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Biomedical subjects

G I Abelev

Publications and source records attributed to G I Abelev.

At least 37 records · Page 2Linked to original sources
PubMed1989

Synthesis of alpha-fetoprotein in hepatocytes is co-ordinately regulated with cell-cell and cell-matrix interactions.

The synthesis of alpha-fetoprotein in primary cultures of adult mouse hepatocytes was studied under different conditions of cultivation. On dried collagen, the majority of cells resumed synthesis of alpha-fetoprotein. Alpha-fetoprotein re-expression was accompanied by the flattening of hepatocytes, loss of gap junctional communication and domain-specific membrane antigens, and by alteration of actin pattern. Cultivation of hepatocytes on polymerized collagen gel did not prevent the re-expression of alpha-fetoprotein and other alterations described above. Hepatocyte cultivation within three-dimensional collagen gel as well as co-cultivation of hepatocytes with liver epithelial cells IAR-20 led to re-establishment of organotypic trabeculae-like structures consisting of polygonal hepatocytes with normal pattern of actin, membrane antigens and cell-cell communication. These structures were almost alpha-fetoprotein-negative. It is suggested that hepatocyte shape is co-ordinately regulated with the switch from an adult "block" of hepatocyte functions to an embryonic one. Three-dimensional extracellular matrix may in turn, influence the maintenance of hepatocyte shape.

Actins↗
PubMed1988

[Epitopic analysis of monoclonal antibodies based on countercurrent isotachophoresis on nitrocellulose membranes].

A variant of the counterflow isotachophoresis on nitrocellulose membranes (NCM) was applied for the analysis of the epitope specificity of monoclonal antibodies (Mabs). Different Mabs against mouse and human alpha-fetoprotein were fixed on the membrane and the immunoreagents were transferred consequently to these dots by the electroendo-osmotic flow. The epitope specificity of the Mabs was estimated by the competition for the homologous antigen between the Mab added to the antigen and the one fixed on the membrane.

Animals↗
PubMed1988

[Countercurrent immunoblotting].

Urinary proteins, concentrated and separated on cellulose-acetate membranes by counterflow isotachophoresis (ITP), were transferred by direct contact onto a strip of nitrocellulose membrane (NCM). ITP in the system of electrolytes: tris-HCl, pH 6.7 (the leading one) and tris-beta-alanine, pH 8.6 (the terminal one) gives rise to a strong electroendo-osmotic flow (EEF) in NCM, directed to the cathode. The rate of the counterflow in the zone, occupied by the leading electrolyte, exceeds the migration rate of any protein possessing anode mobility and present in the zone. Under these circumstances EEF serves as a "conveyer belt" transferring immunological reagents (antibodies, immunoconjugates, peroxidase) through the protein bands, "printed" on NCM. The immunoblots were developed in a standard way with 4-ethyl-1-naphthol as a substrate for antibody-bound peroxidase. The counterflow immunoblotting makes it possible to reveal and characterize light chains of immunoglobulins when they are present in the urine in the range of 20 ng/ml.

Counterimmunoelectrophoresis↗
PubMed1988

[The secretion of monoclonal immunoglobulins in chronic lymphoproliferative diseases].

Altogether 74 patients (57 with CLL; 12 with lymphocytomas including 7 with generalization of disease; 5 with hairy cell leukemia) were examined to detect the secretion of serum monoclonal immunoglobulins (Ig) and Bence Jones (BJ) protein. Electrophoresis of the serum in agarose gel, radial immunodiffusion and immunoelectrophoresis as well as isotachophoresis with immune development for identification of minimal amounts of BJ protein in urine were employed. Monoclonal Ig in the serum and urine (IgG lambda + BJ lambda and IgA kappa + BJ kappa) were found in 2 CLL patients. BJ protein only was revealed in 40.5% of the examinees (kappa:lambda = 4.5:1). Direct correlation between the level of BJ protein secretion and tumor mass was shown. Effective therapy caused the reduction (but not disappearance) of BJ protein in urine. During a 2-year study BJ protein secretion was undetectable in the group of nonsecreting patients with a large tumor mass. Prospects of the use of the results obtained are under discussion.

