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Biomedical subjects

Paolo Colombo

Publications and source records attributed to Paolo Colombo.

At least 37 records · Page 2Linked to original sources
PubMed2004

The surface roughness of lactose particles can be modulated by wet-smoothing using a high-shear mixer.

The surface morphology of a-lactose monohydrate particles was modified by a new wet-smoothing process performed in a high-shear mixer using solvents. Successive steps of wetting and drying of lactose powders during rolling in the mixer's cylindrical bowl were performed. Smoothed particles were tested for size distribution, flow, and packing. The wet-smoothing process flattened the surface and rounded the edges of lactose particles. In comparison with original lactose, an improvement of powder packing and flow properties was evidenced. When the process was performed in the presence of a ternary agent such as magnesium stearate, the smoothing was improved. The evolution of rugosity during the smoothing process was assessed through a fractal descriptor of SEM picture. Atomic force microscopy and surface area measurements quantified the surface rugosity. A very significant reduction of the rugosity, more remarkable in the presence of magnesium stearate, was measured. This new process of powder wet-smoothing allows the preparation of lactose particles with different degrees of smoothed surface for the control of flow and packing properties and particle-particle interactions.

Lactose↗
PubMed2004

Effect of chemical enhancers and iontophoresis on thiocolchicoside permeation across rabbit and human skin in vitro.

The aim of this work was to study the permeation of thiocolchicoside across the skin in vitro. The effect of the chemical enhancer lauric acid and the physical technique of iontophoresis was investigated. Permeation experiments were performed in vitro using rabbit ear skin as barrier. The effect of lauric acid at different concentrations (2% and 4%) and of the vehicle (water, ethanol, or ethanol/water) was investigated. The primary effect of lauric acid was on the partitioning parameter, whereas the diffusive parameter did not change significantly. When human epidermis was used, the permeation parameters were generally lower, although not significantly different from rabbit ear skin. The data obtained with full-thickness human skin indicate that, despite the hydrophilic nature of thiocolchicoside, the resistance to drug transport is not limited to the stratum corneum, but that the underlying dermal tissue can also contribute. Iontophoresis enhanced the flux of thiocolchicoside compared with the passive control. The mechanism by which iontophoresis enhanced thiocolchicoside transport across the skin was electroosmosis. The permeation of thiocolchicoside across the skin can be enhanced using chemical or physical penetration enhancers.

Adjuvants, Pharmaceutic↗
PubMed2004

Drug-beta-cyclodextrin containing pellets prepared with a high-shear mixer.

This work was aimed at investigating the preparation of beta-cyclodextrin-microcrystalline cellulose pellets by means of a high-shear mixer, both in the absence or in the presence of ibuprofen as model drug. Drug loading of pellets was accomplished by means of two alternative techniques: 1) solution layering or 2) powder layering. The prepared pellets were characterised in terms of size distribution, shape factor, friability and dissolution rate. The interaction between ibuprofen and beta-cyclodextrin was monitored by Differential Scanning Calorimetry (DSC). Micro Fourier Transform Infrared spectroscopy (MicroFTIR) was applied to determine the distribution of components within each pellet on a micro scale. Pellets with narrow size distribution and containing up to about 90% of BCD were prepared using water as binder. The process yield resulted around 84 and 63% for drug-free and medicate pellets respectively. Drug loaded pellets with favourable technological and biopharmaceutical characteristics can be obtained both by powder or solution layering techniques. The latter proved to be more suitable for producing pellets with high drug contents, reduced friability and high drug dissolution rates.

Cellulose↗
PubMed2004

Study design and preliminary results from the pilot phase of the PraKtis study: self-reported diagnoses of selected skin diseases in a representative sample of the Italian population.

BACKGROUND: Few data are available on the prevalence of common skin disorders like actinic keratoses in the general population. Such data are mostly needed to better define health needs and to organize medical services. The Prevalence of Actinic Keratoses in the Italian Population Study (PraKtis) was designed to estimate the point prevalence of actinic keratoses and related disorders, e.g. photoaging, in a representative sample of the Italian population. Within the study, information on the history of relevant dermatological diagnoses was also collected. METHODS: The study was conducted in collaboration with DOXA, the Italian branch of the Gallup International Association. A representative sample of people aged 45 years or older was selected by picking them from the electoral rolls according to a stratified random sampling design involving a replacement procedure. A total of 180 interviewers specifically trained to collect data on skin diseases and to take photographs of representative lesions on the face and upper limbs, contacted and interviewed the sampled subjects and performed a face-to-face computer-assisted interview. A final sample of about 12000 subjects was foreseen. RESULTS: The pilot phase of the study was conducted between January 1 and June 30, 2003. A total of 3660 subjects were recruited and interviewed. Overall, an estimated 37% of Italian people reported having ever undergone a dermatological consultation in the past. An estimated 29% reported having ever received a specific dermatological diagnosis by a physician. The frequency of specifically enquired diagnoses, weighted according to the distribution of the Italian population, was as follows: atopic dermatitis 4.7%, other eczematous dermatitides 4.3%, urticaria 4.3%, psoriasis 3.1%, skin tumors 1.6%, vitiligo 0.7% and actinic keratoses 0.3%. CONCLUSION: Skin diseases are frequently reported. The prevalence of actinic keratoses according to self-reported diagnoses was lower than expected based on prevalence data obtained by directly examining people. These discrepancies may be due to underreporting and/or unawareness of lesions by affected people. More precise estimates will be obtained by direct examination of sampled people.

