Biomedical subjects

C Nastruzzi

Publications and source records attributed to C Nastruzzi.

At least 19 recordsLinked to original sources

PubMed2001

Delivery systems for DNA-binding drugs as gene expression modulators.

Despite the large number of publications describing the synthesis and physicocharacterization of the binding between drugs and DNA, relatively few examine drug delivery systems (DDSs) for these molecules. The aim to find DDSs for DNA-binding drugs (DBDs) was prompted mainly to reduce the toxicity and/or enhance the tumor specificity of systemically administered drugs. With this in mind, we have reviewed the biological effects of some DBDs that are currently used as antitumor drugs and describe a brief selection of DDSs currently in clinical trials or on the market.

Journal Article↗

PubMed2001

Acrylic microspheres for oral controlled release of the biguanide buformin.

Spherical microparticles based on methacrylic acid-methyl methacrylate copolymer have been developed. The method chosen for the preparation of such microparticles was suspension radical copolymerization of acrylic comonomers in the presence of the ethyleneglycol dimethacrylate as crosslinking agent. The microparticles obtained were characterised by inverse size exclusion chromatography, scanning electron microscopy, swelling degree and exchange capacity. The porous volume of the microspheres ranged from 0.086 ml/g for the microparticles produced by a methacrylic acid/methyl methacrylate ratio of 1/3 and a 10% degree of crosslinking, to 8.57 ml/g for the microparticles produced by a methacrylic acid/methyl methacrylate ratio of 3/1 and 2% degree of crosslinking (in 0.1 N NaCl in phosphate buffer pH 7.4). Also the pore diameter of the swollen microparticles ranged from a few to 120 A. Buformin tosylate - a classical hypoglycaemic drug - was included in the polymer network of the microparticles during the polymerization process. Due to the water solubility of the drug and its low solubility in the organic phase, the entrapment yield did not exceed 15%. However the amount of encapsulated drug as well as the drug released from the microparticles, was dependent on the methacrylic acid/methyl methacrylate ratio, the degree of crosslinking and solvent/comonomers ratio.

Administration, Oral↗

PubMed2001

Pectin-based microspheres: a preformulatory study.

This paper reports on (a) the production of pectin microspheres and (b) the influence of different experimental parameters and ionic crosslinking on morphological and dimensional characteristics of pectin microspheres. Morphological and dimensional characteristics of pectin were analyzed as a function of the type of pectin, the dispersing phase, the stirring speed, and the emulsifying agent. Crosslinking by calcium chloride and the encapsulation of antibiotics (i.e., metronidazol and tetracycline) gave particles morphologically similar to empty particles but with slower swelling kinetic.

Chemistry, Pharmaceutical↗

PubMed2000

Modulation of estrogen receptor gene transcription in breast cancer cells by liposome delivered decoy molecules.

It is well known that breast carcinomas without estrogen receptor (ER) have a poor prognosis and do not respond to antiestrogenic therapy. In analyzing the question of the lack of ER gene expression, we have considered the possibility to modify the ER gene expression by transfecting ER-negative breast cancer cells with a polymerase chain reaction product mimicking a putative negative regulatory region (--3258/--3157) inside the P3 ER gene promoter. Here we have demonstrated the efficacy of the selected sequence used as a decoy molecule in restoring the ER gene transcription. When this DNA was complexed and delivered by cationic liposomes (PC:DOTAP) a significant increase in the decoy effect was obtained. Breast cancer cells receiving the combination treatment responded substantially better to reactivation of quiescent ER gene than cells that had received DNA with calcium phosphate. This information may be useful for a series of in vitro transfections and also for in vivo application of the decoy strategy that is a potential therapeutic tool to control disease-related genes such as ER gene in breast cancer.

Blotting, Western↗

PubMed2000

Liposomes as carriers for DNA-PNA hybrids.

