"With your age, what do you expect?": Ageism and healthcare of older adults in Spain.

INTRODUCTION: Ageism could influence the relationship between older patients' meeting needs and healthcare professionals' answers. AIMS: To highlight the experience of older adults with healthcare systems, how they perceive ageism from their healthcare providers, and to explore the relationship between perceived ageism and self-perception of aging (SPA). METHODS: We conducted an exploratory qualitative study. The participants were 14 women over 65 who lived alone in their homes. RESULTS: Professional responses ignored the expression of preferences of the older patients and excluded them from decision-making processes. These answers influenced older patients' use of health services. Moreover, the negative aspects predominated in a SPA influenced by the internalization of stereotypes and a relationship weighed down by ageist behaviors on the part of health professionals. CONCLUSION: Explicit situations of ageism influence an imbalance in power relations between older patients and healthcare professionals, a misuse of health services, and a negative SPA.

Dual-Functionalized Nanoliposomes Achieve a Synergistic Chemo-Phototherapeutic Effect.

The enhancement of photodynamic therapy (PDT) effectiveness by combining it with other treatment modalities and improved drug delivery has become an interesting field in cancer research. We have prepared and characterized nanoliposomes containing the chemotherapeutic drug irinotecan (CPT11lip), the photodynamic agent protoporphyrin IX (PpIXlip), or their combination (CPT11-PpIXlip). The effects of individual and bimodal (chemo-phototherapeutic) treatments on HeLa cells have been studied by a combination of biological and photophysical studies. Bimodal treatments show synergistic cytotoxic effects on HeLa cells at relatively low doses of PpIX/PDT and CPT11. Mechanistic cell inactivation studies revealed mitotic catastrophe, apoptosis, and senescence contributions. The enhanced anticancer activity is due to a sustained generation of reactive oxygen species, which increases the number of double-strand DNA breaks. Bimodal chemo-phototherapeutic liposomes may have a very promising future in oncological therapy, potentially allowing a reduction in the CPT11 concentration required to achieve a therapeutic effect and overcoming resistance to individual cancer treatments.

EEM-PARAFAC as a convenient methodology to study fluorescent emerging pollutants degradation: (fluoro)quinolones oxidation in different water matrices.

Commercial (fluoro)quinolones ((F)Qs), ciprofloxacin (CIP), enrofloxacin (ENR), ofloxacin (OFL), oxolinic acid (OA) and flumequine (FLU) (3 µM each), were degraded with solar-photo-Fenton in a compound parabolic concentrator photoreactor (total volume 5 L) in ultra-pure water at pH = 5.0, salty water at pH = 5.0, and simulated wastewater at pH = 5.0 and 7.5. Iron speciation (its hydrolysis and the complexation with (F)Qs 15 µM and/or chlorides 0.5 M) was calculated at pH 5.0, observing, negligible formation of Fe(III)-chloride complexes, and that >99 % of the total (F)Qs are forming complexes stoichiometry 1:1 with Fe(III) (which also increases the percentage of Fe(OH)2+), being minoritarian the free antibiotic form. On the other hand, EEM-PARAFAC (fluorescence excitation-emission matrices-parallel factor analysis) was employed to simultaneously study the behaviour of: i) 4 structure-related groups corresponding to parent pollutants and slightly oxidised by-products, ENR-like (including CIP), OFL-like, OA-like, FLU-like; ii) intermediates still showing (F)Q characteristics (exhibiting analogous fluorescent fingerprint to ENR-like one, but shifted to shorter wavelengths); iii) humic-like substances. The scores from the 4 PARAFAC components corresponding to the parent pollutants were plotted vs. accumulated energy, exhibiting slower decay than their individual removals (measured with HPLC-UV/vis) due to the contribution of the aforementioned by-products to the overall fluorescence. Moreover, thiabendazole (TBZ) 3 µM was added as fluorescence interference. The presence of (F)Qs greatly enhanced TBZ degradation due to (F)Q-Fe(III) complex formation, keeping iron active at pH = 5.0 for Fenton process. The EEM-PARAFAC model was able to recognise the former six components plus an additional one attributable to TBZ-like.

c(RGDfK)- and ZnTriMPyP-Bound Polymeric Nanocarriers for Tumor-Targeted Photodynamic Therapy.

