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RATIONALE AND OBJECTIVES: In response to the COVID-19 pandemic reducing medical student presence on clinical services and in classrooms, academic institutions are utilizing a virtual format to continue medical student education. We describe a successful initial experience implementing a virtual elective in interventional radiology (IR) and provide the course framework, student feedback, and potential improvements. MATERIALS AND METHODS: A 2-week virtual IR elective curriculum was created utilizing a combination of synchronous and asynchronous learning and the "flipped" classroom educational model. Students virtually participated in daily IR resident education conferences, resident-led case review sessions, and dedicated lectures. Asynchronous prelearning material consisted of text and video correlating to lecture topics. Anonymous precourse and postcourse surveys were sent to all participating students (n = 10). RESULTS: Ten students (100%) completed precourse and seven (70%) completed postcourse surveys. Enrolled students were considering residencies in surgery (50%), internal medicine (40%), interventional radiology (30%), and/or diagnostic radiology (30%). Students' understanding of what IRs do and the procedures they perform (p < 0.001), when to consult IR for assistance in patient management (p = 0.005), and the number of IR procedures students could recall (p = 0.015) improved after the course. Case-review sessions and virtual lectures ranked as having the highest education value. Students recommended additional small-group case workshops. CONCLUSION: This successful virtual IR elective provides a framework for others to continue IR medical student education during the pandemic and grow the specialty's presence within an increasingly virtual medical school curriculum. The described model may be modified to improve IR education beyond the COVID-19 era.

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.

Dopamine delivery to the central nervous system (CNS) undergoes the permeability limitations of the blood-brain barrier (BBB). Condensation of dopamine with neutral amino acids could afford potential pro- drugs able to interact with the BBB endogenous transporters and easily enter the brain. To improve the bio-availability of the dopamine prodrug, 2-amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (DOPH), it was encapsulated in unilamellar liposomes of dimiristoylphosphatidylcholine (DMPC)and cholesterol. Vesicles were characterized by dynamic light scattering in order to evaluate their dimensions and vesicle stability, by zeta-potential measurements, by means of electronic microscopy after freeze-fracture and differential scanning calorimetry. The influence of vesicle composition on DOPH chemical and enzymatic stability was also evaluated. The formulated liposome suspensions were found to be stable, monodisperse systems with a negative zeta potential. From the obtained results, it is possible to conclude that, in studied samples, DOPH inclusion in liposomes offers the possibility of preventing photodegradation and of enhancing in vitro plasma stability. These studies suggest the potential of these formulations as a method to prevent DOPH chemical degradation and enzymatic metabolism.

The aim of this work was the preparation, characterization, and comparison of novel pH-sensitive nonphospholipid vesicles (niosomes) from two nonionic surfactants, with different hydrophilic-lipophilic balance values (Tween20-TW20 = 16.7 and Span60-SP60 = 4.7). Surfactants were mixed with cholesterol (CHOL) and its derivative, cholesteryl hemisuccinate (CHEMS), as a pH-sensitive molecule. Vesicles were characterized by dynamic light scattering, in order to evaluate their dimensions and vesicle stability, by zeta-potential measurements and by means of electronic microscopy after freeze-fracture. Ibuprofen (IBU) was used as the model drug, and high-performance liquid chromatography analyses were performed to evaluate drug-entrapment efficiency and release in a neutral, acidic environment. The influence of the vesicle composition on skin accumulation and transdermal permeation of IBU across excised hairless rat skin was investigated by using vertical Gummer diffusion cells. When niosomes with SP60 and CHEMS were prepared, there was a statistically significant increase of skin permeation of IBU, while TW20 niosomes did not show statistically significant differences in P(app) values without the influence of the vesicle size and charge.

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.

