Magnetic field effects on the photohemolysis of human erythrocytes by ketoprofen and protoporphyrin IX

A novel strategy of selective gene delivery by using a uniform magnetic field

The application of a magnetic field to enhance the transfection efficiency has been reported to be mainly dependent on the magnetic force generated by a magnetic field gradient to attract paramagnetic bead-conjugated carrier and polynucleotide complexes. This strategy has the advantage of targeting a point or an area on the culture vessel. However, it is difficult to target deeply placed tissues in vivo. Uniform magnetic field-correlated effect is applicable to such a purpose. Here, we attempted to establish a novel procedure for uniform magnetic field-dependent enhancement of transfection efficiency. We examined the effect of a 1.5 mT uniform magnetic field on cellular reactive oxygen species (ROS) level and transfection efficiency mediated by a ROS-sensitive transfection carrier. Our experimental results revealed that a 1.5 mT uniform magnetic field transiently decreased cellular ROS levels and strongly enhanced transfection efficiency mediated by polyethylenimine (PEI). The uniform magnetic field-dependent enhancement of PEI-mediated in vivo transfection was confirmed in the livers of mice. Local intensification of a uniform magnetic field in a culture dish resulted in selective gene delivery into cells on the target area. Although further examination and improvement are necessary for this procedure, our findings provide a novel option for spatial control of gene delivery.

Intraperitoneal photodynamic therapy mediated by a fullerene in a mouse model of abdominal dissemination of colon adenocarcinoma

Functionalized fullerenes represent a new class of photosensitizer (PS) that is being investigated for photodynamic therapy (PDT) of various diseases, including cancer. We tested the hypothesis that fullerenes could be used to mediate PDT of intraperitoneal (IP) carcinomatosis in a mouse model. In humans this form of cancer responds poorly to standard treatment and manifests as a thin covering of tumor nodules on intestines and on other abdominal organs. We used a colon adenocarcinoma cell line (CT26) stably expressing luciferase to allow monitoring of IP tumor burden in BALB/c mice by noninvasive real-time optical imaging using a sensitive low-light camera. IP injection of a preparation of N-methylpyrrolidinium-fullerene formulated in Cremophor-EL micelles, followed by white-light illumination delivered through the peritoneal wall (after creation of a skin flap), produced a statistically significant reduction in bioluminescence and a survival advantage in mice.

FROM THE CLINICAL EDITOR

This team of investigators report on functionalized fullerenes, to be used as photosensitizer for photodynamic therapy and demonstrate the efficacy of this method in an intraperitoneal carcinomatosis mouse model.

UVA-ketoprofen-induced hemoglobin radicals detected by immuno-spin trapping

Ketoprofen (3-benzoyl-alpha-methylbenzeneacetic acid, KP) is a widely used nonsteroidal anti-inflammatory drug (NSAID) that causes both phototoxicity and photoallergy. Here, we investigated the formation of hemoglobin radicals, in both purified hemoglobin and red blood cells (RBC), induced by ultraviolet A (UVA)-KP by using "immuno-spin trapping," a novel approach that combines the specificity of spin trapping with the sensitivity of antigen-antibody interactions. The methemoglobin (metHb) radicals react covalently with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to form nitroxyl radical adducts that are oxidized to the corresponding nitrone adducts, which in turn are specifically recognized by antiserum against DMPO nitrone. We found that the formation of nitrone adducts in metHb depended on the UVA dose, the KP concentration and the presence of DMPO, as determined by enzyme-linked immunosorbent assay and Western blotting. Adduct formation decreased when irradiation was carried out in the presence of catalase or nitrogen, suggesting that H2O2 plays a key role in KP-UVA-induced metHb radical formation. KP in the dark did not generate metHb radical-derived nitrone adducts, whereas UVA alone resulted in the formation of metHb radical-derived nitrone adducts that increased with UVA dose from 4 to 10 J/cm2. However, KP (25 and 200 microM) plus UVA (4 and 10 J/cm2) resulted in a significant increase in the formation of metHb radical-derived nitrone adducts as compared with UVA or KP alone, indicating that KP photosensitized the production of the metHb radicals in the presence of UVA. In contrast, no metHb radical-derived nitrone adduct was detected in the absence of DMPO, even though KP and UVA were present. We also detected the hemoglobin radical formation in RBC as well as in hemolysates. The endogenous antioxidants and exogenous reduced glutathione inhibited the protein radical formation. These studies have shown that the immuno-spin-trapping technique can be used to detect radical damage in proteins as a result of photosensitizing reactions. The successful detection of protein radical formation caused by KP photosensitization could help further understand the photoallergic effect of this NSAID.