Peptide nucleic acids (PNAs) are DNA mimics composed of N-(2-aminoethyl)glycine units. This structure gives to PNAs (a) resistance to DNases and proteinases, (b) capacity to hybridize with high affinity to complementary sequences of single-stranded RNA and DNA, and (c) capacity to form highly stable (PNA)(2)-RNA triplexes with RNA targets. Furthermore, DNA-PNA hybrid molecules are capable to reversibly interact with DNA-binding proteins, being therefore of interest for studies on regulation of gene expression by the decoy approach. The major conclusion of this paper is that cationic liposomes are able to efficiently complexate DNA-PNA hybrid molecules and mediate their binding to target cells. Our results are of some interest, since, unlike commonly used nucleic acids analogs, PNA oligomers are not taken up spontaneously into the cells. In addition, they are not suitable for an efficient delivery with commonly used liposomal formulations. Transfection of PNA-DNA hybrid molecules to in vitro cultured cells could be of great interest to determine the applications of these new reagents to experimental alteration of gene expression.

DNA↗

PubMed2000

Rheologic and NMR characterization of monoglyceride-based formulations.

This paper describes the production and characterization of semi-solid formulations based on monoglycerides from canola oil and water as drug-delivery systems. In order to obtain new formulations with different characteristics in terms of viscosity, bioadhesiveness, and solubilization capacity, a third component was added to the monoglyceride-water system. Nine excipients were tested, namely soy oil, isopropylmyristate, isopropylpalmitate, tripalmitin, tristearin, glyceryl monostearate, glycerol, propylene glycol, and ethanol. In particular, the effect of each excipient on the viscosity and stability of the formulation was investigated. It was found that ethanol dramatically influenced the viscosity of the monoglyceride-water system, resulting in the formation of stable forms. In addition, ethanol suitably could be used for the solubilization of water-insoluble lipophilic drugs. This promising ternary system was characterized by microscopic, NMR spectroscopic, and rheologic techniques. (1)H and (13)C NMR studies were made of Myverol to verify the molecular structure and isomer distributions of this commercial monoacylglycerol mixture. The microstructure of an isotropic solution consisting of Myverol [1.8% (w/w)], ethanol (42.9%), and water (55.3%) was studied by the multi-component self-diffusion NMR method. From the self-diffusion coefficient (D) of the monoglycerides (8.8 x 10-11 m(2)/s), an "apparent spherical hydrodynamic radius" of ca. 2.48 nm was calculated for the micellar aggregate. A nearly spherical shape is consistent with these values since the extended hydrocarbon chain of the longest monoglyceride (17 carbons) is ca. 2.2 nm long. The D's of water and ethanol reveal they do not associate (no attractive nonbonding interactions) appreciably with the fatty acid micelles.

Biocompatible Materials↗

PubMed2000

In vitro antiproliferative activity of isothiocyanates and nitriles generated by myrosinase-mediated hydrolysis of glucosinolates from seeds of cruciferous vegetables.

A comparison of the effect of isothiocyanates and nitriles derived from some glucosinolates, namely, epi-progoitrin, sinalbin, glucotropaeolin, glucocheirolin, and glucoraphenin, on human erythroleukemic in vitro cultured cells was studied. Many studies have in fact evidenced that a consumption of vegetable containing glucosinolates could reduce the development of colorectal cancer. In the experimental conditions used, the production of isothiocyanates and nitriles from glucosinolates is almost quantitative as confirmed by HPLC or GC-MS analysis. The obtained results demonstrated that in general nitriles are considerably less potent than the corresponding isothiocyanates in inhibiting cancer cell growth. Particularly, the isothiocyanates inhibitory activity on K562 cells growth is higher in the case of products derived from epi-progoitrin, glucotropaeolin, glucoraphenin, and glucocheirolin; while for nitriles the higher activity in inhibiting K562 cells growth is showed by sinalbin-derived product. Considering the antiproliferative activity found for isothiocyanates and nitriles, further studies will be aimed to the possible application of glucosinolate-derived products as chemopreventive cancer agents for the reduction of colorectal cancer.