Age Distribution↗
PubMed2003

Post-iontophoresis transport of ibuprofen lysine across rabbit ear skin.

The aim of this work was to study in vitro the post-iontophoresis transport of ibuprofen lysine across rabbit ear skin, from ibuprofen lysine water solutions (20-200 mg/ml and pH 6.8-7.8). Current densities of 0.125, 0.25, and 0.5 mA/cm(2) were applied either continuously or for 15, 30, and 60 min followed by passive diffusion for up to 5h. The results showed a significantly higher cathodal transport compared to passive flux. Anodal iontophoresis also increased ibuprofen permeation, even though the drug is negatively charged. The application of an electric current for a limited period of time, followed by passive diffusion from the reservoir in contact with the skin, produced much higher post-iontophoresis fluxes of ibuprofen than passive diffusion. Post-iontophoresis transport of ibuprofen from lysine salt solutions linearly depended on the total amount of current applied during iontophoresis, and in the absence of background ions was independent of donor drug concentration. The reason for this behavior was the creation of a drug reservoir in the skin owing to the short period of current application.

Animals↗
PubMed2003

Characterization of the permselective properties of rabbit skin during transdermal iontophoresis.

The use of iontophoresis to enhance transdermal transport of drugs necessitates further investigations on the membrane used to simulate human skin because one of the transport mechanisms involved, electroosmosis, strictly depends on the properties of the skin (i.e., its isoelectric point, IP). The aim of this work was to characterize rabbit ear skin permselectivity by measuring the sodium transport number at different pH values. This method allowed us to estimate the skin IP. To confirm the validity of the method, mannitol flux was measured. In addition, the sodium transport number method was applied to the study of human skin and a model drug iontophoretic flux through rabbit and human skin was evaluated. The results indicate that rabbit ear skin behaves as a permselective membrane, with an IP between 2 and 3. The same result was obtained using human skin. The mannitol flux data confirm that the direction of electroosmotic flow at physiological pH is in the anode-to-cathode direction. Finally, permeation experiments performed with a model drug showed that the relative electroosmotic and electrorepulsive contributions to the total flux are the same for human and rabbit skin. It can be concluded that rabbit ear skin is a suitable model for the study of iontophoretic permeation of drugs.

Administration, Cutaneous↗
PubMed2003

Identification of cross-reactive and genuine Parietaria judaica pollen allergens.

BACKGROUND: The weed Parietaria judaica is one of the most important pollen allergen sources in the Mediterranean area. OBJECTIVE: We sought to identify P judaica pollen allergen, which might be used to serologically distinguish genuine Parietaria sensitization and cross-reactivity to allergens from other weed species (eg, mugwort and ragweed). METHODS: The allergen profile of P judaica IgE-reactive sera from weed pollen-sensitized allergic individuals from the Mediterranean region (n = 36) with high Parietaria pollen exposure and from weed pollen-allergic patients with little or no Parietaria exposure (Austria, n = 42; Scandinavia, n = 8; United States, n = 19) was established by CAP FEIA measurements and by IgE immunoblot inhibition experiments with recombinant allergens. RESULTS: The majority (83%) of the Mediterranean weed pollen-allergic patients mounted high IgE antibody levels (mean specific IgE, 20.89 kUA/L) against recombinant (r) Par j 2, whereas only 7% of the non-Mediterranean weed-allergic patients showed low IgE reactivity to rPar j 2 (mean specific IgE, 1.03 kUA/L). The cytoskeletal protein profilin and a 2-EF-hand calcium-binding allergen were identified as cross-reactive Parietaria allergens, which were recognized preferentially by Parietaria -positive, non-Mediterranean weed pollen-allergic patients. CONCLUSION: rPar j 2 might be used as a diagnostic marker allergen to identify weed pollen-allergic patients who are genuinely sensitized against Parietaria pollen and thus would be particularly suited for specific immunotherapy with Parietaria pollen extract.

