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At least 829 records · Page 46Linked to original sources
PubMed1986

Characterization of monoclonal antibody to DNA.RNA and its application to immunodetection of hybrids.

Monoclonal antibodies were raised to a DNA.RNA heteropolymer duplex prepared by transcription of phi X174 single-stranded DNA with DNA-dependent RNA polymerase. A monoclonal antibody with the highest affinity and specificity was selected. This antibody bound the DNA.RNA heteropolymer and poly(I).poly(dC) equally but 100-fold higher levels of poly(A).poly(dT) were required to achieve a similar degree of binding in competitive binding assays using DNA.[3H]RNA. Single-stranded DNA, double-stranded DNA and RNA, and ribosomal RNA were not bound by the antibody. The observed association constant for the antibody and DNA.[3H]RNA, determined by Scatchard analysis, was 8.5 X 10(10) l/mol assuming independent antibody binding sites. The antibody and an alkaline phosphatase-labeled second antibody were used in an immunodetection method for measurement of hybrids formed between immobilized DNA probes of various lengths and 23 S ribosomal RNA. The colorimetric response of this assay increased linearly with the amount of hybrid formed.

Animals↗
PubMed1988

Production of monoclonal antibodies against human erythropoietin and their use in the purification of human urinary erythropoietin.

Several murine monoclonal antibodies (MAbs) specific for human erythropoietin (HuEpo) were produced by hybridomas obtained from the fusion of murine myeloma cells, P3X63-Ag.8-653, with the splenocytes of mice immunized with recombinant human Epo (rHuEpo). Based on epitope analysis by a competitive binding assay, these MAbs could be classified into at least three groups: (1) 1E10, (2) 1H7, (3) 2D6, 3D6 and 3D8. In a sandwich enzyme-linked immunosorbent assay (ELISA), using these MAbs as the solid-phase antibodies, MAb-bound HuEpo was detected with rabbit anti-HuEpo sera. Some combinations of two different classes of MAbs, such as 1H7 and 3D8, were found to capture much more HuEpo than each MAb used individually. Urinary HuEpo (U-HuEpo) was highly purified from the urine of patients with severe aplastic anemia with about 50% final recovery using an immunoaffinity column on which a mixture of 1H7 and 3D8 was immobilized. The purified U-HuEpo had a specific activity of 77,340 U/mg in a radioimmunoassay (RIA) and of 76,673 U/mg using an in vivo bioassay.

Anemia, Aplastic↗
PubMed1994

Monoclonal antibodies as probes to detect conformational changes in the rat cysteine proteinase inhibitor cystatin A.

Five monoclonal antibodies (MAbs), 77, 114, 138, 175 and 187, were established for rat cystatin A. MAbs 77, 114, 138 and 175 were shown to belong to the IgG1 subclass, whereas MAb 187 was an IgM. These MAbs partially suppressed inhibitory activity of rat cystatin A to papain. Their epitopes were mapped in detail on the molecule by examining the reactivities of the MAbs with NH2-terminally truncated forms and fragments of rat cystatin A by an enzyme-linked immunosorbent assay (ELISA), and by reactivity with the inhibitor on immunoblotting. In competitive binding assays the MAbs did not compete with each other, indicating that the epitopes recognized by these MAbs were substantially different. The conformational epitope recognized by the three MAbs 114, 138 and 175 belonged to one group that was highly sensitive to denaturation, but those epitopes were unchanged by NH2-terminal truncation. MAb 187 was able to recognize a linear epitope present in amino acid residues 15-50 in the NH2-terminal region. MAbs 77 and 114 reacted weakly with mouse cystatin A but not at all with human cystatin A, whereas MAb 187 reacted similarly with mouse cystatin A but at about half that level with human. The MAbs produced in this study should be useful tools for detecting conformational changes in the rat cystatin A molecule.

Amino Acid Sequence↗
PubMed1982

Regulation of the glucocorticoid receptor in human lymphocytes.

