Using X-rays in photodynamic therapy: an overview.

Photodynamic therapy is a therapeutic option to treat cancer and other diseases. PDT is used every day in dermatology, and recent developments in the treatment of glioblastoma, mesothelioma or prostate have demonstrated the efficacy of this modality. In order to improve the efficacy of PDT, different strategies are under development, such as the use of targeted PS or nanoparticles to improve selectivity and the design of light devices to better monitor the light dose. Due to the low penetration of light into tissue, another way to improve the efficacy of PDT to treat deep tumors is the use of upconversion NPs or bi-photon absorption compounds. These compounds can be excited in the red part of the spectrum. A relatively new approach, which we will call PDTX, is the use of X-rays instead of UV-visible light for deeper penetration into tissue. The principle of this technique will be described, and the state-of-art literature concerning this modality will be discussed. First, we will focus on various photosensitizers that have been used in combination with X-ray irradiation. To improve the efficacy of this modality, nanoparticles have been designed that allow the conversion of high-energy ionizing radiation into UV-visible light; these are potential candidates for the PDTX approach. They will be discussed at the end of this review.

Thyroid hormones in male workers exposed to urban stressors.

BACKGROUND: The occupational exposure to urban pollution may induce adverse effects on the human health. METHODS: Plasma levels of thyrotropin stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) of 50 outdoor workers and 50 indoor workers were compared. RESULTS: In the outdoor workers the TSH levels were significantly higher than in the control subjects (p =0.02) while the average of FT3 and FT4 values, was not significantly different compared to the controls (p > 0.05). CONCLUSIONS: The differences found for TSH levels between outdoor and indoor workers, though not high, suggest that, due to greater exposure to environmental pollutants, the outdoor workers are more susceptible to the development of function abnormalities of the thyroid gland compared to indoor workers.

Photocatalytic conversion of gaseous nitrogen trichloride into available chlorine--experimental and modeling study.

In water, chlorine reacts with nitrogen-containing compounds to produce disinfection byproducts such as nitrogen trichloride which induces ocular and respiratory irritations in swimming pool workers. A technical solution has been used to reduce NCl3 exposure to acceptable levels, by adding a stripping step to the water recycling loop. The pollutants extracted are currently rejected into the atmosphere without treatment. However, the physical properties of NCl3 could be harnessed to induce its controlled degradation by direct or indirect light. This paper describes the way to transform NCl3 into oxidizing chlorine by photocatalysis under laboratory conditions. Photocatalytic oxidation efficiently degrades gaseous nitrogen trichloride, producing compounds such as HClO. About 60% of NCl3 decomposed was converted into HClO which could be used as a disinfection compound. A kinetic model is proposed for the photocatalytic process based on a convection/diffusion model. The Langmuir-Hinshelwood model was applied to the chemical part of the mechanism. The apparent quantum yield was also estimated to assess the optimal irradiance for NCl3 transformation. The results show that photocatalysis performs much better than photolysis alone for NCl3 removal, i.e. at least 25 times more efficient.

Environmental and biological monitoring of polycyclic aromatic hydrocarbon levels in outdoor workers exposed to urban stressor.

BACKGROUND: Purpose of this study is to evaluate and to compare the excretion of urinary 1-hydroxypyrene (1-OHPu) in traffic policemen (TP) and drivers (D) of a large Italian city and to evaluate the existence and the degree of correlation between airborne exposure to 15 different polycyclic aromatic hydrocarbons (PAHs) and 1-OHPu levels in the examined population. METHODS: 192 male workers, 115 TP and 77 D, were monitored for 1-HOPu. A subgroup of non-smoking workers (subgroup B: 59 TP and 15 D) was also examined and 15 environmental PAHs was monitored through the personal samplings for the measurement of the particulate phase. RESULTS: The 1-OHPu levels and the values of personal airborne exposure to PAHs were significantly higher among non-smoking TP than among non-smoking D (p < 0.05). In subgroup B the levels of environmental exposure to all the 15 PAHs measured in TP and only 6 of 15 PAHs measured in D were significantly correlated with the values of 1-OHPu (p < 0.05). CONCLUSIONS: Our results suggest that the use of 1-OHPu as an indicator of exposure to PAHs is reliable also for what concerns the study of the low-dose work-related exposure in urban outdoor workers.

From public to occupational health: towards an inverse push-pull paradigm in nanotechnologies innovation.

