bluuebunny/crossref_metadata_2025 huggingface dataset:
THE CHEMICAL MECHANISM and EVOLUTIONARY DEVELOPMENT OF BEETLE BIOLUMINESCENCE
Authors: Wood Keith V.
Published: January 2008

Abstract— Bioluminescence, as a phenotype, has many evolutionary origins, and thus is an example of natural reinvention many times over. Although peculiar, it arises from the same biochemical principles and evolutionary mechanisms as other biochemical reactions. Of these many different bioluminescent systems, that of the luminous beetles is one of the best understood, having been extensively studied for over 50 years. The luminescence ensues from oxidation of a molecule unique to luminous beetles, beetle luciferin, through a catalytic mechanism evolved from ancestral coenzyme A synthetases. Thus, the character of this bioluminescent reaction is in part a consequence of that evolutionary history. Beetle bioluminescence is furthermore unusual in having a range of luminescent colors found among different beetle species and sometimes even within individual beetles. Structural features of the luciferases are responsible for these color differences, although the underlying mechanism is not yet clear.
DIFFERENTIAL RESPONSE OF PHOTOSYNTHETIC PIGMENTS, RUBISCO ACTIVITY and RUBISCO PROTEIN OF Arabidopsis thaliana EXPOSED TO UVB and OZONE
Authors: Rao Mulpuri V. , Paliyath G. , Ormrod D. P.
Published: January 2008

Abstract— The effect of UVB (280–320 nm radiation) and ozone (O3) on growth, photosynthetic pigments, ribulose bisphosphate carboxylase/oxygenase (rubisco) activity and rubisco protein were investigated in Arabidopsis thaliana genotypes wild type Landsberg erecta (LER) and tt5, a flavonoid‐deficient mutant. The UVB exposure for 5 days decreased whole plant dry weight of only tt5 plants, while O3 exposure decreased the whole plant dry weight of both genotypes. The UVB exposure enhanced chlorophylls and carotenoids in both genotypes while O3 exposure decreased photosynthetic pigments in both genotypes. Both UVB and 03 exposure enhanced UV‐absorbing compounds in LER but not in tt5. Ultraviolet‐B exposure decreased initial and total rubisco activities only in tt5 plants, which contained smaller amounts of UV‐absorbing pigments. The effect of UVB was greater on initial rubisco activity resulting in decreased percent activatible rubisco. Ozone exposure decreased initial and total rubisco activities in both genotypes, and the magnitudes of decrease were greater on total rubisco activity, resulting in enhanced levels of percent activatible rubisco. Immunoblot analysis performed with antibodies raised against rubisco large subunit (LSU) and rubisco small subunit (SSU) showed no major changes in the levels of rubisco protein of either genotype irradiated with UVB. However, both rubisco LSU and SSU decreased in tt5 plants exposed to UVB for 7 days (70% of total leaf area necrotic). In contrast, O3 exposure of both the genotypes decreased the levels of rubisco LSU and SSU before the appearance of visible symptoms of injury. These results suggested that UVB‐induced limitations of growth are independent of changes in rubisco protein while O3‐induced growth limitations appeared to be due to a significant reduction in rubisco protein.
TEMPERATURE DEPENDENCE OF CHLOROPHYLL(IDE) SPECTRAL SHIFTS and PHOTOACTIVE PROTOCHLOROPHYLLIDE REGENERATION AFTER FLASH IN ETIOLATED BARLEY LEAVES
Authors: Eullaffroy Philippe , Salvetat Richard , Franck Fabrice , Popovic Radovan
Published: January 2008

Abstract— Absorbance spectroscopy at 77 K was used to investigate the effect of temperature on in vivo chlorophyllide shifts and photoactive protochlorophyllide regeneration after a saturating flash, which transformed all protochlorophyllide to chorophyllide. Photoactive protochlorophyllide present in darkness was stable up to 40°C. The rate of Shibata shift and protochlorophyllide regeneration after flash were strongly temperature dependent in the range 0–25°C. At 0°C, the shift was still observed but no regeneration occurred. Only slight effects were observed in the range 25–40°C. At all temperatures, the process of protochlorophyllide regeneration was significantly slower than the Shibata shift. The final chlorophyll shift from 672 to 674 nm was observed up to 40°C. The implication of these results concerning the pigment‐protein interactions during the Shibata shift are discussed.
ULTRAVIOLET ERYTHEMA SENSITIVITY IN ANAMNESTIC (I‐IV) and PHOTOTESTED (1–4) CAUCASIAN SKIN PHOTOTYPES: THE NEED FOR A NEW CLASSIFICATION SYSTEM
Authors: Snellman E. , Jansén C. T. , Leszczynski K. , Visuri R. , Milan T. , Jokela K.
Published: January 2008

Abstract— The anamnestic skin phototypes (ASP) I‐IV1,2 of 21 Caucasian volunteers were compared with their phototested skin phototypes (PSP) using solar simulating, broadband UV radiation. The Commission Internationale de' éclairage (CIE)‐weighted (i.e. erythemally effective) minimal erythema doses (MED) for solar simulating radiation varied from 20 mJ/cm2 (PSP type 1) to 57 mJ/cm2 (PSP type 4). In only 11 of 21 volunteers did the ASP (I‐IV) and PSP (1–4) classifications coincide, and the MED values of the volunteers within the different ASP groups (I‐IV) overlapped considerably. To compare the reactivity to erythematogenic radiation of different wavelengths, narrowband monochromator irradiations were performed at 298 nm, 310 nm and 330 nm. The CIE‐weighted MED values at these wavelengths (20–80 mJ/cm2) corresponded well with those obtained in the broadband testing. Our results indicate that, with classification by interrogation, Caucasian skin can reliably be classified into only two subtypes, corresponding to Fitzpatrick phototypes I–III and phototype IV, respectively. A classification into four sensitivity types can be achieved by phototesting, only. We propose that the concept of ASP should be used with caution. The concept of PSP 1–4 should be favored.
INTRACELLULAR DAMAGE IN YEAST CELLS CAUSED BY PHOTODYNAMIC TREATMENT WITH TOLUIDINE BLUE
Authors: Paardekooper Michel , Bruune Adriaan W. De , Steveninck John Van , Broek Peter J. A. Van den
Published: January 2008

