LASER FLASH‐INDUCED PHOTOREDUCTION OF PHOTOSYNTHETIC FERREDOXINS AND FLAVODOXIN BY 5‐DEAZARIBOFLAVIN AND BY A
Authors: Navarro Jose A. , Hervas Manuel , Rjeyo Jose J. , Medina Milagros , Gómez‐Moreno Carlos , De la Rosa Miguel A. , Tollin Gordon
Published: January 2008

Abstract Laser flash photolysis has been used to compare the kinetics of reduction of ferredoxin isoforms from the green alga Monoraphidium braunii, and the ferredoxin and flavodoxin from the cyanobacterium Anabaena PCC 7119, by 5‐deazariboflavin semiquinone (dRM) and the viologen analogue 1,l‘‐propylene‐2,2′‐bipyridyI (PDQ +). Similar ionic strength‐independent second‐order rate constants (1.4 × 108M−1 s −1) were obtained for the reduction of both algal ferredoxin isoforms by dRM For the reduction of oxidized flavodoxin by dRM, a more complex behavior was observed, with a second‐order rate constant for dRM. decay of 1.8 × 108M−1 S−1, and a first‐order (i.e. protein concentration independent) rate constant of 450 s−1, that probably corresponds to the protonation of the FMN semiquinone cofactor, which occurs subsequent to electron transfer. A value of 5 × 107M−1 S−1 was obtained for the second‐order rate constant of flavodoxin semiquinone reduction by dRM The reduction of ferredoxins and flavodoxin semiquinone by PDQ + showed nonlinear protein concentration dependencies, consistent with a minimal two‐step mechanism involving complex formation followed by intracomplex electron transfer. A negative ionic strength effect on the kinetic constants was obtained, indicating the existence of attractive electrostatic interactions during electron transfer. With all the ferredoxins the k∞ values (rate constants extrapolated to infinite ionic strength) for the second‐order step of the reduction process (complex formation) are smaller than previously reported for spinach ferredoxin, although Anabaena ferredoxin is somewhat more reactive than are the algal ferredoxins with the viologen. In contrast, the k∞ values for the first‐order component of ferredoxin reduction (intracomplex electron transfer) for the algal ferredoxins are comparable to that for spinach ferredoxin, whereas for this reaction the ferredoxin from Anabaena has a smaller intrinsic reactivity. As compared with the ferredoxins, Anabaena flavodoxin has significantly smaller k∞ values for its interaction with the viologen analogue, both for complex formation and for electron transfer. In all cases the existence of nonproductive electrostatic interactions between the viologen analogue and the proteins is suggested by the data.
INFLUENCE OF THE POOL SIZE OF THE XANTHOPHYLL CYCLE ON THE EFFECTS OF LIGHT STRESS IN A DIATOM: COMPETITION BETWEEN PHOTOPROTECI'ION AND PHOTOINHIBITION
Authors: Arsalane Wafa , Rousseau Bernard , Duval Jean‐Claude
Published: January 2008

Abstract In a study of the relationship between nonphotochemical quenching of fluorescence and the xanthophyll cycle, we show that the diatom Phaeodactylum tricornutum exhibits several interesting characteristics. This xanthophyll cycle consists of only one reversible epoxidating/deepoxidating step (diadinoxanthiddiatoxanthin). Diadinoxan‐thin, which increases from 8 to 17 molecules/100 chlorophyll a (Chl a) during the ageing of the culture, was present as two separate pools, with a portion (of about 5 molecules/100 Chl a) which was never deepoxidated. Under a defined irradiance, the time necessary to abolish net photosynthesis increases with the pool size of diadinoxanthin available for deepoxidation. A close correlation is found between nonphotochemical quenching and the relative ratio of diatoxanthin until the photosytem II center is inactivated. The photoprotective effect of diadinoxanthin deepoxidation is limited to the phase during which quenching of the minimum fluorescence (F0) develops.
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.
EFFECTS OF in vitro EXPOSURE TO ULTRAVIOLET RADIATION ON THE FUNCTIONAL ACTIVITY OF LYMPHOCYTES, WITH EMPHASIS ON SUSCEPTIBILITY OF DIFFERENT SPECIES
Authors: Goettsch WIM , Garssen Johan , Hurks Monique H. , De Gruijl Frank R. , Loveren Henk Van
Published: January 2008