Nanotechnologies are an important set of new technologies no longer at a very early stage in their development. The financial support for R&D in this domain is greater than a few Giga Euros/year for innovation and considerably lower (less than 1-2%) for risk management. At the factory level, As Low As Reasonably Achievable (ALARA) methods have to be used in order to protect workers against possible exposure. New "short-term" toxicological studies show that nano-particles are seldom exempt of effects in humans... Thus, for the general population, more and more anxious about the future, nanotechnologies are the object of numerous debates. Ultimately, the population is asking governmental bodies to take the required preventive measures. Social pressure is now initiated by the public towards innovative industries, which have to prove, before the marketing stage, the absence of any risk for the users and demonstrate a safety driven governance.

Pressure effects on the apparent viscosity of artificial dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine membranes using intramolecular excimer probe.

Emission spectroscopy of intramolecular excimer probes allows the determination of 'equivalent viscosity' of membranes. While increasing the pressure on artificial membrane suspensions, variations in viscosity - essentially related to an increase in the order parameter in the membranes - are observed. In the case of mixed phospholipids, the effect of pressure is amplified, probably due to the existence of holes on the molecular scale between the two lipidic layers.

Structure-dependent induction of bilirubin glucuronidation and lauric acid 12-hydroxylation by arylcarboxylic acids chemically related to clofibrate.

The inductive potency of carboxylic acids, structurally related to clofibrate, on bilirubin UDPglucuronosyltransferase was investigated in the rat. For this purpose, structure-induction relationships were established using ten different arylcarboxylic or chlorophenoxycarboxylic acids. 4'-Chlorophenoxyacetic, -propionic and -isobutyric (clofibric) acids progressively increased hepatic glucuronidation of bilirubin (17%, 43%, 60% greater than controls, respectively) after a 5-day treatment in rat (100 mg/kg per day). 2-Phenylpropionic acid also enhanced bilirubin UDPglucuronosyltransferase activity (50%) in contrast to phenylacetic acid. The other compounds did not, or only slightly, affect this parameter. These results indicate that specific structural features are required for the induction property. Moreover, a good correlation (r = 0.962) was found between the extent of induction and the physiochemical descriptors which characterize the electronic state of the molecules, when analysed by multidimensional regression. Fluorescence polarization revealed that the compounds tested, especially clofibric acid, did not affect, in vivo or in vitro, the anisotropy of two different probes embedded in the microsomal membranes. Finally, since the interaction of the carboxylic acids with the membranes did not modify the latency state of bilirubin UDPglucuronosyltransferase, it was concluded that the increase in enzyme activity was due more to a real induction than to activation of bilirubin UDPglucuronosyltransferase. A close linkage was established between bilirubin UDPglucuronosyltransferase induction and that of cytochrome P-452, as shown by enhanced omega-oxidation of lauric acid. This led to the hypothesis that both processes could be under coordinate regulation and mediated by a molecular interaction depending on the physicochemical properties of the carboxylic acids.

Spectrofluorimetric methods for the measurement of the so called "microviscosity" of lipidic structures.

The cellular interactions involving the membrane depend on its physico-chemical nature and on the topographical distribution of the membrane receptors. At present, the role of the lipidic regions is not well defined; however, it is known than the fluidity or "microviscosity" of the lipidic components controls important processes in cellular biology. Different spectrofluorimetric methods, continuous or time resolved, susceptible to the cohesion of lipidic regions have been developed: 1. The anisotropy of fluorescence where the rotation of probes is studied (linked to the coefficient of diffusional rotation). 2. The inhibition of fluorescence where the kinetics of the reaction is practically diffusion controlled. 3. The formation of emissive intramolecular complexes where the internal rotations of interchromophoric bonds are studied. After the development of kinetic models, the methods have been tested with synthetic and natural organized assemblies. The values of "microviscosity" obtained with these methods may be different because the environments of probes are different. Therefore, the concept of "microviscosity", applied to biological membranes is limited.

Application of synchronous excitation spectrofluorimetry to drug analysis.

Among the analytical techniques available for the determination of toxic products, fluorimetry is, at present, one of the most frequently employed. But in many cases, measurements at low concentrations are interfered with by Rayleigh and Raman scattering. We propose to eliminate, in great part, this interference and hence increase the sensitivity of the method, by using the new synchronous excitation spectrofluorimetry. Application of this technique to the identification and determination of drugs during recent forensic investigations demonstrates its advantages over classical spectrofluorimetry.

A low-cost differential fluorimeter for the detection and determination of LSD in illicit preparations.

The construction and use of a differential fluorimeter for rapid detection of LSD in confiscated material under field conditions is described. The apparatus is robust, electronics-free, compact and inexpensive. Adequate sensitivity is ensured by the high quantum yield of LSD fluorescence and a large degree of specificity is obtained by carrying-out two separate measurements: one in water and one in 1 M NaOH.

