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Biomedical subjects

M C Tanzi

Publications and source records attributed to M C Tanzi.

10 recordsLinked to original sources
PubMed1992

Grafting reactions and heparin adsorption of poly(amidoamine)-grafted poly(urethane amide)s.

Differently terminated poly(amidoamine) (PAA) oligomers were grafted on the surface of poly(ether urethane amide)s (PEUAm), with fumaric or maleic acid moieties. The grafting reaction was Michael-type addition of amino groups to activated double bonds in the PEUAm backbone. PAAs having primary amino, or secondary amino end-groups were directly grafted on the surface of PEUAm sheets. For vinyl-terminated chains an alpha, omega amino-polyether spacer was introduced initially, following the same addition mechanism. Ungrafted and grafted materials were characterized, besides other analytical techniques, by ATR FT-IR spectroscopy. The heparin adsorption on PEAUm films was analysed after its elution from heparinized samples, quantified by coagulation tests (aPTT), and related to the presence of the PAAs chains grafted on to the surface. Results indicate that PAA-grafted PEUAm elastomeric biomaterials, display enhanced heparin adsorption abilities.

Adsorption↗
PubMed1992

Genotoxicity of N-acryloyl-N'-phenylpiperazine, a redox activator for acrylic resin polymerization.

N-Acryloyl-N'-phenylpiperazine is a promoter of redox reactions synthesized recently, and proposed as an activator for the polymerization of acrylic resins for biomedical use. The chemical was analyzed for different genotoxicity endpoints, to obtain both information on its possible mutagenic/carcinogenic potential and a model analysis of a tertiary arylamine, which belongs to a class of chemicals commonly used as polymerization accelerators in the biomaterial field. The genotoxicity endpoints considered were: gene mutation in the Salmonella test; structural and numerical chromosome alterations in Chinese hamster V79 cells, evaluated by the micronucleus test together with an immunofluorescent staining specific for kinetochore proteins; in vitro and in vivo DNA damage, evaluated in V79 cells and in mouse liver by the alkaline DNA elution technique. On the whole, the results indicate that N-acryloyl-N'-phenylpiperazine is to be regarded not so much as a DNA-damaging agent, but as a genomic mutagen. Indeed, it was not mutagenic in Salmonella (though its toxicity did not allow testing concentrations over 70 micrograms/plate), and it was weakly positive in inducing chromosomal fragmentation in vitro (one positive, not dose-related, result out of five different doses tested) and in vivo DNA damage (increases in DNA elution rate never doubling control values). The chemical was, however, clearly positive (with dose-dependent effects up to about 25 times the control value) in causing numerical chromosome alterations, at the maximal non-toxic doses.

Acrylic Resins↗
PubMed1989

Heparinizable segmented polyurethanes containing poly-amidoamine blocks.

A poly-ether-urea-urethane was synthesized by copolymerization of 4,4'-diphenylmethanediisocyanate (MDI), propanediamine, and poly-oxytetra-methylene glycol (M.W. 1000). Two other corresponding copolymers were also synthesized by adding amino terminated poly-amidoamine macromonomers, purposely synthesized, so as to insert relatively small amounts (6 and 15 weight %) of two types of poly-amidoamine segments in the final product. Of the three copolymers several physicochemical and mechanical properties have been determined, and their heparin adsorption ability, blood compatibility, and cytotoxicity evaluated.

Adsorption↗
PubMed1986

New polymeric and oligomeric matrices as drug carriers.

The preparation of polymeric derivatives of drugs, in which drug moieties are covalently linked to polymeric or oligomeric matrices, in such a way that they can be released at the site of action, is one of the most promising ways to achieve results which often can be hardly obtained by other means, such as, for instance, better adsorption by some ways of administration (e.g., oral administration), preferential localization in the body, and longer duration of activity. The aim of this review is to provide an up-to-date picture of the state of art in this field. The synthetic aspects of the preparation of polymeric derivatives of drugs will be discussed, with special emphasis on general methods. The main criteria for selecting a particular type of matrix, and a particular bond between drug and matrix, in order to achieve a given purpose, will be also discussed. The main pharmacological results so far obtained by this technique will be emphasized.

