Search PubMed⌕ Search

Biomedical subjects

E Haber

Publications and source records attributed to E Haber.

At least 235 records · Page 13Linked to original sources
PubMed1979

Isolation and characterization of an active variable domain from a homogeneous rabbit antibody light chain.

The variable domain (VL) of allotype b4 light chains of rabbit IgG was isolated from both nonimmune heterogeneous IgG and a homogeneous antibody directed against type III pneumococcal polysaccharide. Light chains were first isolated and then cleaved under mild acidic conditions between residues 109 and 110. Reduction with dithiothreitol in guanidine hydrochloride cleaved both intradomain disulfide bridges as well as the interdomain disulfide bridge joining the variable and constant domain. The sulfhydryl groups were protected after reduction by p-chloromercuribenzoate. VL was isolated from this mixture of variable and constant domains by affinity chromatography, utilizing sheep antibodies directed against a peptide including residues 110--211 from nonimmune IgG light chain. The isolated VL domain was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and automated Edman degradation. VL from a homogeneous antibody was treated with dithiothreitol to remove p-chloromercuribenzoate, reoxidized, and recombined with homologous heavy chain. The binding of this recombinant to type III pneumococcal polysaccharide was identical with that of the light-chain--heavy-chain recombinant.

Amino Acids↗
PubMed1979

Isolation of a renal thiol protease that activates inactive plasma renin.

1. A thiol protease with properties similar to those of cathepsin B (EC 3.4.22.1) has been isolated and purified from human renal cortex. 2. This enzyme can generate renin activity from renin-suppressed and anephric human plasma at pH 5.5. 3. The renin activity thus generated is inhibited completely by antibody to purified human renal renin. This activation therefore represents the release of inactive renin.

Cathepsin B↗
PubMed1979

Immunogenicity and kinetics of distribution and elimination of sheep digoxin-specific IgG and Fab fragments in the rabbit and baboon.

To evaluate the relative merits of purified IgG and Fab preparations of defined specificity for potential clinical use, immunogenicity studies were carried out in baboon and rabbit experimental models. Distribution and elimination kinetics of purified sheep digoxin-specific IgG and Fab fragments were also studied following intravenous administration to baboons. Serial plasma and urine Fab concentrations were determined from trichloroacetic acid-precipitable 125I counts from pre-labelled preparations and also by measurement of the antibody's functional 3H-digoxin binding capacity. Results were compared with data obtained from IgG by 3H-digoxin binding. Kinetic data analysed by computer-fitted functions demonstrated that plasma Fab disappearance was best described by a tri-exponential function, whereas a bi-exponential function best described the IgG data. Initial distribution half-life (t 1/2) of Fab (0.28-0.32 hr) was considerably shorter than that of IgG (4.0 hr) and contributed a greater proportion of the total fall in plasma level over 24 hr. Fab elimination t 1/2 (9-13 hr) was also shorter than IgG (61 hr), but appreciably longer than earlier estimates in rabbits, guinea-pigs, rats and mice. The total volume of distribution of Fab was 8.7 times greater than that of IgG measured by the same method. Over the first 24 hr after administration 30-45% of administered Fab was recoverable in active form in urine, while 93% of total administered 125I counts from 125I-Fab preparations (bound and free) could be recovered. Less than 1% of administered IgG binding activity was recovered in urine during the initial 24 hr. The relative immunogenicities of sheep digoxin-specific IgG and Fab fragments were studied in six baboons. Both IgG and Fab elicited prompt immune responses when injected intramuscularly with Freund's complete adjuvant. Intravenous injection of soluble sheep IgG resulted in a prompt immune response in one baboon while repeated injections caused only a late, weak response in a second animal. Soluble sheep Fab fragments elicited only delayed and weak responses in the two baboons thus challenged. Further immunogenicity studies in ninteen rabbits showed significantly earlier and greater antibody responses to intravenously administered sheep IgG antigen than to Fab fragments derived from the same IgG population. These studies demonstrate that digoxin-specific Fab fragments undergo more rapid and extensive distribution to the extra vascular compartment and also more rapid renal excretion than IgG. Furthermore, Fab fragments are significantly less immunogenic than the parent IgG population. These data indicate potentially important therapeutic advantages for digoxin-specific Fab compared with IgG when administered for the reversal of life-threatening digitlis toxicity.

Animals↗
PubMed1979

Characterization of an angiotensin binding site in rabbit renomedullary interstitial cells in tissue culture: correlation with prostaglandin biosynthesis.

