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Biomedical subjects

F Dorner

Publications and source records attributed to F Dorner.

114 records · Page 7Linked to original sources
PubMed1975

Escherichia coli enterotoxin: stimulation of adenylate cyclase in broken-cell preparations.

The enterotoxin from cell-free filtrates of the enteropathogenic Escherichia coli strain P-263 was found to stimulate adenylate cyclase activity in broken-cell preparations from myocardial tissue. Particulate and detergent-solubilized fractions from cat heart were incubated with enterotoxin and assayed for adenylate cyclase activity. Adenylate cyclase activity was stimulated by enterotoxin; the extent of stimulation was proportional to the concentration of enterotoxin. The data demonstrate that stimulation of enterotoxin-sensitive adenylate cyclase in this system provides a sensitive in vitro assay, either as an accurate measure of enterotoxin concentration or as an assay for antitoxic titers in sera. A parallel comparison showed that stimulation of fluid production in rabbit intestinal loops by enterotoxin was less sensitive.

Adenylyl Cyclases↗
PubMed1973

Interferon: evidence for its glycoprotein nature.

In an attempt to understand the structure of rabbit interferon, the possibility of carbohydrate being part of the molecule was tested. Interferon incubated with neuraminidase from Vibrio cholera is homogeneous in charge as revealed by isoelectric focusing. Treatment of "asialointerferon" with galactose oxidase (EC 1.1.3.9) from Dactylium dendroides and subsequent reduction with tritiated sodium borohydride yields labeled material with unimpaired antiviral activity. Enzymic incorporation of N-[(14)C]acetylneuraminic acid into tritiated asialointerferon restores the original charge heterogeneity. The newly generated sialointerferon contains both (3)H and (14)C activity. Asialointerferon is retained by an affinity column containing phytohemagglutinin from Phaseolus vulgaris and can be displaced from the adsorbent by a glycoprotein of known structure. It is concluded that rabbit interferon is a glycoprotein containing the terminal oligosaccharide sequence sialic acid --> galactose.

Animals↗
PubMedDate not supplied

Collagen covalently immobilized onto plastic surfaces simplifies measurement of von Willebrand factor-collagen binding activity.

Human collagen type III was immobilized covalently via activated carbohydrate moieties onto hydrazine-treated microtiter plates which could be used to measure von Willebrand factor (vWF) collagen binding activity (vWF:CBA) in an ELISA. Such plates were simple to prepare and remained stable at 4 degrees C and -20 degrees C for at least 2 months. Samples analyzed by this system included (a) normal human vWF fractionated according to the degree of multimerization, (b) normal citrated and EDTA plasma and corresponding serum, and (c) plasma from patients with von Willebrand disease (vWD) types 1 and 2. When related to the concentration of vWF antigen (vWF:Ag), proportionally low levels of vWF:CBA were found for samples lacking the high-molecular-weight multimers, while higher values were obtained for samples containing these multimers. The ratio of vWF:CBA/vWF:Ag sensitively reflected the functional and structural intactness of the vWF molecules for all analyzed samples. Monoclonal antibody directed to the region within the A1 domain of vWF which interacts with the glycoprotein Ib completely inhibited the vWF ristocetin cofactor (vWF:RistCof), while vWF:CBA was not affected. Thus vWF:CBA and vWF:RistCof clearly represent separate, noninterchangeable functional parameters of vWF. In conclusion, our results indicate that the newly described method for the immobilization of collagen onto microtiter plates is suitable for the determination of vWF:CBA. In conjunction with vWF:Ag and the calculated ratio of vWF:CBA/vWF:Ag, this method simplifies the detection and classification of patients with vWD and assists in quality control during the purification of normal vWF.

Biological Assay↗
PubMedDate not supplied

Development of a mammalian cell (Vero) derived candidate influenza virus vaccine.

Influenza vaccine production is dependent on the availability of embryonated hen eggs for virus growth. This is an extremely cumbersome system with many disadvantages with respect to selection of virus variants and presence of adventitious viruses. We have developed an alternative cell culture system which allows rapid production of large volumes of vaccine. The World Health Organisation (WHO) approved Vero cell line was used in serum-free culture to grow a multitude of influenza strains to high titre. This system could be scaled-up to allow vaccine production with a 1200 litre fermenter volume. A purification scheme was developed which resulted in a high purity whole virus vaccine. This was demonstrated to be at least as immunogenic as a conventional egg-derived preparation in a mouse model.

Animals↗