Abstract In this study lymphocytes from blood and/or spleen of different species (rat, mouse, human) were exposed to different doses of ultraviolet radiation (UVR). The functional activity of these lymphocytes was determined using assays for mitogen proliferation and the mixed lymphocyte response (MLR). These experiments demonstrated that in vitro exposure to UVR causes a dose‐dependent decrease of the MLR activity of the irradiated lymphocytes. Viability of lymphocytes and mitogen proliferation responses were also decreased by UVR exposure but less severe in comparison to the MLR. Lymphocytes of rats seem to be more sensitive to UVR as compared to lymphocytes of mice and humans.
WAVELENGTH‐DEPENDENT EFFECTS OF BENZOPORPHYRIN DERIVATIVE MONOACID RING A in vivo AND in vitro
Authors: Waterfield Elizabeth M. , Renke Martin E. , Smits Claire B. , Gervais Michele D. , Bower Robert D. , Stonefield Michael S. , Levy Julia G.
Published: January 2008

Abstract Benzoporphyrin derivative monoacid ring A (BPD‐MA) is a chlorin‐like photosensitizer currently in clinical trials for cancer and psoriasis. It has maximal absorption peaks at both 630 and 690 nm and can be activated at both these wavelengths. In vitro phototoxicity tests using the P8 15 murine mastocytoma cell lines conducted over wavelengths of light between 678 and 700 nm emitted by an argon‐ion pumped dye laser showed that equivalent cell kill could be achieved between 682 and 690 nm. Tests on in vivo phototoxicity of normal skin of DBN2 mice injected with 2 mg/kg of BPD‐MA and exposed to light at 125 J/cm2, between 620 and 700 nm, demonstrated peaks of normal skin damage occurring at 630–640 nm and 680–690 nm. In tests carried out with light between 620 and 700 nm, at 10 nm increments, it was seen that light delivered at 680–690 nm caused slightly more damage to normal skin than light delivered at 630–640 nm. When lower doses of light between 675 and 705 nm were tested using smaller increments, it was determined that equivalent skin damage occurred over a range of 68–95 nm. Antitumor efficacy in tumor‐bearing DBN2 mice was tested between 683 and 695 nm. It was found that equivalent antitumor efficacy, determined by assessing tumor‐free status at 20 days posttreatment, occurred at wavelengths between 685 and 693 nm. When tumor‐bearing animals injected with BPD‐MA at 2 mdkg and exposed to light 3 h later were treated with either 630 or 690 nm light at various doses, it was observed that 690 nm light was more effective at tumor ablation than was 630 nm light, demonstrating that while similar damage to normal skin may be effected by equivalent doses of light at either wavelength, tumor ablation was greater at 690 nm. Further, our data suggest that alternative light sources with bandwidths greater than those of the argon‐ion pumped dye laser (±0.3 nm) may have equivalent efficacy with this photosensitizer.
PHOTOINDUCED REDUCTION OF CYTOCHROME c IN THE PRESENCE OF HYDROPEROXIDE DERIVATIVE OF BIPHENYL
Authors: Matsugo Seiichi , Kayamori‐Sato Nobuko , Konishi Tetsuya
Published: January 2008

Abstract The photosensitive hydroperoxide derivative of biphenyl (BPP) was synthesized by the ozonolysis of phenanthrene in methanol. When cytochrome c (cyt c) was illuminated by UVB light in the presence of BPP (BPPUV), it was reduced both under aerobic and anaerobic conditions. The action spectrum of the reduction was consistent with that of photolytic decomposition of BPP. Both gave maximum reactions at wavelengths around 300–310 nm. Electron spin resonance studies, using 5,5‐dimethyl‐1‐pyrroline N‐oxide as a spin‐trapping reagent, revealed the generation of hydroxyl radicals in the BPPUV system. Product analysis of adamantane oxidation by BPPW also suggested the generation of hydroxyl radicals rather than singlet oxygen. However, the effects of scavengers were complicated. Singlet oxygen scavengers significantly inhibit the reaction while none of the hydroxyl radical scavengers tested was effective in inhibiting the BPPUV‐mediated cyt c reduction. Deuterium oxide, which extends the lifetime of singlet oxygen, inhibited rather than enhanced the reaction. Reduction of cyt c was inhibited by salts, and their activities were correlated to the electron‐donating nature of the anions. These results suggest that reduction of cyt c is mediated by electron transfer from a light‐induced product of BPP, rather than by free hydroxyl radicals or singlet oxygen.
RESEARCH NOTE PHOTOTOXICITY OF CITRAL TOTrichoplusia ni(LEPIDOPTERA: NOCTUIDAE) AND ITS AMELIORATION BY VITAMIN A
Authors: Green Ellen S. , Berenbaum May R.
Published: January 2008