The maleic and fumaric diamides preparation of (O,O-diacetyl)-L-Dopa-methylester [(+)-4, (+)-5] are reported; they were synthesized in order to attenuate marked fluctuations of L-DOPA (LD) plasma levels and to overcome the problem of low bioavailability of LD. The new compounds were characterized evaluating solubility, chemical stability, apparent partition coefficient (log P) and comparing neostriatum dopamine (DA) levels in freely moving rats after i.p. administration of prodrugs [(+)-4, (+)-5] with prodrugs in liposomal formulations [(+)-4Lip, (+)-5Lip]. All the new compounds showed chemical stability in aqueous buffer solutions (pH 1.3 and 7.4). A relatively slow release of LD in human plasma was observed. Among the studied products, prodrug was able to induce sustained delivery of DA in rat striatal dialysate with respect to equimolar i.p admistration of LD. Furthermore, neostriatum DA concentration after administration of the synthesized prodrugs vs. prodrugs in liposomal formulations was compared (+)-4Lip, (+)-5Lip). The results suggest that cis dimeric prodrug (+)-4 and (+)-4Lip can improve the release of DA in rat brain and demonstrate the potential of these formulations for controlled delivery of antiparkinson agents.

Parkinson's disease is a neurodegenerative disease and its symptoms are relieved by administration of L-dopa (LD), which is converted by neuronal aromatic L-aminoacid decarboxylase (AADC), restoring dopamine (DA) levels in surviving neurons. In order to minimize unfavourable side effects, we studied new dimeric LD derivatives, as potential prodrugs for Parkinson's therapeutic treatment. To improve the bioavailability of the synthesized prodrugs, they were encapsulated in unilamellar liposomes of dimiristoylphosphatidylcholine (DMPC) and cholesterol (CHOL). In vivo microdialysis was used to monitor the striatal LD and DA concentrations after i.p. administration of new delivery systems. Bioavailability evaluation was performed by means of the HPLC-EC method. The striatal levels of LD and DA were remarkably elevated after i.p. administration of liposomal formulation of prodrug (+)-1b ([(O,O-diacetyl)-L-dopa-methylester]-succinyldiamide). This formulation showed about 2.5-fold increase in the basal levels of DA in dialysate rat striatum, suggesting that liposomal formulation of (+)-1b significantly increases LD and DA concentrations with respect to equimolar administration of LD itself or free prodrug (+)-1b.

The polysaccharide Scleroglucan, one of the most rigid polymers found in nature, can form a chemical/physical gel, in the presence of borax. The obtained hydrogel was loaded with three different model molecules (Theophylline, Vitamin B12 and Myoglobin) and then, after freeze-drying, was used as a matrix for tablets. The release profiles of the substances from the dosage forms were evaluated; the matrix appeared capable to modulate the diffusion of the chosen molecules, and different diffusion rates were observed, according to the different radii of the tested molecules. Interestingly, in the dissolution medium the matrix undergoes an anisotropic swelling taking place only in the axial direction, while a negligible radial variation occurs. The water uptake of the matrix occurs according to a Fickian process. Samples at two different polymer concentrations (0.7 and 2.3%, w/v) were characterized in terms of rheological and mechanical parameters and the properties were interpreted in terms of the molecular structure obtained by conformational analysis. The flow curves acquired in the viscoelasticity interval, show the effect of the borate ion in improving the resistance of the gel in comparison to the polymer alone. The evaluation of the moduli indicates that the system is viscoelastic, with an appreciable liquid component that increases as the polymer concentration decreases. Also the cohesion of the gel is higher in comparison to the Scleroglucan and is strongly dependent on temperature. The combination of experimental and theoretical conformational analysis approaches, allowed us to propose a model for the structure of the macromolecular network and to give an explanation to the anomalous swelling that was observed. It came out that the polymer can built up a channel structure, mediated via borax ion interaction, that can accommodate guest molecules of different size.

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. © 2002 Elsevier Science B.V. All rights reserved.

Giant cell tumor of the tendon sheath (GCTTS) is a benign proliferative lesion of synovial origin that may affect the joints, bursae and tendon sheaths. We report the case of a giant cell tumor of the tendon sheath arising from the carpal tunnel of the wrist in a 47-year-old woman. The patient underwent ultrasound (US) examination and subsequently magnetic resonance imaging (MRI).SommarioIl tumore gigantocellulare delle guaine tendinee (GCTTS) è una lesione benigna di tipo proliferativo che origina dalla sinovia e che coinvolge le articolazioni, le borse e le guaine sinoviali. Il caso descritto è quello di un tumore gigantocellulare delle guaine tendinee localizzato a livello del canale del carpo riscontrato in una donna di 47 anni. La paziente ha eseguito esame Ecografico e successivamente esame di Risonanza Magnetica.