Brassicaceae↗

PubMed2000

Production of Eudragit microparticles by spray-drying technique: influence of experimental parameters on morphological and dimensional characteristics.

The aim of this study was to evaluate the influence of operating parameters on the characteristics of methacrylate microparticles prepared by spray-drying technique. Eudragit microparticles were prepared by a spray-drying method. The influence of different experimental parameters (i.e., solvent, feed rate, air flow rate, air-drying temperature, and aspiration flow rate) on microparticle morphology, size distribution, and recovery was studied. In addition, different Eudragit types and Eudragit RS concentrations were employed. Optical and electron microscopy were employed to analyze microparticle morphology and dimensional distribution. Finally, prednisolone as model drug was encapsulated in Eudragit RS microparticles. Low feed rate values yielded the best results in terms of microparticle morphology. Changes in nebulizing air flow did not result in a corresponding effect on microparticle characteristics. An increase of air-drying temperature resulted in a reduction of microparticle dimension and recovery. A low flow of drying air was preferable because this resulted in microparticles with an optimal morphology. The polymer concentration affected both morphology and dimensions of microparticles. The encapsulation of prednisolone led to good incorporation efficiencies without altering percentage of recovery, morphology, and mean dimension of the microparticles. The selection of appropriate parameters yielded spray-dried Eudragit RS microparticles characterized by good morphology and narrow dimensional distribution.

Acrylates↗

PubMed2000

Effect of DNA complexation and freeze-drying on the physicochemical characteristics of cationic liposomes.

We describe the use of saccharides, such as sorbitol, mannitol, sucrose, maltodextrin, and dextran, as cyoprotectants for freeze-drying cationic liposomes. Saccharides can protect liposomes either by interacting with phospholipid headgroups or by forming an amorphous glass surrounding the vesicles, thus preventing aggregation, mechanical rupture of membrane, fusion of liposomes, and drug leakage. We have particularly considered liposome characteristics, such as size, zeta potential, and ability in complexing DNA, before and after freeze-drying. Our study indicates that cationic liposomes are able to maintain liposome characteristics after lyophilization and rehydration and maintain the ability to complex DNA even if the strength of the interaction forces was of lower intensity with respect to liposomes before lyophilization.

Binding Sites↗

PubMed2000

Effects of anti-oxidizing vitamins on in vitro cultured porcine neonatal pancreatic islet cells.

Oxidative stress may cause severe cellular damage to both allo- and xeno-transplanted islets, additional to islet graft-directed immunity, in diabetic patients. We thus aimed to examine the effects of antioxidants on in vitro culture-maintained, neonatal porcine cell clusters (NPCCs). NPCCs were treated with antioxidants (vitamins D3 and E) by a certain time of their maturation and differentiation process. Insulin recovery showed that both vitamins D3 and E, unlike untreated controls, resulted in preservation of the islet function for significantly long periods of time. Such effects were also confirmed during NPCCs in vitro static incubation with high glucose. Furthermore, morphologic examination of NPCCs demonstrated that at 16 days of cell culture beta-cell clusters were significantly larger and more intact when exposed to the vitamins as compared to controls. According to these preliminary results, because the employed vitamins, known to retain anti-oxidizing properties, seemed to clearly improve NPCCs morphology and function, they may represent a potentially useful tool for islet culture maintenance in the pre-transplant time period.

Animals↗

PubMed1999

Preparation and characterization of cationic microspheres for gene delivery.

