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PubMed1985

[Immune response in rabbits to tumoral tissue extracts of human colon].

Carcinoembryonic antigen (CEA) was purified after perchloric acid extraction of glycoprotein from human normal and tumoral colon. Antibodies against those extracts as well as purified CEA were raised in rabbits. Sera obtained from animals immunized with tumoral extract in protracted schemes showed disperse behavior on polyacrylamide gel electrophoresis (PAGE) for proteins in the area with gamma, mobility which were markedly increased. In addition, a large increase of proteins with a mobility comparable to alpha 2 proteins was observed. The latter increase was not present in sera of rabbits immunized with normal colon extracts. Low titer antisera were obtained after immunization with either antigen as revealed by immunodiffusion. The relatively highest titers were seen against the glycoprotein fraction of tumor extracts which had previously been enriched by isoelectric focusing. Immunoelectrophoresis of tumor extracts against homologous antisera revealed bands with beta mobility due to the presence of CEA antibodies only in the sera of animals injected with tumor extracts. Antibody titers assayed by radioimmunoassay (RIA) revealed that the highest titers were obtained from tumor glycoprotein extracts was used as an immunogen. Measurements of CEA concentrations in serum of patients with low and high levels of CEA showed non significant differences by statistical analysis, when antisera obtained from different bleedings of the same animals were used. It is concluded that in order to establish a CEA RIA for clinical purposes it is necessary to purify up to the isoelectric focusing step the material to be labelled as tracer or used as standard. Antibody reagent may be obtained by immunizing schemes or protracted schemes using crude perchloric acid extracts of colon tumor.

Adult↗
PubMed1980

Artifacts in the radioimmunoassay of ACTH in tissue extracts and plasma.

Artifacts in studies employing the radioimmunoassay of ACTH may be introduced by the presence of high concentrations of protein or other substances which interfere in the antigen-antibody reaction and by unsuspected damage to the labeled ACTH. We have confirmed the reports of others that extracts of pancreatic, gastrointestinal and other nonpituitary tissues do decrease the binding of labeled ACTH to specific antibody. However, since all known forms of ACTH bind to and can be quantitatively eluted from QUSO, and the apparent immunoreactivity in these tissues does not, we conclude that there is no authentic ACTH detectable in the gut.

Adrenocorticotropic Hormone↗
PubMed1977

Enhancement of [3H-methyl]thymidine incorporation and replication of rat chondrocytes grown in tissue culture by plasma, tissue extracts and vasopressin.

A pituitary mitogenic peptide, which stimulates cellular replication of a variety of cells maintained in tissue culture, has been identified by other investigators. To study this mitogenic substance, we developed an assay to measure mitogenic substances utilizing fetal rat chondrocytes grown in monolayer culture. Mitogenic activity of added test substances was determined by [3H-methyl]thymidine incorporation into trichloroacetic acid insoluble cell products and increase in total cell number after 24 h exposure. Extracts of whole pituitary glands were more potent in stimulating these cellular indices than either those of liver or muscle, confirming that the chondrocytes are sensitive to the described mitogen. Identically prepared extracts of either anterior or posterior pituitary lobes were mitogenic indicating the presence of two or more mitogenic substances in crude pituitary extracts. Synthetic lysine vasopressin and a beef pitressin concentrate stimulated thymidine incorporation into chondrocytes in the absence of calf serum and this effect was additive to that of calf serum, suggesting that the mitogenic substance of posterior pituitary extracts was vasopressin. The maximum effective dose of vasopressin leading to an increase in either thymidine incorporation or total cell number was between 100 to 500 pg/ml, and as little as 50 pg/ml of hormone elicited an increase in total cell number. The mitogenic effect of both vasopressin and calf serum on chondrocytes was partially inhibited by 1 X 10(-4)M N, O'dibutryl cyclic adenosine 3',5' monophosphate suggesting that cell division of chrondrocytes may be under tonic control by the andenylyl cyclase system. We conclude that vasopressin is a potent mitogen for chondrocytes maintained in tissue culture and its presence must be rigorously excluded in evaluating mitogenic activity of pituitary or serum concentrates.

Animals↗