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Biomedical subjects

A Bollen

Publications and source records attributed to A Bollen.

At least 145 records · Page 8Linked to original sources
PubMed1985

Monoclonal antibodies against plasma protease inhibitors: production and characterization of 15 monoclonal antibodies against human antithrombin III. Relation between antigenic determinants and functional sites of antithrombin III.

Fifteen hybridomas secreting monoclonal antibodies against human antithrombin III, originating from two mouse strains, have been produced by the cell fusion technique. Eight monoclonal antibodies belong to the class IgG1, five to the class IgG2a, and two to the class IgG2b. All light chains belong to the kappa group. No cross-reaction of the monoclonal antibodies have been observed with a crude preparation of albumin nor with alpha 1-antitrypsin and alpha 2-antiplasmin. Five of these monoclonal antibodies exhibit a relatively high avidity for antithrombin III. Inhibition experiments showed that the 15 monoclonal antibodies define seven more or less independent antigenic regions on the antithrombin III molecule. Examination of the effects of these antibodies on the inhibitory capacity of antithrombin III toward thrombin activity, either in the presence or in the absence of heparin, showed that several monoclonal antibodies inhibit the antithrombin III activity and allowed to relate some of the antigenic determinants to functional sites on the antithrombin III molecule.

Animals↗
PubMed1984

Characterization of human haptoglobin cDNAs coding for alpha 2FS beta and alpha 1S beta variants.

A human liver library, derived from a heterozygous (Hp2-1) donor, has been used to isolate cDNA clones coding for the haptoglobin (Hp) alpha 1S beta and alpha 2FS beta variants. DNA sequencing has shown that the two variants are identical except for the alpha F duplicated segment in Hp alpha 2FS beta. Four nucleotide changes have been found between the phenotypically different F and S regions of the Hp alpha 2 gene, resulting in an Asp,Lys/Asn,Glu substitution.

Alleles↗
PubMed1984

Expression of human alpha 1-antitrypsin in Escherichia coli.

Complementary DNA coding for human alpha 1-antitrypsin has been placed under the control of the lambda PR promotor carrier by the expression vector pCQV2 [1]. In conditions which allow transcription from this promotor (thermoinactivation of the repressor), Escherichia coli cells harbouring the recombinant plasmid pULB1114 express human alpha 1-antitrypsin (+/- 9000 molecules/cell). The product has a Mr of 44000, corresponding to mature unglycosylated alpha 1-antitrypsin.

Escherichia coli↗
PubMed1984

Monoclonal antibodies against plasma protease inhibitors: II. Production and characterization of 25 monoclonal antibodies against human alpha 1-antitrypsin. Correlation between antigenic structure and functional sites.

Twenty-five hybridomas secreting monoclonal antibodies against human alpha 1-antitrypsin have been produced by the cell-fusion technique (Köhler and Milstein, 1976). All antibodies are specific for alpha 1-antitrypsin and carry gamma 1 heavy chains and kappa light chains. Inhibition experiments showed that these monoclonal antibodies define three independent antigenic regions on the alpha 1-antitrypsin molecule; one of these domains appears to be involved in the interaction between alpha 1-antitrypsin and trypsin. In addition, one monoclonal antibody, AATY39, was used to develop an enzyme-linked immunosorbent assay capable of detecting low levels of alpha 1-antitrypsin in the range of 1 to 2 ng/ml.

Animals↗
PubMed1984

Monoclonal antibodies against plasma protease inhibitors: I. Production and characterization of 23 monoclonal antibodies against human alpha 2-antiplasmin.

23 hybridomas secreting monoclonal antibodies against human alpha 2-antiplasmin, the fast-acting inhibitor of plasmin present in plasma, have been produced by the cell-fusion technique. Isotyping of the monoclonal antibodies has revealed that 14 monoclonal antibodies belong to the class IgG1, 6 to the class IgG2a, and 3 to the class IgG2b. All light chains belong to the kappa group. The specificity and relative avidity of these monoclonals have been determined using an indirect enzyme-linked immunosorbent assay. 13 monoclonals exhibit a relatively high avidity for alpha 2-antiplasmin, 5 are of intermediate avidity, and 5 of low avidity. The epitope specificity of these 23 monoclonal antibodies, originating from a single mouse, have been examined in inhibition experiments. A group of 10 monoclonal antibodies exhibit a very similar inhibition pattern. Partial inhibition effects displayed by 10 other antibodies define partially overlapping antigenic regions. The binding of these antibodies seems to produce a conformational change in the alpha 2-antiplasmin molecule, reducing the binding of two other antibodies. The last antibody defines an independent epitope.

Animals↗
PubMed1984

Expression of human alpha 1-antitrypsin cDNA in the yeast Saccharomyces cerevisiae.