AbstractCitral, a monoterpene aldehyde synthesized by several plant families, was recently shown to exhibit ultraviolet A light (320–400 nm) (UVA)‐enhanced oxygen‐dependent toxicity against bacteria and fungi (Escherichia coliandFusariumspecies). In this study, we report for the first time that citral is phototoxic to insects; at concentrations of 300 ppm in artificial diet, mortality of first instarTrichoplusia ni(cabbage loopers) approached 30% after 120 h of UVA exposure, approximately double the mortality level in the absence of UVA. At 300 ppm, the antioxidant vitamin A reduces citral phototoxicity by about 50% in this species, suggesting that citral phototoxicity against insects is oxygen dependent.
EVIDENCE FOR THE EXISTENCE OF MEMBRANE‐ASSOCIATED PHYTOCHROME IN THE CELL
Authors: Sineshchekov Vitally , Lamparter Tilman , Hartmann Elmar
Published: January 2008

Abstract Comparative fluorescence and photochemical studies of phytochrome in etiolated seedlings of maize and in soluble and membrane‐containing fractions isolated from them were camed out. The membrane fractions prepared in the absence of Mg2+ from etiolated coleoptiles contained 13% of total photoreversible phytochrome, which was readily solubilized by mild detergents. Its molecular size was indistinguishable from soluble phytochrome and equal to nondegraded maize phytochrome. Low‐temperature fluorescence studies with intact tissue found that the position of the emission maximum at 85 K (λmax) and the extent of the phototransformation of the red‐absorbing form (Pr) into the first stable photoproduct, lumi‐R, at 85 K (γ1), varied in different parts of etiolated seedlings: λmax and γ1 reached their maximum values in the tips of coleoptiles and roots, 686 nm and 0.30–0.40, whereas the lowest values, 682 nm and ca 0.05, were observed in the root base. These parameters correlated well with those obtained for the pigment in the soluble and membrane‐containing fractions: 684 and 680 nm, and 0.33 and 0.06, respectively. The extent of the Pr phototransformation into the far red‐absorbing form (Pfr) (γ2) did not differ much: values of 0.80–0.85 and 0.70–0.75 correlated with the high and low values of γ1. These variations of the parameters were interpreted in agreement with our previous observations in terms of two phytochrome A species whose relative concentrations vary depending on the experimental conditions—the longer wavelength bulk light‐labile species with high γ1 (Pr″), and the shorter wavelength minor light‐stable species with low γ1 (Pr″). Close similarity between Pr’and the soluble phytochrome and between Pr″ and the membrane‐bound phytochrome points to the possible origin of the native Pr’and PrPrime; species, thus providing evidence for the existence of membrane‐bound pigment in the cell.
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

The 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

Exposure 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.
CHANGES IN TRANSMISSION CHARACTERISTICS OF POLYMETHYLMETHACRYLATE AND CELLULOSE (III) ACETATE DURING EXPOSURE TO ULTRAVIOLET LIGHT
Authors: Steeneken Steef F. , Buma Anita G. J. , Gieskes Winfried W. C.
Published: January 2008