Prompt and delayed nonsteroidal anti-inflammatory drug-photoinduced DNA damage in peripheral blood mononuclear cells measured with the comet assays

Nonsteroidal anti-inflammatory drug (NSAID)-photoinduced DNA damage in human peripheral blood mononuclear cells measured using the alkaline comet assay is presented. Whereas Tiaprofenic Acid-photoinduced DNA damage was promptly induced (i.e. observed at relatively low radiation doses), Ketoprofen-photoinduced DNA damage was delayed. This prompt and delayed effect is observed with UVA (320-400 nm), UVB (290-320 nm) and solar-simulated radiation and is attributed to the different photochemical properties of NSAID. The results from these experiments, carried out in living cells, confirm the speculations of NSAID-photoinduced DNA damage brought up by the many experiments conducted in solution.

Increasing the life expectancy of carbanions by zeolite inclusion

Carbanions have been detected for the first time in zeolite cavities where their lifetime is more than ten times longer than in solution; included carbanions show Grignard-like behaviour.

Absolute rate constants for water protonation of 1-(3-benzoylphenyl)alkyl carbanions

[reaction: see text] Efficient photodecarboxylation of (3-benzoylphenyl)alkanoic acids with formation of carbanions has enabled the determination of their protonation rate constants in water; the values obtained show that the reactivity toward protonation is determined by the size of the alkyl groups attached to the carbanion center.

A laser flash photolysis study of fenofibric acid in aqueous buffered media: unexpected triplet state inversion in a derivative of 4-alkoxybenzophenone

Laser excitation of aqueous solutions of fenofibric acid (FA) at pH 7.4 show the formation of two reaction intermediates, the triplet state and the hydrated electron. The former is longer lived in water than in acetonitrile; its anionic form decays irreversibly by decarboxylation to give a carbanion that protonates before or after rearrangement. Several spectroscopic and quenching studies suggest that in aqueous media the triplet state of FA has a pi,pi* character, in comparison with an n,pi* character in organic media. Further, the known chemistry of the triplet, including decarboxylation and hydrogen abstraction, occurs predominantly from the n,pi* state, and as a consequence, activation energies are higher when the lowest triplet has a pi,pi* character. Photoionization is more important in aqueous than in organic media and involves a biphotonic process. Hydrated electrons are trapped by FA, leading to the corresponding ketyl radical after protonation.

Photoreactivity of the nonsteroidal anti-inflammatory 2-arylpropionic acids with photosensitizing side effects

The photoreactivity of the nonsteroidal anti-inflammatory 2-arylpropionic acids benoxaprofen, carprofen, naproxen, ketoprofen, tiaprofenic acid, and suprofen is reviewed with special emphasis on fundamental photophysical and photochemical properties. The absorption and emission properties of the excited states of these drugs as well as their main photodegradation routes are summarized. The photochemical mechanisms are discussed on the basis of product studies and detection of short-lived intermediates by means of laser flash photolysis. After dealing with the unimolecular processes, attention is focused on the photosensitized reactions of key biomolecules, such as lipids, proteins or nucleic acids. Finally, a short section on the photobiological effects on simple biological models is also included. Although some earlier citations are included, the literature coverage is in general limited to the last decade.

Mathematical modeling and stochastic H(infinity) identification of the dynamics of the MF-influenced oxidation of hexane

This paper presents a mathematical model explicitly reflecting the magnetic-field-induced transitions in a biologically significant process: n-hexane oxidation. The range of the magnetic field strength is found (0.05-0.3 T) with the trend indicating significant magnetic-field-induced change in the rates of reactions involving hexane (up to 50% at 0.2 T). The equations describing the effects of the magnetic field on the photoinduced free radical reaction of oxidation involving a lipid-modeling substance, hexane, are obtained on the basis of chemical kinetics and data from a batch experiment. The magnetic-field-induced changes in n-hexane oxidation are validated using the identification technique based on the real time input-output data in a separately conducted flow-through experiment.