Abstract— The positively charged photosensitizer toluidine blue (TB) can induce loss of clonogenicity in Kluyveromyces marxianus. Previous studies have revealed that, as a consequence of the localization of this dye at the cell surface, photodynamic action results in extensive damage at the level of the plasma membrane. In this paper, a study is reported on the effect of photodynamic treatment with TB on intracellular enzymes. It is shown that treatment with TB and light resulted in the inhibition of alcohol dehydrogenase, cytochrome c oxidase, glyceraldehyde‐3‐phosphate dehydrogenase and hexokinase. Photodynamic treatment also lowered the ATP levels. The ATP levels could be partially restored in the presence of glucose but not with ethanol. Toluidine blue binding experiments revealed that photodynamic treatment caused a rapid increase in the amount of cell‐associated dye. Moreover, it also appeared that this treatment decreased the binding of TB to the cell surface. It is concluded that TB enters the cell during the first minutes of illumination, whereafter intracellular enzymes are inactivated. The data indicate that photodynamic damage of intracellular sites contributes to the loss of viability.
PHOTOSENSITIZATION AND TISSUE DISTRIBUTION STUDIES OF THE PICKET FENCE PORPHYRIN, 3,1‐TPRO, A CANDIDATE FOR PHOTODYNAMIC THERAPY
Authors: Lawrence David S. , Gibson Scott L. , Nguyen My Lien , Whittemore Kenneth R. , Whitten David G. , Hilf Russell
Published: January 2008

Abstract— From a structurally distinct set of o‐substituted tetraphenylporphyrins, the picket fence porphyrin (PFP), 3,1‐meso‐tetrakis(o‐propionamidophenyl)porphyrin (3,1‐TPro) has been selected as a potential candidate for use in the photodynamic therapy (PDT) of cancer. In this report, the time‐dependent tissue distribution of 14C‐labeled 3,1‐TPro is described along with the results of various treatment regimens. The tissue distribution of radiolabeled 3,1‐TPro is comparable to that of other porphyrin photosensitizers with the advantage of being most effective at 4 h and being cleared rapidly from most tissues. The results of the various treatment regimen experiments, as well as other studies, indicate that the 3,1‐TPro mechanism of action is similar to that of other photosensitizers, but may include some minor differences. The conclusion is that 3,1‐TPro and other PFP offer a class of effective photosensitizers that may be exploited for their structural versatility, straightforward synthesis leading to a compound of high purity and known structure, and stability (both in terms of shelf‐life and in vivo metabolism) as potential candidates for PDT.
UVB‐INDUCED IMMUNE SUPPRESSION AND INFECTION WITH SCHISTOSOMA MANSONI
Authors: Noonanan Franceps.P. , Lewis Freda A.
Published: January 2008

Abstract— Irradiation with ultraviolet B (UVB, 290–320 nm) causes a systemic immunosuppression of cell‐mediated immunity. The question of whether UV immunosuppression modulates the course of infectious diseases is important becauseUVB levels in sunlight are sufficient to predict significant UV‐induced immunosuppression at most latitudes. We have investigated the effect of immunosuppressive doses of UVB on the disease caused by the helminth parasite Schistosoma mansoni. C57BL/6 mice were irradiated once or three times weekly over 60–80 days with UV from a bank of FS40 sunlamps. Each UV treatment consisted of an immunosuppressive UV dose, as determined by suppression of contact hypersensitivity to trinitrochlorobenzene, corresponding to about 15–30 min of noonday tropical sunlight exposure under ideal clear sky conditions. Cumulative UV doses were between 80 and 170 kJ/m2. Worm and egg burdens, liver granuloma diameters and liver fibrosis showed minimal changes(> 20%) compared with parameters in unirradiated animals. Ultraviolet irradiation (a total of 55 kJ/m2 administered in six treatments) did not impair the resistance to rechallenge conferred by vaccination with 60Co‐irradiated cercariae. We have thus observed a dichotomy between UV immunosuppression and both disease and vaccination in this helminth infection, in contrast to the effects of UVB shown in other infectious diseases.
Reduction of Intracellular pH Is Not the Mechanism for the Synergistic Interaction Between Photodynamic Therapy and Nigericin
Authors: Varnes Marie E. , Bayne Marian T. , Bright Gary R.
Published: January 2008