The presence of a glucocorticoid receptor in human lymphocytes is well established, but factors affecting its regulation have not been described. Using a competitive binding whole cell assay, we have examined the binding of [3H]-dexamethasone at 24 and 37 degrees C in untreated normal subjects and in healthy subjects taking various glucocorticoid preparations. At 24 degrees C normal human lymphocytes had 6000 binding sites/cell and a dissociation constant of 4 x 10(-9) M. The administration of 1 mg of dexamethasone, 5 mg of prednisone, and 37.5 mg of cortisone acetate resulted in a 30% decrease in binding sites after 1 week with no change in binding affinity. No changes in the number of binding sites was noted before 1 week and the diminished number persisted for 1 week after discontinuation of glucocorticoid treatment. Lymphocytes from hospitalized patients taking 40-60 mg of dexamethasone daily demonstrated the same change in number of binding sites that was seen in normal subjects taking 1 mg of dexamethasone. When binding assays were carried out at physiologic temperature there was the same decrease in number of binding sites after dexamethasone administration, and in addition, there was a two-fold increase in binding affinity. Glucocorticoid administration results in a time-dependent decrease in the number of lymphocyte glucocorticoid binding sites that is independent of the type of glucocorticoid administered. This is the first in vivo demonstration that glucocorticoids modulate their own receptors in man.

Binding, Competitive↗
PubMed1984

Characterization of a specific androgen receptor in non-Hodgkin's lymphoma cells.

The use of a competitive binding assay has permitted us to detect a cytoplasmic androgen receptor in cells of node biopsies of several patients suffering from non-Hodgkin's malignant lymphomas (NHML). These same cells appear to contain very low or undetectable numbers of estrogen receptor. The androgen receptors are saturated at approximately 2 X 10(-10) M [3H] 5 alpha DHT and Scatchard analyses of the binding data indicated a high affinity constant (Kd = 0.29 +/- 0.19 10(-9) M). The range of receptor sites is 19-327 fmol/mg protein (median = 42 fmol/mg protein). These cytoplasmic receptors are inactivated at 37 degrees C and pronase. The [3H] 5 alpha DHT receptor complex migrates in linear 5-20% sucrose gradients with a sedimentation coefficient of 7S and this peak is shifted to the 4S region under high salt conditions. Physiochemical properties of the binding including binding capacity and steroid specificity, are quite similar to those reported in target organs.

Adolescent↗
PubMed1985

A comparison of estrogen and androgen receptor levels in human prostatic tissue from patients with non-metastatic and metastatic carcinoma and benign prostatic hyperplasia.

Estrogen receptors (ER, N = 72) and androgen receptors (AR, N = 33) were determined by high pressure liquid chromatography (HPLC) in 72 human prostatic tissues obtained at prostatectomy, and exploratory statistical analyses of the resulting data were performed. To facilitate use of these data as well as other pertinent information from the patient charts, a program for a comparatively large data base was implemented on a Wang minicomputer. The median values of cytosolic AR in the four cancer stages examined were statistically different from each other (P = 0.01), with AR increasing from stages A through D. Even though ER differences between the four stages were not significant (P = 0.13), there was a trend, in the data examined, for median ER values to decrease with stages B through D. On the other hand, median BPH values for both ER and AR were found to lie mid-scale compared with the respective cancer stages, leading to the conclusion that receptor measurements probably cannot distinguish between CA and BPH in human prostatic tissue, at least as measured by competitive binding techniques.

Binding, Competitive↗
PubMed1987

Growth inhibition by danazol in a human endometrial cancer cell line with estrogen-independent progesterone receptors.

Since we recently found that danazol, an isoxazol derivative of ethinyltestosterone, has a growth-inhibitory effect on human endometrial cancer cells in primary culture, the effects of danazol on a human endometrial cancer cell line (IK-90 cells), which contains estrogen-independent progesterone receptors (PR), were investigated in the present study. The addition of danazol (1 nM-1 microM) in culture medium caused a decrease in the growth of IK-90 cells in a dose-dependent manner. Competitive binding studies showed that danazol effectively binds to PR in IK-90 cells, and the binding affinity for PR was estimated to be 6.0% of that of R5020. The addition of 1 microM danazol in culture medium resulted in a rapid and significant increase in nuclear PR with a concomitant decrease in cytoplasmic PR in the cells. These findings suggest that danazol has a growth-inhibitory effect on human endometrial adenocarcinoma cells directly through PR system in the cells.

Binding, Competitive↗
PubMed1990

Characterization of thromboxane A2/prostaglandin H2 receptors in human vascular smooth muscle cells.