Active targeting strategies are currently being extensively investigated in order to enhance the selectivity of photodynamic therapy. The aim of the present research was to evaluate whether the external decoration of nanopolymeric carriers with targeting peptides could add more value to a photosensitizer formulation and increase antitumor therapeutic efficacy and selectivity. To this end, we assessed PLGA-PLA-PEG nanoparticles (NPs) covalently attached to a hydrophilic photosensitizer 5-[4-azidophenyl]-10,15,20-tri-(N-methyl-4-pyridinium)porphyrinato zinc (II) trichloride (ZnTriMPyP) and also to c(RGDfK) peptides, in order to target αv ß3 integrin-expressing cells. In vitro phototoxicity investigations showed that the ZnTriMPyP-PLGA-PLA-PEG-c(RGDfK) nanosystem is effective at submicromolar concentrations, is devoid of dark toxicity, successfully targets αv ß3 integrin-expressing cells and is 10-fold more potent than related nanosystems where the PS is occluded instead of covalently bound.

Photo-Fenton reaction at mildly acidic conditions: assessing the effect of bio-organic substances of different origin and characteristics through experimental design.

Urban-waste bio-organic substances (UW-BOS) have been shown to be capable of extending the photo-Fenton reaction to mildly acidic conditions. In this study, the effects of pH (3-7), UW-BOS, H2O2 and iron concentrations on the photo-Fenton process were systematically assessed using a Doehlert experimental design and response surface methodology for two UW-BOS (CVT230 and FORSUD). Solutions of the model antibiotic sulfadiazine (SDZ) were irradiated in a solar simulator equipped with a 550 W Xenon lamp. The results showed that for UW-BOS contents below 30 mg L-1, SDZ removal proceeds at pH 5 with similar rates for both CVT230 and FORSUD, regardless of Fe(III) concentration. For 50 mg L-1 of UW-BOS or higher, CVT230 performs better than FORSUD, even for low Fe(III) content (1-3 mg L-1). In contrast, half-life times of 35-40 min can only be achieved under mildly acidic conditions with FORSUD for iron concentrations higher than 10 mg L-1. The better performance of CVT230 can be associated with its high hydrophilic/hydrophobic ratio, low E2:E3, higher iron content and possibly higher yields of triplet reactive species generation upon solar irradiation. The most appropriate conditions for each UW-BOS studied are discussed for the first time, which are advantageous for possible engineered applications.

Selective Photokilling of Human Pancreatic Cancer Cells Using Cetuximab-Targeted Mesoporous Silica Nanoparticles for Delivery of Zinc Phthalocyanine.

BACKGROUND: Photodynamic therapy (PDT) is a non-invasive and innovative cancer therapy based on the photodynamic effect. In this study, we sought to determine the singlet oxygen production, intracellular uptake, and in vitro photodynamic therapy potential of Cetixumab-targeted, zinc(II) 2,3,9,10,16,17,23,24-octa(tert-butylphenoxy))phthalocyaninato(2-)-N29,N30,N31,N32 (ZnPcOBP)-loaded mesoporous silica nanoparticles against pancreatic cancer cells. RESULTS: The quantum yield (ΦΔ) value of ZnPcOBP was found to be 0.60 in toluene. In vitro cellular studies were performed to determine the dark- and phototoxicity of samples with various concentrations of ZnPcOBP by using pancreatic cells (AsPC-1, PANC-1 and MIA PaCa-2) and 20, 30, and 40 J/cm² light fluences. No dark toxicity was observed for any sample in any cell line. ZnPcOBP alone showed a modest photodynamic activity. However, when incorporated in silica nanoparticles, it showed a relatively high phototoxic effect, which was further enhanced by Cetuximab, a monoclonal antibody that targets the Epidermal Growth Factor Receptor (EGFR). The cell-line dependent photokilling observed correlates well with EGFR expression levels in these cells. CONCLUSIONS: Imidazole-capped Cetuximab-targeted mesoporous silica nanoparticles are excellent vehicles for the selective delivery of ZnPcOBP to pancreatic cancer cells expressing the EGFR receptor. The novel nanosystem appears to be a suitable agent for photodynamic therapy of pancreatic tumors.

