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PubMed1999

Molecular mechanisms of photosensitization XIII: a combined differential scanning calorimetry and DNA photosensitization study in non steroidal antiinflammatory drugs-DNA interaction.

A combined differential scanning calorimetry (DSC) and photosensitization study has been carried out on the interaction of several NSAID on DNA, both from calf thymus and pBR 322 plasmid. The investigated compounds were both non-steroidal anti-inflammatory drugs as well as compounds related to NSAIDs for structural similar properties, to find evidence for their ability to interact with DNA as a function of steric hindrance and polarity of the chemical structures. The considered NSAIDs were diflunisal (DFN, a salicylic derivative), naproxen (NAP), ketoprofen (KPF), suprofen (SPF) and tiaprofenic acid (TIA, arylpropionic acids). The structural criterion used was related to three different aromatic groups, biphenyl, naphthalene and benzophenone (BZP). In fact drug-DNA interaction can be revealed by variations of the enthalpies and temperatures of unfolding of DNA obtained by comparison of calorimetric peaks, where a decrease of the enthalpy is associated with the drug-DNA interaction, by engaging electrostatic bonds. Testing their ability in inducing DNA cleavage when UVA irradiated can evidence the photosensitizing properties of the drug. A good correlation was found between calorimetric and photosensitization studies. From the results obtained it can be reasonably supposed that the photocleavage depends only on the drug molecules bound to DNA.

Animals↗
PubMed2005

Distribution of photosensitizers in bladder cancer spheroids: implications for intravesical instillation of photosensitizers for photodynamic therapy of bladder cancer.

PURPOSE: Uniform intratumor distribution of sufficient photosensitizer is one of the important aspects of photodynamic therapy for solid tumors. METHODS: Multicellular spheroids derived from a human transitional cell carcinoma cell line (MGHU3) were used as a surrogate system of tiny solid tumors to study intratumor distribution of photosensitizers. Photosensitizers included Photofrin, hypocrellins (HBEA-R1/R2, HBBA-R2), aluminum phthalocyanine chloride (AlPC), benzoporphyrin derivative monoacid ring A (BPD-MA), protoporphyrin-IX (PpIX), and liposomal formulations of HBBA-R2 and BPD-MA. Spheroids were incubated with various doses of the above drugs for 1-4 hours, and were examined by confocal microscopy. RESULTS: Histology showed all cells were healthy in spheroids less than 400 microm in diameter. Scanning electron microscopy showed tight cell-to-cell interdigitation in spheroids. HBEA-R1/R2 distributed more uniformly in spheroids than other drugs. Free hypocrellins and BPD-MA penetrated spheroids centripetally deeper than AlPC, Photofrin, and PpIX. Liposomal HBBA-R2 and BPD-MA penetrated less than their free formulations. CONCLUSIONS: The spheroids mimic solid tumors prior to neovascularization. Based on drug distribution in spheroids, hypocrellins and BPD-MA appear superior to Photofrin, AlPC and PpIX for intravesical administration for bladder cancer phototherapy.

Administration, Intravesical↗
PubMed1984

Mechanisms of contact photosensitivity in mice. IV. Antigen-specific suppressor T cells induced by preirradiation of photosensitizing site to UVB.

Mice were successfully contact photosensitized with 3,3',4',5-tetrachlorosalicylanilide (TCSA) plus black light irradiation. Pre-exposure of the photosensitizing site (ca 5 cm2) to UVB (280 to 320 nm; 400 mJ/cm2) rendered mice unresponsive to a challenge reaction. Cell transfer experiments demonstrated that the spleens from the nonreactive mice contained suppressor T cells (Ts) that were antigen-specific and that blocked the afferent limb of contact photosensitivity to TCSA. To exert suppressive functions, Ts required another population of cyclophosphamide-sensitive T cells that resided in the spleens of nonsensitized mice. The results provide evidence that UVB-induced aberrant homeostasis of the skin caused a marked suppression of immune system that is associated with the generation of Ts.