The present study utilizes a newly synthesized TXA2/PGH2 mimetic, I-BOP, to characterize the TXA2/PGH2 receptor in suspensions of cultured human vascular smooth muscle cells. [125I]-BOP bound in a saturable and specific manner (Kd = 2.6 +/- 0.6 nM; Bmax = 33,540 +/- 6,200 sites/cell; 69 fmoles/mg protein, n = 12). Competition binding assays were performed with [125I]-BOP and the TXA2/PGH2 receptor antagonists SQ29548, L657925 and L657926 and the receptor agonist U46619. I-BOP induced concentration-dependent increases in intracellular free calcium which were inhibited by SQ29548. The results provide radioligand binding evidence for the presence of a TXA2/PGH2 receptor in human vascular smooth muscle cells.

Binding, Competitive↗
PubMed1990

Lack of biological activity of preproendothelin [110-130] in several endothelin assays.

A 21 amino acid peptide containing the prepropendothelin sequence from amino acids 110 to 130 and two intrachain disulfide bonds was synthesized and tested for biological activity in the following endothelin assays: 1.) a competition binding assay using [125I]ET-1 and dog heart membranes, 2.) three RIA's using 125I-ET-1, -2 and -3 and the respective anti-ET rabbit antisera; and 3.) a contractile activity bioassay using hamster aortic rings. The synthetic peptide which has been referred to as the "endothelin-like" peptide occurs 36 amino acids C-terminal to endothelin in the prepro-protein sequence. It contains only 40% sequence homology to the three endothelin isoforms, but has the same sequence and cyclization pattern of cysteines at positions 1, 3, 11 and 15. Despite the overall similarity in secondary structure to the three isoforms of endothelin and sarafotoxin S6b, preproendothelin [110-130] had no activity in any of the assays when tested at concentrations of 10(-10)M to 10(-5)M.

Amino Acid Sequence↗
PubMed1996

Increased hepatic endothelin-1 levels and endothelin receptor density in cirrhotic rats.

Endothelin-1 (ET-1), the most powerful agent to cause constriction of the hepatic vasculature, is synthesized in the liver by sinusoidal endothelial cells. Circulating ET-1 levels have been shown to increase in liver cirrhosis. As liver could be a major source of increased plasma ET-1 as well as a target for its pathologic actions, this study was designed to determine hepatic ET-1 and ET receptor(s) in experimental liver cirrhosis. Cirrhosis was induced in rats by intraperitoneal administration of carbon tetrachloride for 8 weeks. Hepatic ET-1 was measured by radioimmunoassay and ET receptors were determined by radioligand competition binding procedure. A four fold increase in ET-1 concentration accompanied by a 65% increase in ET-receptor density was observed in the cirrhotic liver. There was no change in the ET receptor affinity. The capacity of the liver to metabolize ET-1 was reduced significantly in cirrhosis. Interestingly, transforming growth factor-beta, hepatic levels of which increase in cirrhosis, stimulated ET-1 synthesis in cultured Ito cells. It has been shown that ET-1 is a potent constrictor of Ito cells that proliferate and transform into highly contractile myofibroblasts in liver cirrhosis. Thus, interactions between ET-1 and Ito cells may have significant implications in the pathogenesis and complications of liver cirrhosis.

Animals↗
PubMed1979

A novel fluorinated derivative of diethylstilbestrol.

The synthesis of the diethylstilbestrol (DES) derivative with fluorine atoms present in the positions ortho to the hydroxyl in each ring is described. In vitro studies in a system containing horse radish peroxidase/H2O2 demonstrate extensive oxidation of tetrafluorodiethylstilbestrol to the corresponding dienestrol derivative. Tetrafluorodiethylstilbestrol and DES had comparable in vivo uterotropic activities at a dose of 100 microgram/kg. Competitive binding experiments demonstrated 20-25 fold reduced interaction with the mouse uterine estrogen receptor. This compound may be useful as an experimental estrogen in distinguishing between the biological and toxic effects of DES.

Animals↗
PubMed1987

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on hepatic and uterine estrogen receptor levels in rats.