In magnetic resonance imaging (MRI), the degree of contrast can be improved by using suitable contrast agents. The diethylenetriaminepentaacetic acid (DTPA) complexes of paramagnetic ions have been proposed for this purpose. This paper deals with extensive simulations of the distribution of species in blood plasma when solutions of manganese(II), copper(II), iron(III) and gadolinium(III) ions (as their soluble salts and as DTPA complexes) are injected. The various interaction equilibria, for which formation constants are known, are considered in order to assess toxic side-effects associated with their use in MRI. The data obtained support from the thermodynamic point of view, the use of GdDTPA, and suggest that the administration of a slight excess of ligand would guarantee complete coordination of the toxic gadolinium ion, and only minor interaction with the metal ions naturally present in blood plasma.

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.

The clinical diagnosis of synovial lesions is difficult and radiographic findings may establish a confident diagnosis only in some cases. MR imaging has become the technique of choice in evaluating these lesions, because a presumptive diagnosis can be made in most cases. The purpose of this study was to evaluate the joint synovial disease through intravenous contrast MRI examination and the following histological validation.Forty-eight patients were considered, twenty-seven women and twenty-one men, with pain relief or collectively determined by a known joint synovial disease, who underwent MRI at our institution between 2000 and the second half of 2010. All patients underwent magnetic resonance imaging using a low field magnet (0.2 Tesla) or high field magnet (1,5Tesla).Only nine patients were diagnosed with an inflammatory arthropathy, in the remaining cases non-inflammatory arthropathy of which the most frequent form was pigmented villonodular synovitis (PVNS) was diagnosed.MRI is able to provide an accurate representation of all the pathological changes involved in the joint space following acute or chronic inflammation and to define the characteristic features useful in differential diagnosis.

Pigmented villonodular synovitis (PVNS) is characterized by hyperplasia of the synovial tissue in joints, of tendon sheaths, and of the mucous membranes, or fibrous tissue adjacent to the tendons. Its etiology is unknown. We report a case of diffuse intra-articular PVNS of the right knee in a 38-year-old man. Ultrasound and magnetic resonance imaging (MRI) features of the disease are described.SommarioLa sinovite pigmentosa villonodulare (PVNS) consiste in un’iperplasia della membrana sinoviale delle articolazioni, dei tendini, delle membrane mucose o dei tessuti fibrosi adiacenti ai tendini. La sua eziologia è sconosciuta. Il caso che presentiamo è quello di una forma diffusa intarticolare di PVNS a carico del ginocchio di destra in un paziente maschio di 38 anni descritto sia con ultrasuoni che con Risonanza Magnetica.

Breast augmentation and breast reconstruction are increasingly common operations. All radiologists need to be able to recognize the normal appearances of the more commonly used implants on various imaging modalities and breast radiologists in particular are facing new challenges when imaging the women involved. This work aims to review the normal and abnormal findings in women undergoing breast implant surgery using ultrasonography, mammography, and magnetic resonance imaging.SommarioGli interventi chirurgici additivi e di ricostruzione della mammella sono sempre più comuni. Tutti i radiologi dovrebbero essere in grado di riconoscere, attraverso le varie metodiche, il normale aspetto delle protesi mammarie più spesso utilizzate; in particolar modo i radiologi che si occupano di diagnostica senologica. Scopo di questo lavoro è quello di ricapitolare gli aspetti radiologici, normali e patologici delle protesi mammarie, agli esami ecografici, mammografici e di risonanza magnetica.