Allergens↗
PubMed1997

Photosensitivity in lupus erythematosus, UV photoprovocation results compared with history of photosensitivity and clinical findings.

Photosensitivity, one of the presenting symptoms in lupus erythematosus (LE), is still poorly defined and varying prevalence figures have been reported. The possibility of a coexisting photodermatosis, especially polymorphous light eruption (PLE), has often not been taken into account. We report the results of ultraviolet A (UVA) and B (UVB) photoprovocation tests in 67 clinically photosensitive patients who had confirmed discoid LE (DLE), systemic LE (SLE) or subacute cutaneous LE (SCLE). The results are compared with a detailed history of photosensitivity and with clinical and serological findings. A pathological photoprovocation reaction, graded as weak, moderate or strong, was induced with either UVA or UVB in 69% of patients with LE, in 100% of those with SCLE, in 70% of those with SLE and in 64% of those with DLE, but in none of 14 controls. Only 16% of the pathological reactions were strong and long-lasting, resembling LE lesions, while 48% were moderate or weak and transient, clinically like PLE. Fifty-three per cent of the provocation reactions which were biopsied showed a PLE-like histology or a non-specific inflammatory reaction, and most of them were clinically moderate or weak reactions of short duration. In the remaining, mostly clinically strong or long-lasting reactions, the histology was consistent with LE. A history of sunlight sensitivity did not predict a pathological photoprovocation result but a positive association between the presence of SSA/Ro or SSB/La antibodies and a pathological photoprovocation reaction was found. We have shown that PLE coexists with LE and that both PLE- and LE-like lesions can be induced with UV radiation in LE patients.

Adolescent↗
PubMed1992

The molecular mechanism of photoporphyrin (YHPD)'s photosensitization--laser Raman spectroscopic study of microcosmic and photosensitive damage of YHPD to protein.

Laser Raman spectroscopy was used to investigate the microcosmic and photosensitive damage of YHPD to lysozyme, of which the three-dimensional structure has been elucidated. The experimental results shown by various damages of the main-chain and side-chain of lysozyme are as follows: (i) Phe and Cys are also damaged by photosensitization of YHPD, except for Trp, Tyr, Met, 1/2Cys and His; (ii) the order of the photosensitized sensitivity of various groups of these amino acids have been described; (iii) Trp and Tyr buried in the three-dimensional structure of the protein are damaged very greatly, and (iv) the main-chain conformation of the protein has changed considerably, such as a decrease in orderly structure (alpha-helix, beta-sheet and beta-turn) and a simultaneous increase in random

Hematoporphyrin Derivative↗
PubMed2000

A selenopyrylium photosensitizer for photodynamic therapy related in structure to the antitumor agent AA1 with potent in vivo activity and no long-term skin photosensitization.

Cationic chalcogenopyrylium dyes 5 were synthesized in six steps from p-aminophenylacetylene (9), have absorption maxima in methanol of 623, 654, and 680 nm for thio-, seleno-, and telluropyrylium dyes, respectively, and generate singlet oxygen with quantum yields [Phi((1)O(2))] of 0.013, 0.029, and 0.030, respectively. Selenopyrylium dye 5-Se was phototoxic to cultured murine Colo-26 and Molt-4 cells. Initial acute toxicity studies in vivo demonstrate that, at 29 mg (62 micromol)/kg, no toxicity was observed with 5-Se in animals followed for 90 days under normal vivarium conditions. In animals given 10 mg/kg of 5-Se via intravenous injection, 2-8 nmol of 5-Se/g of tumor was found at 3, 6, and 24 h postinjection. Animals bearing R3230AC rat mammary adenocarcinomas were treated with 10 mg/kg of 5-Se via tail-vein injection and with 720 J cm(-2) of 570-750-nm light from a filtered tungsten lamp at 200 mW cm(-2) (24 h postinjection of 5-Se). Treated animals gave a tumor-doubling time of 9 +/- 4 days, which is a 300% increase in tumor-doubling time relative to the 3 +/- 2 days for untreated dark controls. Mechanistically, the mitochondria appear to be a target. In cultured R3230AC rat mammary adenocarcinoma cells treated with 0.1 and 1.0 microM 5-Se and light, mitochondrial cytochrome c oxidase activity was inhibited relative to cytochrome c oxidase activity in untreated cells. Irradiation of isolated mitochondrial suspensions treated with 10 microM dye 5-Se inhibited cytochrome c oxidase activity. The degree of enzyme inhibition was abated in a reduced oxygen environment. Superoxide dismutase, at a final concentration of 30 U, did not alter the photosensitized inhibition of mitochondrial cytochrome c oxidase by dye 5-Se. The data suggest that singlet oxygen may play a major role in the photosensitized inhibition of mitochondrial cytochrome c oxidase.

