RESUMEN

Preclinical and clinical evidences have demonstrated that astroglial-derived S100B protein is a key element in neuroinflammation underlying the pathogenesis of Parkinson's disease (PD), so much as that S100B inhibitors have been proposed as promising candidates for PD targeted therapy. Pentamidine, an old-developed antiprotozoal drug, currently used for pneumocystis carinii is one of the most potent inhibitors of S100B activity, but despite this effect, is limited by its low capability to cross blood brain barrier (BBB). To overcome this problem, we developed a non-invasive intranasal delivery system, chitosan coated niosomes with entrapped pentamidine (inPentasomes), in the attempt to provide a novel pharmacological approach to ameliorate parkinsonism induced by subchronic MPTP administration in C57BL-6 J mice. inPentasomes, prepared by evaporation method was administered daily by intranasal route in subchronic MPTP-intoxicated rodents and resulted in a dose-dependent manner (0.001-0.004 mg/kg) capable for a significant Tyrosine Hydroxylase (TH) positive neuronal density rescue in both striatum and substantia nigra of parkinsonian mice. In parallel, inPentasomes significantly decreased the extent of glial-related neuroinflammation through the reduction of specific gliotic markers (Iba-1, GFAP, COX-2, iNOS) with consequent PGE2 and NO2- release reduction, in nigrostriatal system. inPentasomes-mediated S100B inhibition resulted in a RAGE/NF-κB pathway downstream inhibition in the nigrostriatal circuit, causing a marked amelioration of motor performances in intoxicated mice. On the basis of our results, chitosan coated niosomes loaded with pentamidine, the inPentasome system, self-candidates as a promising new intranasal approach to mitigate parkinsonism in humans and possibly paves the way for a possible clinical repositioning of pentamidine as anti-PD drug.

Asunto(s)

Antiinflamatorios/administración & dosificación , Antiparkinsonianos/administración & dosificación , Quitosano/administración & dosificación , Trastornos Parkinsonianos/tratamiento farmacológico , Pentamidina/administración & dosificación , Administración Intranasal , Animales , Antiinflamatorios/química , Antiinflamatorios/farmacocinética , Antiparkinsonianos/química , Antiparkinsonianos/farmacocinética , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Quitosano/química , Quitosano/farmacocinética , Dopamina/metabolismo , Liberación de Fármacos , Liposomas , Masculino , Ratones Endogámicos C57BL , Mucosa Nasal/metabolismo , Trastornos Parkinsonianos/metabolismo , Trastornos Parkinsonianos/patología , Pentamidina/química , Pentamidina/farmacocinética

RESUMEN

The majority of active agents do not readily permeate into brain due to the presence of the blood-brain barrier and blood-cerebrospinal fluid barrier. Currently, the most innovative and promising non-invasive strategy in brain delivery is the design and preparation of nanocarriers, which can move through the brain endothelium. Niosomes can perform brain delivery, in fact polysorbates, can act as an anchor for apolipoprotein E from blood plasma. The particles mimic LDL and interact with the LDL receptor leading to the endothelial cells uptake. The efficacy of niosomes for anticancer therapeutic applications was correlated to their physicochemical and drug delivery properties. Dimensions and ζ-potential were characterized using dynamic light scattering and asymmetric flow-field fractionation system. Lipid bilayer was characterized measuring the fluidity, polarity and microviscosity by fluorescent probe spectra evaluation. Morphology and homogeneity were characterized using atomic force microscopy. Physicochemical stability and serum stability (45% v/v fetal bovine and human serum) were evaluated as a function of time using dynamic light scattering. U87-MG human glioblastoma cells were used to evaluate vesicle cytotoxicity and internalisation efficiency. From the obtained data, the systems appear useful to perform a prolonged (modified) release of biological active substances to the central nervous system.