Allergens↗
PubMed2003

Skin permeation of 5-methoxypsoralen from topical dosage forms.

The topical photochemotherapy of dermatoses with psoralens (PUVA therapy) requires an adequate drug level at the target site (basal epidermis) at the time of UVA radiation. The aim of this work was to enhance 5-methoxypsoralen transport to the basal epidermis, with the goal to shorten the delay between drug application and UVA irradiation. 5-Methoxypsoralen transport through rabbit skin was studied in vitro from topical formulations (water solution, gel. and emulsion). The results obtained show that the use of the emulsion increased the flux through rabbit ear skin, even if partitioning was not favorable. Additionally, the time lag was sensibly reduced, compared with the gel and solution. Furthermore, drug accumulation in human skin in vitro was determined using the thin slicing technique. Human skin accumulation profile was significantly higher for the emulsion, compared with the gel, indicating that the delay between psoralen application and UVA irradiation can be shortened.

5-Methoxypsoralen↗
PubMed2003

The allergens of Parietaria.

Parietaria is a genus of dicotyledonous weeds of the Urticaceae family including several species and its pollen grain is one of the most important allergenic sources in the Mediterranean area. Species belonging to this genus induce IgE responses in approximately 10 million people. Identification of allergens by means of independent strategies suggest that the allergens of the two more common species, Parietaria judaica and Parietaria Officinalis, show molecular weights ranging between 10 and 14 kD and that the allergens of the two extracts are highly cross-reactive. Biochemical analysis and molecular cloning allowed the isolation and immunological characterization of the two major allergens of the P. judaica pollen, Par j 1 and Par j 2. Sequence comparison suggests that the P j major allergens of P. Judaica belong to the nonspecific lipid transfer protein family, and three-dimensional modeling by homology has revealed that both proteins present a very conserved structural motif composed of four alpha-helices. Immunological analysis has shown that Par j 1 and Par j 2 are able to bind most of the P. Judaica-specific IgE and some of their IgE determinants have been mapped. Recombinant Par j 1 and Par j 2 allergens have been shown to possess immunological properties equivalent to their natural counterpart and their availability represents a fundamental tool for the diagnosis and therapy of Parietaria pollen allergy.

Allergens↗
PubMed2003

The suitability of disintegrating force kinetics for studying the effect of manufacturing parameters on spironolactone tablet properties.

The aim of this paper was to study the effect of the granulate properties and tablet compression force on disintegrating force behavior in order to investigate the capability of the disintegrating force to characterize tablets that have the same composition but were manufactured in different conditions. Several tablets containing spironolactone in the external or internal granulated mixture of calcium carbonate and maize starch differing in particle size distribution, were prepared at 3 compression levels. The force developed by tablets during water uptake and disintegration was measured and plotted versus time. The curves obtained were analyzed by the Weibull equation in order to calculate the parameters characterizing the tablet disintegration kinetics. The disintegrating force time parameter, the maximum force developed, and the area under the curve were determined. In general, the reduction of time parameter value and/or the increase in maximum force developed corresponded to an acceleration in tablet disintegration. In addition, the area under the force curve increased in stronger tablets, monitoring in a sensitive way the tablet structural changes introduced by compression force. The results showed that the disintegrating force measurement can detect small changes in the structure of the tablet that cannot be discriminated by pharmacopoeia tests. The effect of manufacturing, in particular compression force, on tablet properties was quantified by the parameters of disintegrating force kinetics.

Chemistry, Pharmaceutical↗
PubMed2003

Assignment of disulphide bridges in Par j 2.0101, a major allergen of Parietaria judaica pollen.

Par j 2.0101, a major allergen of the Parietaria judaica pollen, was expressed in E. coli, purified to homogeneity and fully characterised both at the structural and the functional level. The recombinant rPar j 2.0101 protein showed an allergenic activity in histamine release, skin prick tests and capacity to bind IgE, almost identical to that of the native allergens purified from aqueous pollen extract. The complete pattern of S-S bridges of rPar j 2.0101 was determined by enzymatic digestion with endoproteinase Lys-C followed by mass spectrometric analysis of the resulting peptide mixtures. The eight cysteines occurring in the allergenic protein were found to be paired into the following four disulphides: Cys35-Cys83, Cys45-Cys60, Cys61-Cys106 and Cys81-Cys121. This structural information probes Par j 2.0101 to attain a 3-D fold consistent with that of the non-specific lipid transfer protein (ns-LTP) family and it represents an effective molecular basis to develop modified antigens by selective site-directed mutagenesis for immunotherapy.