Adenocarcinoma↗
PubMed1988

Photosensitization by antitumor agents. 5. Daunorubicin-photosensitized oxidation of NAD(P)H in aqueous and N,N-dimethylformamide/aqueous solutions--an electron paramagnetic resonance study.

An EPR spectrum of the semiquinone radical of daunorubicin (D) was recorded upon illumination (480 nm) of the drug and NAD(P)H in deaerated aqueous and DMF/aqueous solutions. In the latter solvent system, an EPR spectrum with hyperfine structure was recorded. The kinetics of the photoinduced generation and decrease of the EPR signal intensity in the dark were measured. Second order rate constants for the radical recombination were derived for the two solvent systems. Photosensitized production of the superoxide radical, upon illumination of daunorubicin and NAD(P)H, in aerated aqueous or DMF/aqueous solutions, is evidenced by employing a spin trap DMPO (5,5-dimethyl-1-pyrroline-N-oxide) and an SOD assay. 5-Iminodaunorubicin (5-ID), in contrast to the parent compound (D), does not possess photosensitizing properties.

Daunorubicin↗
PubMed2003

Gamma-band phase clustering and photosensitivity: is there an underlying mechanism common to photosensitive epilepsy and visual perception?

Photosensitive epilepsy (PSE) is the most common form of human reflex epilepsy, appearing in up to 10% of epileptic children. It also offers a highly reproducible model to investigate whether changes in neuronal activity preceding the transition to an epileptic photoparoxysmal response (PPR) may be detected. We studied 10 patients with idiopathic PSE (eight female, mean age 26 years, range 9-51 years) using magnetoencephalography. In addition, we also studied the responses of five normal controls (mean age 24 years, age range 9-35 years) and three non-photosensitive epileptic patients (mean age 10 years, range 8-11 years). Spectral analysis of the MEG signals recorded during intermittent photic stimulation revealed relevant information in the phase spectrum. To quantify this effect, we introduced a second order response feature of the stimulus-triggered visual response preceding the PPR: the phase clustering index, which measures how close the phases of successive periods are grouped for each frequency component for all periods of the stimuli applied. We recorded a total of 86 PPRs, including several absence seizures, in nine of the 10 patients. We found that an enhancement of phase synchrony in the gamma-band (30-120 Hz), harmonically related to the frequency of stimulation, preceded the stimulation trials that evolved into PPRs, and differed significantly from that encountered in trials not followed by PPR or in control subjects. This novel finding leads us to postulate that a pathological deviation of normally occurring synchronization of gamma oscillations, underlying perceptional processes, mediates the epileptic transition in PSE.

Adolescent↗
PubMed1992

The mechanism of photosensitization in photodynamic therapy: chemiluminescence caused by photosensitization of porphyrins in saline containing human serum albumin.

Chemiluminescence (CL) caused by photosensitization of porphyrins in phosphate buffered saline (PBS) solution containing 3% human serum albumin (HSA) was observed for the first time. Irrespective of porphyrins concerned, CL shows a spectrum ranging from 380 to 520 nm with a peak near 450 nm and decays almost single-exponentially with a lifetime of about 15 s. The intensity of CL depends on concentrations of porphyrins and HSA in PBS solution. We have examined a number of porphyrins and observed CL for the compounds with triplet lifetimes longer than 0.1 ms. The appearance and quenching of CL by photosensitization of porphyrin-HSA systems indicate that type II reaction by singlet oxygen occurs significantly in photodynamic therapy resulting in hypoxic regions in environments surrounding the sensitizer.

