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Biomedical subjects

E Mihaesco

Publications and source records attributed to E Mihaesco.

At least 37 records · Page 2Linked to original sources
PubMed1985

An anti-human mu chain monoclonal antibody: use for detection of IgM antibodies to Toxoplasma gondii by reverse immunosorbent assay.

A precipitating anti-human mu chain monoclonal antibody (designated Tibi 82 McAb) was produced by the cell fusion technique. This McAb (isotype: IgG1 kappa) reacted by radioimmunoassay with all 10 human IgM proteins tested. In contrast, no reactivity was observed with IgG, IgA, IgE, lambda and kappa chains. 19 S IgM proteins were precipitated by Tibi 82 McAb using the Ouchterlony method under standard conditions. Hence specificity of this McAb for the C mu 2 domain was characterized by inhibition of precipitin reactions using human IgM fragments. Despite its narrow specificity for the C mu 2 domain, such a McAb could be used for IgM capture in the detection of specific IgM to Toxoplasma gondii employing the IgM immunosorbent agglutination assay (IgM-ISAGA). Tibi 82 McAb was compared with 3 anti-human IgM polyclonal reagents in the routine analysis of 117 sera. With 2 of them, a correlation coefficient of 0.976 was obtained and Tibi 82 McAb was more sensitive than the third polyclonal reagent tested. The IgM-ISAGA technique was shown to be reproducible using Tibi 82 McAb and similar anti-human mu chain McAbs could permit the wider development of reverse immunosorbent methods for the detection of specific IgM in various infectious diseases.

Antibodies, Anti-Idiotypic↗
PubMed1984

The primary structure of mu-chain-disease protein BOT. Peculiar amino-acid sequence of the N-terminal 42 positions.

The complete primary structure of the mu heavy-chain disease (mu-HCD) protein BOT has been determined. The monomeric HCD-mu-chain consists of 391 amino-acid residues, lacking the VH and mu CH1 domains but including the entire CH2, CH3 and CH4 domains (349 residues). The sequence of the preceding 42 N-terminal residues which we designate as the "pre-C-part" presents no homology to any known variable or constant immunoglobulin sequence, but contains an internal homology of positions 10-19 to positions 20-29. The origin of the "pre-C-part" structure and the deletion of the mu CH1 domain of protein BOT are discussed.

Amino Acid Sequence↗
PubMed1983

Crystals of the human heavy chain disease protein Riv and human Fc fragment are isomorphous: further evidence for conformational flexibility in the hinge region of immunoglobulins.

Protein Riv is a human gamma 1 heavy chain disease immunoglobulin variant with a deletion of the entire VH and CH1 domains and consisting of most of the hinge region plus the CH2 and CH3 domains. Crystals of this protein are orthorhombic, belonging to the space group P2(1)2(1)2(1), with a = 80.1 A, b = 145.5 A, c = 50.1 A. These crystals are shown to be isomorphous with crystals of a human Fc fragment, indicating that the hinge region and the initial part of the CH2 domain of protein Riv do not assume a unique conformation in the crystalline state.

Crystallization↗
PubMed1983

Biochemical and biosynthetic studies of a crystallizable human gamma 1 heavy-chain disease protein.

We have studied the structure of a crystallizable gamma 1 heavy-chain disease protein that lacks the entire VH and C gamma 1 domains. The protein starts within the hinge region at aspartic acid 221 (Eu numbering). The native protein is a disulphide-linked dimer with an apparent molecular weight of 52,000, consistent with the biochemical data obtained on the whole protein and its cyanogen bromide fragments. The carbohydrate content of this protein was 6.8%. As shown by biosynthesis experiments intracytoplasmic gamma chains synthesized by neoplastic cells had an apparent molecular weight similar to that of the serum heavy-chain disease protein. These data are compared with those obtained for other gamma 1 heavy-chain disease proteins beginning in the hinge region, and the mechanisms leading to those abnormal Ig products are discussed.

Amino Acid Sequence↗
PubMed1982

[Light chain or monoclonal immunoglobulin deposition disease: physiopathogenic concepts].

Although recently identified, this disease is by no means exceptional. It is characterized by the deposition in various organs of an amorphous substance which differs from the amyloid substance and contains monoclonal immunoglobulin determinants: either a light kappa or lambda chain, or a light and a heavy chain. The severity of the disease is due to various organs being involved, notably the kidneys. There is in every case a monoclonal plasmocytic or lymphoplasmocytic proliferation which may appear as benign. In almost one-third of the cases no monoclonal immunoglobulin can be detected in the serum. In a study of immunoglobulin biosynthesis, 6 out of 8 patients showed striking structural abnormalities. The relationship between these very unusual lg's and tissue deposition is discussed in detail.

Chemical Phenomena↗
PubMed1981

Detection of J chain in lymphomas and related disorders.