Abstract— Ultraviolet‐transparent polymethylmethacrylate (PMMA) and cellulose (III) acetate (CA) (often used as a cut‐off filter in UVB [280–320 nm] biological effect studies) were exposed to a 20 W Philips TL 12 lamp to examine changes in transmission characteristics due to UVB exposure. Transmission of UVB and biologically weighted UVB (UVBE(DNA)) through PMMA were similar, 88.3 and 83.5%, respectively. The absorption characteristics of PMMA did not change with time at any of the UV irradiance levels applied. However, transmission of UVB and UVBBE(DNA)) through new CA differed considerably: 59% versus only 11%, respectively. Also, spectral absorption characteristics changed with time due to degradation of CA, at a rate that was dependent on the incident UVB irradiance. The decrease in transmission through CA of both UVB and UVBE(DNA) can be described by exponential functions. The CA that was wrapped around the UV lamp showed dramatic changes in UV absorption over the first few hours of use. However, when CA was placed at a longer distance from the light source initial degradation was less. It is concluded that PMMA can be applied in UV effect studies as a reasonable alternative for quartz. The CA should, however, be used with care, because the large transmission decreases that were observed strongly hamper an accurate calculation of (biologically weighted) UVB dose rates.
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.
CONTRASTING STRUCTURAL IMPACTS INDUCED BY cis‐syn CYCLOBUTANE DIMER AND (6–4) ADDUCT IN DNA DUPLEX DECAMERS: IMPLICATION IN MUTAGENESIS AND REPAIR ACTIVITY
Authors: Kim Jong‐Ki , Patel Dinshaw , Choi Byong‐Seok
Published: January 2008

Abstract—

The relative biological importance of cis‐syn cyclobutane dimer and pyrimidine(6–4)pyr‐imidone photoadduct ([6–4] photoadduct) appears to be dependent on the biological species, dipyrimidine sites and the local conformational variation induced at the damaged sites. The single‐stranded deoxyn‐ucleotide 10‐mers containing the site‐specific (6–4) adduct or cis‐syn cyclobutane dimer of thymidylyl (3'‐5')‐thymidine were generated by direct photolysis of d(CGCATTACGC) with UVC (220–260 nm) irradiation or UVB (260–320 nm) photosensitization. Three‐dimensional structures of the duplex cis‐syn and (6–4) decamers of d(CGCATTACGC)d(GCGTAATGCG) were determined by NMR spectroscopy and the relaxation matrix refinement method. The NMR data and structural calculations establish that Watson‐Crick base pairing is still intact at the cis‐syn dimer site while the hydrogen bonding is absent at the 3'‐side of the (6–4) lesion where the T → C transition mutation is predominantly targeted. Overall conformation of the duplex cis‐syn decamer was B‐DNA and produced a 9° bending in the DNA helix, but a distinctive base orientation of the (6–4) lesion provided a structural basis leading to 44° helical bending. The observed local structure and conformational rigidity at the (6–4) adduct of the thymidylyl(3'‐5')‐thymidine (T‐T [6–4]) lesion site suggest the potential absence of hydrogen bonding at the 3' sides of the (6–4) lesion with a substituted nucleotide during replication under SOS conditions. Contrasting structural distortions induced by the T‐T (6–4) adduct with respect to the T‐T cis‐syn cyclobutane pyrimidine photodimer may explain the large differences in mutation spectrum and repair activities between them.
PHOTOPHYSICS OF METHYLENE BLUE‐POLYNUCLEOTIDE COMPLEXES IN THE PICOSECOND TIME RANGE: INFLUENCE OF THE LOCAL STRUCTURE OF THE POLYNUCLEOTIDE
Authors: Enescu Mironel , Lindqvist Lars
Published: January 2008

Abstract—

The photophysics of methylene blue (MB) complexed with 2'‐deoxycytidylyl‐2'‐deoxygua‐nosine, polydeoxyguanylic‐deoxycytidylic acid, polydeoxyguanylic‐polydeoxycytidylic acid and poly‐guanylic acid, respectively, was investigated by transient absorption spectroscopy with a time resolution of ˜1 ps. The decays of the transient difference spectra indicate that the radiationless process responsible for the strong shortening of the S, state lifetime of MB associated with a guanine in the polynucleotide chain is similar to that already observed in the case of the MB—guanosine‐5'‐monophosphate complex, that is, the excited state decays by return of molecules to the ground state without formation of a detectable intermediate state. The local structure of the polynucleotide apparently does not change the nature of the deactivation process but influences significantly the deactivation rate. Thus, the intercalation of MB between guanosine and cytosine increases this rate constant (as compared to that of the MB—guanosine‐5'‐monophosphate complex) while the interaction of MB intercalated with a supplementary guanine has an opposite effect. The results are discussed in connection with the photosensitizing effect of MB in nucleic acid damage.
DECAY KINETICS OF N, N, N', N‐TETRAMETHYLBENZIDINE PHOTOCATIONS IN FROZEN MICELLAR SOLUTION OF CETYLTRIMETHYLAMMONIUM BROMIDE
Authors: Wolff Thomas , Weber Susanne , Böhm Britta , Schütz Andreas
Published: January 2008