Asunto(s)

Barrera Hematoencefálica/efectos de los fármacos , Encéfalo/efectos de los fármacos , Sistemas de Liberación de Medicamentos/métodos , Liposomas/administración & dosificación , Liposomas/toxicidad , Animales , Barrera Hematoencefálica/metabolismo , Encéfalo/metabolismo , Bovinos , Línea Celular Tumoral , Humanos , Liposomas/química , Albúmina Sérica/administración & dosificación , Albúmina Sérica/química , Albúmina Sérica/toxicidad

RESUMEN

Nanodiamonds are a novel class of nanomaterials which have raised much attention for application in biomedical field, as they combine the possibility of being produced on large scale using relatively inexpensive synthetic processes, of being fluorescent as a consequence of the presence of nitrogen vacancies, of having their surfaces functionalized, and of having good biocompatibility. Among other applications, we mainly focus on drug delivery, including cell interaction, targeting, cancer therapy, gene and protein delivery. In addition, nanodiamonds for bone and dental implants and for antibacterial use is discussed. Techniques for detection and imaging of nanodiamonds in biological tissues are also reviewed, including electron microscopy, fluorescence microscopy, Raman mapping, atomic force microscopy, thermal imaging, magnetic resonance imaging, and positron emission tomography, either in vitro, in vivo, or ex vivo. Toxicological aspects related to the use of nanodiamonds are also discussed. Finally, patents, preclinical and clinical trials based on the use of nanodiamonds for biomedical applications are reviewed.

Asunto(s)

Microscopía Fluorescente/métodos , Nanocápsulas/química , Nanodiamantes/uso terapéutico , Prótesis e Implantes , Composición de Medicamentos/métodos , Nanocápsulas/ultraestructura , Nanodiamantes/química

RESUMEN

Core-shell gold nanoparticles [AuNPs], stabilized with a hydrophilic polymer, poly(3-dimethylammonium-1-propyne hydrochloride) [PDMPAHCl], have been used for the immobilization of bovine serum amine oxidase [BSAO]. The functionalized surface of the hybrid nanoparticles is pH responsive, due to the presence of aminic groups that carry out a double role: on one hand they act as ligands for the gold nanoparticle surface, allowing the colloidal stabilization and, on the other hand, they give a hydrophilic characteristic to the whole colloidal suspension. The core-shell nanoparticles [Au@PDMPAHCl] have been characterized by using UV-vis and X-ray photoelectron spectroscopy, DLS, ζ-potential measurements and by FE-TEM microscopy. BSAO enzyme can be loaded by non-covalent immobilization onto Au@PDMPAHCl nanoparticles up to 70% in weight, depending on the pH values of the environmental medium. Activity tests on Au@PDMPAHCl-BSAO bioconjugates confirm an enzymatic activity up to 40%, with respect to the free enzyme activity. Moreover, our results show that loading and enzymatic activity are rather interrelated characteristics and that, under appropriate polymer concentration and pH conditions, a satisfactory compromise can be reached. These results, as a whole, indicate that Au@PDMPAHCl-BSAO bioconjugate systems are promising for future biomedical applications.

Asunto(s)

Amina Oxidasa (conteniendo Cobre)/sangre , Oro/química , Nanopartículas/química , Polímeros/química , Animales , Bovinos , Microscopía Electrónica de Transmisión , Espectroscopía de Fotoelectrones , Espectrofotometría Ultravioleta

RESUMEN

In the present paper physical gels, prepared with two polysaccharides, Xanthan and Locust Bean Gum, and loaded with non-ionic surfactant vesicles, are described. The vesicles, composed by Tween20 and cholesterol or by Tween85 and Span20, were loaded with Monoammonium glycyrrhizinate for release experiments. Size and zeta (ζ)-potential of the vesicles were evaluated and the new systems were characterized by rheological and dynamo-mechanical measurements. For an appropriate comparison, a Carbopol gel and a commercial gel for topical applications were also tested. The new formulations showed mechanical properties comparable with those of the commercial product indicating their suitability for topical applications. In vitro release experiments showed that the polysaccharide network protects the integrity of the vesicles and leads to their slow release without disruption of the aggregated structures. Furthermore, being the vesicles composed of molecules possessing enhancing properties, the permeation of the loaded drugs topically delivered can be improved. Thus, the new systems combine the advantages of matrices for a modified release (polymeric component) and those of an easier permeability across the skin (vesicle components). Finally, shelf live experiments indicated that the tested gel/vesicle formulations were stable over 1 year with no need of preservatives.

