Carol J. Smith

α1-Fetoprotein: Separation of two molecular variants by affinity chromatography with concanavalin A-agarose

Alpha1-Fetoprotein present in fetal/newborn rat serum and in hepatoma-bearing human serum has been resolved into two molecular variants by concanavalin A-agarose affinity chromatography. The concanavalin A-reactive variant has been purified by gel filtration column chromatography, preparative block electrophoresis and immunoadsorption affinity chromatography.

Rat alpha-fetoprotein: In vitroproduction of four molecular variants by clonal cell lines

Abstract Mass and six clonal cultures derived from Morris hepatoma 7777 by standard tissue culture techniques synthesize and secrete alpha-fetoprotein in vitro . During serial passage, the alpha-fetoprotein which accumulates in the media of these cultures contains two concanavalin A-affinity molecular variants. Each of the concanavalin A-affinity molecular variants shows two electrophoretic variants. Mass and clonal cell populations of hepatoma cells continue to secrete in vitro four molecular variants of rat alpha-fetoprotein known to occur in vivo . These results demonstrate for the first time that individual hepatoma cells have the potential to synthesize four molecular variants of alpha-fetoprotein and that this phenotypic property is maintained during serial subculture in vitro .

CONCANAVALIN‐A‐AFFINITY MOLECULAR HETEROGENEITY OF HUMAN HEPATOMA AFP AND CORD‐SERUM AFP

Glycosylation of alpha-fetoprotein (AFP) by human primary hepatocellular carcinoma (PHC) is abnormal. Concanavalin A (Con A)-affinity molecular variant patterns of serum AFP from patients with PHC are different from those of cord-serum AFP. Different patients with PHC exhibit different Con-A-affinity AFP molecular variant patterns, and the pattern remains constant over time in a given individual. The degree of deviation of the AFP molecular variant pattern from the molecular pattern of AFP secreted by neonatal liver cells is independent of the total serum AFP concentration. We propose that analysis of the AFP lectin-affinity molecular heterogeneity will improve the discrimination between malignant and nonmalignant liver disease in cases when the degree of elevation of the serum AFP concentration is nondiagnostic.

ORIGIN OF AMNIOCENTESIS‐INDUCED RISES OF ALPHA‐FETOPROTEIN CONCENTRATIONS IN MATERNAL SERUM

An elevation of alpha‐fetoprotein concentration in maternal serum occurred in 7 of 65 patients (11 per cent) following amniocentesis. Analysis of the molecular heterogeneity of the alpha‐fetoprotein by chromatography on concanavalin A‐agarose indicated that the source of the alpha‐fetoprotein was fetal serum in three patients and amniotic fluid in four patients.

The expression of α-fetoprotein and albumin genes in rat liver during chemical carcinogenesis

Abstract The effect of the hepatocarcinogen 3′-methyl-4-dimethylaminoazobenzene on α-fetoprotein (AFP) and albumin gene expression in rat liver was studied. Serum concentrations of AFP and albumin were measured. Amounts of AFP mRNA and albumin mRNA in rat livers were determined by hybridization of total cytoplasmic RNAs to their cDNAs. Dramatic increases in serum AFP concentrations coincided with increases in AFP biosynthesis and amount of AFP mRNA in livers of carcinogen-treated rats. In contrast, no or little change in albumin mRNA concentration was found in livers of rats treated with 3′-methyl-4-dimethylaminoazobenzene. Concomitantly, there was little change in liver albumin biosynthesis or serum albumin concentrations during hepatocarcinogenesis.

A method for the separation and identification of basic amino acids and hexosamines

Abstract A method is described for separating and quantifying basic amino acids and hexosamines simultaneously from the column chromatography on Dowex 50W X8 of serum acid hydrolysates. Based on color development with 2,4,6-trinitrobenzene-1-sulfonic acid, differences in the absorption spectra of the trinitrophenylation products of the two types of compounds are characteristic. The ratio of O.D. 355: O.D. 475 provides a quick identification of the type of compound, amino acid or hexosamine.

Serum glycoprotein synthesis by the fetal rat

Abstract 1. 1. The 16–21-day gestation fetal rat was shown to be capable of synthesizing the carbohydrate portion of its serum glycoproteins. 2. 2. The pattern of carbohydrate labeling of fetal rat serum glycoproteins following the injection of radioactivity labeled glucosamine is similar to that of the normal adult rat. Approx. 80% of the maternal protein-bound radioactivity and 90% of the fetal protein-bound radioactivity is recovered as glucosamine and the remainder as sialic acid.

Comparison of fetal and newborn rat serum protein-bound carbohydrates with those of adult rats.

Abstract 1. 1. Serum protein-bound hexose, hexosamine, sialic acid and fucose were determined in normal, pregnant, injured adult rat and in normal fetal rat. 2. 2. The protein-bound carbohydrates of normal adult and pregnant rat serum were similar. 3. 3. The protein-bound carbohydrates of fetal and injured adult rat serum differed both from those of normal and pregnant adults and from each other. 4. 4. The rat serum protein-bound hexosamine is glucosamine.

Alpha‐fetoprotein: Is the Pattern of Concanavalin A‐affinity Molecular Variants a Marker for Synthesis by Neoplastic Cells in the Rat?

The post‐secretory metabolism of the two concanavalin A‐affinity molecular variants of rat alpha‐fetoprotein was studied in normal adult rats. The serum half‐lives of the two alpha‐fetoprotein molecular variants and unfractionated alpha‐fetoprotein are the same. There is no quantitatively significant interconversion of the two alpha‐fetoprotein concanavalin A‐affinity molecular variants in normal adult rat serum. These results indicate that the pattern of alpha‐fetoprotein concanavalin A‐affinity molecular variants present in rat serum reflects their relative rates of synthesis rather than differences in their rates of catabolism following secretion from the liver cell.

Quantitative determination of glucosamine by column chromatography and radioisotope dilution.

Abstract A specific method for the quantitative determination of protein-bound glucosamine using radioisotope dilution and ion-exchange chromatography is described. Plasma glucosamine levels of a group of normal male humans and hospitalized patients are reported. Evidence is presented that variable preferential destruction of either the added isotopically labeled glucosamine or the protein-bound glucosamine is not a significant factor in the results obtained.