Abstract—

After UV irradiation of rapidly frozen solutions of N, N, N', N'‐tetramethylbenzidine (TMB) in dilute aqueous micellar cetyltrimethylammonium bromide at 80 K, the ESR signal corresponding to the TMB+ cation was detected indicating photoionization. This signal was monitored as a function of time at various temperatures between 80 K and 260 K. On a timescale of a few days the signal decayed to a plateau value that was stable for months. Two distinct second‐order processes for the decay from the initial to the plateau value were observed: one prevailing at low temperatures with an activation energy of 0.6 kJ/mol, and one prevailing at T > 220 K with an activation energy of 13 kJ/mol. By means of spin probe investigations the latter process was shown to be connected with a local softening of the region adjacent to the micellar surface.
INACTIVATION OF CELL SURFACE RECEPTORS BY PHEOPHORBIDE a, A GREEN PIGMENT ISOLATED FROM Psychotria acuminata
Authors: Glinski Jan A. , David Eva , Warren Thomas C. , Hansen Gordon , Leonard Scott F. , Pitner Phillip , Pav Susan , Arvigo Rosita , Balick M. J. , Panti Eligio , Grob Peter M.
Published: January 2008

Abstract— The inhibition of cytokine and monoclonal antibody binding to cell surfaces caused by an extract of Psychotria acuminata, a medicinal plant used in the traditional medicine of the people of Belize (Central America), was attributed to the presence of pheophorbide a and pyropheophorbide a Since the binding of tumor necrosis factor‐alpha, interleukin‐8, complement factor 5a as well as epidermal growth factor to target cells was dramatically reduced, the inhibition was not receptor or cytokine specific. In addition, the respective binding of radiolabeled monoclonal antibodies CL203 and R15.7 to the cell surface antigens intracellular cell adhesion molecule‐1 and lymphocyte function‐associated antigen‐1 ß‐chain was decreased by pretreatment of cells with pheophorbide a as well. In all cases, the inhibition by pheophorbides was dependent on the simultaneous presence of light, indicating causative involvement of a photodynamic process. These observations are not unique to pheophorbides and can be extended to porphyrins as well as to other photodynamic agents. Cytotoxicity resulting from photodynamic therapy (PDT) has been documented by many studies. Our investigations suggest that the inactivation of cell surface receptors contributes not only to the antitumor effect of PDT but also to the systemic immunosuppression, a serious side effect of PDT.
HYDROGEN PEROXIDE MEDIATES UV‐INDUCED IMPAIRMENT OF ANTIGEN PRESENTATION IN A MURINE EPIDERMAL‐DERIVED DENDRITIC CELL LINE
Authors: Caceres‐Dittmar Gisela , Ariizumi Kiyoshi , Xu Shan , Tapia Felix J. , Bergstresser Paul R. , Takashima Akira
Published: January 2008

Abstract— Ultraviolet‐B (290–320 nm) radiation is known to impair the antigen‐presenting cell (APC) function of Langerhans cells (LC), skin‐specific members of the dendritic cell (DC) family. We sought to address mechanisms of this effect, focusing on the role played by hydrogen peroxide. For this purpose, we used a newly established murine DC line, XS52, which resembles epidermal LC in several respects. The APC capacity of XS52 cells, using two different CD4* T cell clones as responders, was inhibited significantly (>50%) by exposure to UV radiation (unfiltered FS20 sunlamps) at relatively small fluences (50–100 J/m2). Ultraviolet radiation also inhibited growth factor‐dependent proliferation of XS52 cells. On the other hand, cell surface phenotype was relatively well preserved after irradiation; expression levels of B7‐1 and B7‐2 were reduced slightly, while other molecules (e.g. Ia, CD54, CD1 la and CD18) were not affected. With respect to the role played by hydrogen peroxide, pretreatment with purified catalase (900 U/mL) prevented UV‐induced inhibition of APC function. Short‐term exposure to 3 miM H202 or f‐butyl H202 mimicked UV radiation by inhibiting APC function. Finally, intrinsic catalase activity was substantially lower in XS52 cells compared with Pam 212 keratinocytes. These results indicate that the generation of hydrogen peroxide alone is sufficient to produce some, but not all, of the deleterious effects of UV radiation on DC derived from the skin.
SPECTROSCOPIC AND PHOTOACOUSTIC STUDIES OF HYPERICIN EMBEDDED IN LIPOSOMES AS A PHOTORECEPTOR MODEL*
Authors: Lenci F. , Angelini N. , Ghetti F. , Sgarbossa A. , Losi A. , Vecli A. , Viappiani C. , Taroni P. , Pifferi A. , Cubeddu R.
Published: January 2008

