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Biomedical subjects

C Nastruzzi

Publications and source records attributed to C Nastruzzi.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1998

Human leukemic K562 cells treated with cytosine arabinoside: enhancement of erythroid differentiation by retinoic acid and retinol.

Human leukemia K562 cells can be induced to erythroid differentiation when treated with a variety of compounds, including hemin, cytosine arabinoside and 5-azacytidine. Following erythroid induction, K562 cells express at high level gamma-globin and accumulate both Hb Portland and Hb Gower 1. In this paper we determined whether a combination treatment of K562 cells with suboptimal concentrations of cytosine arabinoside and retinoids lead to full expression of differentiated functions. Cell growth kinetics studies, intracellular detection of hemoglobin by benzidine staining and hemoglobin analysis by cellulose acetate were performed. The results obtained show that (a) retinoic acid and retinol are not able to induce differentiation of K562 cells and (b) cytosine arabinoside induces differentiation only when used at 100-300 nmol/l concentrations. In addition, our data demonstrate that erythroid differentiation of K562 occurs when 40 micromol/l of retinoic acid or retinol are added together with 75 nmol/l cytosine arabinoside.

Antimetabolites, Antineoplastic↗
PubMed1997

Myrosinase-generated isothiocyanate from glucosinolates: isolation, characterization and in vitro antiproliferative studies.

Epidemiological and pharmacological studies have shown that colorectal cancer development could be reduced by consuming vegetables that contain glucosinolates. In view of this the effect of some glucosinolates and their isothiocyanate (ITC)-derived products on in vitro cell growth was studied. We report the isolation and characterization of ITCs derived from glucosinolates by using HPLC, GC-MS, and NMR techniques. The in vitro activity of ITCs on human erythroleukemic K562 cells has been investigated by using two alternative approaches: the in situ and pre-mix methods. No differences in antiproliferative activity were found comparing the effect of ITCs produced either of these methods. In the experimental conditions used, the production of ITCs from glucosinolates is almost quantitative as confirmed by HPLC or GC-MS analysis. The ITCs' inhibitory activity on K562 cells growth is particularly evident in the cases of ITCs derived from sinigrin, progoitrin, epi-progoitrin, glucotropaeolin and glucocheirolin. Finally, the antiproliferative activity of the ITCs obtained from glucoraphenin, taken as an example, was determined on other tumor cell lines with a different origin and hystotype. Considering the antiproliferative activity found for ITCs these compounds could be considered potentially responsible for the reduction of colorectal cancer associated with diets rich in cruciferous vegetables. Further studies will be aimed at the possible application of glucosinolate-derived products as chemopreventive cancer agents.

Cell Division↗
PubMed1996

Gelatin microspheres: influence of preparation parameters and thermal treatment on chemico-physical and biopharmaceutical properties.

The aim of this paper was to investigate the influence of preparation parameters on gelatin microspheres production, chemico-physical characteristics and drug encapsulation. In particular, we focussed our attention on the manufacturing parameters such as amount of polymer, stirring speed, presence and concentration of surfactants. As model drugs, TAPP-Br, clonidine hydrochloride and bromocriptine mesylate were chosen in order to compare their encapsulation and release characteristics with microspheres. In the second part of this work, a study of the influence of thermal treatment on the microspheres is reported, performed with the aim to possibly modify gelatin dissolution and drug release. In particular, the effect of this treatment was evaluated on microsphere characteristics such as swelling, porosity and dissolution, and finally on the release profiles of the encapsulated drugs.

Adrenergic alpha-Agonists↗
PubMed1996

Experimental study on protein transmission through the human muscle fascia: preliminary results and application theory in lymphedema.

The presence of proteins (albumin and globulins) in lymphedematous tissue not only gives rise to colloidosmotic pressure but also produces an electrostatic charge endowing the proteins with individual features and different migration rates. The working hypothesis of the experimental study is to transfer lymph proteins from the upper fascia accumulation area to a subfascial drainage area by subjecting them to an adequate difference in potential. A double chamber, variable volume system with separation wall able to contain a 1 cm square of muscle fascia, was designed and built; the aim of the apparatus was to reproduce the subcutaneus zone separated by the fascia interposition, from the muscle-vascular zone. At the system was applied a variable electric field in six different experiments: 4 using porous synthetic membranes and 2 using human muscle fascia.

Biological Transport↗
PubMed1994

Macrophages loaded with doxorubicin by ATP-mediated permeabilization: potential carriers for antitumor therapy.