A novel microfluidic liposomal formulation for the delivery of the SN-38 camptothecin: characterization and in vitro assessment of its cytotoxic effect on two tumor cell lines.

PURPOSE: Irinotecan (CPT-11) and SN-38 - its active metabolite - are alkaloid-derived topoisomerase I interactive compounds widely used in various cancer therapy protocols. To solve the problems associated with the instability of their lactone ring at physiological pH and with the extreme insolubility of SN-38, the development of delivery carriers (eg, liposomes) has been considered a subject of unquestionable medical interest. This article focuses on the development of an alternative protocol to the classical lipid-film hydration procedures to obtain a pharmaceutical formulation for SN-38. METHODS: SN-38-loaded liposomes (SN-38lip) were produced by microemulsification, without a prior lipid-film preparation step, and characterized by different methods. Formulation parameters were determined by photon correlation spectroscopy, and the SN-38 entrapment efficiency was evaluated by absorbance spectroscopy. SN-38lip was obtained as a dry, white powder by lyophilization. MTT and LDH assays were conducted to assess the cytotoxic effect of SN-38, both in liposomal (SN-38lip) and solubilized form (SN-38sol); flow cytometry was used to quantify SN-38 uptake and to analyze cell-cycle phase distribution after drug exposure. RESULTS: Microfluidic, stable, and controlled sized, negatively charged liposomes, with high SN-38 incorporation efficiency into egg yolk phosphatidylcholine (EPC)/L-α-dioleoyl-phospathidylserine (DOPS) (9:1) vesicles (SN-38lip), were prepared. A lyophilized powder of SN-38lip, easily reconstitutable while retaining physicochemical parameters, was finally obtained. The efficacy of SN-38lip was assessed by in vitro studies with two tumor cell lines (HeLa and Caco-2) and compared with that of SN-38sol. It demonstrated the highest uptake of SN-38lip, in accordance with its highest cytotoxicity effect, in comparison with that of SN-38sol. In addition, different cell-cycle alterations were induced in both cell lines by the liposomal formulation. CONCLUSION: The results highlight the potential usefulness of the procured SN-38 liposomal formulation and provide the basis for conducting in vivo studies that allow the development of alternative strategies for colorectal cancer treatment.

Improved selectivity and cytotoxic effects of irinotecan via liposomal delivery: A comparative study on Hs68 and HeLa cells.

Irinotecan (CPT-11) is an effective chemotherapeutic agent widely used to treat different cancers. Otherwise, the liposomal delivery of anti-tumor agents has been shown to be a promising strategy. The aim of this study has been to analyze the effect of liposomal CPT-11 (CPT-11lip) on two human cell lines (Hs68 and HeLa) to establish the suitability of this CPT-11 nanocarrier. We have demonstrated the highest uptake of CPT-11lip in comparison with that of CPT-11sol, in lactate buffer, and that CPT-11lip was internalized in the cells through an endocytic process whereas CPT-11sol does so by passive diffusion. CPT-11lip was not cytotoxic to normal fibroblast Hs68 cells, but induced a massive apoptosis accompanied by cell senescence in HeLa cells. CPT-11lip treatment modified the morphology of HeLa cells, induced different cell cycle alterations and accumulated into lysosomes in both cell lines. In particular, CPT-11lip treatment showed that surviving HeLa cells remained in a state of senescence whereas only a temporal growth arrest was induced in Hs68 cells. Results of RT-PCR indicated that the different responses in Hs68 (survival) and HeLa cells (apoptotic death), seemed to be induced by a p53- and p53- independent mechanism, respectively. An analysis of DNA damage also determined that released CPT-11 from liposomes was able to reach the nucleus and exert a genotoxic effect in both cell lines, which was repaired in Hs68 but not in HeLa cells. All results indicate that phospholipid-cholesterol liposomes possess optimum properties for CPT-11 delivery, being biocompatible and selectively cytotoxic against HeLa tumorigenic cells.