Abstract— In photoresponsive ciliates, like Blepharisma japonicum and Stentor coeruleus, the photoreceptor pigments responsible for photomotile reactions are hypericin‐type chromophores packed in highly osmiophilic subpellicular granules. Liposomes loaded with hypericin can constitute a simple model system, appropriate for understanding the primary light‐induced molecular events triggering the sensory chain in these microorganisms. Optical absorption, steady‐state and time‐resolved fluorescence and pulsed photoacoustic calorimetry have been used to measure spectral distributions, fluorescence lifetimes, radiative and radiationless transition quantum yields of hypericin when assembled into egg L‐a‐phosphatidylcholine liposomes. With respect to hypericin ethanol solutions, both absorption and fluorescence maxima are 5 nm red shifted when the pigment is inserted into the lipidic microenvironment, regardless of the hypericin local concentration. Increasing by 100 times the hypericin local concentration decreases the relative fluorescence quantum yield by a factor of around 150 and the fraction of thermally released energy, conversely, increases from 0.6 to 0.9. From the analysis of fluorescence lifetimes and their relative amplitudes it appears that a subnanosecond living component is predominant at the highest hypericin local concentrations.
IDENTIFICATION OF A LARGE GENOMIC REGION IN UV‐IRRADIATED HUMAN CELLS WHICH HAS FEWER CYCLOBUTANE PYRIMIDINE DIMERS THAN MOST GENOMIC REGIONS
Authors: Kantor G. J. , Deiss‐Tolbert D. M.
Published: January 2008

Abstract— Size separation after UV‐endonuclease digestion of DNA from UV‐irradiated human cells using denaturing conditions fractionates the genome based on cyclobutane pyrimidine dimer content. We have examined the largest molecules available (50–80 kb; about 5% of the DNA) after fractionation and those of average size (5–15 kb) for content of some specific genes. We find that the largest molecules are not a representative sampling of the genome. Three contiguous genes located in a G+C‐rich isochore (tyrosine hydroxylase, insulin, insulin‐like growth factor II) have concentrations two to three times greater in the largest molecules. This shows that this genomic region has fewer pyrimidine dimers than most other genomic regions. In contrast, the p‐actin genomic region, which has a similar G+C content, has an equal concentration in both fractions as do the ß53 and ß‐globin genomic regions, which are A+T‐rich. These data show that DNA damage in the form of cyclobutane pyrimidine dimers occurs with different probabilities in specific isochores. Part of the reason may be the relative G + C content, but other factors must play a significant role. We also report that the transcriptionally inactive insulin region is repaired at the genome‐overall rate in normal cells and is not repaired in xeroderma pigmentosum complementation group C cells.
RESPONSE OF THE WILD‐TYPE and HIGH LIGHT‐TOLERANT MUTANT OF Anacystis nidulans AGAINST PHOTOOXIDATIVE DAMAGE: DIFFERENTIAL MECHANISM OF HIGH LIGHT TOLERANCE
Authors: Singh D. P. , Verma Kavita
Published: January 2008

Abstract— A high light‐tolerant mutant of Anacystis was able to tolerate about three‐fold higher light energy irradiance (30 W m‐2) than the wild type (10 W m‐2). The loss of sulfhydryl content and rate of lipid peroxidation in the wild‐type cells is lower than in the mutant cells at high light irradiance. This phenomenon in the wild type is probably due to high light‐induced severe photoinhibitory conditions resulting in a decreased rate of O2 evolution. Results on the bleaching of the N, N'‐dimethyl‐p‐nitrosoaniline at high light irradiance show a higher rate of bleaching in the wild‐type than in the mutant cells. Further, results on the rate of N, N'‐dimethyl‐p‐nitrosoani)ine bleaching in the presence of radical scavengers like sodium azide, histidine and sodium formate (10 mM, each) suggest that singlet oxygen is the predominant oxygen species produced in both the wild‐type and mutant cells under high light. However, a similar quenching effect of formate in the mutant cells is indicative of increased formation of hydroxyl radicals. This observation is further corroborated by higher rate of lipid peroxidation. In addition to this, the superoxide dismutase activity is higher in the mutant (1.2 unit) than in the wild type. Taken together, these results suggest that the cells of the high light‐tolerant mutant have an efficient intracellular mechanism to transform the free oxygen radicals.
EFFECT OF HEMATOPORPHYRIN DERIVATIVE ON HEMATOLOGICAL PARAMETERS IN RATS
Authors: Khanum Farhath , Anilakumar K. R. , Santhanam K.
Published: January 2008