Allergens↗
PubMed2003

Stress-induced injuries and trace element concentrations in vascular leaf plants from an urban environment (Palermo, Italy).

We examined leaf injuries and measured trace element concentrations in vascular plants from an urban ecosystem with distinct stress valences (the city of Palermo), and compared them with samples of the same species from sites where the stress potential is lower. Urban pollution influences macro-, micro- and toxic element concentrations in leaves. Therefore these leaves can be used as markers of the chemical and biological effects of atmospheric pollution. We studied the trace element content in the leaves of two species, oleander and oak, both fairly tolerant plants and good indicators and bio-monitors of pollution contaminants. Samples were collected at various sites in different periods.

Cities↗
PubMed2002

Distribution and quantification of polyethylenimine oligodeoxynucleotide complexes in human skin after iontophoretic delivery using confocal scanning laser microscopy.

Iontophoresis may be a potentially useful technique for the delivery of oligonucleotides into the skin. To enhance intracellular uptake during iontophoresis, we investigated the dermal delivery of oligodeoxynucleotides (ODN) as a polyelectrolyte complex with polyethylenimine (PEI). Perpendicular cross-sectioning was performed to visualize and quantify the penetration properties of double labeled PEI/ODN complexes across full thickness human skin. Due to the net positive charge of the complexes, anodal iontophoresis was expected to enhance skin delivery by electrorepulsion compared to passive diffusion. Confocal laser scanning microscopy demonstrated that non-complexed ODN could penetrate the skin after 1 h of cathodal iontophoresis but not by passive diffusion or anodal iontophoresis. However, extensive degradation occurred as documented by a dramatic decrease of fluorescence intensity within viable skin tissue after 10 h. Anodal iontophoresis of the complexes led to a deep penetration of both the TAMRA-labeled ODN and the Oregon Green-labeled PEI. A constant increase in fluorescence indicated a protective effect of the polymer against nuclease degradation. Co-localization of red and green fluorescence was noted within numerous nuclei of epidermal keratinocytes. In contrast, passive diffusion of the complexes did not lead to successful uptake into keratinocytes and was limited to the stratum corneum. Complexation of ODN by PEI, therefore, seems to be a promising method to enhance both the transport of charged complexes into the skin and to facilitate intracellular uptake, which may potentially be useful for the local treatment of skin diseases using ODN.

Drug Carriers↗
PubMed2002

Inertization of hazardous dredging spoils.

Vitrification and production of ceramics materials starting from sediment excavated from Venice lagoon is described. This sediment is classified as toxic waste because contains several heavy metal ions and organic pollutants and was successfully vitrified at 1200-1350 degrees C. Twenty weight percentage of glass cullet, coming from a community glass recycling program, was added to the raw materials, previously calcined at 900 degrees C, as a way of adjusting the variations of composition of the individual sediment batches. Chemical durability (leaching) tests showed that the optimized glass compositions are inert, and thus not only volume reduction but also inertization of the waste was obtained by this process. Moreover, the economics of the entire process was analysed. The valorization of the waste was accomplished by the subsequent processing of the glass derived from the inertization. Glass ceramic materials were produced by viscous phase sintering of pressed glass powders which crystallized during the densification process. Sintered glass ceramic products had good mechanical characteristics (HV = 7.5 GPa, bending strength 150 +/- 8 MPa), making them suitable for applications in the building industry.

Ceramics↗
PubMedDate not supplied

Folate-conjugated iron oxide nanoparticles for solid tumor targeting as potential specific magnetic hyperthermia mediators: synthesis, physicochemical characterization, and in vitro experiments.

New folate-conjugated superparamagnetic maghemite nanoparticles have been synthesized for the intracellular hyperthermia treatment of solid tumors. These ultradispersed nanosystems have been characterized for their physicochemical properties and tumor cell targeting ability, facilitated by surface modification with folic acid. Preliminary experiments of nanoparticles heating under the influence of an alternating magnetic field at 108 kHz have been also performed. The nanoparticle size, surface charge, and colloidal stability have been assessed in various conditions of ionic strength and pH. The ability of these folate "decorated" maghemite nanoparticles to recognize the folate receptor has been investigated both by surface plasmon resonance and in folate receptor expressing cell lines, using radiolabeled folic acid in competitive binding experiments. The specificity of nanoparticle cellular uptake has been further investigated by transmission electron microscopy after incubation of these nanoparticles in the presence of three cell lines with differing folate receptor expression levels. Qualitative and quantitative determinations of both folate nanoparticles and nontargeted control nanoparticles demonstrated a specific cell internalization of the folate superparamagnetic nanoparticles.

Cell Line, Tumor↗