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E Haber

Publications and source records attributed to E Haber.

At least 145 records · Page 8Linked to original sources
PubMed1986

Antigenic competition at the level of peptide-Ia binding.

We examined the direct binding of a hen egg white lysozyme peptide, HEL(46-61), to membrane I-Ak (protein encoded in the A locus of the I region) molecules in the presence of detergent. A number of synthetic peptide derivatives, which did not stimulate our T-cell reactive hybridomas, competed for the binding of HEL(46-61) to I-Ak and also inhibited the functional presentation of HEL(46-61). Inhibitors included a peptide lacking a tyrosine at position 53 and a peptide corresponding to the autologous lysozyme peptide. Presentation was examined with cells or with supported planar phospholipid membranes bearing only I-Ak and HEL(46-61). Other peptides that did not compete for the binding did not inhibit functional presentation. We concluded that the binding of an immunogenic peptide to I-A is critical for presentation, that the I-A molecule does not discriminate between autologous and foreign related determinants but does recognize structurally different peptides. Our evidence suggests that our immunogenic peptide bears noncontiguous amino acids critical for contact I-A binding interspersed with amino acids critical for interaction with T cells.

Amino Acid Sequence↗
PubMed1986

Antigenic determinants in proteins coincide with surface regions accessible to large probes (antibody domains).

We evaluated surface areas on proteins that would be accessible to contacts with large (1-nm radius) spherical probes. Such spheres are comparable in size to antibody domains that contain antigen-combining sites. We found that all the reported antigenic sites correspond to segments particularly accessible to a large sphere. The antigenic sites were also evident as the most prominently exposed regions (hills and ridges) in contour maps of the solvent-accessible (small-probe) surface. In myoglobin and cytochrome c, virtually all of the van der Waals surface is accessible to the large probe and therefore potentially antigenic; in myohemerythrin, distinct large-probe-inaccessible, and nonantigenic, surface regions are apparent. The correlation between large-sphere-accessibility and antigenicity in myoglobin, lysozyme, and cytochrome c appears to be better than that reported to exist between antigenicity and segmental flexibility; that is, surface regions that are rigid often constitute antigenic epitopes, whereas some of the flexible parts of the molecules do not appear antigenic. We propose that the primary reason why certain polypeptide-chain segments are antigenic is their exceptional surface exposure, making them readily available for contacts with antigen-combining sites. Exposure of these segments frequently results in high mobility and, in consequence, to the reported correlation between antigenicity and segmental flexibility.

Cytochrome c Group↗
PubMed1986

Monoclonal antibodies of predetermined specificity for fibrin: a rational approach to monoclonal antibody production.

Three monoclonal antibodies (MAbs) (55D10, 59D8, and 64C5) have been produced by an immunization strategy that uses a synthetic heptapeptide from the amino terminus of the beta-chain in human fibrin. These MAbs bind to human fibrin in the presence of 4 mg/ml human fibrinogen in solid-phase radioimmunoassay. Ligand specificity studies demonstrate that antifibrin immunoreactivity is completely inhibited by a series of synthetic fibrin-like beta-peptides that bear the position-2 histidyl residue. Although the presence of this residue on the epitope is necessary for its recognition by a fibrin-specific antibody, the presence of the histidyl residue alone is not sufficient for antibody recognition.

Animals↗
PubMed1986

A monoclonal antibody specific for the amino terminal sequence of human prorenin identifies a common epitope on renal and amniotic fluid inactive renins.

A synthetic nonapeptide corresponding to the predicted amino terminus of human prorenin was synthesized and used as an antigen in the production of mouse hybridomas. Forty-seven clones producing antibody to this peptide were identified and screened for ability to bind to partially purified amniotic fluid inactive renin in a soluble phase assay. None showed activity. One purified antibody, 4D3-3C4, was found to bind by Western blotting to renal and amniotic fluid inactive renins, molecular size 52 kDa, after gel electrophoresis in sodium dodecyl sulphate (SDS) following reduction with mercaptoethanol. In contrast, the anti-renin monoclonal antibody, R3-27-6, recognizes active renin, molecular size 38 kDa, and two inactive renin species, 42 kDa and 52 kDa, in the same renin preparations. Kidney and amniotic fluid apparently contain an inactive renin that possesses the complete prorenin sequence. These data indicate that high molecular weight inactive renin from both kidney and amniotic fluid contain an epitope, accessible to antibody only after denaturation, which represents the amino-terminal octapeptide sequence of prorenin. The inactive renin preparations tested also contain smaller fragments which either possess this epitope or do not, while still reacting with antibodies to active renin. It is likely that all these smaller inactive renin species are the result of proteolysis, either post-synthetic or in vitro.

Amniotic Fluid↗
PubMed1986

In vivo diagnostic and therapeutic uses of monoclonal antibodies in cardiology.

