Photophysical and photobiological studies of a silicon tribenzonaphthoporphyrazinato incorporated into liposomes for photodynamic therapy use

Nanostructured drug delivery systems (NDDS), such as liposomes, represent a growing area in biomedical research. These microheterogeneous media can be used in many biological systems to provide appropriate drug levels with a specific biodistribution. The photophysical properties of a silicon derivative of tribenzonaphthoporphyrazinato (Si-tri-PcNc) incorporated into liposome were studied by steady-state techniques, time-resolved fluorescence and laser flash photolysis. All the spectroscopy measurements performed allowed us to conclude that Si-tri-PcNc in liposome is a promising NDDS for PDT. The in vitro experiments with liposomal NDDS showed that the system is not cytotoxic in darkness, but exhibits a substantial phototoxicity at 1 microM of photosensitizer concentration and 10.0 J/cm2 of light. These conditions are sufficient to kill about 80% of the cells.     

GABAB receptor intracellular trafficking after internalization in Paramecium

The number of neurotransmitter receptors on the plasma membrane is regulated by the traffic of intracellular vesicles. Golgi-derived vesicles provide newly synthesized receptors to the cell surface, whereas clathrin-coated vesicles are the initial vehicles for sequestration of surface receptors, which are ultimately degraded or recycled. We have previously shown that GABAB receptors display a punctuate vesicular pattern dispersed on the cell surface and throughout the cytoplasm and are internalized via clathrin-dependent and -independent endocytosis. Here we have studied constitutive GABAB receptor trafficking after internalization in Paramecium primaurelia by confocal laser scanning microscopy and multiple immunofluorescence analysis. After internalization, receptors are targeted to the early endosomes characterized by the molecular markers EEA1 and rab5. Some of these receptors, destined for recycling back to the plasma membrane, traffic from the early endosomes to the endosomal recycling compartment that is characterized by the presence of rab4-immunoreactivity (IR). Receptors that are destined for degradation exit the endosomal pathway at the early endosomes and traffic to the late endosome-lysosome pathway. In fact, some of the GABAB-positive compartments were identified as lysosomal structures by double staining with the lysosomal marker LAMP-1. GABAB vesicle structures also colocalize with TGN38-IR and rab11-IR. TGN38 and rab11 are proteins found in association with post-Golgi and recycling endosomes, respectively.     

Thermal cis–trans isomerization of 4-diethylamino-4′-methoxyazobenzene in poly(D(−)3-hydroxybutyrate) and its hydroxyvalerate copolymer as a probe for characterizing their aging

The aging of bacterial polyester poly(D (—)3-hydroxybutyrate) has been studied by coloring it with 4-diethylamino-4′-methoxyazobenzene and determining the reduction in isomerization rate of the dye with aging, such a reduction being a measure of the loss in polymer sequential mobility that is responsible for the considered phenomenon. A preliminary test carried out on poly(ethylene terephthalate) colored with 4-diethylaminoazobenzene proved the isomerization of the dispersed dye to be a sound probe for determining the aging process. In the case of the bacterial polyester, the aging process appeared even above the polymer T_g value measured by calorimetric analysis. The kinetics and rate coefficients of aging were determined at 30°C for the examined polymers. Aging in the copolymer poly(hydroxybutyrate-hydroxyvalerate) was also investigated. © 1995 John Wiley & Sons, Inc.     

On the integration of healthcare emergency systems in Europe: theWETS project case study

The European Union (EU) is characterized by a large number of different emergency healthcare (EHC) systems. In this situation, a common policy for healthcare emergency handling is largely prevented and is a cause of an increase of the costs associated with such systems all over Europe. There is, hence, a need for a homogenization and integration of healthcare emergency systems in Europe. This turns out to be difficult because of the ethical, political, legal, and technological differences and peculiarities of the European scenario and the large investments that would be needed in this sector. The process of integration passes through the identification of the main functionalities-driven by the user needs in their real life conditions-along with the technologies that are best fitted for supporting them. In this paper, several aspects related to these problems are analyzed and a real case study, drawn from the project “Worldwide Emergency Telemedicine Services” (WETS), supported by the European Commission (DG-XIII), is presented. Within WETS, several pilot sites (in Italy, Spain, Greece, Denmark, and Iceland) consider different aspects of the integration of healthcare emergency systems with particular focus on the sharing of solutions that “traditionally” belong to different environments (i.e., land, air, and sea). The involvement of important hospitals, ship companies, airlines, and emergency health institutions allows us to devote a large part of this two-year project (1998-1999) to validate and demonstrate the results of the development phase in real-life conditions. Some more concrete details are given for the Italian pilot site, where the authors operate     