Anthracene-based fluorescent nanoprobes for singlet oxygen detection in biological media.

We have developed a novel singlet oxygen nanoprobe based on 9,10-anthracenedipropionic acid covalently bound to mesoporous silica nanoparticles. The nanoparticle protects the probe from interactions with proteins, which detract from its ability to detect singlet oxygen. In vitro studies show that the nanoprobe is internalized by cells and is distributed throughout the cytoplasm, thus being capable of detecting intracellularly-generated singlet oxygen.

Langmuir monolayers and Differential Scanning Calorimetry for the study of the interactions between camptothecin drugs and biomembrane models.

CPT-11 and SN-38 are camptothecins with strong antitumor activity. Nevertheless, their severe side effects and the chemical instability of their lactone ring have questioned the usual forms for its administration and have focused the current research on the development of new suitable pharmaceutical formulations. This work presents a biophysical study of the interfacial interactions of CPT-11 and SN-38 with membrane mimetic models by using monolayer techniques and Differential Scanning Calorimetry. The aim is to get new insights for the understanding of the bilayer mechanics after drug incorporation and to optimize the design of drug delivery systems based on the formation of stable bilayer structures. Moreover, from our knowledge, the molecular interactions between camptothecins and phospholipids have not been investigated in detail, despite their importance in the context of drug action. The results show that neither CPT-11 nor SN-38 disturbs the structure of the complex liposome bilayers, despite their different solubility, that CPT-11, positively charged in its piperidine group, interacts electrostatically with DOPS, making stable the incorporation of a high percentage of CPT-11 into liposomes and that SN-38 establishes weak repulsive interactions with lipid molecules that modify the compressibility of the bilayer without affecting significantly neither the lipid collapse pressure nor the miscibility pattern of drug-lipid mixed monolayers. The suitability of a binary and a ternary lipid mixture for encapsulating SN-38 and CPT-11, respectively, has been demonstrated.

Poly(D, L-lactide-co-glycolide) nanoparticles as delivery agents for photodynamic therapy: enhancing singlet oxygen release and photototoxicity by surface PEG coating.

Poly(D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) are being considered as nanodelivery systems for photodynamic therapy. The physico-chemical and biological aspects of their use remain largely unknown. Herein we report the results of a study of PLGA NPs for the delivery of the model hydrophobic photosensitizer ZnTPP to HeLa cells. ZnTPP was encapsulated in PLGA with high efficiency and the NPs showed negative zeta potentials and diameters close to 110 nm. Poly(ethylene glycol) (PEG) coating, introduced to prevent opsonization and clearance by macrophages, decreased the size and zeta potential of the NPs by roughly a factor of two and improved their stability in the presence of serum proteins. Photophysical studies revealed two and three populations of ZnTPP and singlet oxygen in uncoated and PEGylated NPs, respectively. Singlet oxygen is confined within the NPs in bare PLGA while it is more easily released into the external medium after PEG coating, which contributes to a higher photocytotoxicity towards HeLa cells in vitro. PLGA NPs are internalized by endocytosis, deliver their cargo to lysosomes and induce cell death by apoptosis upon exposure to light. In conclusion, PLGA NPs coated with PEG show high potential as delivery systems for photodynamic applications.

Formulation and in vitro characterization of thermosensitive liposomes for the delivery of irinotecan.