Antibodies, long used as discriminating tools in immunoassay, are now being used in vivo, both in diagnosis and therapy. In cardiovascular medicine, applications that have reached the stage of clinical trial include the reversal of digitalis intoxication by digoxin-specific antibodies and the imaging of cardiac necrosis with monoclonal myosin-specific antibodies. An exciting future prospect, still in an early experimental stage, is the application of fibrin-specific monoclonal antibodies to both the visualization of thrombi and emboli and the targeting of fibrinolytic agents.

Adolescent↗
PubMed1986

Scintigraphic quantification of myocardial necrosis in patients after intravenous injection of myosin-specific antibody.

The Fab fragments of antimyosin antibodies, labeled with 99mTc, were used in the scintigraphic examination of 30 patients with myocardial infarction. The ability to detect necrosis and determine its extent from the antimyosin scan were compared with the results of quantitative regional wall motion analysis by contrast ventriculography at 10 to 14 days and 99mTc-pyrophosphate imaging. Antimyosin images recorded by planar and single photon-emission computed tomography (SPECT) delineated areas of myocardial necrosis in 27 of 30 patients (90%) compared with a 91% sensitivity of pyrophosphate in 21 of 23 patients. Infarct size was determined by both antimyosin and pyrophosphate SPECT images. Results by both techniques showed a significant correlation with computer-derived hypokinetic segment length (r = .79 for both, p = .002) and peak creatine kinase (r = .9 for both, p less than .01). Although sensitivity for and correlations with markers of necrosis were similar with both techniques, infarct size by pyrophosphate SPECT was 1.7 times larger than infarct size by antimyosin SPECT (p less than .01). Certain zones in the infarct area were differentially labeled; the nature and irreversibility of injury within these zones remains to be clarified.

Antibodies↗
PubMed1986

Renin inhibitors.

Explore the source record for details and available documents.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1986

Study of the antigenic determinants of human renin.

The primary structure of human renin, recently established from the complementary DNA sequence of its messenger RNA, shows a strong homology to other aspartyl proteases. This homology has permitted the construction of a model of the three-dimensional structure of renin based on the crystallographically determined structures of three aspartyl proteases: penicillopepsin, endothiapepsin, and rhizopuspepsin. Using an algorithm in which a spherical probe approximating the size of the antibody-binding domain (1-nm radius) was allowed to contact the surface of the renin model, we predicted 12 to 15 peptides to be immunogenic epitopes. We synthesized peptides corresponding to three different regions of the model: Cys-Gly-Ser-Asp-Pro-Gln-His-Tyr-Glu-Gly-amide (C-180-188), Tyr-Leu-Leu-Cys-Glu-Asp-Gly-Cys-Leu-Ala-Leu-amide (Y-215-224; disulfide bond between cysteines) and Tyr-Gly-Ser-Ser-Thr-Leu-Leu-Cys-Glu-Asp-Gly-Cys-Leu-Ala-Leu-amide (Y-211-224; disulfide bond between cysteines), and Cys-Tyr-Ser-Ser-Lys-Lys-Leu-Cys-Gly (C-290-296-G; disulfide bond between cysteines). All four peptides were tested for their binding to 11 polyclonal and 7 monoclonal antibodies raised against pure human renin, in both a solution assay and an enzyme-linked immunosorbent assay. Peptides Y-215-224 and Y-211-224 bound to all 11 polyclonal antibodies in the solution assay, and peptide Y211-224 bound to eight of them in the enzyme-linked immunosorbent assay. Therefore, region 211-224 can be identified as a major epitope of the human renin molecule.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1986

Monoclonal antibodies as molecular probes to study structural heterogeneity between human and animal renins and other aspartyl proteinases.

Monoclonal antibodies may be helpful in comparing the structural homology of renins of various animal species as well as other aspartyl proteinases. We obtained four hybridoma lines secreting monoclonal antibodies that inhibited 3 Goldblatt mU human renin enzymatic activity with apparent IC50 of 1.1 X 10(-6)-4 X 10(-8) M. Each antibody was specific for human renin and did not cross-react either with other proteins tested nor with renins of other species in an immunoradiometric assay. These antibodies did not inhibit the enzymatic activities of nonprimate renins or nonrenin aspartyl proteinases tested. These data indicate that certain structural determinants of human renin activity may be uniquely different from those of nonprimate renins or nonrenin aspartyl proteinases.

Animals↗
PubMed1986

[Modification of monoclonal antibodies by polymers possessing chelating properties].

Monoclonal antibodies to heavy chains of the heart myosin were chemically modified by chelate polymers containing EDTA or DTPA residues. The modification allows binding up to 90 atoms of heavy metals (e.g. 111In, Mn2+, Cd3+) per protein globule, i.e. an increase in the specific activity of labeling 20 to 50-fold in comparison with previous methods. Specific affinity of the modified protein is preserved. Conjugates obtained may be useful for in vivo immuno-imaging.

Animals↗
PubMed1985

Immunodetection of human fibrin using monoclonal antibody-64C5 in an extracorporeal chicken model.