Asunto(s)

Antiinflamatorios no Esteroideos/química , Galactanos/química , Ácido Glicirrínico/química , Liposomas/química , Mananos/química , Gomas de Plantas/química , Polisacáridos Bacterianos/química , Resinas Acrílicas/química , Administración Tópica , Preparaciones de Acción Retardada , Liberación de Fármacos , Geles , Hexosas/química , Cinética , Polisorbatos/química , Soluciones , Tensoactivos/química

RESUMEN

Phospholipid and non-phospholipid vesicles are extensively studied as drug delivery systems to modify pharmacokinetics of drugs and to improve their action in target cells. It is believed that the major barrier to efficient drug delivery is entrapment of drugs in the endosomal compartment, since this eventually leads to its degradation in lysosomes. For these reasons, the knowledge of internalization pathway plays a fundamental role in optimizing drug targeting. The aim of this work is to characterize pH-sensitive Tween 20 vesicles, their interaction with macrophage-like cells and their comparison with pH-sensitive liposomes. The effect of different amounts of cholesteryl hemissucinate on surfactant vesicle formation and pH-sensitivity was studied. To evaluate the initial mode of internalization in Raw 264.7 and the intracellular fate of neutral and pH-sensitive formulations, flow cytometry in presence and in absence of selected inhibitors and fluorescence microscopy in absence and presence of specific fluorescent endocytotic markers were used. The obtained results showed that the surfactant vesicle pH-sensitivity was about two or three fold higher than that obtained with pH-sensitive liposomes in the presence of serum in vitro. The uptake mechanism of surfactant vesicles, after incubation with macrophage-like cells, is comparable to that of liposomes (clathrin-mediated endocytosis).

Asunto(s)

Endocitosis/fisiología , Macrófagos/metabolismo , Fosfolípidos/farmacocinética , Polisorbatos/farmacocinética , Tensoactivos/farmacocinética , Animales , Transporte Biológico/efectos de los fármacos , Fenómenos Biofísicos , Línea Celular , Vesículas Citoplasmáticas/química , Vesículas Citoplasmáticas/metabolismo , Endocitosis/efectos de los fármacos , Fluoresceínas/metabolismo , Colorantes Fluorescentes/metabolismo , Concentración de Iones de Hidrógeno , Liposomas/química , Liposomas/metabolismo , Liposomas/farmacocinética , Ratones , Microscopía Fluorescente , Fosfolípidos/química , Fosfolípidos/metabolismo , Polisorbatos/metabolismo , Polisorbatos/farmacología , Tensoactivos/metabolismo , Tensoactivos/farmacología

RESUMEN

We have investigated the formation of complexes between negatively charged niosomal vesicles (hybrid niosomes), built up by dicethylphosphate [DCP], Tween 20 and Cholesterol, and three linear differently charged cationic polyions, such as alpha-polylysine, epsilon-polylysine, and polyethylvinylpyridinium bromide [PEVP], with two different substitution degrees. Our aim is to investigate the interaction mechanism between anionic-nonionic vesicles (hybrid niosomes) and linear polycations, characterizing the resulting aggregates in view of possible applications of these composite colloidal particles as vectors for multidrug delivery. In order to explore the aggregation behavior of the complexes and to gain information on the stability of the single niosomal vesicles within the aggregates, we employed dynamic light scattering (DLS), laser Doppler electrophoretic measurements, and fluorescence measurement techniques. The overall phenomenology is well described in terms of the re-entrant condensation and charge inversion behavior, observed in different colloidal systems. The aggregate size and overall charge depend on the charge ratio between vesicles and polyions, and the aggregates reach their maximum size at the point of charge inversion (re-entrant condensation). While the overall phenomenology is similar for all three polycations investigated, the stability and the integrity of the hybrid niosomal vesicles forming the aggregates strongly depend on the chemical structure of the polycations. The role of the polycations in the aggregation process is discussed by identifying specific interactions with the niosomal membrane, pointing out their importance for possible applications as drug delivery vectors.

Asunto(s)

Liposomas/química , Iones/química , Estructura Molecular

RESUMEN

Polysaccharide-coated liposomes have been studied for their potential use for peptide drug delivery by the oral route because they are able to minimize the disruptive influences on peptide drugs of gastrointestinal fluids. The aim of this work was to synthesize and characterize a modified polysaccharide, O-palmitoylscleroglucan (PSCG), and to coat unilamellar liposomes for oral delivery of peptide drugs. To better evaluate the coating efficiency of PSCG, also scleroglucan (SCG)-coated liposomes were prepared. We studied the surface modification of liposomes and the SCG- and PSCG-coated liposomes were characterized in terms of size, shape, zeta potential, influence of polymer coating on bilayer fluidity, stability in serum, in simulated gastric and intestinal fluids and against sodium cholate and pancreatin. Leuprolide, a synthetic superpotent agonist of luteinizing hormone releasing hormone (LHRH) receptor, was chosen as a model peptide drug. After polymer coating the vesicle dimensions increased and the zeta potential shifted to less negative values. These results indicate that both SCG- and PSCG-coated liposomes surface and DSC results showed that PSCG was anchored on the liposomal surface. The stability of coated-liposomes in SGF, sodium cholate solution and pancreatin solution was increased. From this preliminary in vitro studies, it seems that PSCG-coated liposomes could be considered as a potential carrier for oral administration.

