PubMed Health⌕ Search

Biomedical subjects

C J Abeyounis

Publications and source records attributed to C J Abeyounis.

At least 19 recordsLinked to original sources
PubMed1990

Isolation and characterization of rat carcinoembryonic antigen.

A rat tumor-associated antigen with properties similar to those of human carcinoembryonic antigen (CEA) has been detected with rabbit immune sera in extracts of transplantable rat colonic adenocarcinoma, RCA-1. This antigen, termed rat CEA, was also detectable by a monkey antihuman CEA serum and a rat monoclonal antibody to rat CEA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of perchloric acid extracts of RCA-1 tumor, followed by immunoblotting with the above-mentioned anti-CEA reagents, revealed that rat CEA activity resided in components with a molecular weight of approximately 350 kD. The glycoprotein nature of these components was indicated by positive staining with periodic acid-Schiff. Sephadex G-200 chromatography, as well as Sepharose 4B chromatography with and without sodium dodecyl sulfate indicated that the 350-kD components existed in the extracts as molecular aggregates. The 350-kD material, which had been purified by an affinity column containing rat monoclonal antibodies to rat CEA, reacted with the rabbit and monkey anti-CEA sera. This provided strong evidence that serological activity of rat CEA was confined to the 350-kD components.

Animals↗
PubMed1989

Analysis of differing patterns of cross-reactivity of honeybee and yellow jacket venom-specific IgE: use of purified venom fractions.

Prior studies of sera from insect sting-allergic patients have analyzed the relationship of coexisting honeybee venom- and yellow jacket venom-specific IgE. Radioallergosorbent (RAST)-inhibition tests with these venoms revealed four different patterns of activity. In this present study, purified fractions prepared from these venoms were used to analyze these varying patterns. The hyaluronidases of yellow jacket venom and honeybee venom showed extensive cross-reaction. The phospholipases from these venoms showed minimal cross-reactivity; antigen 5 was restricted to yellow jacket venom. There was a high molecular weight component in yellow jacket venom with immunologic properties similar to honeybee venom acid phosphatase. Sera from individual patients showed quantitative and qualitative differences in the reactions to the major components of both venoms. The differences in the RAST-inhibition patterns in patients with elevated levels of both honeybee venom- and yellow jacket venom-specific IgE are accounted for by these differences as well as by differences in the cross-reactivity between the individual components.

Animals↗
PubMed1988

Serological relationship between rat and human carcinoembryonic antigen.

Enzyme immunoassays showed that a rabbit antiserum to rat carcinoembryonic antigen (CEA) had high activity with extracts containing human CEA, which was almost completely inhibited by extracts containing human or rat CEA. Little or no inhibition was obtained with extracts of normal human or rat tissues or by human blood group A or B substances. A monkey antiserum to human CEA had strong activity against extracts containing rat CEA, and little or no activity against extracts of normal rat liver or kidney or a CEA-negative rat colon tumor. Activity of the monkey antiserum against rat CEA was almost completely inhibited by extracts containing rat or human CEA. Little or no inhibition was obtained with extracts of normal rat or human tissues. These results suggest that human and rat CEA share antigenic determinants and that they may be analogous moieties.

Animals↗
PubMed1988

Monoclonal rat antibodies to rat carcinoembryonic antigen.

An IgM-class rat monoclonal antibody, designated 5B1, was produced against rat carcinoembryonic antigen. This antibody, which can be considered an autoantibody, formed a single precipitation line in a gel diffusion test with an extract of the CEA-positive rat colonic adenocarcinoma, RCA-1. This line gave a reaction of complete identity with a line formed by a rabbit antiserum specific for rat CEA. 5B1 also bound to extracts of the RCA-1 tumor in EIA, but did not bind at all to extracts of the CEA-negative rat colonic adenocarcinoma, RCA-2, nor to extracts of normal rat tissues including liver, kidney and intestine. Inhibition tests showed that the activity of the monoclonal antibody in EIA was abolished by extracts of RCA-1 tumor, but was hardly affected by extracts of the other tissues.

Animals↗
PubMed1987

Thermostable ethanol-insoluble antigens of human heart muscle.

