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Biomedical subjects

F Loth

Publications and source records attributed to F Loth.

At least 37 records · Page 2Linked to original sources
PubMed1991

Bead cellulose derivatives as supports for immobilization and chromatographic purification of proteins.

Characteristic data are presented for Divicell, a macroporous bead cellulose with excellent flow parameters. The preparation of Divicell derivatives and their properties are described with respect to their application as chromatographic supports. The ion exchangers Divicell DEAE and Divicell CM were manufactured in two types with different exclusion limits and an available capacity for proteins of up to 100 mg/ml gel. Divicell Blue is a bead cellulose with covalently bound Cibacron Blue F3G-A and was found to be a very suitable adsorbent for the selective separation and purification of human serum albumin. Activation of Divicell with sodium periodate, epichlorohydrin and 5-norbornene-2,3-dicarboximido carbonochloridate provided activated supports used for immobilization of ligands in organic solvents and in aqueous solutions. Coupling of amines, diamines, amino acids, carbohydrates and proteins is described. The immobilized ligands retained their biological activity as determined by their specific adsorption of proteins. Divicell alkyl derivatives were tested in hydrophobic interaction chromatography with bovine serum albumin as a model. Examples are presented of the application of Divicell derivatives to the purification of biomacromolecules such as immunoglobulins and lectins by affinity chromatography. The results were comparable to those obtained using the corresponding Sepharose-derived absorbents.

Animals↗
PubMed1990

Polyalkylenes used as stationary phases for preparative reversed-phase liquid chromatography.

Polyethylene and polypropylene were employed as stationary phases for preparative liquid chromatography and compared with LiChroprep RP-18. Polyalkylene phases are chemically stable and have homogeneous hydrophobic surfaces, but they are physically less resistant than silica-based phases. The influence of organic modifiers and salt ions on the capacity factors of aromatic hydrocarbons and peptides was determined. Peptides prepared by solid-phase peptide synthesis were purified on polypropylene. The results demonstrate the usefulness of polyalkylenes in preparative reversed-phase liquid chromatography, particularly for basic peptides.

Chromatography, Liquid↗
PubMed1990

A newly developed LDL-binding material.

Results of in vitro and ex vivo experiments with a newly developed LDL-binding material are presented. This material consists of macroporous bead cellulose which is capable to bind selectively LDL. LDL-cholesterol is considerably decreased after contacts of plasma or serum samples with this bead cellulose. On the other hand high density lipoproteins (HDL) and other plasma components (proteins, enzymes, electrolytes, and metabolic substances) remained high or unchanged. Triglycerides (TG)--transported by very low density lipoproteins--are also bound up to a certain degree. 1 g of the adsorbent wet mass binds at least 20 mg cholesterol. The capacity suffices to decrease two- to threefold increased cholesterol and LDL plasma levels to the low normal range following passage of the sevenfold plasma volume' through two the three LDL adsorbent columns (results of perfusion experiments). In vitro and dog experiments revealed only slight drops of the hemolytic capacities of the classic complement pathway and moderate decreases of the alternative one. But no detectable side effects were noticed in the dog experiments.

Adsorption↗
PubMed1989

Low density lipoprotein binding by macroporous bead cellulose.

Cellulose of a certain macroporous structure is capable of binding selectively low density lipoproteins (LDL) whilst maintaining high density lipoprotein (HDL) levels. It was ascertained that the porous structure of the cellulose causes binding of LDL and that also diffusion processes play a role. To a certain extent special bindings such as hydrogen bonds between cellulose and LDL and/or hydrophobic interactions may furthermore be of importance for the LDL fixation.

Adsorption↗
PubMed1988

[Results of the chronic compression of visceral arteries in animal experiments].

Occlusions of different visceral arteries were imitated by progressive swelling substance constriction in 30 mongrel dogs. The variants of the developed collateral circulation could be proved by the postoperative angiographies. There is given reference to the importance of the connections of the visceral vascular system among one another and for the abdominal surgery of the human. Evidence is given that occlusions of the celiac artery and of the superior mesenteric artery are compensable only with the formation of large collateral vascular systems. But on certain circulation conditions the inferior mesenteric artery has a great significance too.

Animals↗
PubMed1987

In vitro investigations with selective adsorbents for IgE and IgM.

In vitro studies were carried out with IM-T. This adsorbent consists of polyvinyl alcohol joined with tryptophan side chains and was delivered by ASAHI Medical Co., Ltd., Tokyo/Japan. It was found that IM-T binds immunoglobulins G and M and also immune complexes only moderately but IgE was adsorbed in remarkable amounts. A clear dose-dependent was adsorbed in remarkable amounts. A clear dose-dependent manner of the IgE adsorption could be stated. Kinetic studies revealed that the binding was only slow and gradual.

Animals↗
PubMed1986

[The release of immobilized substances from Symplex capsules].

A new procedure of microencapsulation was studied with regard to substance release and quantification of diffusion processes on the capsule membrane. The permeability behaviour on the capsule membrane was especially studied in metabolites, which are essential for immobilized biological objects (i.g. preimplantative mammal embryos). Peptide and proteohormones, cyanmethemoglobin and proteins were enclosed in simple and multiple Symplex Capsules. All substances examined are able to pass the Symplex membrane. The speed of release is influenced by the size of the capsule, the ion force, temperature, concentration of immobilized substances as well as their linear and globular structur. Compared with simple capsules the release of substances from multiple capsules was delayed. Corresponding to the results found under the experimental design described the Symplex membrane can be considered as coating for the compartmentation of cells, that allows the passage of essential substances for the immobilized objects. The method of microencapsulation used and described has various ways of application.

Capsules↗
PubMed1985

The encapsulation of pancreatic islets. Investigation of insulin secretion and content in vitro.

Polyelectrolyte complex capsules from cellulose sulphate can be formed by precipitation in a polycation bath. The application of this new method for encapsulation of pancreatic islets requires investigations whether and to what extent cellulose sulphate injures viability and functionality of the pancreatic islets. Islets cultures in the presence of 2% cellulose sulphate for up to 3 weeks are characterized by unchanged insulin content, secretion and biosynthesis when compared to appropriate controls.

Animals↗
PubMed1983

[Immobilization of proteins and cell fragments using a new method of microencapsulation].

Cytochrome c, hemoglobin, urease and liver microsomes were microencapsulated in aqueous solution by use of a new method. The membrane of the microcapsules consist of a symplex, which is formed predominantly by electrostatic interactions between a polymeric polyanion and a polymeric polycation. The membrane is characterized by high mechanical stability and is a barrier for globular substances with molecular weights larger than 12000, but permeable for substances with lower molecular weight. The microcapsules contain the protein or microsomes and additionally the polymeric polyanion in the liquid interior. Structure and function of microencapsulated proteins and microsomes are preserved. The developed method of microencapsulation opens new possibilities for the application of biomacromolecules, particularly for extracorporal detoxification.

Animals↗