The effect of the lipid composition on the physicochemical properties of a liposomal carrier containing irinotecan (CPT-11) and its in vitro antitumoral activity on a colon cancer cell line has been investigated. The paper describes the procurement of a novel and easy-to-prepare temperature-sensitive carrier for CPT-11 and proves its suitability as delivery system on the basis of its ability to incorporate the drug and on its efficiency to promote drug internalization. Permeability data, studied in vitro in a simulated biological medium at different temperatures, showed that both the nature of the lipids and the ratio in which they have been mixed play a key role in the release of the encapsulated product. Stable temperature-sensitive liposomes with good drug incorporation efficiency were obtained and characterized. The cellular uptake and the cytotoxic activity of the CPT-11 liposomal formulation were compared with those corresponding to the free drug with promising results, being concentration and time dependent and significantly higher. Thus, it could be interpreted that the greatest cytotoxic effect of liposomal CPT-11 was because of the increased uptake provided by the liposomal carrier. Studies of cell cycle and annexin V binding showed drug-induced changes in cell cycle dynamics and the proapoptotic effect of liposomal CPT-11.

Liposomal temocene (m-THPPo) photodynamic treatment induces cell death by mitochondria-independent apoptosis.

BACKGROUND: The cell death pathway activated after photodynamic therapy (PDT) is controlled by a variety of parameters including the chemical structure of the photosensitizer, its subcellular localization, and the photodynamic damage induced. The present study aims to characterize a suitable m-THPPo liposomal formulation, to determine its subcellular localization in HeLa cells and to establish the cell death mechanisms that are activated after photodynamic treatments. METHODS: Liposomes containing m-THPPo were prepared from a mixture of DPPC and DMPG at a 9:1 molar ratio. In order to procure the best encapsulation efficiency, the m-THPPo/lipid molar ratio was considered. HeLa cells were incubated with liposomal m-THPPo and the subcellular localization of m-THPPo was studied. Several assays such as TUNEL, annexin V/propidium iodide and Hoechst-33258 staining were performed after photodynamic treatments. The apoptotic initiation was assessed by cytochrome c and caspase-2 immunofluorescence. RESULTS: m-THPPo encapsulated in liposomes showed a decrease of the fluorescence and singlet oxygen quantum yields, compared to those of m-THPPo dissolved in tetrahydrofuran. Liposomal m-THPPo showed colocalization with LysoTracker® and it induced photoinactivation of HeLa cells by an apoptotic mechanism. In apoptotic cells no relocalization of cytochrome c could be detected, but caspase-2 was positive immediately after photosensitizing treatments. CONCLUSIONS: Photodynamic treatment with liposomal m-THPPo leads to a significant percentage of apoptotic morphology of HeLa cells. The activation of caspase-2, without the relocalization of cytochrome c, indicates a mitochondrial-independent apoptotic mechanism. GENERAL SIGNIFICANCE: These results provide a better understanding of the cell death mechanism induced after liposomal m-THPPo photodynamic treatment.

Cellular and vascular effects of the photodynamic agent temocene are modulated by the delivery vehicle.

The effects of the drug delivery system on the PDT activity, localization, and tumor accumulation of the novel photosensitizer temocene (the porphycene analogue of temoporfin or m-tetrahydroxyphenyl chlorin) were investigated against the P815 tumor, both in vitro and in DBA/2 tumor bearing mice. Temocene was administered either free (dissolved in PEG(400)/EtOH mixture), or encapsulated in Cremophor EL micelles or in DPPC/DMPG liposomes, chosen as model delivery vehicles. The maximum cell accumulation and photodynamic activity in vitro was achieved with the free photosensitizer, while temocene in Cremophor micelles hardly entered the cells. Notwithstanding, the micellar formulation showed the best in vivo response when used in a vascular regimen (short drug light interval), whereas liposomes were found to be an efficient drug delivery system for a tumor cell targeting strategy (long drug-light interval). PEG/EtOH formulation was discarded for further in vivo experiments as it provoked lethal toxic effects caused by photosensitizer aggregation. These results demonstrate that drug delivery systems modulate the vascular and cellular outcomes of photodynamic treatments with temocene.

Do folate-receptor targeted liposomal photosensitizers enhance photodynamic therapy selectivity?