Organ-specific reactions were observed between thermostable ethanol-insoluble (BE) fraction of human heart muscle and its corresponding rabbit antiserum by means of tanned cell hemagglutination test, enzyme immunoassay, and gel precipitation test. Two heart-specific components could be identified using gel precipitation and immunoblotting procedures. Antibodies to human heart muscle BE combined also with heart BE preparations from mammals other than man; these interspecies cross-reactions included also rabbit heart BE pointing to the 'auto' nature of some of the antibodies under investigation. The heart antigens under study were distinct from the organ-specific antigen demonstrated by Espinosa and Kaplan in acid extract of human heart muscle.

Agglutination Tests↗
PubMed1986

Tumor immunity in rats immunized with rat carcinoembryonic antigen.

Active immunization of rats with an emulsion consisting of Freund's complete adjuvant (FCA) and an extract of rat tumor containing carcinoembryonic antigen (CEA) induced clear-cut protection from growth of the syngeneic CEA-positive tumor, RCA-1. No protection was observed in rats treated with FCA alone nor was there protection against a tumor that no serologically detectable CEA. The results suggested that the tumor immunity exhibited by the immunized rats was mediated by an immune response specific for rat CEA. It was shown further that multiparous rats were more resistant to growth of RCA-1 tumor than nulliparous rats. This suggested that immunization against rat CEA, which is an oncofetal antigen, may occur during pregnancy.

Adenocarcinoma↗
PubMed1985

Allergenic components of bald-faced hornet (V. maculata) venom.

Bald-faced hornet (V. maculata) venom collected by electrical stimulation was fractionated using molecular exclusion gel-filtration and ion-exchange chromatography. Four fractions were selected for in-depth analysis. These were analyzed for phospholipase, hyaluronidase and protease enzyme activities, antigenicity as measured by reaction with anti-hornet venom rabbit serum, and allergenic activity, as determined by RAST reaction with sera from hornet-sensitive patients. The results of these studies suggest that the fractions containing phospholipase, hyaluronidase and protease possess allergenic activity. In addition, there appear to be other allergenic components in hornet venom. Allergic patients differ in their reactivity to the various allergenic components in hornet venom and may have IgE antibodies to one or more of these components.

Allergens↗
PubMed1985

Induction of antibodies in rats to a rat carcinoembryonic antigen.

In a previous communication, carcinoembryonic antigen (CEA) of rat, which is an analogue to human CEA, was demonstrated in gastrointestinal adenocarcinomas induced in inbred Fischer rats by injection of 1,2-dimethylhydrazine. Antibodies detectable by enzyme immunoassay were elicited in Fischer rats by immunization with a perchloric acid extract of the CEA-containing rat tumor, RCA-1, incorporated into Freund's complete adjuvant. Specificity studies showed that activity of the rat antisera could be virtually abolished by inhibition with the tumor extract used at a concentration of 25 micrograms/ml. Inhibition by newborn rat tissues required extract at a concentration of 250 micrograms/ml. Extracts of normal adult tissues did not inhibit at these concentrations, but did inhibit at a concentration of 2,500 micrograms/ml. The results showed that rat CEA, though present in low concentration in normal adult rat tissue, is capable of eliciting an immune response in rats.

Adenocarcinoma↗
PubMed1985

Comparison of measurements of serum venom-specific IgG by radioimmunoassay and enzyme immunoassay.

Honeybee venom (BV)-, yellow jacket venom (YJV)- and honeybee venom phospholipase A (PLA)-specific IgG were measured by radioimmunoassay (RIA) and enzyme immunoassay (RIA) in 54 sera of insect-allergic patients. In the majority of sera, results of the two tests were similar. Discordant results were found in 1 of 21 sera in tests with PLA, 4 of 23 sera in tests with BV, and 1 of 16 sera in tests with YJV. The RIA measured higher antibody titers in 5 of these 'outlier' sera. The results suggest that with a few exceptions, the two assays are similar for detection of venom- and PLA-specific IgG.

Antibodies↗
PubMed1985

Effect of immunization or cyclophosphamide treatment on growth of EL-4 leukemia cells in syngenic C57BL/6 mice.