Effect of a 7-tesla homogeneous magnetic field on mammalian cells

When two types of mammalian cells, mouse leukemia cells, P388, and Chinese hamster fibroblast cells, V79, were grown under a 7-tesla (T) homogeneous magnetic field which was produced by a newly constructed superconducting magnet biosystem (SBS), the growth pattern of cells under 7 T magnetic field and the geomagnetic field control showed no differences. The DNA distribution of the two cells was compared by flow cytometry after exposure to 7 T for 3 and 24 h, but there was no significant differences between magnet-exposed cells and unexposed cells. When the two types of cells were exposed to different concentrations of the antitumor agent, bleomycin (BLM), for 3 h under 7 T, their viable cell numbers were almost the same as that of the control although sensitivity to BLM was different between the two cells. These results suggest that the 7 T homogeneous magnetic field exerts no adverse effects on mammalian cells.

Mutagenicity and co-mutagenicity of static magnetic fields detected by bacterial mutation assay

Possible mutagenic and co-mutagenic effects of strong static magnetic fields were estimated using bacterial mutagenicity test. Mutagenic potential of static magnetic fields up to 5T (T:1T=10,000 G) was not detected by the bacterial mutagenicity test using four strains of Salmonella typhimurium (TA98, TA100, TA1535 and TA1537) and Escherichia coli WP2 uvrA either in the pre-incubation method or in the plate incorporation method. In the co-mutagenicity test, E. coli WP2 uvrA cells were treated with various chemical mutagens and were simultaneously exposed to a 2T or a 5T static magnetic field. Mutation rate in the exposed group was significantly higher than that in the non-exposed group when cells were treated with N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), ethylmethanesulfonate (EMS), 4-nitroquinoline-N-oxide (4-NQO), 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ) or 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide (AF-2). The mutagenicity of 2-aminoanthracene (2-AA), 9-aminoacridine (9-AA), N4-aminocytidine and 2-acetoamidofluorene (2-AAF) was not affected by the magnetic field exposure. Possible mechanisms of the co-mutagenicity of magnetic fields are discussed.

Photosensitizing drugs containing the benzophenone chromophore

The nonsteroidal anti-inflammatory agents ketoprofen, tiaprofenic acid, suprofen and tolmetin, together with the anti-hyperlipoproteinemic drug fenofibrate and the anti-arrhythmic amiodarone can be included in the group of benzophenone-derived photosensitizing drugs. They contain a diaryl ketone chromophore and mediate the development of phototoxic reactions. In some cases, photoallergic responses have been reported. These properties have been substantiated in clinical reports, as well as by means of in vivo and in vitro assays. Tolmetin is phototoxic in vitro, however there are no reports on photosensitization by this drug in humans. In general, photochemical and photobiological studies strongly suggest that photosensitization involves formal hydrogen abstraction (either in a single step or via electron transfer followed by proton transfer) by the benzophenone-like chromophore from the excited triplet state. In the case of amiodarone, the radicals generated by photodehalogenation from the triplet are responsible for the photosensitivity side-effects.

Photophysical and photobiological processes in the photodynamic therapy of tumours

Photodynamic therapy (PDT) is an innovative and attractive modality for the treatment of small and superficial tumours. PDT, as a multimodality treatment procedure, requires both a selective photosensitizer and a powerful light source which matches the absorption spectrum of the photosensitizer. Quadra Logic's Photofrin, a purified haematoporphyrin derivative, is so far the only sensitizer approved for phase III and IV clinical trials. The major drawbacks of this product are the lack of chemical homogeneity and stability, skin phototoxicity, unfavourable physicochemical properties and low selectivity with regard to uptake and retention by tumour vs. normal cells. Second-generation photosensitizers, including the phthalocyanines, show an increased photodynamic efficiency in the treatment of animal tumours and reduced phototoxic side effects. At the time of writing of this article, there were more than half a dozen new sensitizers in or about to start clinical trials. Most available data suggest a common mechanism of action. Following excitation of photosensitizers to long-lived excited singlet and/ or triplet states, the tumour is destroyed either by reactive singlet oxygen species (type II mechanism) and/or radical products (type I mechanism) generated in an energy transfer reaction. The major biological targets of the radicals produced and of singlet oxygen are well known today. Nucleic acids, enzymes and cellular membranes are rapidly attacked and cause the release of a wide variety of pathophysiologically highly reactive products, such as prostaglandins, thromboxanes and leukotrienes. Activation of the complement system and infiltration of immunologically active blood cells into the tumorous region enhance the damaging effect of these aggressive intermediates and ultimately initiate tumour necrosis. The purpose of this review article is to summarize the up-to-date knowledge on the mechanisms responsible for the induction of tumour necrotic reactions.