Abstract— Previous studies showed that photodynamic therapy (PDT) sensitized by aluminum phthalocyanine can be dramatically potentiated by the K+/H+ ionophore nigericin. Nigericin equilibrates intracellular pH (pHi) and extracellular pH (pHe) and is most effective in potentiating PDT damage when cells are in an acidic environment (pH 6.5‐6.7). We therefore hypothesized that the ability of nigericin to lower pHi is causally related to its ability to potentiate PDT. To test this, the pHi of A549 cells was reduced using pHe‐adjusted growth medium, with or without addition of amiloride and 4,4'‐diisothiocyanato‐stilbene‐2,2'‐disulfonic acid, inhibitors of the membrane‐based exchangers responsible for regulating pHi. Using fluorescence ratio imaging, we found that pHi can be equilibrated to within ± 0.05 pH unit, in the pH range of 6.0‐6.8, for up to 1 h after pHe adjustment. Cells equilibrated to various pHi were subjected to PDT at various light fluences, then plated for clonogenic survival immediately after PDT treatment. There is no significant effect of lowering pHi, to values as low as 6.23, on the toxicity of PDT, regardless of whether pHi is lowered by adjustment of the medium alone or by addition of exchange inhibitors. However, cells equilibrated to pHi 6.0 are more sensitive to PDT, with survival reduced by 1 log at 20 kJ/m2 and 1.5 log at 30 kJ/m2, relative to cells treated at a pHi of 6.8 (controls). In contrast, 20 μM nigericin in medium at pHe 6.7 reduces pHi to 6.55, but reduces the surviving fraction at 20 kJ/m2 by nearly 3 logs relative to controls. These data conclusively demonstrate that the ability of nigericin to potentiate PDT is not directly related to its ability to lower pHi. Furthermore, they show that the expression of PDT damage is independent of pHi, except at the very low value of 6.0. Photodynamic therapy does not induce apoptosis in A549 cells, at surviving fractions of 0.1 to 0.01, under any of the treatment conditions used in this study.
Induction of Cyclobutane Pyrimidine Dimer Photolyase in Cultured Fish Cells by UVA and Blue Light
Authors: Mitani Hiroshi , Uchida Nobuhiro , Shima Akihiro
Published: January 2008

Abstract— The cyclobutane pyrimidine dimer (CPD) photolyase in fish cells is known to be regulated by environmental factors, such as light, hydrogen peroxide and growth inhibition. The induction of CPD photolyase by light in cultured goldfish cells was dependent on the wavelength of the light, and UVA and blue light had high inductive activity. The spectrum for CPD photolyase activity was different from that for the induction. Treatment with blue or yellow light for a short time, which did not induce any CPD photolyase, induced high CPD photolyase activity in the presence of the photosensitizers, TPPS (monosulfonated meso‐tetraphenyl porphine) and ALPS (aluminum phthalocyanine tetrasulfonate), respectively. These results suggest that the induction of CPD photolyase might be triggered by active oxygen produced by light and cellular photosensitizers. We also found that immediately after treatment with UVA, blue light or a photosensitizer in combination with light, cellular attachment to the substratum was enhanced, as was the CPD photolyase activity. Pretreatment with a flavonoid, quercetin, inhibited both photoinduction of CPD photolyase and enhancement of cellular attachment. Vitamin E inhibited only photoinduction of CPD photolyase activity. Treatment with H7, a strong inhibitor for protein kinase C, after light treatment inhibited photoinduction of CPD photolyase activity, but an analogue of H7, Ha1004, which is a weak inhibitor of protein kinase C, did not have such an effect.
In Vivo Fluence Rate Effect in Photodynamic Therapy of Early Cancers with Tetra(m‐hydroxyphenyl)chlorin
Authors: Blant Snezana Andrejevic , Woodtli Alain , Wagnières Georges , Fontolliet Charlotte , van den Bergh Hubert , Monnier Philippe
Published: January 2008

Abstract— Several parameters affect clinical trials in photodynamic therapy and influence the therapeutic outcome. Beside drug dose, light dose, drug‐light interval and other variables, the fluence rate is a parameter that can influence the therapeutic results. In this study we have evaluated the fluence rate effect with a second‐generation photosensitizer, tetra(m‐hydroxyphenyl)chlorin (mTHPC) using a 7,12‐dimethylbenz(a)anthracene induced early squamous cell carcinoma of the Syrian hamster cheek pouch as a tumor model. Following injection of 0.5 mg/kg of mTHPC, irradiation tests were performed at two drug‐light intervals, 4 and 8 days. Wavelength and light dose were adapted from those applied routinely in clinical trials. Irradiations at 652 nm were carried out with fluences ranging from 8 to 20 J/cm2 delivered at fluence rates of 15 and 150 mW/cm2. Similar tests were also performed at 514 nm with a fluence of 80 J/cm2 delivered at fluence rates ranging from 25 to 125 mW/cm2. At both wavelengths and drug‐light intervals for a given fluence, the higher fluence rates resulted in less tissue damage in tumor and healthy mucosae. However, the lower fluence rates yielded slightly less therapeutic selectivity. This study confirms that the fluence rate is of major importance in clinical PDT.
P840‐Reaction Centers from Chlorobium tepidum–Quinone Analysis and Functional Reconstitution into Lipid Vesicles
Authors: Frankenberg Nicole , Hager‐Braun Christine , Feiler Ute , Fuhrmann Markus , Rogl Hans , Schneebauer Nikolaus , Nelson Nathan , Hauska Günter
Published: January 2008

Membranes of Chlorobium tepidum contain about 35, 45 and2–10 molecules of menaquinone‐7, chlorobium quinone (1′‐oxo‐menaquinone‐7) and of the polar menaquinone (probably 1′‐OH‐menaquinone‐7) per reaction center, respectively. None of these quinones was retained during the isolation of P840‐reaction centers beyond the detection limit of about 0.2 quinones per reaction center, neither in the core complex nor in functionally intact reaction center preparations. The latter is shown to catalyze the formation of an electrochemical proton gradient in the presence of ascorbate and phenazinium methosulfate, when it is incorporated into lipid vesicles.
Photophysical Properties of Some Methyl‐Substituted Angelicins: Fluorometric and Flash Photolytic Studies
Authors: Elisei F. , Aloisi G. G. , Lattarini C. , Dall'Acqua F. , Guiotto A.
Published: January 2008

