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Biomedical subjects

Jirí Lenfeld

Publications and source records attributed to Jirí Lenfeld.

4 recordsLinked to original sources

Immunoaffinity reactors for prion protein qualitative analysis.

The cellular prion protein (PrPc) represents the substrate for generation of conformational aberrant PrP isoforms which occur in human and animal prion diseases. The published two-dimensional maps of human PrPc show a vast microheterogeneity of this glycoprotein. The main goal of this project was to develop a highly specific immunoaffinity reactor for qualitative analysis of PrP cellular isoforms isolated from brain homogenate, cerebrospinal fluid and other tissues. New techniques for affinity proteomics, carriers and immobilization chemistry were applied. The choice of matrix (chemical and magnetic properties, particle size and distribution, porosity) was the key factor that influenced the quality of the reactor and the nature of final applications. Mouse anti-prion IgGs directed to N-terminal and C-terminal epitopes (residues 23-40 and 147-165) were grafted in different manners to magnetic micro- and nanoparticles particularly developed for micro-CHIP application. High operational and storage stability of affinity reactors with minimized nonspecific absorption were achieved. The quality of the immunoreactors was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblotting and by two-dimensional electrophoresis.

Animals↗

Immunomagnetic separation and detection of Salmonella cells using newly designed carriers.

Magnetic nonporous poly(HEMA-co-EDMA) and poly(HEMA-co-GMA) microspheres were prepared by dispersion copolymerisation of 2-hydroxyethyl methacrylate (HEMA) and ethylene dimethacrylate (EDMA) or glycidyl methacrylate (GMA) in the presence of magnetite. They were functionalized by polyclonal Salmonella antibodies via the trichlorotriazine method. Salmonella cells were then successfully identified using cultural and polymerase chain reaction (PCR) methods after their immunomagnetic separation. The PCR sensitivity of target cell detection was negatively influenced by the presence of some compounds used in the process of particle preparation. In some cases, magnetic poly(HEMA-co-EDMA) microspheres with immobilized proteinase K were used for degradation of intracellular inhibitors present in Salmonella cells.

Electrophoresis, Agar Gel↗

Characterization of deoxyribonuclease I immobilized on magnetic hydrophilic polymer particles.

Magnetic bead cellulose particles and magnetic poly(HEMA-co-EDMA) microspheres with immobilized DNase I were used for degradation of chromosomal and plasmid DNAs. Magnetic bead particles were prepared from viscose and magnetite powder. Magnetic poly(HEMA-co-EDMA) microspheres were prepared by dispersion copolymerization of 2-hydroxyethyl methacrylate and ethylene dimethacrylate in the presence of magnetite. Divalent cations (Mg(2+), Ca(2+), Mn(2+) and Co(2+)) were used for the activation of DNase I. A comparison of free and immobilized enzyme (magnetic bead particles) activities was carried out in dependence on pH and activating cation. The maximum of the activity of immobilized DNase I was shifted to lower pH compared with free DNase I. DNase I immobilized on magnetic bead cellulose was used 20 times in the degradation of chromosomal DNA. Its residual activity was influenced by the nature of activating divalent cation. The immobilized enzyme with decreased activity was reactivated by Co(2+) ions.

Cations, Divalent↗

Oriented immobilization of galactose oxidase to bead and magnetic bead cellulose and poly(HEMA-co-EDMA) and magnetic poly(HEMA-co-EDMA) microspheres.

In order to obtain an active and stable oxidation reactor for daily use in biochemical laboratory we decided to immobilize galactose oxidase orientedly through a carbohydrate chain to the magnetic carriers. We used hydrazide derivatives of non-magnetic and magnetic bead cellulose and of magnetic and non-magnetic poly(HEMA-co-EDMA) microspheres. Activation of the enzyme molecules was done by sodium periodate in the presence of supplements (fucose, CuSO4, catalase). Orientedly immobilized galactose oxidase presents high storage stability and lower susceptibility to inappropriate microenvironmental conditions. Reactor reactivated by three pulses of D-galactose retained practically 100% of its native activity after 6 months. The positive properties of both magnetic carriers were entirely confirmed.

Animals↗