Abstract— Wistar rats were injected with hematoporphyrin derivative (Hpd) intraperitoneally and kept in the dark. Rats were sacrificed 2, 24, 48 and 72 h after injection. It was observed that Hpd in the dark did not affect the hemoglobin content and number of erythrocytes, while the leukocyte count was increased and blood pH decreased. Blood levels of glucose and lactate were increased significantly. Because the food intake was similar in all the groups, glycogenolysis was suspected to be the source of increased glucose levels in blood. However, a significant increase in the glycogen content of the livers of Hpd‐treated rats was observed, which rules out glycogenolysis. Hyperglycemia may result due to a number of reasons such as stimulation of the central nervous pathways innervating the liver and adrenal medulla, excessive glucogenesis in liver from glycogen and noncarbohydrate sources, emotional stress, anesthesia and hormonal effects. The present study rules out hyperglycemia due to anesthesia and glucogenesis in the liver. Maintenance of blood glucose levels is a highly complex mechanism. Further investigations to understand these mechanisms are in progress.
PHTHALOCYANINE FLUORESCENCE AT HIGH CONCENTRATION: DIMERS OR REABSORPTION EFFECT?
Authors: Dhami S. , Mello A. J. De , Rumbles G. , Bishop S. M. , Phillips D. , Beeby A.
Published: January 2008

Abstract— For tetrasulfonated aluminum phthalocyanine (AlPcS4), dimer formation is characterized in the absorption spectrum by a broadening of the Q‐band and the appearance of a new band at the red edge of the spectrum. The high concentrations required to produce dimers, however, often leads to anomalous observations in fluorescence spectroscopy. In the present study, we have examined the photophysical characteristics of two dye systems; AlPcS4 in a 66% ethanol/water mixture and disulfonated aluminum phthalocyanine in methanol. Using absorption spectroscopy, the formation of dimers is shown to be prevalent only in the case of AlPcS4. The fluorescence emission spectra in both cases, however, exhibit similar spectral changes with increasing dye concentration. The measured fluorescence decay profiles for both dyes also show similar trends: They are monoexponential, invariant with emission wavelength and have decay times that increase with dye concentration. These distortions are sometimes incorrectly attributed to dimer fluorescence. We find no evidence for the existence of dimer fluorescence and demonstrate that these data can be readily explained, by taking into consideration the effects of reabsorption of fluorescence.
FORMATION OF PROTEIN‐BOUND 3,4‐DIHYDROXYPHENYLALANINE IN COLLAGEN TYPES I AND IV EXPOSED TO ULTRAVIOLET LIGHT
Authors: Kato Yoji , Nishikawa Takashi , Kawakishi Shunro
Published: January 2008

Abstract— Collagen was exposed to an ultraviolet (UV) lamp that emitted predominantly in the UVB range. The cross‐linking of collagen type I and type IV by UV irradiation was observed. Amino acid analyses revealed that Tyr residues in both collagen types I and IV were decreased by irradiation. In collagen type IV, losses of His and Met residues were also observed. These losses of collagen type IV may be due to the degradation of Trp, which exists in collagen type IV and decreased drastically during UV irradiation. To clarify the mechanism of Tyr modification in both types of collagen, the degradation products of Tyr were analyzed. Dityrosine, which is a dimer of the Tyr residue, could not be detected in the acid hydrolysates of UV‐irradiated collagen. However, 3,4‐dihydroxyphenylalanine, DOPA, was detected in the hydrolysates using HPLC with an electrochemical detector. The amounts of DOPA in the acid hydrolysates of collagen exposed to UV light for 24 h were approximately 350 pmol/mg protein (collagen type IV) and 80 pmol/mg protein (collagen type I). The DOPA formed may partially contribute to photoaging of the skin.