One of the current goals in photodynamic therapy research is to enhance the selective targeting of tumor cells in order to minimize the risk and the extension of unwanted side-effects caused by normal cell damage. Special attention is given to receptor mediated delivery systems, in particular, to those targeted to folate receptor. Incorporation of a model photosensitizer (ZnTPP) into a folate-targeted liposomal formulation has been shown to lead an uptake by HeLa cells (folate receptor positive cells) 2-fold higher than the non-targeted formulation. As a result, the photocytotoxicity induced by folate-targeted liposomes was improved. This selectivity was completely inhibited with an excess of folic acid present in the cell culture media. Moreover, A549 cells (folate receptor deficient cells) have not shown variations in the liposomal incorporation. Nevertheless, the differences observed were slighter than expected. Both folate-targeted and non-targeted liposomes localize in acidic lysosomes, which confirms that the non-specific adsorptive pathway is also involved. These results are consistent with the singlet oxygen kinetics measured in living cells treated with both liposomal formulations.

Automatic segmentation of long-term ECG signals corrupted with broadband noise based on sample entropy.

Biomedical signals are nonstationary in nature, namely, their statistical properties are time-dependent. Such changes in the underlying statistical properties of the signal and the effects of external noise often affect the performance and applicability of automatic signal processing methods that require stationarity. A number of methods have been proposed to address the problem of finding stationary signal segments within larger nonstationary signals. In this framework, processing and analysis are applied to each resulting locally stationary segment separately. The method proposed in this paper addresses the problem of finding locally quasi-stationary signal segments. Particularly, our proposed algorithm is designed to solve the specific problem of segmenting semiperiodic biomedical signals corrupted with broadband noise according to the various degrees of external noise power. It is based on the sample entropy and the relative sensitivity of this signal regularity metric to changes in the underlying signal properties and broadband noise levels. The assessment of the method was carried out by means of experiments on ECG signals drawn from the MIT-BIH arrhythmia database. The results were measured in terms of false alarms based on the changepoint detection bias. In summary, the results achieved were a sensitivity of 97%, and an error of 16% for records corrupted with muscle artifacts.

Kinetics of singlet oxygen photosensitization in human skin fibroblasts.

The roles played by singlet oxygen ((1)O(2)) in photodynamic therapy are not fully understood yet. In particular, the mobility of (1)O(2) within cells has been a subject of debate for the last two decades. In this work, we report on the kinetics of (1)O(2) formation, diffusion, and decay in human skin fibroblasts. (1)O(2) has been photosensitized by two water-soluble porphyrins targeting different subcellular organelles, namely the nucleus and lysosomes, respectively. By recording the time-resolved near-IR phosphorescence of (1)O(2) and that of its precursor the photosensitizer's triplet state, we find that the kinetics of singlet oxygen formation and decay are strongly dependent on the site of generation. (1)O(2) photosensitized in the nucleus is able to escape out of the cells while (1)O(2) photosensitized in the lysosomes is not. Despite showing a lifetime in the microsecond time domain, (1)O(2) decay is largely governed by interactions with the biomolecules within the organelle where it is produced. This observation may reconcile earlier views that singlet oxygen-induced photodamage is highly localized, while its lifetime is long enough to diffuse over long distances within the cells.

Photosensitization of skin fibroblasts and HeLa cells by three chlorin derivatives: Role of chemical structure and delivery vehicle.