The production and characterization of cationic microparticles based on Eudragit RS and cationic agents (i.e. a cationic acrylic polymer and three different cationic surfactants) for the delivery of nucleic acids is here described. It was found that morphological and dimensional characteristics of microparticles were influenced by the type and concentration of cationic agent employed and by some experimental parameters such as stirring speed, emulsifying agent and type of rotor. The desoxiribonucleotide Defibrotide (DFT) was associated with positively charged microparticles and its in vitro release kinetics from microparticles were determined. A study of the in vitro toxicity of cationic microparticles on cultured human cell line K562 was also performed, demonstrating that DDAB(18) microparticles display very low cytotoxicity.

Acrylic Resins↗

PubMed1999

In vitro effect on human leukemic K562 cells of co-administration of liposome-associated retinoids and cytosine arabinoside (Ara-C).

The administration of retinoids has been demonstrated to be of potential utility in the therapy of a wide spectrum of neoplastic pathologies due to the ability to induce differentiation in a large variety of primary tumor cells as well as in vitro cultured cell lines. Moreover, a number of compounds, including hemin, cytosine arabinoside, and 5-azacytidine are able to induce erythroid differentiation of the erythroleukemic cell line K562. In this paper we determined whether a combined treatment of K562 cells with suboptimal concentrations of cytosine arabinoside and retinoids containing liposomes lead to a full expression of differentiated functions. Liposomes were prepared by reverse phase evaporation technique followed by extrusion through polycarbonate filters. Cell growth kinetics studies and intracellular detection of hemoglobin by benzidine staining were performed. The results obtained showed that the combined treatment with liposomes containing retinoids and sub-optimal concentration of ara-C is an effective strategy to induce K562 cell differentiation, minimizing at the same time toxic effects. Control experiments aimed to determine possible selection of subpopulations of K562 cells suggest that the observed results are not related to toxicity and/or potential selection of induced cells. In conclusion, liposomally delivered retinoids could be proposed for differentiation therapy as an effective strategy in the treatment and management of malignancy. In addition, the finding that liposomally delivered retinoids increase the capacity of cytosine arabinoside to induce erythroid differentiation, could be of interest in studies aimed at the development of treatment able to reactivate fetal globin genes in beta-thalassemia patients.

Cell Differentiation↗

PubMed1999

Physico-chemical characterization of Ca-alginate microparticles produced with different methods.

In the present paper the physico-chemical characterization of Ca-alginate microparticles produced with different methods is presented. Ca-alginate microparticles were obtained either by emulsification method or by dripping an aqueous alginate solution into a solution of calcium salt. Inverse Size Exclusion Chromatography (ISEC) was used for the determination of dimensions of the pores and porous volume of microparticles having a mean diameter of 220 microm when obtained by emulsification method. The same technique was used to study the variation of the pore size and porous volume with pH. The results were related with the content of calcium and sodium in the microparticles, before and after their treatment with different HCl solutions. For the particles with a mean diameter of 1.2 mm (obtained by dripping method) we adopted an other approach based on the steric exclusion of solute at equilibrium. For a convenient interpretation of the obtained data, determination of water regain, swelling degree, and scanning electron microscopy (SEM) were performed. Finally, a comparison of the characteristics of microparticles produced by ionic and epichlorohydrin crosslinkings was made. The maximum dimensions of the pores of the microparticles obtained by emulsification were found smaller than those obtained by other technics. The variation of the dimensions of the pores and porous volume with pH is not significant. The structure of the chemically crosslinked beads with epichlorohydrin is more elastic and the swelling is reversible; after drying and reswelling process, the dimensions of the pores and porous volume of these microparticles remain unchanged. On the opposite, for the microparticles obtained by emulsification or dripping method in the presence of calcium ions, these characteristics are changed after a first drying process.

Alginates↗

PubMed1999

Dextran cross-linked gelatin microspheres as a drug delivery system.