Prolonged survival of C57BL/6 (B6) mice bearing syngenic EL-4 leukemia cells resulted from immunization with irradiated EL-4 cells on the day of inoculation of live leukemia cells. No prolongation of survival was observed if the irradiated cells were injected 6 or 13 days after live cell inoculation. Protection also was observed in EL-4-bearing mice that were treated with cyclophosphamide (CY) rather than by immunization, however, the protective effects were observed only when CY treatment was instituted 6 days after inoculation of live leukemia cells. No protection was seen when CY was administered on the day of, or 13 days after inoculation of live leukemia cells. In fact, administration of CY on the day live EL-4 cells were inoculated appeared to enhance the lethal effects of the tumor. In mice that underwent combined treatment, i.e., immunization and CY, prolonged survival was seen only in the group that received combined treatment 6 days after inoculation of live leukemia cells. No protection was seen in mice receiving combined treatment on the day of or 13 days after inoculation of live leukemia cells. The role that suppressor T cells might play in the observed results is discussed.

Animals↗
PubMed1985

Rabbits immunized with mixtures of staphylococcal protein A and autologous IgG produce anti-human IgG antibodies.

The results of this study provide evidence that protein A may render IgG immunogenic in the autologous host. Antibodies to human but not rabbit IgG were detected in sera of rabbits immunized with a mixture of autologous serum and protein A. Anti-human IgG antibodies appeared within 2 weeks at which time the antibodies were of the IgM class. Upon further immunization, both IgM and IgG antibodies were produced with the IgG class predominating. The antibodies elicited by a mixture of protein A with autologous IgG resembled those which arise in response to autologous IgG that has been denatured by physicochemical means, in that they react mainly with foreign species IgG and weakly, if at all, with IgG of rabbit origin.

Animals↗
PubMed1984

Use of dialyzed venoms in the radioallergosorbent test.

Optimal concentrations of honeybee, hornet and yellow jacket venoms were used in the radioallergosorbent test (RAST) before and after dialysis. RAST titers in the majority of sera from insect-allergic patients increased significantly with the dialyzed yellow jacket and hornet venom-coupled discs. Of 26 sera which had negative RASTs with crude venom, 20 became positive with dialyzed venom. No change in RAST results was found with crude and dialyzed honeybee venom. The low molecular weight component in the vespid venoms removed by dialysis had no specific activity in RAST inhibition experiments, suggesting nonspecific blocking of binding sites. These results indicate the importance of the appropriate antigen preparation coupled to discs in the RAST.

Allergens↗
PubMed1981

Purification of a human pancreas-specific antigen.

Using an antibody reagent, an organ-specific antigen has been purified from human pancreas. Purification was achieved using ammonium sulfate and ethanol precipitations, concanavalin A-Sepharose affinity chromatography, anion-exchange chromatography and gel filtration. The antigen had a molecular weight of approximately 68,000 as determined by gel filtration, was not dissociated into subunits by sodium dodecyl sulfate, and did not bind to immobilized concanavalin A. The biological significance of this antigen in pancreatic cancer is being studied.

Animals↗
PubMed1979

The use of staphylococcal protein A in the mixed agglutination test.

A mixed agglutination (MA) test employing staphylococcal protein A (SpA) instead of an antiglobulin reagent has been developed for the detection of IgG antibodies bound to cell-surface antigens. In the SpA MA test, a single indicator system may be used for the detection of IgG antibodies from several mammalian species. The sensitivity of this test compares favorably with that of the conventional MA test in the detection of most mammalian IgG. The main advantage of the conventional SpA MA test is its usefulness in the study of antigens on cells because of adherence of antibody-coated indicator erythrocytes.

Animals↗
PubMed1978

Studies on skin-reacting transplantation antibodies.

Evidence is presented that skin-reacting transplantation antibodies (SRTA) can be elicited not only by skin allografts, but also by injection of dispersed allogeneic lymphoid cells. Two mechanisms of action of SRTA, which are not mutually exclusive, are compatible with the experimental results. (1) SRTA may act as homocytotropic antibodies, producing skin reactions by fixing to the skin of the test animal and combining with circulating antigens brought to the test site. (2) SRTA may produce skin reactions by combining directly with "sessile" antigens in the skin. Genetic studies showed that the antigens combining with SRTA are inherited as simple Mendelian traits. Furthermore, it was shown that these antigens are not related to the major rat histocompatibility antigens, Ag-B, nor are they related to any other described rat alloantigen system. Thus, the antigens responsible for SRTA belong to a new antigenic system.

Animals↗