Nucleotide sequences coding either for the precursor or the mature form of human alpha 1-antitrypsin have been placed under the control of the yeast ARG3 expression signals. Recombinant plasmids pRIT10782 and pRIT10787 express the precursor or the mature alpha 1-antitrypsin species, respectively, in two different yeast strains, with yields ranging between 0.3 and 1% of total soluble proteins. The alpha 1-antitrypsin synthesized in yeasts was specifically recognized by polyclonal and monoclonal antibodies raised against human alpha 1-antitrypsin. In addition, it was shown to be biologically active in its mature form only, with optimal activity in a peptidase-deficient yeast strain.

Antibodies, Monoclonal↗
PubMed1983

Molecular cloning of human haptoglobin cDNA: evidence for a single mRNA coding for alpha 2 and beta chains.

Human haptoglobin (Hp) is a plasma glycoprotein composed of alpha and beta polypeptide chains that are covalently associated by disulfide bonds. It had been suggested that alpha and beta polypeptides could be synthesized via a common precursor polypeptide. We report the molecular cloning of DNA complementary to human Hp mRNA. One of the clones, pULB1148, carries a full length copy coding for both alpha 2 and beta polypeptides. In vitro translation of human liver mRNA hybridizing with this cDNA gives a protein mol. wt. of 49000 daltons. The sequence of the alpha 2 beta cDNA shows the presence of a single Arg residue between Gln 142 of the alpha 2 chain and Ileu 1 of the beta chain. With a few minor exceptions, the DNA sequence fits the previously published amino acid sequences. The differences are the presence of an Asp residue at position 52 of alpha 2 instead of Asn, the existence in beta of only one Lys residue between Gly 65 and the following Gln, the presence of Ser and Cys at positions 218-219 instead of Cys-Ser, and of Asp residues at positions 205 and 235 instead of Asn.

Amino Acid Sequence↗
PubMed1983

Solid-phase enzyme immunoassay of urokinase using monoclonal antibodies.

Using two monoclonal antibodies directed against urokinase, we have developed a micro enzyme-linked immunosorbant assay (ELISA) to detect and measure urokinase in biological fluids. The system presents the following characteristics: simple and rapid procedure, reproducibility, sensitivity (urokinase levels down to 1 ng/ml) and evaluation of the enzyme in biological fluids such as urine, pleural effusions, and ascitic fluids without preliminary purification.

Antibodies, Monoclonal↗
PubMed1983

Cloning and expression in Escherichia coli of full-length complementary DNA coding for human alpha 1-antitrypsin.

A cDNA library prepared from human liver was screened for alpha 1-antitrypsin, a major constituent of plasma which functions as inhibitor of proteolytic enzymes. The library was screened using a 12-base-long synthetic oligodeoxyribonucleotide corresponding to a known DNA fragment of human alpha 1-antitrypsin and by hybrid-selection of alpha 1-antitrypsin mRNA. A plasmid, pULB1523, was identified carrying a cDNA insert of about 1400 bp coding for human alpha 1-antitrypsin. Restriction mapping and DNA sequence analysis indicated that the 1400 bp code for the signal peptide and for the complete mature alpha 1-antitrypsin molecule. In addition, a solid-phase enzyme-linked immunoassay showed that pULB1523 expresses human alpha 1-antitrypsin in bacteria. Fusion of the alpha 1-antitrypsin sequence to the leader sequence of the beta-lactamase gene (plasmid pKT287) resulted also in the expression of the protein in bacteria.

Base Sequence↗
PubMed1981

Monoclonal antibodies against urokinase.

Hybridomas secreting antibodies against human urokinase have been produced by the cell-fusion technique (Köhler & Milstein, 1976). They belong to the IgG1 and IgG2 classes. Fixation and inhibition of the binding of 125 I-labelled urokinase, in radioimmunoassay, show that two of the monoclonal antibodies exhibit a high titer in ascitic fluids, a good sensitivity, and no cross reaction with other enzymes showing partial sequence homology with urokinase. Moreover, one of the monoclonal antibodies is able to inhibit the enzymatic activity of urokinase using a chromogenic substrate.

Animals↗
PubMed1980

Translational fidelity in Escherichia coli: antagonistic effects of neaA and ramC gene products on the ribosome function.

A double mutant carrying the ramC and neaA mutations has been constructed by Plvir transductions. This mutant, which carries alterations in ribosomal proteins S5 and S17, behaves like to wild-type bacteria in the following respects: it no longer exhibits the restriction of informational suppressors normally associated with the neaA mutation (altered protein S17); ribosomes from the double mutant show increased intrinsic and neamine-induced misreading in vitro in contrast to ribosomes from the neaA strain, although still less than the misreading level of ribosomes from the ramC (altered protein S5) strain. These properties suggest that ribosomal proteins S5 and S17 act cooperatively to balance translational fidelity.

Escherichia coli↗