The effect of cholesterol on the formation and hydration behavior of solid-supported polysorbate 20 (Tween 20)/cholesterol self-assemblies was investigated by means of in situ energy-dispersive X-ray diffraction in a wide range of relative humidity (0.4RH1). At low hydration, Tween 20 and cholesterol were found to demix, with the latter molecules forming crystallites with a pseudobilayer structure (d approximately = 34 A). Water adsorption promoted the progressive solubilization of cholesterol crystallites. When in the presence of enough cholesterol, the formation of niosomal bilayer membranes rich in Tween 20 occurred (RH approximately = 0.985). Upon further hydration, two distinct regimes associated with remarkable changes in the niosomal membrane structure were identified. In the first regime (0.985RH0.988), the swelling of the lamellar d spacing was due to the enlargement of the membrane thickness. In the second regime, the structure of Tween 20/cholesterol membranes was quite insensitive to hydration, and the thickness of the intermembrane water layer increased substantially. Remarkably, the curve of the calculated number of waters per surfactant molecule showed a distinct break at RH approximately 0.988, suggesting that the observed structural change in niosomal membranes was most likely due to the completion of the filling of the Tween 20 hydration shell. At full hydration, niosomal membranes exhibited the same lamellar d spacing of niosomes vesicles in aqueous solution. The process completely reversed upon dehydration.

Cancer of supernumerary breast or ectopic breast tissue has haigher incidence than the cancer on ortotopic breast. This finding puts some problems about the diagnosis and therapy of ectopic breast cancer. The Authors describe their personal experience in three patients surgically treated and discuss about problems and solutions of this pathology.

This study was conducted to evaluate the role of computed tomography cystography (CTC) and virtual cystoscopy (VC) with 64-slice CT in diagnosing bladder lesions using flexible cystoscopy as the reference standard.Twenty-eight patients with suspected bladder cancer and ten patients who had undergone transurethral resection of the bladder were studied by CTC and VC in both the supine and prone positions after distending the bladder with air. The patient population was divided into three groups based on lesion size at flexible cystoscopy. Results of the CT study were compared with those of flexible cystoscopy.Flexible cystoscopy depicted 88 bladder lesions in the 38 patients examined. Sensitivity and specificity values of CTC and VC alone were constantly lower than those of the combined-approach (group 1: 93.10% and 92.31%; group 2: 100% and 100%; group 3: 100% and 100%, respectively). Receiver operating characteristic (ROC) curve analysis showed that the combined approach decreases the lower dimensional threshold for lesion detection (1.4 mm).VC and CTC with 64-slice CT are promising diagnostic techniques for bladder cancers measuring 1-5 mm. Further studies on larger patient populations are required to validate our results.

By clinical observation and surgical treatment of a patient with cutaneous B-cell non-Hodgkin lymphoma, the Authors describe the nosological approach, the correct diagnosis and the surgical treatment in this disease.

Non-viral gene therapy is based on the development of efficient and safe gene carrier systems able to transfer DNA into cells. Polyethylenimine (PEI), the most promising non-viral vector, with its high cationic-charge-density potential is able (1) to compact DNA in complexes (polyplexes) smaller than those formed by liposomes (lipoplexes) and (2) to destabilize the endosomal membrane by a 'proton sponge' effect. Several PEI's hydrophobic modifications were reported in the last several years but in some cases a reduced transfection efficiency was observed. The mechanism underlying this phenomenon is not well understood so far. In order to extensively investigate these mechanisms, we reported a physicochemical and biological study of selected hydrophobic PEI's derivatives grafted with chains of different length and percentages of substitution able to form vesicles (polycationic liposomes) and to bind DNA. Their properties were studied by means of dynamic light scattering, freeze-fracture microscopy, potentiometric titrations, gel retardation assays, polyanion exchange reactions, toxicity assays, in vitro transfections, and fluorescence microscopy. Our results indicate that even if polyplexes are able to pass through the cellular membrane, the stability of PEI's hydrophobic polyplexes likely explain their different transfection efficiency in vitro.

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 coate 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, ζ 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 ζ 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.

The synthesis of a novel lipophilic diethylentriamino­tetracetic(DTTA)-dodecane gadolinium complex is reported. The Gd-DTTA-dodecane complex is able to form mixed micelles with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and a non-ionic surfactant like Tween 80. This novel multicomponent system can find potential application in magnetic resonance angiography (MRA).

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 drugswas determined considering the drug percentage penetrated into liposomial vesicles. The found lipohilicity order was amlodipine >mexiletine > indapamide.

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.

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.

In this paper second order statistics of the SIR (signal-to-interference ratio) are derived in the presence of cross correlated shadowing components. An analytical approach is proposed that extends to second order statistics the Wilkinson's approximation method for the power sum of log-normal components. The method is used to evaluate the outage occurrence rate for various propagation scenarios, characterized by different shadowing correlation decay distances and cross-correlations among shadowing components. Simulation results are then used to validate the analysis.