Lymph node specimens from 125 patients with malignant lymphomas and related disorders were studied by immunoperoxidase procedure for the presence of intracytoplasmic immunoglobulin (CIg) and J chain CIg staining was present in 22/24 cases of lymphoplasmacytic-lymphoplasmacytoid lymphomas, and in 10/10 cases of extramedullary plasmacytomas and myelomas. In the majority of these cases J chain could be demonstrated in plasmacytoid or neoplastic plasma cells. In 21/36 cases of immunoblastic lymphomas, intracytoplasmic Ig staining was present. In only two of the 36 cases were the lymphomatous cells stained positively for J chain. J chain was not detected in other lymphomas such as lymphocytic lymphomas, follicular lymphomas, lymphoblastic lymphomas or in Reed-Sternberg cells or hairy cells. J chain was demonstrated in mature plasma cells and immunoblastic cells in hyperplastic lymph nodes, and in angioimmunoblastic lymphadenopathy. These findings show that J chain is not detectable in all B cell lymphomas even in the presence of CIg synthesis, irrespective of class.

Cytoplasm↗
PubMed1980

The primary structure of the constant part of mu-chain-disease protein BOT.

The complete primary structure of the constant part of the mu-chain-disease protein, BOT, was established. It includes the whole CH2, CH3 and CH4 domains. two amino acid changes were found, at positions 309 (Ser leads to Gly) and 333 (Val leads to Gly) (GAL numbering). In two additional monoclonal mu chains (SCO and CO), the same positions showed an amino acid variability. From these data it may be concluded that four types of mu chains exist in the human: (1) GAL type with Ser-309 and Val-333; (2) OU type with Gly-309 and Val-333; (3) SCO type with Ser-309 and Gly-333; (4) BOT/CO type with Gly-309 and Gly-333. The meaning of this molecular polymorphism is discussed.

Amino Acid Sequence↗
PubMed1980

Presence of J chain in human lymphoid cells.

The presence of J chain in normal lymphoid cells (examined at various stages of differentiation) and in lymphocytes and plasma cells from patients with malignant haematologie disorders was determined by the immunofluorescence technique. J chain was not detectable in the cytoplasm or on the surface of either pre-B or B cells, but was present in a few peripheral blood lymphocytes that contained intracellular immunoglobulins of various classes. After pokeweed mitogen stimulation, intracellular synthesis of J chain and immunoglobulins appeared simultaneoulsy and was most pronounced during early days of culture. These data indicate that J chain is not expressed during the earliest stages (pre-B and B cells) of differentiation of lymphoid cells and that the synthesis of J chain is closely linked to the production of immunoglobulin chains, irrespective of the class. Examination of lymphoid cells from bone marrow and peripheral blood of patients with various lymphoproliferative diseases (secretory and non-secretory multiple myeloma or Waldenström's macroglobulinaemia, H- or L-chain diseases, chronic lymphocytic leukaemia, plasma cell leukaemia, and angioimmunoblastic lymphoma) revealed that J chain was present in various proportions of the cells that contained monomeric (IgG, IgD or IgA) or polymeric (IgA or IgM) immunoglobulins, as well as in cells from patients with H- or L-chain diseases. No correlation was apparent between the presence of J chain in lymphoid cells and their ability to secrete their product. Preliminary data indicate that J chain may participate in the intracellular assembly of immunoglobulins from their component chains.

B-Lymphocytes↗
PubMed1980

Synthesis of abnormal heavy and light chains in multiple myeloma with visceral deposition of monoclonal immunoglobulin.

In a patient treated for IgA kappa myeloma, bone marrow relapse and a sharp drop in the serum IgA level paralleled tissue deposition of non-amyloid material reactive with anti-kappa anti-alpha sera in immunofluorescence studies of kidney and liver biopsies. Clinical manifestations were progressive renal failure with nephrotic syndrome, with both tubular and glomerular lesions (including nodular glomerulosclerosis), hepatomegaly, cardiac and neurological symptoms. Biosynthesis experiments showed the production of alpha chains diminished in length by about one domain which were rapidly degraded predominantly after secretion and of two species of light chains; normal-sized light chains which assembled with alpha chains and abnormally short ones which were secreted as free light chains. The apparent molecular weight of the light chains was larger in secretions than in cytoplasmic extracts, suggesting their glycosylation. These results suggest a causal relationship between tissue deposition and production of abnormal immunoglobulins by a variant clone, the emergence of which was possibly induced by Melphalan therapy.

Bone Marrow↗
PubMed1974

"Alpha chain disease" protein def: internal deletion of a human immunoglobulin A1 heavy chain.

Protein Def is a human alpha chain disease protein related to alpha1 immunoglobulin heavy chain. The molecular weight of the polypeptide portion of the monomeric molecule is 29,300, which is a little greater than half of a normal alpha1 chain. The NH(2)-terminal of the polypeptide is heterogenous and, after a short segment corresponding to the variable region, displays a gap which comprises the C(H)1 constant domain. Normal synthesis resumes at a valine residue in the hinge region just before a segment which contains a partially duplicated fragment and the interheavy disulfide bonds. From there on, the molecule is apparently normal. Protein Def is therefore synthesized as an internally deleted alpha1 heavy chain, followed by postsynthetic amino-terminal proteolysis. It is postulated that codon(s) specifying valine at the hinge region may be a recognition site for reinitiating synthesis after internal gaps equivalent to position 216 in gamma chain disease proteins.

Amino Acid Sequence↗