Asunto(s)

Glucanos/química , Leuprolida/química , Liposomas/química , Animales , Bovinos , Química Farmacéutica , Sistemas de Liberación de Medicamentos/métodos , Estabilidad de Medicamentos , Fármacos para la Fertilidad Femenina/administración & dosificación , Fármacos para la Fertilidad Femenina/química , Fármacos para la Fertilidad Femenina/farmacocinética , Jugo Gástrico/química , Jugo Gástrico/metabolismo , Glucanos/sangre , Glucanos/síntesis química , Secreciones Intestinales/química , Secreciones Intestinales/metabolismo , Leuprolida/administración & dosificación , Leuprolida/farmacocinética , Membrana Dobles de Lípidos/química , Liposomas/sangre , Liposomas/síntesis química , Espectroscopía de Resonancia Magnética/métodos , Nanotecnología/métodos , Pancreatina/química , Pancreatina/metabolismo , Tamaño de la Partícula , Colato de Sodio/química , Colato de Sodio/metabolismo , Espectrofotometría Infrarroja/métodos , Electricidad Estática

RESUMEN

In this work, we report the preparation, the characterization and interaction with cells of novel pH-sensitive non-phospholipid vesicle formulations, from a non-ionic surfactant mixed with cholesterol (CHOL) and his derivative cholesteryl hemisuccinate (CHEMS), as pH-sensitive molecule. This molecule, can destabilize the vesicle lipid bilayer when exposed to an acidic environment, with a subsequent release of vesicular content, enhancing the cytoplasmatic delivery of drugs to target cells. Vesicles were characterized by static and dynamic light scattering, in order to evaluate their dimensions, bilayer thickness and vesicle stability. Membrane permeability changes were determined by the release of entrapped hydroxypyrene-1,3,6-trisulfonic acid (HPTS). Also diphenylhesatriene (DPH) fluorescence anisotropy and zeta potential measurements were used to evidence the pH sensitivity. Furthermore vesicles were characterized by means of electronic microscopy after freeze-fracture. The interaction of non-lipid vesicles containing different fluorescent dyes with Raw 264.7, mouse monocite macrophage, were analyzed by flow cytometric analysis. The obtained results indicate that the pH-sensitive vesicular structures show good plasma stability and relevant pH-sensitivity. Moreover this formulation was able to interact with target membranes (i.e. plasma or endosomal membrane) and to release the encapsulated material into the cytoplasm.

Asunto(s)

Colesterol/química , Concentración de Iones de Hidrógeno , Macrófagos/citología , Tensoactivos/química , Animales , Línea Celular , Colesterol/metabolismo , Endocitosis , Colorantes Fluorescentes/química , Técnica de Fractura por Congelación , Ratones , Microscopía Electrónica de Transmisión , Permeabilidad , Fosfolípidos/química , Fosfolípidos/metabolismo , Plasma , Tensoactivos/metabolismo

RESUMEN

The lipophilicity of some cardiovascular drugs was determined by capillary electrophoresis (CE). Mexiletine, amlodipine and indapamide, the drugs considered, were in contact with liposomial vescicles for 2, 4 or 6 h. After the contact time the drugs, penetrated into liposomial vesicles, were determined by CE using phosphate buffer (pH 6.3 or 7.4) or borate buffer (pH 9). The lipophilicity of three drugs was determined considering the drug percentage penetrated into liposomial vesicles. The found lipohilicity order was amlodipine > mexiletine > indapamide.