High affinity binding sites for angiotensin II have been identified and characterized in rabbit renomedullary interstitial cells in tissue culture. Binding studies were performed using monoiodinated angiotensin II of high specific activity; the angiotensinase inhibitors dithiothreitol and phenylmethylsulfonylfluoride were added to the incubation medium to retard degradation of the labeled hormone. Uptake of 125I angiotensin II was maximal at pH 7.4 and Scatchard analysis indicated a single binding site with a KD of 3.1 nM. Binding to a particulate preparation of the cells was rapid and reversible. Competition for binding by angiotensin II analogs correlated with their biologic potencies: (Sar1Ala8) AII greater than AII greater than (desAsp1) AII greater than greater than 3-8 hexapeptide. The 1-7 heptapeptide was completely ineffective in displacing the labeled angiotensin II from its binding sites. Angiotensin II directly stimulated prostaglandin (PG) biosynthesis by the renomedullary cells in tissue culture; the concentration of angiotensin II that resulted in half maximal stimulation of PG biosynthesis (6.5 nM) was similar to the concentration of angiotensin II that resulted in half maximal occupancy of binding sites (3.1 nM). These results suggest that the renomedullary cells may provide a model homogeneous tissue for the study of the angiotensin receptor and the hormonal regulation of prostaglandin biosynthesis.

Angiotensin II↗
PubMed1979

Inhibitors of renin and their utility in physiologic studies.

The enzyme renin is the initiator of a series of steps that ultimately leads to the generation of angiotensin II, a potent pressor peptide that also has both a direct and indirect role in renal sodium conservation. Renin's action on its protein substrate, angiotensinogen, is inhibited by specific antibody, a peptide produced by actinomyces, pepstatin and its derivatives, and by peptide analogs of a segment of the endogenous substrate. These inhibitors vary considerably in specificity, inhibitory constant, and utility for in vivo studies.

Antigen-Antibody Reactions↗
PubMed1978

Isolation of an active variable-domain fragment from a homogeneous rabbit antibody heavy chain. Physiochemical and immunological properties.

A fragment corresponding to most of the variable domain of the rabbit heavy chain (VH) was obtained by tryptic digestion of the midly reduced and aminoethylated heavy chain from rabbit antibody 3T72. The domain size peptide was purified by gel filtration and shown to extend between residues 11(Leu) and 122(Lys) of the heavy chain by sequence analysis. The molecular size of the fragment (approximately 11 000) was determined by gel filtration under denaturing conditions. Under nondenaturing conditions (20 mM sodium acetate, pH 5.5, 0.1 M NaCl), however, the fragment exists as a mixture of monomeric and dimeric species. The varable-domain fragment retains the allotypic determinants of the heavy chain (a1), as shown by double diffusion on agar plates and radioimmunoassay. Upon recombination of the heavy-chain variable-domain fragment with its homologous light chain, partial recovery of specific binding activity toward the SIII polysaccharide antigen was demonstrated. The method reported here is reproducible (with yields varying between 40 and 60%) and may provide a general method for obtaining the variable region of the heavy chain for antigen binding and allotypic and amino acid sequence studies.

Amino Acid Sequence↗
PubMed1978

Light chain variable region sequence of rabbit antipneumococcal type III polysaccharide antibody 3368.

The amino acid sequence of the amino-terminal 111 residues (variable region) for the light chain of the homogeneous rabbit antipneumococcal type III polysaccharide antibody 3368 was determined. This sequence was obtained principally through automated Edmann degradations of the intact light chain and of peptides generated by tryptic digestion of the citraconylated light chain. With these methods only 2 mumol of purified light chain was required to determine the reported sequence. When compared with the light chains of four other antipneumococcal type III polysaccharide antibodies, the 3368 light chain exhibits a unique sequence in those segments of the variable region that contribute to formation of the antigen binding site (complementarity-determining regions) (10 or 11 residue differences in 12 positions). The 3368 light chain also demonstrates an insertion of three residues relative to the other four light chains in the complementarity-determining region at positions 89 to 98. These five light chains have greater than 80% sequence homology for the portion of the variable region which is not involved in antigen binding (framework).

Amino Acid Sequence↗
PubMed1978

Renin inhibitors.

Explore the source record for details and available documents.

Angiotensin II↗
PubMed1978

Production of antibody to tetanus toxoid by continuous human lymphoblastoid cell lines.

Peripheral lymphocytes from human volunteers boosted with tetanus toxoid were cultured after in vitro infection with Epstein-Barr virus. Forty-four continuous lymphoblastoid lines were established which continued to secrete human gamma globulin; seven of these secreted antibody to tetanus toxoid. Subcultures derived from limiting dilution experiments continued to secrete the antibody. Some of these antibody-secreting cells have been in continuous culture for more than 6 months.

Antibody Formation↗