The potential use of a fibrin-specific monoclonal antibody-64C5 as a thrombus detecting agent was examined in a quantifiable extracorporeal circulatory model using the chicken. This species was selected because antibody-64C5 did not cross-react with chicken fibrin. Human fibrinogen was clotted with human thrombin and factor XIII on filter paper disks, which were then inserted into an ex-vivo chamber that interrupted an extracorporeal loop between a carotid artery and a jugular vein. Antibody-64C5 was injected intravenously and after an equilibration period, disks bearing human fibrin were placed in the extracorporeal chamber and exposed to circulating antibody. Uptake which was quantified by treating the disks with 125I-goat antimouse-(Fab')2 was rapid, with 70 percent of maximal uptake occurring within 10 min. Fibrinolysis, although measurable, had no adverse effect upon uptake of the monoclonal antifibrin-64C5.

Animals↗
PubMed1985

Antibody-directed urokinase: a specific fibrinolytic agent.

A specific fibrinolytic agent was synthesized by covalently coupling urokinase to a monoclonal antibody that was fibrin-specific and did not cross-react with fibrinogen. The antibody was raised against a synthetic peptide representing the seven amino-terminal residues of the beta chain of human fibrin. The urokinase-antifibrin conjugate retained the original binding specificity of the antibody and showed 100-fold increased fibrinolysis in vitro when compared to unmodified urokinase. The presence of human fibrinogen at plasma concentration did not influence these properties.

Antibodies, Monoclonal↗
PubMed1985

Quantifying cell death in the myocardium: myosin specific antibody in the evaluation of membrane defects.

Methods for evaluating cardiac myocyte necrosis utilizing antibodies specific for the heavy or light chains of cardiac myosin are reviewed. Cell death, associated with sarcolemmal disruption, results in the leakage of myosin light chains from the cytoplasm as well as the accessibility of myosin heavy chains to exogenous specific antibodies. Measurement of plasma light chain concentration has been useful in the diagnosis of myocardial infarction, though more recently, patients with congestive cardiomyopathy associated with an inflammatory infiltrate have been identified by an elevated plasma light chain concentration. The binding of myosin heavy chains to necrotic myocytes has been useful in the study of mechanisms of ischemic cell death in cell culture, in the diagnosis and quantification of myocardial infarction, both experimentally and clinically, and more recently in the study of experimental myocarditis and cardiac transplantation. It is hoped that these methods may evolve as useful clinical tools in the identification of those cardiomyopathy patients whose course is characterized by rapid myocyte loss.

Animals↗
PubMed1985

Recognition of peptide orientation: studies with angiotensin II in the guinea-pig.

Antipeptide sera of defined subspecificities were obtained when angiotensin II was unidirectionally conjugated to its carrier protein. Antisera with predominantly amino terminal specificity were produced when guinea-pigs were immunized with angiotensin II conjugated via its carboxy terminus to thyroglobulin. When angiotensin II was coupled via its amino terminus, carboxy terminal-specific antisera were obtained. The same conjugates failed to provide antisera with the corresponding specificities when rabbits were used instead of guinea-pigs. This work demonstrates that the peptide-protein coupling strategy may affect the specificity of the resulting antiserum.

Angiotensin II↗
PubMed1985

Binding and structural diversity among high-affinity monoclonal anti-digoxin antibodies.

High-affinity monoclonal antibodies specific for the cardiac glycoside digoxin provide a useful system for the study of structure-function relationships between antibody combining site and specific antigenic determinants. Fifteen high-affinity monoclonal anti-digoxin antibodies were produced when spleen cells from A/J mice immunized with digoxin coupled to human serum albumin (Dig-HSA) were fused with the non-secreting murine myeloma Sp2/0 cell line. Each subcloned hybridoma antibody was analyzed for affinity and specificity for structurally related cardiac glycosides by a radioimmunoassay based on the adsorption of free [3H]digoxin to dextran-coated charcoal. All of the anti-digoxin hybridoma proteins demonstrated high affinity constants ranging from 10(9) to 10(12) M-1. Using seven different analogs of digoxin, binding specificities of the monoclonal antibodies were assessed by inhibition radioimmunoassay. The 15 hybridomas produced from fusions involving five mice could be divided into eight sets on the basis of these binding specificities. Certain antibodies exhibit a preference for the aglycone portion of digoxin, while others are more specific for the tridigitoxose sugar moiety of digoxin. Monoclonal antibody H- and L-chains were subjected to N-terminal amino acid sequence analysis. The antibodies may be divided into several sequence homology sets for both H- and L-chains. In most instances, homologous heavy chains are associated with a set of homologous light chains. Homologous partial sequences, however, do not correlate with similar antigenic specificities and affinities for digoxin. Thus the fine specificity for antigen is not dependent on VH- and VL-encoded sequences alone. These data illustrate the broad diversity of the elicited response to a single hapten, even in inbred mice.

Amino Acid Sequence↗