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Biomedical subjects

K H Kroner

Publications and source records attributed to K H Kroner.

7 recordsLinked to original sources
PubMed1999

Controlled shear filtration: A novel technique for animal cell separation.

A novel rotary microfiltration technique specifically suited for the separation of animal cells has been developed. The concept allows the independent adjustment of wall shear stress, transmembrane pressure, and residence time, allowing straightforward optimization of the microfiltration process. By using a smooth, conically shaped rotor, it is possible to establish a controlled shear field in which animal cells experience a significant hydrodynamic lift away from the membrane surface. It is shown in preliminary experiments that shear-induced cell-rupture speeds up membrane clogging and that cell debris poses the most significant problem in harvesting of BHK cell cultures by dynamic microfiltration. However, a threshold value of shear stability exists which depends on the frequency of passing the shear field, the residence time in the shear field, as well as on cell status. By operating close to this threshold value, cell viability can be maintained while concentration polarization is efficiently minimized. By applying this concept, it is possible to attain flux rates several times higher compared to conventional crossflow filtration. Controlled shear filtration (CSF) can be used for batch harvesting as well as for cell retention in high cell density systems. In batch harvesting of hIL-2 from rBHK cell culture, a constant flux rate of 290 L h-1 m-2 has been adjusted without indication of membrane clogging or fouling.

Animals↗
PubMed1992

Surface-modified membranes as a matrix for protein purification.

Recently introduced membrane-based chromatographic supports for protein separation are available either with a coupled ligand, e.g., protein A, protein G or ion-exchange groups, or as activated matrices for coupling a desired ligand. The coupling conditions for protein A and immunoglobulin G to an epoxy-activated membrane were determined. The performance of the prepared affinity membranes was investigated using pure rabbit immunoglobulin G and protein A as a model system. For practical application monoclonal antibodies from cell culture supernatant were purified with a prepared protein A membrane and for comparison with a sulphonic acid ion exchange membrane.

Antibodies, Monoclonal↗
PubMed1981

Technical aspects of extractive enzyme purification.

We see the advantages of extraction processes for large-scale enzyme isolation and purification in the high capacity of the method, savings in process time and energy, high activity yields and the possibilities for continuous processing at all stages. Commercially available equipment can be used for separation of aqueous two-phase systems with minor modifications. It is hoped that, through using such technology, intracellular enzymes will become available in large quantities and at lower cost.

Biochemistry↗
PubMed1978

Procedure for the simultaneous large-scale isolation of pullulanase and 1,4-alpha-glucan phosphorylase from Klebsiella pneumoniae involving liquid-liquid separations.

A procedure for the simultaneous large-scale isolation of pullulanase and 1,4-alpha-glucan phosphorylase from Klebsiella pneumoniae is described. The pullulanase is solubilized from the cell wall by cholate treatment; cells and cell debris are removed by partition in a poly(ethylene glycol) (PEG)-dextran two-phase system and from the upper (PEG) phase of this system the pullulanase is isolated by ultrafiltration and precipitation with N-cetyl,N-,N-,N-trimethyl ammonium bromide to a purity of about 80% with a yield of 70%. The preparations are free of alpha-amylase activity. The cell containing dextran-rich phase is passed through a Manton-Gaulin homogenizer. Then the phosphorylase is separated from the cell debris by partition in a second PEG-dextran system. From the top phase of this system the phosphorylase is isolated by distribution in a PEG-salt two-phase system followed by batch adsorption on carboxymethyl-Sephadex in a yield of 55%, a purity of around 90%, and nearly free of glycosyltransferase activity. All steps in the isolation of the two enzymes can be performed easily in a large scale.

Cell Fractionation↗