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Biomedical subjects

A Vogt

Publications and source records attributed to A Vogt.

At least 199 records · Page 11Linked to original sources
PubMed1978

Differences in the isoelectric focussing pattern of antibodies to human serum albumin eluted from an immunoadsorbent (HSA-sepharose) with thiocyanate ions.

Anti HSA-antibodies were isolated from HSA-sepharose by direct and stepwise elution with 0.5 M, 2.0 and 3.0 M KSCN at different pH values. The antibody fractions, especially those eluted stepwise, varied in their isoelectrofocussing pattern. Nearly all antibody molecules with an isoelectric point (PI) lower than 6.5 were eluted with 0.5 M KSCN. Application of increasing KSCN concentrations led to the recovery of antibody fractions showing a parallel shift in the PI to the region higher than 7.5. These differences were not correlated with differences in antibody avidity. The effect of KSCN does not seem to be restricted to the combining sites of the antibody. The dissociation of the antibody from the antigen is apparently facilitated by an interaction of KSCN with the remainder of the antibody molecule thereby influencing the overall net charge.

Animals↗
PubMed1978

Masking of protein antigen by modification of amino groups with carbobenzoxychloride (benzyl chloroformate) and demasking by treatment with nonspecific protease.

Cryostat sections of various substrates were treated with carbobenzoxychloride in acetone to modify antigens. By applying specific fluorescent antibodies, it could be shown that the antigenic determinants of rabbit gamma-globulin and bovine insulin were totally masked. The antigenicity of ACTH was markedly reduced, whereas the polysaccharide antigens of Salmonella typhimurium were only partially masked. After masking, antigenicity could be restored by treatment with nonspecific protease. The reversible protection of amino groups by carbobenzoxychloride may be a way to preserve protein antigens during embedding in plastics, as such materials also bind to amino groups, blocking the antigenicity of proteins.

Acetone↗
PubMed1978

Effect of antibody avidity on the induction of renal injury in anti-glomerular basement membrane nephritis.

Antibodies to glomerular basement membrane (GBM) of the rat could be fractionated according to their avidity by elution from trypsin-digested GBM (bound to Sepharose) with increasing concentrations of KSCN. The percentage of kidney-fixing antibody in each fraction and the degree of proteinuria induced as determined 24 h after injection increased with the avidity of the antibody fraction when equal doses were administered.

Animals↗
PubMed1977

Solid-phase enzyme immunoassay for immunoglobulin M antibodies to cytomegalovirus.

A sensitive, solid-phase enzyme immunoassay for the detection of immunoglobulin M antibodies to cytomegalovirus is described. The results of the enzyme immunoassay correlated well with those obtained by an indirect immunofluorescence method. Horseradish peroxidase proved to be a more sensitive label than alkaline phosphatase. Nonspecific reactions, occurring with commercially available cytomegalovirus antigens, could be avoided by using a nuclear antigen prepared from sonically disrupted nuclei of cytomegalovirus-infected cells.

Alkaline Phosphatase↗
PubMed1977

Quantity of antibody synthesized in a single cell during the primary immune response.

Following immunization of mice with SRBC the kinetics of antibody synthesis by individual immunocompetent cells during the primary immune response were investigated. The diameter of the average hemolytic plaque using a modified Jerne plaquing technique, was taken to be an estimate of the antibody production by a single cell. We found an increase, followed by a decrease, of the average plaque diameter during the primary immune response. The increase of average plaque diameters is probably due to the raised rate of synthesis of antibody molecules. This increase can be accelerated by adjuvants. The decrease late in the primary immune response could be explained by an internally regulated switch from IgM to IgG antibody synthesis. The results are consistent with the mathematical approach of HELLWIG (1,2).

Adjuvants, Immunologic↗
PubMed1977

[Coagulation analytical studies in coli enterotoxemia in swine].

Store pigs with spontaneous outbreaks and experimental endotoxin shock were kept under observation in the context of coagulation analysis. Heparin was applied to some of the animals to disrupt the plasmatic coagulation system. The thrombocyte count in animals with endotoxin infusion declined by some 50 to 65 percent of the original level. No statistically secured difference was found to exist between heparinised animals, on the one hand, and non-heparinised, on the other. The aggregation and adhesion of thrombocytes in all shock animals was more pronounced than that in the controls. The fibrinogen levels were lowered in both the animals with spontaneous outbreaks and the experimental animals. Thrombocyte alteration was not found to have been dependent on activation of the plasmatic coagulation system. In endotoxin shock cases activation of plasmatic coagulation proteins was found to be preceded by rise in thrombocyte aggregation.

Animals↗
PubMed1977

[On the possibility of a rapid method for sensitivity testing of mycobacteria by determination of H3-uracil incorporation (author's transl)].

Dubos-Tween Albumin cultures (8.0 ml) were set up with 10(6) viable bacteria per ml. After incubation for 48 hours 0.25 muC H3-uracil per ml was added. At the same time the antituberculoticum was introduced. The final concentrations were 1 microgram, 0.25 microgram and 0.025 microgram for INH; 4.0 microgram for SM; 32 microgram and 0.32 microgram for RMP; 2.0 microgram and 1.0 microgram for ETH; 0.5 microgram and 0.25 microgram for PAS. The incorporation rate clearly depended on the degree of sensitivity of the bacteria. Determing the incorporation rate of H3-uracil allowed the result to be read after only one week (fig. 1 and fig. 2) instead of 4 to 6 weeks using the conventional method on solid media. It was also found that turbidity measurements of the cultures (fig. 2) gave an equaly reliable result enabling this latter method to be performed in less well equipped laboratories.

Drug Resistance, Microbial↗
PubMed1975

[Improving bacteriological diagnosis by using culture medium during transport of specimens (author's transl)].

It is well known that long transport diminishes the chances of isolating causative micro- organisms, especially from swabs. In a trial, in which beta-haemolytic streptococci were kept for 24-hours at room temperature, culturing failed even if more than one million bacteria had been placed on the swab. Culture medium consisting of agar with 0.5% human albumin made it possible to isolate beta-haemolytic streptococci even after transport and with a count of less than a hundred micro-organisms per swab. The use of selective nutrient media may be necessary because of the sometimes marked multiplication during transport when there are mixed organisms. The nutrient medium was used during six small epidemics of scarlet fever in Freiburg and proved superior to the usual dry swab. In parallel studies of patients and contacts the causative beta-haemolytic streptococcus was isolated three times as often.

Agar↗
PubMed1975

A two-stage method for cross-linking antibody globulin to ferritin by glutaraldehyde. III. Size and antibody activity of the conjugates.

Immunoferritin conjugates consist of conjugates of different size. They can be separated in 4.5% polyacrylamide gel electrophoresis into at least 4 bands. The amount of the smallest 1:1 conjugate, in which one antibody molecule is linked to one ferritin molecule, is highest in coupling products with low overall yields of conjugated ferritin. Therefore relatively mild reaction conditions are recommended. With increasing size the antibody binding capacity of the conjugate is reduced.

Animals↗