On diffusion in organized assemblies and in biological membranes.

The following paper is a brief presentation of problems related to the concepts of diffusion coefficient D and so-called viscosity eta used to characterize the cohesion of biological membranes. The first approach to this problem is a recall of the definition of D and eta in liquids. It appears that the models developed with exogenous probes to account for the diffusion-viscosity relationship are not verified in membranes. The existence of complex diffusional mechanisms, the influence of the size of the probe are presented. The results of a model calculation suggest that there is no direct correlation other than great simplifications, between the diffusion coefficient and viscosity. The calculations are then extended to actual biological assemblies and the influence of proteins on the motion of the probe considered. The limitations of the methods involving exogenous probes for determining the cohesion of biological membranes are discussed.

Membrane labelling by fluorescent probes: incorporation of TMA-DPH in erythrocyte membranes.

A study of the labelling of isolated resealed erythrocyte membranes by TMA-DPH has been carried out. A quantitative study shows that saturation appears to take place when increasing the relative quantity of probe bulk concentration to membrane concentration; this is readily interpreted by a simple incorporation model with a limited number of sites in the membrane. A qualitative study shows that an increase in the labelling leads to an evolution of the probe fluorescence properties; the existence of different types of sites is involved in the interpretation but the system is too complex to allow it to be represented by a simple model. As a consequence of this study, care has to be taken in labelling biological material so as to avoid excessive probe incorporation.

The "bathroom game": a systematic program for the elimination of encopretic behavior.

The present investigation utilized a unique, variable ratio schedule of reinforcement (the "bathroom game") to treat a 10-year-old encopretic male. Dependent measures included confirmed incidents of (a) soiling and (b) appropriate bowel movements monitored across an ABAB design (Baseline 1, "Bathroom Game 1", Baseline 2, "Bathroom Game 2") with one-year follow-up. During "bathroom game" conditions, contingent monetary rewards were provided for non-instances of soiling and appropriate bowel movements. Such rewards were progressively and systematically leaned-out over the course of treatment on a pre-determined variable ratio schedule. Results indicated a clear demonstration of functional control and clinically significant treatment effects during both experimental periods. These findings are discussed with regard to the positive features of the "bathroom game" procedure and recommendations are made for future investigations in the area.

[Determination of the membrane fluidity of human blood platelets by measuring the anisotrophy of the fluorescence emission]. / Détermination de la fluidité de la membrane des plaquettes sanguines humaines par mesure de l'anisotropie de l'émission de fluorescence.

Incorporation in vitro of 1,6-diphenyl-1,3,5 hexatriene (DPH) in washed human blood platelets was studied to determine a reference value of fluorescence emission anisotropy of DPH and thus the "microfluidity " of platelet lipid zones. Parameters evaluated were the effect of time of incorporation of the marker, of temperature (25 and 37 degrees C), and of cellular concentration, as well as the effect of platelet aging, enabling determination of valid experimental conditions for studying interaction with drug molecules.

Photodynamic molecular beacons triggered by MMP-2 and MMP-9: influence of the distance between photosensitizer and quencher onto photophysical properties and enzymatic activation.

Angiogenesis is a key step in the tumoral progression process. It is characterized by an over-expression of a number of matrix metalloproteinases (MMP). Among these MMPs, gelatinases (MMP-2 and MMP-9) are known to play a critical role in tumor angiogenesis and the growth of many cancers. Photodynamic Molecular Beacons (PMB) can be designed for cancer treatment by associating a chlorin-like photosensitizer and a black hole quencher linked by a gelatinase substrate peptide with the aim of silencing photosensitizer toxicity in non-targeted cells and restore its toxicity only in surrounding gelatinases. This article provides a report on the synthesis and photophysical and biochemical studies of new families of PMB, using tetraphenylchlorin and a black hole quencher as a donor-acceptor pair, and MMP specific sequence (H-Gly-Pro-Leu-Gly-Ile-Ala-Gly-Gln-Lys-OH or H-Pro-Leu-Gly-Leu-OH) to keep them in close proximity. Different spacers were used to evaluate the influence of the distance between the photosensitizer and the quencher on the photophysical properties and enzymatic activation of the PMB. Time-resolved quenching experiments were performed and FRET energy transfer could be observed. Photosensitizers' triplet state band in transient absorption disappears in PMB. However, even if both MMP-2 and MMP-9 were found to efficiently cleave the peptide alone, no cleavage was observed for all PMB. Further studies would be required to assess the ability of the PMB constructs to retain the sensitivity of the peptide linker to be cleaved by matrix metalloproteinases.