This paper describes the results of a study of the photophysical properties of various methyl‐angelicins (MA) in solvents of different polarity and proticity. The behavior of their excited singlet and triplet states was investigated by fluorometry and nanosecond laser flash photolysis. On the basis of semiempirical (ZINDO/S‐CI) calculations and the solvent effect on the absorption and fluorescence properties, the lowest excited singlet state (S1) is assigned to a partially allowed π, π* state. The close lying S2state is n,π* in nature. The efficiency of the decay pathways of S1(fluorescence, intersystem crossing and internal conversion) strongly depends on the energy gap between the S1and S2states consistent with the manifestation of “proximity effect.” Thus, MA in cyclohexane decay only through S1→ S0internal conversion, while in acetonitrile and ethanol, where the n, π* state is located at higher energy, their fluorescence and intersystem crossing increase significantly. The lowest excited triplet states (T1) were characterized in terms of their absorption spectra, decay kinetics, molar absorption coefficients and formation quantum yields. The interaction of T1MA with molecular oxygen leads to an efficient formation of singlet oxygen, as evidenced by the appearance of characteristic IR phosphorescence centered at 1269 nm.
Role of Calcium in Photodynamically Induced Cell Damage of Human Fibroblasts
Authors: Hubmer Alexander , Hermann Anton , Überreigler Karl , Krammer Barbara
Published: January 2008

Photodynamically induced changes in the cytoplasmic free calcium concentration ([Ca2+]i) and its role in cell damage were investigated in human skin fibroblasts using confocal laser microscopy. Fluorescence and absorbance spectrophotometry measurements indicate that the photosensitizer aluminum phthalocyanine tetrasulfonate (AlPcS4) binds to the plasma membrane and only after irradiation is able to enter the cells, causing massive morphologic alterations. Upon irradiation of sensitizer‐treated cells, the increase in [Ca2+]i is related to the amount of light and extracellular [Ca2+]e. The increase in [Ca2+]i was substantially reduced in the absence of [Ca2+]e. Cell damage or death after photodynamic treatment was prevented and shifted toward higher fluence by increasing [Ca2+]i at high [Ca2+]e and was greater at low [Ca2+]e. Application of Ca2+ channel blockers, such as Co2+, Cd2+ or verapamil, could not prevent the increase of [Ca2+]i. Our results indicate that activation of the photosensitizer, AlPcS4, causes an influx of Ca2+, which protects cells from photodamage. At low [Ca2+]e and high fluence values, release of Ca2+ from internal stores probably as a protective measure occurs in order to increase the [Ca2+]i.
Effect of Low‐Dose Gamma Radiation on HIV Replication in Human Peripheral Blood Mononuclear Cells
Authors: Xu Y. , Conway B. , Montaner J. S. G. , O'Shaughnessy M. V. , Greenstock C. L.
Published: January 2008

Recent studies have demonstrated that UV light and x‐irradiation enhance human immunodeficiency virus (HIV) gene expression. There are few published data on related effects of γ‐radiation. This may be of clinical relevance, as radiotherapy has been used extensively for the treatment of acquired immunodeficiency syndrome associated conditions. With this in mind, we have studied the effects of γ‐radiation on HIV replication in mononuclear cells (MC). These cells were obtained from five seronegative healthy donors, exposed to0–200 cGy γ‐radiation, stimulated with phytohemagglutinin‐P (PHA‐P) for 24 h, infected with a laboratory strain of HIV (HTLV‐IIIB, multiplicity of infection = 0.001), then carried in culture for 14 days. Overall, when considering p24 antigen levels on days 7 and 11 in cultures established from cells exposed to 50 cGy, the maximal levels were significantly higher than those measured in the parallel control cultures taken as a whole (P < 0.05), with viral replication enhanced as much as 1000‐fold in one case. No significant cytotoxicity was observed following exposure to doses up to 50 cGy. The mechanism of the observed effect remains unknown but may relate to direct gene activation and/or free radical generation, leading to such activation. To date, there is no evidence that viral stimulation occurs following therapeutic radiation in a clinical setting.
PUVA Therapy is Preferable to UVB Phototherapy in the Management of HIV‐Associted Dermatoses
Authors: Morison Warwick L.
Published: January 2008

Both methoxsalen plus UVA (PUVA) therapy and UVB phototherapy are commonly used in the management of human immunodeficiency virus‐associated dermatoses but UVB phototherapy appears to be the preferred treatment. There are several considerations, in particular therapeutic efficacy and therapeutic profile, which suggest that PUVA therapy might be more effective, This needs to be established in clinical trials.
Risk Assessment of UVB Effects on Resistance to Infectious Diseases
Authors: Garssen Johan , Goettsch Wim , Gruijl Frank de , Loveren Henk Van
Published: January 2008

The aim of this study was to develop a qunatitiative risk assessment of lowered resistance to Infections in humans due to (solar) ultraviolet B (UVB) exposure. We followed the steps for risk assessment as defined by the U. S. National Academy of Sciences: (1) hazard identification, (2) dose‐response assessment, (3) exposure assessment, and (4) risk characterization. For step 1, the suppressory effects of UVB radiation on the immune system have been reviewed, suplemented with new data, and analyzed. Experiments on UV‐induced immunosuppression cannot be performed with humans for ethical reasons, but herpes simplex virus infection appears to be the human paradigm. Thus, UVB radiation appears to be a potential hazard to immunologic functions, Step 2 is crucial, but dose‐response relationships for infections have never been measured in humans. We used our earlier doseresponse rat data for suppression of lymphocyte stimulation and computed that the UVB dose resulting in a 50% reduction of lymphocyte stimulation by Listeria monocytogenes is 6.800 J/m2. Using mixed skin lymphocyte response assays we found that humans are 3.8 times less sensitive than rats (interspeices variation (IEVI). To account for the 2.5 percentile of most susceptible individuals in a population, and additional factor (intraspecies varations (IAV) was introduced (0.5 for humans). Using these data, we computed that 13.100 J/m2 of UVB radiation emitted by FS40 lamps would suppress 50% of the proliferative response of lymphocytes to L. monocytogenes in most sensitive skin type 2 humans. In step 3, we assumed the action spectrum for the responses analyzed by us as indentical to an action spectrum for suppression of contact hypersensitivity that is available in the literature. This led us to step 4, where we calculated that approximately 100 min of solar exposure at around noon in Italy or Spain would suppress the resistance to infections by L. monocytogenes in the most sensitive humans.
Structure‐Photodynamic Activity Relationships of a Series of 4‐Substituted Zinc Phthalocyanines
Authors: Margaron Philippe , Grégoire Marie‐Josée , Ŝĉasnár Vladimir , Ali Hasrat , van Lier Johan E.
Published: January 2008