Asunto(s)

Fármacos Cardiovasculares/análisis , Liposomas/análisis , Química Farmacéutica , Electroforesis Capilar/métodos

RESUMEN

In this paper, the experimental conditions for preparing ampicillin-loaded surfactant vesicles (SVs) are described. Our studies are focused on the potential use of a vesicular polymeric dispersion as ampicillin delivery system for topical application. The main components of the formulation are uncharged and charged SVs loaded with ampicillin and dispersed in a gellan solution. The following issues are addressed: the drug encapsulation efficiency (e.e.), the kinetic of drug release from the delivery systems, the antimicrobial activity of vesicle-entrapped ampicillin. The in vitro permeation experiments through a synthetic lipophilic barrier (Silastic) and through porcine skin are carried out to evaluate the potential use as a dermal formulation. The use of both a synthetic and a biological membrane allows to discriminate between the effects related to variations of thermodynamic parameters and those correlated to biological factors. The release rate of ampicillin is increased by encapsulation in neutral and negatively charged SVs and the permeation rate was slowed by dispersion of drug-loaded SVs in gellan solution. Finally, studies of antimicrobial activity on prepared systems evidenced that ampicillin encapsulated in SVs exhibit a higher activity than the free drug.

Asunto(s)

Ampicilina/administración & dosificación , Ampicilina/farmacología , Penicilinas/administración & dosificación , Penicilinas/farmacología , Administración Tópica , Algoritmos , Animales , Cromatografía Líquida de Alta Presión , Dimetilpolisiloxanos , Sistemas de Liberación de Medicamentos , Electroquímica , Técnica de Fractura por Congelación , Técnicas In Vitro , Luz , Membranas Artificiales , Tamaño de la Partícula , Permeabilidad , Dispersión de Radiación , Siliconas , Absorción Cutánea , Porcinos , Termodinámica

RESUMEN

Vitamin A is widely employed in pharmaceuticals and cosmetics. The all-trans (AT) isomer (100% of biological potency) is sensible to different factors, such as light, heat and formulation components, leading to its degradation or isomerization. The main objective of this work was to study, in model cosmetic lipophilic vehicles, the degradation of retinyl palmitate (RetP) to the less active cis-isomers in presence of widely used conservative agents (propyl gallate and Vitamin E). Two lipophilic phases were used (liquid paraffin and almond oil) because liquid paraffin, almost composed of satured hydrocarbons, is not degraded by light exposure, while almond oil, containing several double bonds, could interfere with light-induced degradative process of RetP. In the first phase, the more suitable analytical method was chosen between normal and reverse phase HPLC to follow the degradation of RetP. In the second phase, RetP light-induced degradation was studied to simulate storage condition effect on cosmetic products ageing. The results showed that: (a) the reverse phase HPLC technique, unable to separate the all-trans from the 13-cis and 9-cis isomers, derived by Vitamin A isomerization, leads to an incorrect quantitation of RetP; (b) the lipophilic vehicle influences the isomerization-degradation process; (c) the conservative agents do not protect from degradation.

Asunto(s)

Luz/efectos adversos , Metabolismo de los Lípidos , Vitamina A/análogos & derivados , Vitamina A/metabolismo , Química Farmacéutica , Diterpenos , Portadores de Fármacos/análisis , Portadores de Fármacos/metabolismo , Lípidos/análisis , Ésteres de Retinilo , Vitamina A/análisis

RESUMEN

Model glycopeptides of the general formula Boc-Ala-Thr(G-D)-A(1)-A(2)-Leu-Leu-Lys(N)-Ala-OMe, where D = dansyl (dimethyl aminonaphthalenesulphonyl), G = glucosyl and N = naphthyl, while A(1)-A(2) = Ala-Leu or Aib-Aib, and denoted as D-G-Ala-N and D-G-Aib-N, respectively, were used to investigate glycoprotein-membrane interactions. They carry two fluorophores (D and N), covalently linked to the glucose ring and the lysine side chain, respectively, while the threonine side chain is O-glycosylated. CD spectra in different solvent media suggest that both glycopeptides attain an ordered structure, possibly a helix-like conformation. By combining FRET (fluorescence resonance energy transfer) experiments with molecular mechanics data, the most probable structures of both glycopeptides were built up, starting from both a right-handed (rh) alpha- and 3(10)-helix. They were found to populate an alpha-helical conformation, a result further confirmed by the very good agreement between theoretical and experimental quenching efficiency only observed when the backbone chain was in alpha-helix. The association of D-G-Ala-N with model membranes (liposomes) was studied by CD, fluorescence decay, fluorescence anisotropy, and collisional quenching experiments. The binding does not alter the structural features of the peptide because the CD spectral patterns are unaffected by the association. The peptide orientation inside the phospholipidic bilayer is guided by the polar glucose molecule lying in the water phase. The insertion of the hydrophobic backbone chain into the membrane, seeing the probes only partially accessible from the external solution, is characterized by a significant degree of heterogeneity, an increase in vesicles size, and a relevant stabilizing effect on the membrane itself against rupture by methanol.