Cotton cellulose: Enzyme adsorption and enzymatic hydrolysis

Adsorption of a crude cellulase complex from Trichoderma viride on variously pretreated cotton celluloses has been studied in the framework of the Langmuir approach, in the temperature range 2–8°C. The saturation amount of adsorbed enzyme has been related to their susceptibility to hydrolysis. In every case the adsorption process was found to be faster by 2–3 orders of magnitude than the hydrolysis step to give end products. For one substrate, the Langmuir parameters were found to be fairly well correlated with the value of the Michaelis constant K_m, measured for its enzymatic hydrolysis, and the adsorptive complex (ES)_ad was indistinguishable from the complex (ES) of the Michaelis–Menten model for the hydrolysis.     

Cross-phase modulation in polarization shift-keying lightwave systems

We investigate the effect of cross-phase modulation in wavelength-division-multiplexed polarization-modulation lightwave systems. Analytical expression for the Q factor penalty in terms of signal power, the number of channels, and other parameters are derived. The theory is compared with numerical experiments.     

Oxygen permeation through films of compatibilized polypropylene/polyamide 6 blends

Polypropylene/polyamide 6 blends were prepared by melt mixing, without or with the addition of a suitable commercial product, a polypropylene grafted with 1% maleic anhydride, used as an interfacial modifier. The oxygen permeation through their films was studied as a function of temperature and the effect of the presence of the compatibilizer on the barrier properties of the material was examined. In addition, the diffusion coefficients were measured. The relationships between transport parameters and blend morphology were investigated by microscopic observations, together with chemical etchings, and a simple model was applied for interpreting the experimental permeation data. Differential scanning calorimetry was used in the determination of the degree of crystallinity of the blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1941–1949, 1999     

Transfer phenomena of volatile organic compounds in thermoplastic polymers and polymer blends by supercritical carbon dioxide

The low-temperature uptake of the flavouring agents limonene and vanillin from supercritical carbon dioxide (CO₂SCF) into films of a poly(ethylene terephthalate)-based copolyester (PET-G), polycaprolactam (PA6), and isotactic poly(propylene) (PP), also blended with hydrogenated oligo(cyclopentadiene) or polycaprolactam, have been investigated through thermogravimetric determination of the additive amount released in the temperature range 30–230°C. The uptake of an additive strongly depends on its relative solubility in the polymer and in CO₂SCF: limonene can easily be transferred into lipophilic PP-based and PET-G polymers, also due to the plastifying action of CO₂SCF on PET-G, while only the more polar vanillin can be taken up by hydrophilic PA6. The CO₂SCF treatment is particularly suitable for the low-temperature uptake of heat-sensitive flavours into polymeric substrates to be used in “active” packaging.     

Morphology and supermolecular structure of polypropylene–poly(1-butene)–hydrogenated oligo(cyclopentadiene) ternary blends

Ternary blends containing polypropylene, poly(1-butene), and hydrogenated oligo(cyclopentadiene) have been studied using microscopic, calorimetric, and X-ray diffraction techniques. While no phase separation was found to occur in the melt for all the considered compositions, demixing phenomena were observed by scanning electron microscopy in the ternary blends after crystallization of both polyolefins. On the other hand, a homogeneous surface without the presence of separate domains was observed for blends quenched avoiding the crystallization of polypropylene. The composition has been found to affect the crystallization and the melting properties of the ternary blends and the crystal modification of polypropylene. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1878–1882, 1998