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M Jozefowicz

Publications and source records attributed to M Jozefowicz.

52 records · Page 3Linked to original sources
PubMed1984

Preparation of an asymmetric semipermeable membrane with anticoagulant activity.

In this paper we report the preparation of a new asymmetric semipermeable styrene-isoprene-styrene block-copolymer membrane. Its modification by addition of gaseous N-chlorosulphonylisocyanate alters neither its permselectivity nor its water permeability rate. This modified membrane possesses an antithrombic activity which depends on antithrombin III. The actual active surface in contact with proteins is very large because the whole macroporous underlayer is modified and accessible to the proteins.

Biocompatible Materials↗
PubMed1984

Interactions of human platelets with insoluble anticoagulant modified polystyrene resins.

The interactions of two insoluble anticoagulant polystyrene derivatives with human platelets were studied in an in vitro system similar to a chromatography column. Blood was pumped through the column and platelets were counted before and after passage through the column. Interaction of platelets with the beads led to retention of platelets in the column. The same experiment was performed with several donors. Different pretreatments were assayed and compared for both materials: platelet poor plasma, antithrombin III-depleted platelet poor plasma and an antithrombin III solution. Platelet retention depends on the polymer composition: the material containing glutamic acid sulphamide groups, which has a larger anticoagulant activity in plasma than the materials only substituted by sulphonate groups, is always less reactive towards platelets. The differences in the effects of pretreatment on both materials can be correlated with the variations of antithrombin adsorption on the synthetic surfaces.

Anticoagulants↗
PubMed1983

Affinity of purified thrombin or antithrombin III for two insoluble anticoagulant polystyrene derivatives: I. In vitro adsorption studies.

In previous papers, we described insoluble polystyrene derivatives which exhibit a heparin-like antithrombic activity in plasma. In order to ascertain the heparin-like mechanism of this activity we have studied the interactions of thrombin and antithrombin III with two polymers of this series: sulphonated polystyrene and sulphonate-glutamic acid sulphonamide polystyrene. The adsorption was measured using purified enzyme and enzyme inhibitor and polymer beads whose average diameter was about 25 micron. The maxima of adsorption approximately correspond to a monolayer of protein. The results are discussed with respect to the most common isotherms used in chemisorption and the affinities of the enzyme and its inhibitor for both materials are evaluated: kT congruent to 10(7) (M/I)-1, kAT congruent to 3.10(5) (M/I)-1.

Adsorption↗
PubMed1983

Anticoagulant activity of amino acid modified polystyrene resins: influence of the carboxylic acid function.

In previous papers, we have described the preparation and heparin-like properties of insoluble modified polystyrene resins. We now report results obtained with amino acid sulphamide resins that are virtually devoid of sulphonate groups and with resins bearing both sulphonate groups as well as amino acid sulphamides with spacers of various lengths. The absence of sulphonate groups does not affect the anticoagulant activity of the former type of resin. The biologic activity of the latter type of resin is dependent upon the length of the spacer between the amino and carboxylic acid functions. Maximal anticoagulant potency is attained with a spacer consisting of three methylene groups. Biologic activity is reduced with spacers that are less than or greater than this critical size.

Anticoagulants↗
PubMed1982

Interactions of anticoagulant insoluble modified polystyrene resins with plasmatic proteins.

In previous papers, we have described the preparation and heparin-like properties of insoluble modified polystyrene resins. We now report results about the interactions of several coagulation factors with some of these materials. Most of the non-activated factors are neither adsorbed nor modified, except factor V and prekallikrein. In contrast thrombin, antithrombin III and factor Xa adsorb on the surface of such insoluble polymers. Thrombin can be desorbed by addition of a polycationic compound. The inactivation of thrombin or factor Xa by antithrombin is catalysed by the presence in the mixture of these insoluble materials as it is with soluble heparin. The initial velocity of these reactions is second order for both types of catalysis-homogeneous or heterogeneous - as previously reported for soluble heparin. In the case of these insoluble materials, the inhibition of protease by antiprotease seems to be accelerated when complexes are formed between the polymer and the proteins.

Adsorption↗
PubMed1979

Interactions between human plasma proteins and heparin-poly(methyl methacrylate) copolymer.

A solid Heparin-PMMA copolymer has been synthetized by a radical polymerization of methyl methacrylate from oxidative reaction initiated by Ce4+ ions in the presence of heparin. Covalently linked heparin was 10% of copolymer weight. The antithrombin activity of the copolymer corresponded to 1% of grafted heparin. PMMA sequence of the copolymer played the leading role in fibrinogen, immunoglobulins, transferrin and albumin adsorption. These proteins adsorbed on the copolymer, showed different competitive desorption pattern in the presence of whole plasma: fibrinogen presented the highest degree of affinity for the copolymer. The heparin part of the copolymer was responsible for antithrombin III adsorption and for decrease of factor V activity. Active antithrombin III was eluted. An inactivation of factor V in plasma was observed using high concentrations of soluble heparin. This result suggested that copolymer heparin chains, even devoid of antithrombin activity were involved in this inactivation. With Heparin-PMMA copolymer, plasma clotting pro-enzymes behaved differently than on heparin-sepharose copolymer:disappearance of factor XI activity, decrease in prekallikrein activity and activation of factor IX were observed. PMMA sequences were responsible for factor IX activation.

Adsorption↗
PubMed1977

Properties of heparin--poly(methyl methacrylate) copolymers. II.

A heparin--poly(methyl methacrylate) copolymer in which heparin has been covalently bound was studied. This copolymer showed no release of heparin but presented heparin-like anticoagulant activity when suspended in plasma. After contact with plasma, the copolymer lost part of its antithrombin activity which could be restored by a high ionic-strength medium. Because of its solid form, this copolymer offers new possibilities for producing interesting anticoagulant surfaces.

Anticoagulants↗