Asunto(s)

Glicopéptidos/química , Proteínas de la Membrana/química , Secuencia de Aminoácidos , Biopolímeros/química , Dicroismo Circular , Polarización de Fluorescencia , Liposomas , Modelos Moleculares , Estructura Molecular , Oligopéptidos/química , Conformación Proteica , Soluciones , Espectrometría de Fluorescencia , Termodinámica

RESUMEN

Our research on topical application of lidocaine-loaded non-ionic surfactant vesicles (NSVs) was prompted by the great interest on new delivery systems for local anaesthetics. This study is focused on a novel formulation of NSVs entrapping lidocaine in the form of a free base (LID) and a hydrochloride (LIDHCl). NSVs were prepared from polyoxyethylene sorbitan monolaurate (Tween20) and cholesterol. The effect of vesicle composition and environmental pH condition (8.6-5.5) on drug encapsulation efficiency (e.e.) was investigated. Experimental strategies involved: freeze-fracture, microscopy technique, dynamic light scattering, permeation through Silastic and mouse abdominal skin, in vitro release kinetics of vesicle-entrapped drugs, fluorescence quenching analyses. Diffusion experiments showed that the flux of charged lidocaine through Silastic membrane was possible only after the vesicle encapsulation. Permeation through mouse abdominal skin of LIDHCl loaded vesicles showed a higher flux and a shorter lag time with respect to classical liposome formulations, while LID permeation rate was quite similar for NSV and liposome formulations. Vesicles were also prepared in the presence of dicetylphosphate (DCP) and N-cetylpyridinium chloride (CP) to obtain negatively and positively charged vesicles respectively, but in this case the e.e. of the drug was negligible. The possible reason of the remarkable lower e.e. observed with charged vesicles was investigated by means of fluorescence quenching experiments.

Asunto(s)

Anestésicos Locales/química , Lidocaína/química , Membrana Dobles de Lípidos/química , Tensoactivos/química , Anestésicos Locales/farmacocinética , Animales , Cápsulas , Difusión , Portadores de Fármacos , Concentración de Iones de Hidrógeno , Lidocaína/farmacocinética , Membrana Dobles de Lípidos/farmacocinética , Masculino , Ratones , Ratones Desnudos , Absorción Cutánea/fisiología , Tensoactivos/farmacocinética

RESUMEN

New hydrogels obtained by a crosslinking reaction between the polycarboxylated derivative of scleroglucan (sclerox) and 1, 6-hexanedibromide have been prepared and characterized. Different ratios between the alkane dihalide and sclerox yielded products with appreciably different properties. Water uptake by the hydrogel with a low degree of crosslinking was remarkably affected by ionic strength. The diffusion of a model molecule (theophylline) through the swelled crosslinked polymers was studied and the theoretical analysis leading to the calculation of permeability coefficients in different environmental conditions is reported. Tablets prepared with one of the new hydrogels behaved as swellable monolithic systems suitable for sustained drug release.

Asunto(s)

Preparaciones de Acción Retardada/farmacocinética , Glucanos/química , Hidrogeles/química , Hidrogeles/síntesis química , Teofilina/farmacocinética , Bromuros/química , Reactivos de Enlaces Cruzados/química , Difusión , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Concentración Osmolar , Permeabilidad , Estadística como Asunto , Comprimidos , Vasodilatadores/farmacocinética

RESUMEN

We analyzed the binding and fusogenic properties of surfactant vesicles (SVs), composed of ionic and nonionic surfactants and cholesterol, with the surface of different human lymphoid cells. The influence of charge on SVs-cell interaction was evaluated by monitoring the presence of fluorescent sodium calcein artificially entrapped in the vesicles using optical fluorescence microscopy and laser scanning confocal microscopy. Our results clearly indicate that only negatively charged vesicles bind and fuse with the plasma membrane of human lymphoid cells, and the number of SVs bound to the cell surface was variable among the positive cells. Thin section electron microscopy illustrated that the fusogenic events of SVs with the cell plasma membrane mostly occurred at smooth and nonvillous regions of the cell surface. Taken together, our results suggest that binding and fusion of SVs with the cell plasma membrane might be dependent on interactions with specific membrane components that preferentially recognize negatively charged SVs.