Administration of a single dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 20 or 80 micrograms/kg) resulted in significantly decreased hepatic and uterine estrogen receptor (ER) levels in 25-day-old female Long-Evans rats. By contrast, estradiol (5 and 15 micrograms/kg) administration increased hepatic and uterine ER levels, while a combination of 2,3,7,8-TCDD plus estradiol resulted in uterine and hepatic ER levels which were similar or lower than those observed after treatment with only 2,3,7,8-TCDD. In addition, 2,3,7,8-TCDD significantly decreased the effects of estradiol on uterine wet weight increase. Competitive binding studies showed that estradiol did not bind to the aryl hydrocarbon (Ah) receptor and that 2,3,7,8-TCDD did not bind to the ER. The effects of structure on the activity of polychlorinated dibenzo-p-dioxin congeners on their activity to down-regulate hepatic and uterine ER levels were determined by using 2,3,7,8-TCDD, 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), 1,3,7,8-TCDD, and 1,2,4,7,8-PeCDD. Both 2,3,7,8-TCDD and 1,2,3,7,8-PeCDD exhibit high affinities for the Ah receptor and at dose levels of 80 micrograms/kg the hepatic ER levels were decreased 42 and 41%, respectively, and uterine ER levels were decreased 53 and 49%, respectively. 1,3,7,8-TCDD and 1,2,4,7,8-PeCDD bind less avidly to the Ah receptor and at dose levels of 400 micrograms/kg these compounds decreased hepatic ER levels 36 and 40%, respectively, and uterine ER levels 21 and 24%, respectively. These results support a role for the Ah receptor in the down-regulation of uterine and hepatic ER levels in the female rat by 2,3,7,8-TCDD and this effect may be associated with the decrease in spontaneous mammary and uterine tumors observed in female rats treated with 2,3,7,8-TCDD.

Animals↗
PubMed1983

Monoclonal antibodies to the HN glycoprotein of Newcastle disease virus. Biological characterization and use for strain comparisons.

We have isolated nine hybridomas secreting monoclonal antibodies directed against the HN glycoprotein of D26 strain of Newcastle disease virus (NDV) and classified them into three groups by their biological reactivities. The group I antibodies from six clones had high hemagglutination inhibition (HI) and neutralization titers, and exhibited neuraminidase inhibition (NI) activity with substrates, both bovine fetuin and N-acetyl neuraminlactose, although the levels of maximum inhibition were greater with the former substrate. The group II antibodies from two clones also had high HI activity but showed a strongly substrate-dependent NI, with efficient inhibition against fetuin and a total lack of inhibition against neuraminlactose. These antibodies had neutralization capacity but the titers were much lower than those of group I antibodies. One clone (group III) secreted antibody which exhibited HI and NI with either substrate but no detectable neutralization activity. Frequency of isolation of antigenic variants and competitive binding assays have shown that group I and group II antibodies may recognize distinct regions not overlapping each other whereas antibodies placed within each of the two groups are to the respective same overlapping regions. The site of group III seemed to be close to or overlap the group I determinant but distinct from group II region. Using the isolated monoclonal antibodies we compared seven heterologous strains by HI and neutralization tests as well as by enzyme-linked immunosorbent assay. The results indicated that the regions recognized by group I antibodies would be conserved among the strains whereas those by the other two antibody groups might undergo considerable changes.

Antibodies, Monoclonal↗
PubMed1983

Evidence for three separate antigenic sites on the G1 protein of La Crosse Virus.

Competitive binding assays with monoclonal antibodies have been used to show that there are a minimum of three nonoverlapping antigenic sites on the G1 glycoprotein of La Crosse virus. One of these sites contains the epitopes for three of the five monoclonal antibodies employed and is involved with both hemagglutination and neutralization. A second site contains the epitope for an antibody that inhibits hemagglutination but has no neutralizing activity. The third site encompasses the epitope for an antibody that at present has no identified biological role.

Antibodies, Monoclonal↗
PubMed1984

The major surface glycoprotein of simian rotavirus (SA11) contains distinct epitopes.

The polypeptide specificities on monoclonal antibodies previously derived against the SA11 simian, NIC bovine, and Wa human strains of rotavirus were determined by radioimmunoprecipitation of infected cell lysates. All the monoclonal antibodies derived using NIC and Wa were found to be directed against the major component of the inner capsid, while most of the SA11 monoclones were directed against the major outer capsid glycoprotein. When several SA11 glycoprotein-specific monoclonal antibodies were used in competitive binding studies, four distinct epitopes, which correlated with the functional activities of the antibodies, were defined. One epitope appeared most critical for virus neutralization, another was involved to a lesser extent, and the remaining two epitopes seemed to have no role. A possible topographical arrangement of these epitopes is suggested.

Animals↗
PubMed1986

Characterization of epitopes on the measles virus hemagglutinin.