In many cell types extracellular ATP (ATPe) has been shown to cause reversible plasma membrane permeabilization to low molecular weight (< 900 Da) water-soluble compounds. In the present report we have exploited this technique to incorporate the anticancer drug doxorubicin (DXR), molecular mass 543 Da, into the cytoplasm of two mouse cell lines that had previously been shown to express the ATPe-gated pore, J774 macrophages and tumor necrosis factor (TNF)-resistant L929 fibroblasts. Compared to passively loaded cells, ATPe-mediated reversible permeabilization allowed an at least 4-fold increase in DXR intracellular trapping (0.5 pg/cell versus 2 pg/cell). Analysis of the release kinetics at 37 degrees C showed that about 40% of total intracellular DXR was discharged during the first hour from both ATPe-permeabilized and passively loaded cells; about 15% further release was observed upon incubation up to 4 h. DXR release profiles were similar in ATPe-permeabilized and passively loaded cells. ATPe-permeabilized, DXR-loaded (ATPe-DXR) cells strongly inhibited the proliferation of K562 tumor cells. Taken together these results indicate that ATPe-mediated reversible plasma membrane permeabilization can be effectively used to load cells of different histotypes with high concentrations of DXR. This approach could permit to vehicle high doses of anticancer agents by using living cells while reducing systemic toxic effects.

Adenosine Triphosphate↗
PubMed1994

Differential inhibition of DNA/protein interactions by aromatic amidines with 2, 3 and 4 benzamidine residues.

We have recently reported that aromatic polyamidines are powerful inhibitors of in vitro proliferation of tumour cell lines and in vivo tumorigenicity of melanoma cells xenografted into nude mice. Interestingly, we have found that tetrabenzamidines are able to bind DNA, and to inhibit the interaction between transacting factors and specific target DNA sequences. In order to obtain more detailed information on structure-activity relationships, we have analysed the effects of different aromatic polyamidines on the binding of a recombinant protein, the Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1), to the target sequence of EBV DNA, containing the 12 bp palindromic consensus TAGCATATGCTA. The results obtained suggest that aromatic polyamidines inhibit the interactions between DNA-binding proteins and target DNA sequences with different efficiency, depending (i) on the number of amidine residues and (ii) on the presence of halogen substitutions (Cl, Br or I) on the benzene rings of tetra-benzamidine molecules.

Amidines↗
PubMed1992

DNA binding activity and inhibition of DNA-protein interactions. Differential effects of tetra-p-amidino-phenoxyneopentane and its 2'-bromo derivative.

In the present study are reported the differential DNA binding activity of the anti-tumor polyamidine tetra-p-amidinophenoxyneopentane (TAPP-H) and its 2'-halo derivative (TAPP-Br), and their effects on the binding of the recombinant Epstein-Barr virus (EBV) nuclear antigen to a synthetic oligonucleotide mimicking the target DNA sequence present in the EBV genome. In addition, the proliferation kinetics and cell cycle analysis of human leukemia K562 cells treated with TAPP-H and TAPP-Br are reported. The possible in vivo relationship between DNA binding affinity and cytotoxicity is also discussed.

Antigens, Viral↗
PubMed1992

New isoxazole derivatives of retinoids: synthesis and activity on growth and differentiation of tumor cells.

The effects of several newly synthesized isoxazole analogues of retinoids on differentiation and proliferation of 'in vitro' cultured tumor cell lines are reported. Some of the tested compounds exhibit significative differentiating action, inducing adipogenic conversion of the Chinese hamster FH06T1-1 cell line in a range of 2-10 times the activity of retinoic acid and retinol. In addition, most of the compound tested display antiproliferative activity comparable to that of natural retinoids. The reported data could be of interest for experimental anticancer therapy.

Adipose Tissue↗
PubMed1991

Transgenic mice mimic the methylation pattern of the human HLA-DR alpha gene.

The methylation pattern of the human HLA-DR alpha gene has been studied in different tissues of transgenic mice. Offspring from two transgenic lines was selected for this analysis, carrying the integrated HLA-DR alpha gene in either single or multiple (8-10) copies per diploid genome. In transgenic animals two distinct methylation patterns of the HLA-DR alpha gene are generated, due to a complete methylation of all the GCGC and CCGG sites the former, and to unmethylation restricted to one or both the GCGC sites located in the 5' portion of the HLA-DR alpha gene, the latter. Unmethylation restricted to the 5' portion of the HLA-DR alpha gene is a highly conserved feature in human tissues and in vitro cultured cell lines; therefore, it is concluded that the methylation pattern of the human HLA-DR alpha transgene may be faithfully reconstituted in transgenic animals. Northern blotting analysis of the RNA isolated from tissues of the transgenic mouse carrying single-copy HLA-DR alpha transgene demonstrates its tissue specific expression, suggesting that transgenic mice may represent an "in vivo" experimental system to study the relationship between methylation state and transcriptional activation.

Animals↗