Humans↗
PubMed1984

Piroxicam-induced photosensitivity. In vivo and in vitro studies of its photosensitizing potential.

A 36-year-old woman developed a photolocalized erythematous papulovesicular eruption while taking piroxicam. Histologic study revealed a superficial and deep spongiotic dermatitis. Phototesting with ultraviolet B (UVB) and ultraviolet A (UVA) was abnormal at the time the patient was seen and after oral challenge with the drug for 5 days. A modified lymphocyte transformation test was positive. The photosensitizing potential of the drug was evaluated in vivo and in vitro. In vivo studies consisted of phototesting twelve medical students before and after intake of piroxicam during 5 consecutive days. No lowering of the minimal erythema dose (MED) values or abnormal reactions to UV and visible light were observed in these students. In vitro studies by the Candida plate method and by photohemolysis showed negative results. Our studies suggest a systemic photoallergy mechanism requiring wavelengths in the UVA range for the reaction. This drug should be avoided in patients receiving photochemotherapy.

Adult↗
PubMed1982

Mechanisms of contact photosensitivity in mice: II. Langerhans cells are required for successful induction of contact photosensitivity to TCSA.

The role of Langerhans cells in the induction of contact photosensitivity (CPS) to tetrachlorosalicylanilide (TCSA) was investigated in mice. CPS was induced by 2 daily paintings of 50 microliters of 1% TCSA in acetone plus black light irradiations for 2.5 hr. Both ears were challenged with 20 microliters of 0.1% TCSA in ethanol plus black light irradiation for 2.5 hr on day 5, and ear thickness was read at 24 hr. The density of LCs detected as ATPase-positive cells dramatically decreased 2 days after exposure to UVB. CPS was not induced by painting the photoallergen to the skin which had been pre-irradiated with UVB. The ear swelling response returned to the normal level when the mice were sensitized 12 days after UVB exposure in accordance with the complete regeneration of ATPase-positive cells. Dose of UVB in the present study did not affect the development of CPS through systemic mechanism. These demonstrations indicate that LCs play an important role in the induction of CPS.

Animals↗
PubMedDate not supplied

[The dangers of olaquindox. Photoallergy, chronic photosensitive dermatitis and extreme increased photosensitivity in the human, hypoaldosteronism in swine].

The antibiotic olaquindox, an ingredient added to porker feed to increase overall performance, caused a photoallergic contact eczema and subsequently a chronic photosensitive dermatitis with increased UV-A- and UV-B-sensitivity in a breeder of small pigs. Through the use of sun creams he developed an additional (photo)allergic contact eczema to the sunscreens contained in the creams.

Animal Husbandry↗
PubMed1983

Photosensitivity in South Africa. III. Ovine hepatogenous photosensitivity caused by the plant Athanasia trifurcata L. (Asteraceae).

Hepatogenous photosensitivity was experimentally induced in 1 out of 4 sheep dosed with milled Athanasia trifurcata. This is an unpalatable aromatic shrub commonly found along the south-western and south-eastern Cape coast on overgrazed, recently burnt or disturbed veld, up to an altitude of 1 300m. The liver lesions ranged from a few small multifocal areas of necrosis in 1 animal to various zonal patterns of necrosis (centrizonal, midzonal and peripheral) in each of the other 3. Botanical, toxicological and clinical data are given.

Animals↗
PubMed1983

Photosensitivity in South Africa. IV. Pathological changes in the liver in ovine photosensitivity caused by the plant Asaemia axillaris (Thunb.) Harv. Ex Jackson.