Abstract— Radioiodinated zinc phthalocyanine including [125I]ZnPcI4 and differently sulfonated [65Zn]ZnPcS (ZnPcS4, ZnPcS3, ZnPcS2 and ZnPcS1.75, a mixture of adjacent di and 25% mono) were prepared in order to study cell uptake and release kinetics in EMT‐6 cells. The same compounds were evaluated for their in vitro phototoxicity and the biological parameters were compared to partition coefficients to arrive at quantitative structure‐activity relationships (QSAR). At 1 μM in 1% serum, at 37°C, all dyes showed rapid cell uptake during the first hour followed by a slow accumulation phase. After 24 h, the highest cellular concentration was observed with the lipophilic ZnPcI4, followed by the amphiphilic ZnPcS2 and ZnPcS1.75. The hydrophilic ZnPcS4 and ZnPcS3 showed lower uptake. Dye release from dyeloaded cells during incubation in dye‐free medium could reach up to 60% and was shown to depend mainly on the amount of drug incorporated rather than the type of compound. These results suggest that care should be taken in interpreting dye toxicity data, which involve in vitro cell manipulations in dye‐free medium, particularly during in vitro/in vivo protocols. The EMT‐6 cell survival after 1 h or 24 h incubation with 1 μM dye in 1% serum followed by exposure to red light was assessed by means of the colorimetric 3‐(4,5‐dimethylthiazol‐2‐yl)‐diphenyl‐tetrazolium bromide (MTT) assay. Photocytotoxicities correlated inversely with the tendencies of the dyes to aggregate. Increased dye uptake by the cells also correlated with their activities, except for the lipophilic ZnPcI4, which showed the highest cell uptake but little phototoxicity. The QSAR between phototoxicity and the log of the partition coefficients (phosphate‐buffered saline and n‐octanol) gave a parabola with optimal partition values corresponding to the adjacent sulfonated ZnPcS2.
Benzophenothiazine and Benzoporphyrin Derivative Combination Phototherapy Effectively Eradicates Large Murine Sarcomas
Authors: Cincotta Louis , Szeto Donna , Lampros Elana , Hasan Tayyaba , Cincotta Anthony H.
Published: January 2008

Abstract— The tumoricidal effects of photochemotherapy with two photosensitizers, 5‐ethylamino‐9‐diethylaminobenzo[a] phenothiazinium chloride (EtNBS) and benzoporphyrin derivative monoacid ring A (BPD‐MA), were evaluated separately and in combination against the EMT‐6 fibrosarcoma implanted subcutaneously in BALB/c mice. Animals carrying tumors 8‐10 mm in diameter were divided into eight different groups (∼20/group) and subjected to various photoirradiation and drug conditions. The tumor response to photodynamic therapy (PDT) was measured as the mean tumor wet weight 2 weeks post‐PDT. The combination treatment with 5.25 mg/kg EtNBS and 2.5 mg/kg BPD‐MA followed by photoirradiation with 100 J/cm2 at 652 nm and then by 100 J/cm2 at 690 nm resulted in a 95% reduction in the average tumor weights compared to controls (no light, no drugs) with 76% of the mice being tumor free 2 weeks post‐PDT. Because treatment with EtNBS or BPD‐MA at twice the light dose and drug concentration resulted in either no significant reduction in tumor weights or increased the lethality of treatment, respectively, the data suggest that the enhanced PDT effect observed with the combination of drugs is synergistic rather than additive. Histology of tumors 24 h post‐PDT with the combination of drugs showed nearly complete destruction of the tumor mass with little or no damage to the vasculature and no extravasation of red blood cells. There was no damage to the normal skin adjacent to the tumor. Fluorescence microscopy of EMT‐6 cells incubated in vitro with the two photosensitizers revealed that they were localized to different intracellular compartments. The fluorescence pattern from frozen tumor tissue slices following the in vivo administration of the photosensitizers indicated a greater intracellular localization for EtNBS vs BPD‐MA.
Infrared Light‐Emitting Diode Radiation Causes Gravitropic and Morphological Effects in Dark‐Grown Oat Seedlings
Authors: Johnson Corinne F. , Brown Christopher S. , Wheeler Raymond M. , Sager John C. , Chapman David K. , Deitzer Gerald F.
Published: January 2008

Abstract— Oat (Avena sativa cv Seger) seedlings were irradiated with IR light‐emitting diode (LED) radiation passed through a visible‐light‐blocking filter. Infrared LED irradiated seedlings exhibited differences in growth and gravitropic response when compared to seedlings grown in darkness at the same temperature. Thus, the oat seedlings in this study were able to detect IR LED radiation. These findings call into question the use of IR LED as a safe‐light for some photosensitive plant response experiments. These findings also expand the defined range of wavelengths involved in radiation‐gravity (light‐gravity) interactions to include wavelengths in the IR region of the spectrum.
Purification and Partial Characterization of (6‐4) Photoproduct DNA Photolyase from Xenopus laevis
Authors: Kim Sang‐Tae , Malhotra Khushbeer , Taylor John‐Stephen , Sancar Aziz
Published: January 2008