Measles virus hemagglutinin epitopes were analyzed using nine monoclonal antibodies (MAbs) in competitive binding assays (CBA) and by in vitro selection of antigenic variants. In CBA the nine MAbs formed four different but partially overlapping binding groups. In vitro selected variants were analyzed by radioimmune precipitation assay, hemagglutination inhibition (HI), and neutralization assays. Seven operationally distinct MAb antigenic sites could be delineated: two sites were defined by two MAbs to each and five sites by single MAbs. Variants which had lost reactivity to different combinations of MAbs were generated by a branched sequential selection procedure. The most epitopically modified variants had lost reactivity in all assays to eight MAbs. None of these variants showed any major changes in hemagglutination nor neurotropism per se. Only minor changes were detected by HI in reactivity of these variants with human measles antiserum indicating that the epitopic changes were not of major epidemiological significance at least in terms of HI.

Antibodies, Monoclonal↗
PubMed1987

Monoclonal antibodies to the glycoprotein of vesicular stomatitis virus (New Jersey serotype): a method for preliminary mapping of epitopes.

Of the nine antigenic determinants on the glycoprotein (G) of the New Jersey serotype of vesicular stomatitis virus (VSV) identified by competitive binding of 25 monoclonal antibodies (MAbs), those relegated to epitopes I, II, III, and IV exhibited no significant ability to neutralize virus infectivity but some nonneutralizing MAbs cross-reacted by ELISA with the G protein of VSV-Indiana. High-titered neutralization of homotypic virus was exhibited by epitope V, VI, and VII MAbs but quite variable neutralizing activity was found among MAbs of epitope "family" VIII and particularly the heterogeneous epitope "family" IX. Peptide mapping of the epitopes was not feasible because most MAbs would not bind by Western blotting to G protein under standard conditions of proteolysis or disulfide bond reduction. Therefore, a technique was devised for roughly locating epitopes by protease footprinting of G protein partially protected by individual MAbs complexed with staphylococcal protein A-Sepharose beads. Under these conditions, MAbs to all nine epitopes protected a similar 12-kDa fragment of the G protein from proteolysis by Staphylococcus aureus V8 protease. N-Terminal amino acid sequencing mapped two of these 12-kDa peptide footprints to a position on the G protein extending from amino acid 219 to about 100 amino acids downstream. Although MAbs to only one epitope bound to the 12-kDa fragment by Western blotting, these data suggest, but do not prove, that all nine epitopes of the undenatured VSV-New Jersey G protein are clustered at the middle 20% of a highly structured protein. This method may help to identify the general regions for epitopes on complex proteins of as yet unknown three-dimensional structure.

Amino Acid Sequence↗
PubMed1990

Discrimination of hepatitis B virus (HBV) subtypes using monoclonal antibodies to the PreS1 and PreS2 domains of the viral envelope.

We report the production and characterization of murine anti-PreS2 and anti-PreS1 monoclonal antibodies (mAb) and demonstrate their utility in discriminating hepatitis B virus (HBV) subtypes. On the basis of Western blotting and reciprocal competition binding to HBV virions, at least five distinct epitopes have been identified in the PreS domain: two within the PreS1 region and three within the PreS2 region. All PreS2 mAb bind M protein (gp33 and gp36) but only one group binds strongly to M and L proteins (p39 and gp42). This group determinant was mapped to peptide residues 120-145. The second group bound to an endoglycosidase F-sensitive epitope which is defined by a mannose-rich glycan at ASN 123 in the PreS2 region. The third group was mapped to peptide residues 150-174 and was reactive with the M envelope proteins but not L or S proteins on Western blots. All PreS1 mAb bind L protein but not M protein on Western blots. Using these mAb, HBV subtype assays were developed allowing evaluation of the Paris (1975) HBsAg subtype panel members along with other HBsAg-positive specimens. All Paris subtype members (except ayw2 and ayw3) could be easily distinguished by differential PreS2 mAb reactivity. The Paris subtypes, adw2, adw4, and adr, could be classified as distinct groups by PreS2 and PreS1 mAb binding. Specimens from Hong Kong and the United States classified as adw2 in the S region fell into two groups based on PreS2 mAb binding: one having reactivity similar to Paris adw2 subtype and the other having identical reactivity to Paris ayw1 subtype. Furthermore, some specimens classified as adr in the S region gave similar reactivity to the Paris ayr subtype in the PreS2 and PreS1 regions. One complicating factor in this approach toward subtyping was the discovery that some HBsAg positive sera may contain factors which block PreS epitopes. Grouping of HBV subtypes by PreS1, PreS2, and S mAb reactivity may allow better correlation with groupings based on HBV DNA sequence homology.

Animals↗