Asunto(s)

Fusión de Membrana/fisiología , Polisorbatos/metabolismo , Tensoactivos/metabolismo , Colesterol/metabolismo , Humanos , Liposomas , Células Tumorales Cultivadas

RESUMEN

The formulation of a new controlled delivery system, based on a novel type of matrix obtained by the chemical reaction carried out in an aqueous medium on a mixed physical gel of gellan and scleroglucan, is described in this paper. The preparation yielded a new co-crosslinked polysaccharide (CCP) hydrogel, bearing carboxylic groups, that showed a sustained release behaviour that can be modulated by means of calcium ions. For the characterization of CCP, diffusion experiments through the swelled hydrogel were carried out in different environmental conditions and the release from tablets prepared with CCP and a model drug was evaluated. The addition of CaCl2 in the formulation of the dosage forms allowed a further marked reduction in delivery rate to be obtained; this effect is to be related to the free ionized carboxylic groups still present in the gellan moiety of CCP. The different behaviour of Ca+2 and Na+ ions is discussed.

Asunto(s)

Reactivos de Enlaces Cruzados/química , Preparaciones de Acción Retardada/química , Polisacáridos/química , Calcio/química , Secuencia de Carbohidratos , Difusión , Geles , Hidrogel de Polietilenoglicol-Dimetacrilato , Datos de Secuencia Molecular , Permeabilidad , Comprimidos

RESUMEN

The ability of gellan to form gels in the presence of calcium ions enabled us to prepare capsules by gelation of this polysaccharide around a core containing starch, calcium chloride and a model drug. Release from the dried capsules was studied in vitro by means of the rotating basket technique (USP) in different environmental conditions (distilled water, pH = 2.0, pH = 6.8) and the effects of the presence of increasing amounts of drug in the formulation were also investigated. The behaviour of the gellan capsules was compared with that of beads prepared with the same polysaccharide but containing different additives. Results obtained indicate that gellan is suitable for the formulation of sustained release capsules and that solvent uptake by the dried capsules is most likely the main factor capable of affecting the rate of delivery from the tested preparations.

Asunto(s)

Preparaciones de Acción Retardada , Polisacáridos Bacterianos/metabolismo , Cloruro de Calcio/química , Cloruro de Calcio/metabolismo , Cápsulas , Medios de Cultivo , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Rastreo , Almidón/química , Almidón/metabolismo

Asunto(s)

Ciclopentolato/administración & dosificación , Midriáticos/administración & dosificación , Animales , Cápsulas , Córnea/metabolismo , Ciclopentolato/química , Ciclopentolato/farmacocinética , Técnicas In Vitro , Masculino , Midriáticos/química , Midriáticos/farmacocinética , Soluciones Oftálmicas , Conejos

RESUMEN

The results are reported of the first round of a biennial mammographic screening of women aged 50-64 years started in the Health District of Leno (Brescia, Italy) in December 1985. A total of 7662 women are invited and 5235 attended the programme (68.3%), 87 underwent biopsy or surgery and 39 were found to have a malignant tumor (positive predictive test value: 44.8%; detection rate: 7.5%). The series of 39 cancers found at screening included 4 carcinoma in situ (10.3%); of the invasive tumors, 8 were less than or equal to 10 mm (20.5%); 20 were 11-20 mm in greatest diameter (51.3%) and 7 were 21-40 mm (17.9%). Twenty-four cases showed no axillary lymph node involvement (61.5%), and none of them had metastasis at the time of diagnosis. On the basis of pTNM, 69.2% of cases was classified stage I, 17.9% stage II, none stage III and 2.6% stage IV.

Asunto(s)

Neoplasias de la Mama/prevención & control , Mamografía , Tamizaje Masivo , Biopsia , Mama/patología , Neoplasias de la Mama/diagnóstico por imagen , Neoplasias de la Mama/patología , Femenino , Humanos , Italia , Tamizaje Masivo/organización & administración , Persona de Mediana Edad , Estadificación de Neoplasias , Cooperación del Paciente