Abstract— The (6‐4) photoproduct DNA photolyase was detected in two vertebrate animals Crotalus atrox (rattlesnake) and Xenopus laevis (South African clawed toad). The enzyme was extensively purified from X. laevis and characterized. The highly purified enzyme is fluorescent with an excitation maximum at 420‐440 nm and emission maximum at 460‐480 nm. The photorepair action spectrum matches the fluoresoence excitation spectrum with a 430 nm maximum.
Elastic Fiber‐Associated Proteins of Skin in Development and Photoaging
Authors: Werth V. P. , Shi X. , Kalathil E. , Jaworsky C.
Published: January 2008

Abstract— We sought to use antibodies against structural (tropoelastin, fibrillin) and nonstructural (decay‐accelerating factor [DAF], serum amyloid P [SAP]) components of elastic fibers to characterize fiber structure in neonatal skin, normal adult skin and adult skin with solar elastosis from advanced photoaging. We found by immunohisto‐chemistry and by western blotting that DAF, unlike SAP, is present on cutaneous elastic fibers in neonates and young children, suggesting that DAF may play an early, integral role in protecting elastic fibers from destruction by complement. The most superficial portion of oxytalan fibers stained with antibodies against fibrillin and DAF, while anti‐tropoelastin stained only the deeper portion of oxytalan fibers. This suggests that deep oxytalan fibers are composed of both elastin and microfibrils, while the most superficial component is composed solely of microfibrillar proteins. Solar elastosis showed increased fibrillin, DAF, tropoelastin and SAP. Thus, solar elastosis is composed of both microfibrillar and elastin proteins.
Chemically Initiated Electron Exchange Luminescence of Silyloxyaryl‐Substituted Spiroadamantyl Dioxetanes: Kinetics and Excited State Yields
Authors: Trofimov Alexei V. , Mielke Karsten , Vasil'ev Rostislav F. , Adam Waldemar
Published: January 2008

Abstract— The kinetics of the fluoride‐induced decomposition of the thermally stable silyloxyaryl‐substituted spiroadamantyl dioxetanes 1a,b and the excited state formation of this chemically initiated electron exchange luminescence (CIEEL) have been investigated. Two limiting kinetic regimes flash and glow have been identified, which depend on the fluoride concentration, the first at high, the second at low [F‐] triggering, whose detailed kinetic analysis affords the rate constants for the deprotected dioxetanes 2a,b cleavage in acetonitrile and dimethyl sulfoxide and chemiluminescence measurements the CIEEL and phen‐olate 4 (CIEEL emitter) excitation yields. Chloro‐substi‐tution in the spiroadamantyl dioxetane does not affect the deprotection step k2 but leads to a ca five‐fold faster cleavage of the deprotected dioxetane 2, while the chemiexcitation yield is the same for both dioxetanes. The energies of the first excited singlet and triplet states of the emitting phenolate 4 were estimated by AM1 configuration interaction calculations with explicit consideration of acetonitrile as solvent (self‐consistent reaction field approach). The first excited singlet and triplet state of the CIEEL emitter phenolate 4 possess π,π* character, as suggested by the π‐type molecular orbitals and the large singlet‐triplet energy gap. The chemiexcitation of both singlet and triplet states of the excited phenolate 4 is feasible during the dioxetanes 1a,b cleavage, but the experimentally determined high singlet excitation yields suggest that preferentially the phenolate 4 singlet state is populated in the fluoride ion‐triggered CIEEL process.
Cell Cycle Kinetics Following UVA Irradiation in Comparison to UVB and UVC Irradiation
Authors: de Laat Annemarie , van Tilburg Marloes , van der Leun Jan C. , van Vloten Willem A. , de Gruijl Frank R.
Published: January 2008

Abstract— There is limited information about the carcinogenic effect of longwave ultraviolet radiation (UVA: 315‐400 nm). In particular very little is known about the relevant genotoxic damage caused by physiological doses of UVA radiation. A general response of cells to DNA damage is a delay or arrest of the cell cycle. Conversely, such cellular responses after UVA irradiation would indicate significant genotoxic damage. The aim of this study is to compare cell cycle kinetics of human fibroblasts after UVC (190‐280 nm radiation), UVB (280‐315 nm radiation) and UVA irradiation. Changes in the cell cycle kinetics were assessed by bivariate flow cytometric analysis of DNA synthesis and of DNA content. After UVC, UVB or UVA irradiation of human fibroblasts a suppression was seen of bromodeoxyuridine (BrdU) incorporation at all stages of S phase. The magnitude of this suppression appeared dose dependent. Maximum suppression was reached at 5‐7 h after UVB exposure and directly after UVA exposure, and normal levels were reached 25 h after UVB and 7 h after UVA exposure. The lowered BrdU uptake corresponded with a lengthening of the S phase. No dramatic changes in percentages of cells in G1, S and G2/M were seen after the various UV irradiations. Apparently, UVA irradiation, like UVB and UVC irradiation, can temporarily inhibit DNA synthesis, which is indicative of genotoxic damage.
Apoptosis is an Early Event During Phthalocyanine Photodynamic Therapy‐Induced Ablation of Chemically Induced Squamous Papillomas in Mouse Skin
Authors: Agarwal Rajesh , Korman Neil J. , Mohan Rajiv R. , Feyes Denise K. , Jawed Seema , Zaim M. Tarif , Mukhtar Hasan
Published: January 2008