Hyalocyte-like cells are more numerous in the posterior chamber than they are in the vitreous of the rabbit eye.

The distribution and concentration of free cells inside the eye chambers of rabbits were investigated using semi-quantitative analysis of histological paraffin sections. Studies using light (methacrylate sections) as well as transmission and scanning electron microscopy were undertaken for the morphological characterization of the free cells. Immunocytochemistry and autoradiography were employed in an attempt to find out their nature and their origin, respectively. It was observed that cells morphologically similar to the vitreous hyalocytes were more numerous inside the posterior chamber than were the hyalocytes in the cortical vitreous. Neither the hyalocytes nor the posterior-chamber cells reacted with an antibody to rabbit macrophages. The finding of labeled free cells after an intravitreal injection of 3H-thymidine indicates that these cells can renew themselves and that their number does not depend exclusively on monocytes migrating from the blood stream to the eye chambers, as is believed to occur. In conclusion, hyalocytes or hyalocyte-like cells are more concentrated in the posterior chamber than they are in the vitreous. Both the hyalocytes and the posterior-chamber cells could not be characterized as fully developed macrophages.

Identification and quantitative determination of LSD by fluorescence: new data.

Tests for the detection of lysergic acid diethylamide (LSD) are not always specific; to cope with this problem the authors have developed a fluorimetric apparatus and technique for the detection and identification of LSD in samples seized from illicit traffic in drugs. The fluorimeter is not electronic and is simple to make and use, inexpensive, easy to handle and suitable for field analyses. With the new, highly sensitive and selective method of synchronous excitation spectrofluorimetry, a toxicological analytical laboratory can confirm measurements made in the field and make an immediate determination of the quantity of LSD in the samples seized. The agreement between results obtained using differential fluorimetry or synchronous spectrofluorimetry and chromatographic techniques was found to be excellent. Quantitative analysis is very useful because the amount of LSD per "dose" can vary, from one batch to another, from a few tenths of a microgram to several hundred micrograms.

Determination of stereochemistry in the fatty acid hydroperoxide products of lipoxygenase catalysis.

High-performance liquid chromatography has been found to be an effective method for the determination of absolute configuration in the products of the lipoxygenase-catalyzed oxygenation of polyunsaturated fatty acids. Methyl esters of fatty acid hydroperoxides that had been reduced to the corresponding alcohols were converted into (+)-alpha-methoxy-alpha-trifluoromethylphenylacetic acid esters. Enantiomeric alcohols were converted into diastereomeric esters that were readily resolved by normal-phase HPLC. The instrumental requirements for the technique are an isocratic HPLC and a uv absorbance monitor. The method was found to be effective in the determination of stereochemistry in the products derived from the action of plant lipoxygenases on linoleic acid. In addition, the chromatography of the derivatives obtained from lipoxygenase catalysis on arachidonic acid was found to be effective for the assignment of stereochemistry in those products. A comparison of the chromatography of these derivatives with that for the corresponding menthyloxycarbonyl derivatives demonstrated the superiority of this approach for the resolution of the diastereomeric pairs. The technique was applied to the determination of stereochemistry in the products derived from soybean lipoxygenase isoenzymes under a variety of experimental conditions.

Oxygenation of trans polyunsaturated fatty acids by lipoxygenase reveals steric features of the catalytic mechanism.

Lipoxygenase, a nonheme iron dioxygenase, catalyzes the oxygenation of 1,4-diene units in polyunsaturated fatty acids, forming conjugated diene hydroperoxides as the primary products. The naturally occurring all-Z geometry for the olefins in the polyunsaturated fatty acid has long been thought to be a substrate requirement for the enzyme. A rigorous test of this hypothesis using the two isomeric (9E,12Z)- and (9Z,12E)-9,12-octadecadienoic acids was carried out. Both isomeric substrates were found to be catalytically oxygenated by soybean lipoxygenase 1 at a significant fraction of the rate of the reaction of the natural substrate, linoleic acid. Product determinations revealed that a thermodynamically unfavorable E to Z isomerization at the 9,10-position occurred when (9E,12Z)-9,12-octadecadienoic acid was converted into the 13-hydroperoxide by lipoxygenase 1. Determination of the stereochemistry at the oxygenated position in the products indicated that a comparable isomerization at the 12,13-position did not occur when the 9Z,12E isomer was employed. The distribution of products obtained from oxygenation at the 9-position supported the hypothesis that the enzyme catalyzes the reaction in one of two substrate orientations, conventional and head to tail reversed. The observations can be understood on the basis of the steric demands on intermediates in the proposed mechanism of action as well as by catalysis by the active-site iron atom.