Spectrophotometric and conductivity determinations were performed for aqueous solutions of ascorbic acid in the concentration range of 5.7 × 10−5 to 10− M. The results show a significant bathochromic shift of up to 30 nm of λmax with a decrease in ascorbic acid concentration. The discrepancy between the absorbance values at λmax and λfix was found to reach up to three absorbance units. These results have important implications for ascorbic acid stability tests and other systems in which ascorbic acid degradation occurs. When absorbance is directly read for ascorbic acid solutions of various concentrations, λmax should be determined for each individual solution.

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.

Gellan beads containing a model molecule, clay, and in most cases oil and a surfactant were prepared. The release from the obtained beads was studied in vitro with different techniques and the effects of the presence of varying amounts of oil in the formulation was investigated. The behaviour of gellan was compared with that of alginate in the same experimental conditions. The results indicate that gellan is suitable for the formulation of sustained release beads and that, for the tested preparations, the presence of oil results in a marked reduction in delivery rate. From release experiments, carried out with the various formulations and with different concentrations of the substances used as models, it can be suggested that the swelling of the matrix seems to be the most likely factor responsible for the overall rate of delivery.

The Authors analyze the role of microsurgery in the treatment of chronic obstructive arteriopathies. In accordance with their results, they stress the usefulness of the microtechniques in the rescue of ischaemic limbs due to distal occlusion, and how these procedures are less dangerous than amputation, even though results are not long lasting.

By means of in vitro experiments, performed with a three compartment diffusion cell, we show how the presence of surfactants, often present in the formulation of dentifrices and mouthrinses, may affect the availability of calcium and its permeation rate through the proteic layer covering dental enamel (acquired pellicle). Mucin was the protein used to simulate the pellicle. Experiments were performed at different surfactant concentrations (i.s. below and above CMC) and also in the presence of fluoride ions that are capable of enhancing enamel remineralization. The mechanisms involved, mainly related to the interaction of surfactant monomers with the model protein, are discussed in this paper.

Swelling and diffusion experiments, performed in vitro with tablets prepared with scleroglucan and several hydrophilic and hydrophobic additives, indicate that it is possible to modulate drug delivery from the matrix by appropriate choice of the nature and amount of the additive. The additives in the formulations may affect the mechanisms (zero order, diffusion, erosion) involved in the release of drugs from the dosage forms.

The transport of undissociated and ionized organic molecules (benzamide, salicylic acid and 4' aminopropiophenone) through perfluorosulfonate ionomer membranes is reported and discussed in this paper. The diffusion properties were markedly affected by pH conditions and by the presence in solution of cations as Na + or Ca 2+ . The release of benzamide from an impregnated Nafion® membrane in different environmental conditions was also studied.

A new polymeric film, ethylene-vinyl-NN-diethylglycinate random copolymer, has been studied to evaluate possible applications of such a material to produce controlled release dosage forms. Protonation of the substituted amino groups took place to different extents according to environmental pH conditions. The polymeric film proved to be permeable only to uncharged species, the rate of diffusion of which increased with the increasing charge of the membrane. This effect might be related to strong polymer-proton interactions affecting structure and transport properties of the film and enhancing the solvation process. The charged form of a number of barbituric acid derivatives did not diffuse through the membrane. The uncharged forms permeated the polymeric sheeting at rates consistent with their partition coefficients and which increased with the increasing charge of the polymer.

Experimental evidence has been obtained which demonstrates that the synthesis of the IgA moiety of the secretory IgA molecule occurs in cells separate from those in which the secretory piece component is synthesized. The data supporting this have been described in excellent reviews and will not be reiterated here (1,2). Immunochemical evidence which establishes that the secretory and serum IgA portions may be derived from the same source in humans is lacking.

Bile acids have been absorbed on a microporous polypropylene membrane and the diffusion of ionic and non-ionic compounds through the barriers obtained has been studied at different pH values. Results indicate that permeation rates are affected by environmental pH conditions and an explanation of this behaviour is proposed. This study represents an approach for a pH-controlled drug delivery system.