Abstract— Photodynamic therapy (PDT) is a promising new modality to treat malignant neoplasms including superficial skin cancers. In our search for an ideal photosensitizer for PDT, Pc 4, a silicon phthalocyanine, has shown promising results both in in vitro assays and in implanted tumors. In this study we assessed the efficacy of Pc 4 PDT in the ablation of murine skin tumors; and the evidence for apoptosis during tumor ablation was also obtained. The Pc 4 was administered through tail vein injection to SENCAR mice bearing chemically induced squamous papillomas, and 24 h later the lesions were illuminated with an argon ion‐pumped dye laser tuned at 675 nm for a total light dose of 135 J/cm2. Within 72‐96 h, almost complete tumor shrinkage occurred; no tumor regrowth was observed up to 90 days post‐PDT. As evident by nucleosome‐size DNA fragmentation, appearance of apoptotic bodies in hematoxylin and eosin staining and direct immunoperoxidase detection of digoxigenin‐labeled genomic DNA in sections, apoptosis was clearly evident 6 h post‐PDT at which time tumor shrinkage was less than 30%. The apoptotic bodies, as evident by the condensation of chromatin material around the periphery of the nucleus and increased vacuolization of the cytoplasm, were also observed in electron microscopic studies of the tumor tissues following Pc 4 PDT. The extent of apoptosis was greater at 15 h than at 6 and 10 h post‐PDT. Taken together, our results clearly show that Pc 4 may be an effective photosensitizer for PDT of nonmelanoma skin cancer, and that apoptosis is an early event during this process.
Effects of Solar UVB Radiation on Growth, Flowering and Yield of Central and Southern European Maize Cultivars (Zea mays L.)
Authors: Saile‐Mark M. , Tevini M. , Mark U.
Published: January 2008

Abstract— Different cultivars of maize (Zea mays L.) originating from Central and South Europe were grown from June to September 1994 for 16 weeks in two greenhouses covered with different UVB‐absorbing (280–320 nm) plastic foils. Using the ambient UVB radiation level of a southern location (Portugal, 38.7°N) in one of the greenhouses as an enhanced radiation compared to the reduced radiation in the second greenhouse, an increase of about 12% of UVB was simulated. Six of the eight cultivars examined showed significant reductions in height of up to 18.9% at all developmental stages under increased UVB. In contrast to this, the fresh and dry weight as well as the leaf area was reduced under UVB only at early developmental stages, but with ongoing development the UVB stressed plants caught up. The total content of absorbing compounds of the maize cultivars was completely unaffected by UVB. A flowering delay up to a maximum of 5 days was observed under higher UVB in several cultivars. Probably due to this delay in the cob development the yield decreased to 27.7% under higher UVB at the first harvest after 12 and 14 weeks, whereas at the second harvest after 14 and 16 weeks yield reduction levelled off.
The Mechanism of Photochemical Release of Nitric Oxide from S‐Nitrosoglutathione
Authors: Wood Paul D. , Mutus Bulent , Redmond Robert W.
Published: January 2008

Abstract— Laser flash photolysis of S‐nitroso complexes of glutathione (GSNO) and bovine serum albumin (BSANO) via excitation at 355 nm has been used to investigate the photogeneration of nitric oxide (NO) and subsequent radical reactions. In the case of GSNO, liberation of NO was confirmed by its oxidation of oxyhemoglobin to met hemoglobin. Initial NO release is via homolytic cleavage of the S‐N bond to produce the glutathione thiyl radical, GS, which can subsequently react with (a) ground‐state GSNO (k= 1.7 × 109M−1/i> s−1) to yield additional NO and oxidized glutathione, GSSG; and (b) oxygen (k= 3.0 × 109M−1 s−1) to give the glutathione peroxy radical, GSOO, which subsequently reacts with ground‐state GSNO (k= 3.8 × 108M−1 s−1), also producing additional NO and GSSG. The relative concentrations of oxygen and GSNO in the system determine the major pathway for removal of G'. These secondary reactions occur at such high rates that they preclude radical recombination under low‐intensity irradiation conditions. The quantum yield of overall loss of GSNO thus varies with both GSNO and oxygen concentrations; a value of 0.66 was determined for an aerated solution of GSNO (0.86 mM). In the case of GSNO, therefore, generation of NO is not due solely to homolysis of the S‐N bond; secondary reactions of the radicals formed lead to further NO liberation. In rationalizing the known phototoxicity of GSNO, possible contributions from thiyl and thiyl‐derived radicals should be considered. In contrast to GSNO, direct excitation of BSANO (containing one bound NO group per molecule) led to photodecomposition with a quantum yield of 0.09 but no evidence was obtained for liberation of NO into the bulk medium.
Synergistic Interaction of Photodynamic Treatment with the Sensitizer Aluminum Phthalocyanine and Hyperthermia on Loss of Clonogenicity of CHO Cells
Authors: Rasch Monique H. , Tijssen Karmi , VanSteveninck John , Dubbelman Tom M. A. R.
Published: January 2008

Abstract— When CHO cells were exposed to hyperthermia and subsequently to photodynamic treatment, the combined effects were additive but in the reverse sequence the interaction was synergistic. The synergistic interaction comprised two quite different components: (1) photodynam‐ically induced sensitization of cellular proteins and/or supramolecular structures for thermal inactivation and (2) a photodynamically induced inhibition of the cellular repair system for sublethal thermal damage. The first component of the synergistic interaction was reflected by a change of the Arrhenius parameters of thermal cell killing. A lowering of the activation energy of this process was responsible for the synergistic interactions, whereas a concomitant decrease of the frequency factor, opposing this effect, actually caused a much lower degree of synergism at higher temperatures. This component of the synergistic interaction did not respond to the insertion of an intermediate incubation period between the two treatments. The second component of the synergistic interaction, viz. the interference with the ability of cells to survive sublethal thermal damage, was reversible, as an intermediate incubation between photodynamic treatment and hyperthermia resulted in its repair. The photodynamically induced inhibition of the ability of cells to survive sublethal thermal damage was not related to ATP or glutathione depletion, inhibition of de novo protein synthesis or impairment of degradation of damaged protein molecules. Restoration of the repair system for sublethal damage depended on a metabolic process and required free intracellular Ca2+, suggesting that a cell signaling pathway may be involved. Thus, in a practical sense the magnitude of the synergistic interaction between photodynamic treatment and hyperthermia depends on the length of the interval between the two treatments and on the temperature and duration of the subsequent thermal treatment. This may have significant consequences for the development of clinical protocols.
The Immunological Effect of 8‐Methoxypsoralen and UVA Treatment on Murine T‐Cell Leukemia
Authors: Cheng Ting‐Ying , Shen Fung‐Win , Lin Rong‐Hwa
Published: January 2008