This paper describes the use of oxidized dextran as a cross-linker for the preparation of gelatin microspheres. Microspheres were obtained by a thermal gelation method and their dissolution kinetic was examined. In order to find evidence of sugar mediated cross-linking, swelling tests and gelatin microspheres dissolution experiments were performed. The obtained results indicated that oxidized dextran can form a cross-linked gelatin network which can reduce the dissolution of gelatin. More interestingly, gelatin microspheres treated by both native and oxidized dextran slow down, even if to a different extent, the release of the antitumor drug TAPP-Br used as a model compound. Taken together, our results suggest that oxidized dextran could be an interesting means to cross-link gelatin microspheres allowing the use of this delivery formulation for controlled release of drugs.

Dextrans↗

PubMed1999

Liposomes, micelles and microemulsions as new delivery systems for cytotoxic alkaloids.

This review describes the design and performance of specialized delivery systems, such as liposomes, micellar solutions and microemulsions, for the administration of cytotoxic alkaloids. Special attention is directed towards three types of compound, Vinca, Camptotheca and Taxus alkaloids, which have been previously indicated as of promise as antitumour agents but which still present serious drawbacks. In this respect, this review analyses different delivery strategies that are able to substantially improve the therapeutic applicability of such antitumour drugs.

Journal Article↗

PubMed1998

In vitro stability of polymerase chain reaction-generated DNA fragments in serum and cell extracts.

The potential use of polymerase chain reaction (PCR)-generated DNA fragments (PCR-DNAs) as pharmaceutical agents has previously been suggested, with the demonstration of the in vitro cellular internalization and biologic activity of PCR-DNA decoy molecules targeted to human estrogen receptor gene. In order to provide information on the stability of these double-stranded DNA molecules, the nuclease resistance of PCR-DNAs of different sizes was studied in different conditions and experiments. Simulating in vitro and in vivo transfection protocol, we demonstrated that PCR-DNAs exhibited good stability toward fetal bovine serum (FBS) and adult human serum nuclease digestion. In addition, when the protective activity of liposome-based formulations toward nuclease digestion was tested, it was shown that the stability of PCR-DNAs could be further increased (up to 7 days) when a liposome-mediated delivery system was employed.

Adult↗

PubMed1998

Sugar cross-linked gelatin for controlled release: microspheres and disks.

The aim of the present paper was to find a 'biocompatible' means to cross-link gelatin-based pharmaceutical devices. In particular, we have studied the ability of native and oxidized mono- and di-saccharides to induce the cross-linking of gelatin. To this end, gelatin discs and gelatin microspheres were produced and their dissolution kinetics at 37 degrees C were examined. In order to find evidence of sugar-mediated cross-linking, DSC and FTIR experiments were performed. The obtained results indicated that both native and oxidized sugars resulted to different extents, in the formation of a cross-linked gelatin network able to reduce the dissolution of gelatin. These results suggest that oxidized mono- and disaccharides could be an interesting method by which to cross-link gelatin thereby reducing the risk of toxic side effects arising from the use of synthetic cross-linkers.

Biocompatible Materials↗

PubMed1998

Cross-enzyme inhibition by gabexate mesylate: formulation and reactivity study.

Gabexate mesylate (GM; commercialized under the brand name FOY) is a nonantigenic synthetic inhibitor of plasmatic and pancreatic serine proteinases that is used therapeutically in the treatment of pancreatitis and disseminated intravascular coagulation and as a regional anticoagulant for hemodialysis. The inhibitory effect of GM on nitric oxide synthase as well as serine proteinases and swine kidney copper amine oxidase, all acting on cationic substrates, has been investigated. On the basis of the available X-ray crystal structures of the enzymes considered, the possible binding mode(s) of GM has(have) been analyzed. The enzyme cross-inhibition by GM suggests that the use of this drug should be under careful control. With the aim to improve the scarce plasma stability of GM, the positively charged drug has been complexed to the surface of preformed anionic liposomes. The liposome-complexed GM half-life increases about five-fold, indicating the protective effect of liposomes on GM degradation. Moreover, the GM complexation with liposomes does not alter its inhibitory activity on NOS-I and porcine pancreatic trypsin.

Drug Carriers↗