Capsules↗
PubMed1985

Heparinizable graft copolymers from chlorosulphonated polyethylene with poly(amido-amine) segments.

The synthesis and the physical characterization of three graft copolymers (PES/PAA) obtained from chlorosulphonated polyethylene (PECS) and three different secondary amino end-capped poly(amido-amine)s are reported. The properties of these heparinizable materials appear to be suitable for constructing prosthetic devices for biomedical use. The heparin adsorbing ability and the stability of the complex with heparin of the three copolymers have been evaluated, by means of biological tests, as activated Partial Thromboplastin Time (PTT) and Thrombin Time (TT).

Adsorption↗
PubMed1985

Polyacrylonitrile membranes in hemodialysis: blood-surface interactions.

Investigations of blood-surface interaction phenomena with polyacrylonitrile-based membrane (AN-69) during hemodialysis are reported. The amount and surface distribution of adhering white blood cells (WBC), and adsorbed proteins (Pt) have been evaluated by image analysis of WBC, spectrophotometry and SDS-polyacrylamide gel electrophoresis of desorbed proteins. The protein contents of the patient's serum have been also investigated by SDS-electrophoresis. Results indicate that the distribution of both WBC, and Pt is non-uniform, and higher (71%, and 79% of the total detected amount, respectively) in the half membrane near the blood inlet (PAN-IN); PAN-IN and PAN-OUT eluates show the same protein bands by electrophoresis. The concentration of the proteins stably adsorbed on the membranes appears not to be related to their concentration in the patient's serum. A relatively strong band at MW = 14,400 in PAN eluates could be interpreted as the presence of lysozyme bound to the AN-69 membranes.

Acrylic Resins↗
PubMed1984

Fractionation techniques in a hydro-organic environment. II. Acryloyl-morpholine polymers as a matrix for electrophoresis in hydro-organic solvents.

The properties of gels prepared either from acryloyl-morpholine (ACM) or from its mixtures with acrylamide and crosslinked either with bisacrylylpiperazine or with methylenebisacrylamide have been described. ACM-containing gels are compatible with organic solvents. If polymerized in water and dried, they are able to reswell, e.g., in dimethyl sulfoxide or dimethylformamide. If polymerized in presence of dimethylformamide, they form perfectly clear gels, whose mechanical properties are by far superior than those of similar plain polyacrylamide formulations.

Acrylic Resins↗
PubMed1984

Synthesis and characterization of poly(amido-amine)s belonging to two different homologous series.

Systematic work on the synthesis and characterization of two series (referred to as type A and B) of poly(amido-amine)s with tertiary amino-groups in the main chain is reported. The polymers were synthesized by polyaddition of alpha, omega-bis-(methyl-amino) alkanes with 1,4-bis-acryloylpiperazine (type A) and 1,12-bis-acryloyl-n-diaminododecane (type B). These materials, which will be employed in the preparation of block and graft copolymers for biomedical use, have been characterized by means of various techniques and the most interesting features are reported.

Adsorption↗
PubMed1983

Heparin adsorbing capacities at physiological pH of three poly(amido-amine) resins, and of poly(amido-amine)-surface-grafted glass microspheres.

Three poly(amido-amine)s of similar structure in the form of highly hydrophilic crosslinked resins, have been prepared, and tested for their heparin-adsorbing capacity at physiological pH. They showed different capacities, and their capacities were related to their basicities. One of the same polymers was grafted on the surface of glass microspheres. After treatment, it was shown that the microspheres could adsorb significant amounts of heparin. In all cases most of the adsorbed heparin was hardly eluted with saline, plasma, or blood, but could be recovered by eluting with 0.1 M NaOH. The resins were found to have some haemolytic properties, but no haemolysis was observed with the grafted microspheres.

Adsorption↗