Hepatic lesions in 4 field cases of ovine hepatogenous photosensitization caused by the plant, Asaemia axillaris (Thunb.) Harv. Ex Jackson, are described. The liver was usually swollen, friable and yellowish-brown, with distinct lobulation. Microscopically, the lesions ranged from peripheral coagulative necrosis in 1 animal to others with scattered single cell or small foci of necrosis as well as hepatocellular degeneration and unrest, ductular proliferation, portal fibroplasia and cholestasis. The liver lesions are compared with those of previously reported experimental cases of A. axillaris poisoning in sheep. The significance of zonal necrosis and factors that may have a bearing on their production in different hepatotoxic plant poisoning in sheep and cattle in South Africa are discussed.

Animals↗
PubMed1983

Photosensitivity in South Africa. V. A comparative study of the pathology of the ovine hepatogenous photosensitivity diseases, facial eczema and geeldikkop (Tribulosis ovis), with special reference to their pathogenesis.

The subject of this study was the pathological and scanning electron microscopical changes in the biliary systems of sheep suffering from facial eczema or geeldikkop (Tribulosis ovis), or made photosensitive by ligation of the common bile duct. While an obliterative cholangitis is responsible for the retention of phylloerythrin in facial eczema, the occlusion of bile ducts with crystalloid material (microliths) appear to perform a similar function in geeldikkop. The similarities and differences between the 2 diseases are discussed in the light of their pathogenetic mechanisms.

Animals↗
PubMed1984

The non-photosensitized potentiation by the photosensitizer hematoporphyrin of the horseradish peroxidase-catalyzed H2O2-mediated oxidation of NADPH to NADP+.

Horseradish peroxidase is known to oxidize NADPH in a reaction initiated by hydrogen peroxide. The present study demonstrates that the photosensitizer hematoporphyrin acting in a non-photodynamic manner, has a marked potentiating effect on the nucleotide oxidation rate. Over 90 percent of the NADPH oxidation product is enzymatically active NADP+. The ratio of NADPH oxidized to NADPH added indicates the existence of a chain reaction. It is suggested that the enzymatic generation of hematoporphyrin transients which are usually generated photodynamically, may be responsible for the acceleration in rate of reduced nucleotide oxidation.

Catalase↗
PubMed1988

Photosensitization by antitumor agents, 4. Anthrapyrazole-photosensitized formation of single strand-breaks in DNA.

Single-strand breaks can be introduced into PM2 closed-circular DNA upon illumination with blue light, in the presence of the anthrapyrazole antitumor agent, compound 1. Damage is observed already after 1 min of blue light illumination, and is significantly enhanced by the presence of electron donors such as NADH, ascorbic acid or Fe(III)/EDTA complex. The photosensitizing properties were not observed for anthrapyrazole analogues with one or more hydroxyl substituents in the chromophore of the drug. The inhibitory effects of sodium azide, methanol, mannitol, SOD, and catalase suggest an oxygen-dependent mechanism of strand-break production, probably involving hydroxyl radicals. However, a second mechanism involving drug molecules bound to the DNA is also indicated under anoxic conditions in the presence of NADH.

Anthracyclines↗
PubMed1990

Water-soluble metal naphthalocyanines--near-IR photosensitizers: cellular uptake, toxicity and photosensitizing properties in NHIK 3025 human cancer cells.

Metal naphthalocyanine complexes (MNCSs) absorb light in the near-IR spectral region (760 nm) where tissue penetration is optimal and they have been proposed as agents for photodynamic therapy (PDT). Sulphonated derivatives of tris-(2,3-naphthalocyanato) bis-chloroaluminium(III) and zinc(II) with various degrees of sulphonation were prepared. Cellular uptake, aggregation in cellular environments, cytotoxicity and photosensitizing properties were studied. Three of the four dyes studied were taken up by cells to a satisfactory degree and were not cytotoxic at the concentration used (10 micrograms ml-1). The least sulphonated sample of zinc naphthalocyanine produced some phototoxic effects (LD50 = 1.12 J cm-2). All the other samples of sulphonated naphthalocyanine were found to be aggregated inside the NHIK 3025 cells, preventing any significant PDT effect.

Biological Transport, Active↗