The chemical nature of the sensitizer and its selective uptake by malignant cells are decisive to choose an appropriate biocompatible carrier, able to preserve the photosensitizing characteristics of the dye. In this paper we demonstrate the photodynamic properties of three chlorins, derived from chlorophyll a, and the usefulness of liposomal carriers to design pharmaceutical formulations. The chlorins have been quantitatively incorporated into stable liposomes obtained from a mixture of L-alpha-palmitoyloleoylphosphatidylcholine and L-alpha-dioleoylphosphatidylserine in a 13.5:1.5 molar ratio (POPC/OOPS-liposomes). The chlorin uptake by skin fibroblasts increases steadily, reaching in all cases a plateau level dependent on both the chlorin structure and the vehicle employed. The photophysical properties of the three chlorins in THF are nearly identical and fulfill the requirements for a PDT photosensitizer. Incorporation of chlorins into liposomes induces important changes in their photophysics, but does not impair their cellular uptake or their cell photosensitization ability. In fact we observe in the cells the same photophysical behavior as in THF solution. Specifically, we demonstrate, by recording the near-IR phosphorescence of 1O2, that the chlorins are able to photosensitize the production of 1O2 in the cell membrane. The cell-photosensitization efficiency depended on the chlorin and cell line nature, the carrier, and the length of pre-incubation and post-irradiation periods. The high photodynamic activity of chlorin-loaded liposomes and the possibility to design liposomal carriers to achieve a specific target site favors this approach to obtain an eventual pharmaceutical formulation.

Interaction of tocopherols and phenolic compounds with membrane lipid components: evaluation of their antioxidant activity in a liposomal model system.

This paper describes the use of complex liposomes as real membrane models to evaluate the potential benefits of several antioxidants in relation to lipid peroxidation. The xanthine oxidase/Fe(3+)-ADP-EDTA and the Fe(2+)/H2O2 systems have been used to generate hydroxyl radicals and the water soluble azo-compound 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) to generate carbon centered radicals (A*) by thermal decomposition. The antioxidant behavior of the rosemary and citrus plant extracts and vitamin-E and vitamin-E acetate alpha-tocopherols have been analyzed. The order of effectiveness in avoiding radical chain reactions has been established by using the colorimetric thiobarbituric acid reaction and the fluorescent probe DPH-PA. ESR spectroscopy has been used to carry out the pursuit of the oxidation processes on the basis of the identification of the radical species resulting from the oxidant system and the ability of the antioxidants to act as scavengers for hydroxyl and AAPH-derived radicals. The modification of the main transition temperature for the lipid mixture and the splitting of the calorimetric peak in the presence of the antioxidants were demonstrated by differential scanning calorimetry. The results obtained showed that the phenols-containing plant extracts and alpha-tocopherols perturb the phase behavior of the BBE lipid bilayer and have a fluidifying effect that could favor the known antioxidant capability and scavenging characteristics of these compounds. 31P-NMR results could be interpreted as, after the incorporation of these antioxidants, those lipid molecules interacting with antioxidants give rise to lamellar phase spectral components with resonance position at lower fields or to isotropic signals in accordance with a higher motion of their phosphate groups.

Design and characterization of liposomes containing long-chain N-acylPEs for brain delivery: penetration of liposomes incorporating GM1 into the rat brain.

PURPOSE: To develop a suitable liposomal carrier to encapsulate neu roactive compounds that are stable enough to carry them to the brain across the blood-brain barrier with the appropriate surface characteri tics for an effective targeting and for an active membrane transport. METHODS: Liposomes containing glycosides and a fusogenic lipid were prepared by extrusion. Photon correlation spectroscopy, fluorescent spectroscopy, and differential scanning calorimetry were used to characterize liposomal preparations. Tissue distribution was determined by using 3H-cholesterylhexadecylether as a marker. RESULTS: The incorporation of glycoside determinants and N-palmitoylphosphatidylethanolamine gives liposomes with similar in tial size, trapped volume, negative surface charge, bilayer fluidity, and melting temperature, except for monosialoganglioside-containing liposomes, which showed less negative surface charge and the highe size, trapped volume and melting temperature. All glycosilated formulations gave liposomes able to retain up to the 95% of encapsulated carboxyfluorescein after 90 min at physiologic temperature even in the presence of serum. Monosialoganglioside liposomes were recovered in the cortex, basal ganglia, and mesencephalon of both brain hemispheres. The liver uptake was higher for sulfatide- and glucose-liposomes, whereas the higher blood levels were observed for glucose- and mannose-liposomes. CONCLUSIONS: These results show the suitability of such liposomal formulations to hold encapsulated drugs. Moreover, the brain uptake of monosialoganglioside liposomes makes them good candidates as drug delivery systems to the brain.