Abstract— 8‐Methoxypsoralen (8‐MOP) plus long‐wavelength UV radiation (UVA, 320–400 nm) have been used to treat various diseases such as cutaneous T‐cell lymphoma, systemic scleroderma, rheumatoid arthritis and rejection of heart transplants. However, the immunological mechanism of this treatment remains unknown. In this report, we investigated the effect of 8‐MOP/UVA on the modulation of the immunogenicity of a T‐cell leukemia cell line (RL ♂l cells). The results demonstrated that the stimulator function of the in vitro 8‐MOP/UVA‐treated RL♂ cells was enhanced in both RL ♂1‐specific allogeneic and syngeneic immune responses. Furthermore, the enhancement of the immunogenicity of the 8‐MOP/UVA‐treated RL♂ cells was found to be strongly associated with the increase of intercellular adhesion molecule‐1 expression on these 8‐MOP/UVA‐treated tumor cells. Therefore, our findings suggested that the alteration of the expression of the immune‐related cell surface molecules might be an important effect of 8‐MOP/UVA treatment on the elevation of the immunogenicity of the 8‐MOP/UVA‐treated tumor cells.
Delayed Oxidative Photodamage induced by Photodynamic Therapy
Authors: Kessel David , Luo Yu
Published: January 2008

Abstract— Apoptotic DNA fragmentation was observed 60 min after photodynamic therapy of murine leukemia cells in culture, using either of two photosensitizers with predominantly lysosomal targets. When the radical scavengers trolox or α‐tocopherol succinate were present during irradiation, the subsequent appearance of apoptotic cells was prevented, as was phototoxicity. Addition of either scavenger during the 60 min after irradiation provided only partial protection from apoptosis and phototoxicity; this protection was abolished if the addition was delayed for 10 min. These results are consistent with a model whereby long‐persisting photoproducts continue the initiation of apoptosis for approximately 10 min after irradiation has ceased.
Unsymmetrically Substituted Benzonaphthoporphyrazines: A New Class of Cationic Photosensitizers for the Photodynamic Therapy of Cancer*
Authors: Michelsen U. , Schnurpfeil G. , Sobbi A. K. , Wöhrle D. , Kliesch H.
Published: January 2008

Abstract— Unsymmetrical zinc(II) complexes of benzonaphthoporphyrazines 5 a‐12a bearing between one and eight pyri‐dyloxy substituents are synthesized by statistical tetra‐merization of 6‐(l,l‐dimethylethyl)‐2,3‐naphthalenedi‐carbonitrile (1) with 4‐(3‐pyridyloxy)‐ or 4,5‐bis‐(3‐pyri‐dyloxy)‐1,2‐benzenedicarbonitrile (2, 3). Methylation of 5a‐12a leads to the cationic pyridyloxybenzonaphtho‐porphyrazines 5b‐ 12b having between one to eight positive charges. The Q‐band transition in the visible spectra exhibits a bathochromic shift from 680 to 760 nm dependent upon the number of annelated naphthalene rings. The singlet oxygen quantum yields of the benzonaphthoporphyrazines determined by the dye‐sensitized photoox‐idation of 1,3‐diphenylisobenzofurane is surprisingly high (in the range of zinc phthalocyanine). The photoox‐idative stabilities of the photosensitizers described quantitatively by first‐order kinetics decrease with the number of annelated naphtho groups. A linear correlation between the logarithm of the decomposition rate constant and the position of the highest occupied molecular orbital (HOMO)‐level of the photosensitizers is found. Destabi‐lization of the HOMO leads to a decrease of the pho‐tostability. Due to their adjustable long wavelength absorption, their intramolecular polarity axis and their different hydrophilic/hydrophobic character, these novel compounds may be suitable photosensitizers for the photodynamic therapy of cancer.
Kinetic Analysis of Apoptosis Induction in Human Cell Lines by UVA and 8‐MOP
Authors: Vowels Benjamin R. , Yoo Elisa K. , Gasparro Francis P.
Published: January 2008

Whereas previous studies have indicated that DNA damage as a result of 8‐methoxypsoralen (8‐MOP) and UVA treatment leads to cell death, this study establishes the minimum concentrations of 8‐MOP and UVA necessary to induce apoptosis in human T‐lymphocytic and mono‐cytic cell lines. In order to assess apoptosis, we used fluorescent microscopy to examine changes in light scattering as well as internucleosomal DNA fragmentation. Generation of a dose response curve showed that the minimum combination of UVA and 8‐MOP that was necessary to induce greater than background levels of apoptosis within 24 h of treatment was 0.5 J/cm2 UVA and 12.5 ng/mL of 8‐MOP. A striking observation was that UVA alone at doses 1.0 J/cm2, but not 8‐MOP alone (6300 ng/mL), induced significant apoptosis in the Sup‐T1 cell line within 24 h. Although the percentage of apoptotic Sup‐T1 cells induced by UVA alone was not as great as that of 8‐MOP and UVA in combination, a highly significant correlation between the product of the concentration of 8‐MOP (ng/mL) times the dose of UVA (J/ cm2) and the percentage of apoptotic cells was observed. This correlation provides an important tool for studying the relationship of UVA‐induced DNA damage to apoptosis induction. Moreover, it will provide a means by which early events in the apoptotic pathway can be dissected.