Adult↗
PubMed1987

Mixed precipitation in gel: a new method of identification and characterization of monoclonal antibodies.

A mixed precipitation in the gel (MPG) technique is suggested for detection and characterization of monoclonal antibodies (MAbs). The MPG is based on the formation of a mixed precipitate composed of an antigen, the corresponding MAb and precipitating polyclonal antiserum. MAb incorporated into the precipitate is revealed by Fab'-peroxidase conjugate added to polyclonal antiserum. The MPG technique was applied to hybridoma screening as well as for the antigen and epitope specificity analysis of different MAbs. The MPG is a one-step, simple, inexpensive technique and valuable for the study of any antigen which could be revealed by immunodiffusion.

Agar↗
PubMed1985

[Determination of monoclonal antibody specificity by mixed precipitation ingel].

The enzyme-immunodiffusion technique is advanced which permits testing monoclonal antibodies included in the precipitate line formed in gel by polyclonal antibodies with the corresponding antigen. Rat or mouse monoclonal antibodies were mixed with polyclonal rabbit antiserum to the antigen at issue. The precipitate formed by immunogen and rabbit polyclonal antibodies included monoclonals.

Animals↗
PubMed1984

Counterflow immunoisotachophoresis on cellulose acetate membranes.

Discontinuous electrophoresis on cellulose acetate membranes with the use of 0.06 M Tris-HCl (pH 6.7) as the leading electrolyte and 0.012 M Tris-beta-alanine (pH 8.6) as the terminating one results in concentration of the proteins present in the system on the Cl-/beta-alanine- boundary. If the antigen solution is placed in a "pocket" ahead of the moving boundary, a counterflow to the cathode arises due to electroendosmosis. At constant voltage the migration rate of the boundary drops and that of electroendosmosis does not change until they become equal. In such a stationary position, the antigen-containing solution is passing through the Cl-/beta-alanine- boundary to the cathode, while all the proteins are completely "absorbed" on the boundary as highly concentrated bands. Addition of ampholytes to the antigen solution contributes to the isotachophoretic separation of a protein mixture on the strip. The concentrated and separated antigens can be revealed by immunofixation, immunodiffusion, or crossed immunoelectrophoresis in gel. The technique is approximately 100 times more sensitive compared to the usual immunodiffusion and immunoelectrophoresis methods on cellulose acetate membranes, and is applicable to the detection of trace amounts of antigens in the urine, liquor, amniotic fluid, tears, and other biological fluids with low protein contents.

Animals↗
PubMed1983

Alpha-fetoprotein synthesis in relation to structural peculiarities in postnatal and regenerating mouse liver.

The localization of alpha-fetoprotein (AFP) and of antigens of liver-cell plasma membrane (Ag I, Ag II and Ag III) was studied in adult, postnatal and regenerating (CCl4 or paracetamol-treated mouse liver). Ag I, Ag II and Ag III were solubilized by Triton X-100 from ghosts of the mouse liver cells. The purification of antigens was performed by gel filtration on Sephadex G-200 or Ultrogel ACA-54 with subsequent treatment of antigenic fractions eluted from the column with 5% HClO4. Ag I and Ag II are common for liver and some other mouse organs, but Ag III is strictly specific for liver. The Ag I is predominantly found in the region of the bile capillaries. Ag II and Ag III are mainly present on membrane adjoining blood sinusoids. The distribution of these three antigens in newborn mouse liver is quite different from that in adult liver and reflects the specific arrangement of hepatocytes at different stages of development - the acinar structure in newborn liver and the plate structure in the adult organ. During regeneration as well as during postnatal development, AFP has been found in areas of marked tissue rearrangement. In both cases, these areas lose the plasma membrane antigens, especially Ag I - the antigen of bile capillary. The reappearance of Ag I on the surface of liver cells coincides with cessation of AFP synthesis and establishment of definitive plate structure. The possible role of liver plate structure in the regulation of AFP synthesis is discussed.

Animals↗
PubMed1983

Alphafetoprotein: the genesis.

A historical account of the finding of alphafetoprotein is presented. The problems in its initial isolation, purification and source are described. Some interesting potential future studies are also discussed.

Animals↗
PubMed1982

[Alpha-fetoprotein synthesis in clonogenic cells of rat hepatoma McA-RH 7777].

Production of alpha-fetoprotein (AFP) was determined in single cells of hepatoma McA-RH7777 and in the clones of their progeny. To elucidate the heritability of this trait in a series of cell generations, a variety of local hemolysis in gel was devised. According to the method the cells and red cells conjugated with protein A were placed on the polylysine covered surface and layered with agarose gel containing antibodies. AFP production by single cells was determined from the formation of plaques--areas of red cell hemolysis. The cells forming the plaques (+AFP) and not forming them (-AFP) were distinguished and their reproduction was followed up. After 7-14 days the cells were fixed and stained by the immunoperoxidase technique with antibodies to AFP. High efficacy of the cloning has been demonstrated for both +AFP- and -AFP-cells (69 and 71%). Negative cells preserved their phenotype more frequently, producing homogenous negative clones, whereas +AFP cells gave "negative" clones in 1/3 of the cases. Both cells gave mixed clones in a small percentage of the cases. At present the AFP trait in these cells is being studied by recloning.

Animals↗
PubMed1981

[Independence of alpha-fetoprotein expression from production of adult rat serum proteins in hepatoma McA-RH7777].

Clonal cell lines were isolated from rat hepatoma McA-RH7777 to study expression of alpha-fetoprotein (AFP) in these clones. AFP contained by the cells was determined by immunofluorescent and immunoperoxidase staining, while AFP secreted into the medium by aggregate-hemagglutination and immunoisotachophoresis. The existence of the clones that drastically differ in the intensity of AFP synthesis was demonstrated, with these clones being implicated in the monitoring of AFP synthesis. The differences between the clones gradually diminished in the course of long-term cultivation. It was also shown that the clones under consideration secreted, apart from AFP, at least 8 proteins of adult rat serum. One of the proteins was identified as transferrin. No albumin was detected in the cultural media tested. The level of AFP production did not correlate with the synthesis of other serum proteins and thus seems likely to be controlled by an independent mechanism.

Animals↗
PubMed1979

[Counter-flow isotachophoresis on cellulose acetate membranes. Role of electroendosmosis].

A variant of counter-flow isotachophoresis of proteins on cellulose acetate membranes is proposed. The liquid counter-flow is created by electroendosmosis in the membrane. Proteins are concentrated at the Kolrausch boundary during isotachophoresis in the presence of ampholytes. The method permits one to make microanalysis of proteinic mixtures in diluted solutions, and it can be used in combination with immunodiffusion and immunoelectrophoretic methods of antigenic protein detection.

Antigens↗
PubMed1979

[Two-layer rocket-electrophoresis on cellulose-acetate membranes].

Two-floor rocket-electrophoresis on gelatinated acetate cellulose membrane "Cellogel" has been developed. The method is based on electroimmunodiffusion detection of the antigen on the acetate-cellulose membranes, containing monospecific antiserum of the test-system. The procedure is followed by the detection of precipitation bands ("rockets") by staining, if the reaction is conducted in the visible zone or by the further treatment of the acetate-cellulose strips, containing invisible precipitates with antiglobulin antibodies, the complement or their combination. An increase in the method sensitivity up to 30-60 ng/ml in the visible zone of the reaction is achieved by simultaneous reduction in the antibody concentration and the growth of the absolute quantity of the antigen, subjected to electrophoresis, up to 50-100 microliters. The method has been applied to human alpha-fetoprotein.

Electrophoresis, Cellulose Acetate↗