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Biomedical subjects

S L Morrison

Publications and source records attributed to S L Morrison.

At least 163 records · Page 9Linked to original sources
PubMed1982

Association constants of hybridoma antibodies specific for alpha (1 leads to 6) linked dextran determined by affinity electrophoresis.

Binding constants of monomers of seven BALB/c IgM, four BALB/c IgA, and one C57BL/6 IgA anti-alpha (1 leads to 6) dextran hybridoma antibodies with dextran B512 and with isomaltoheptaose were determined by affinity electrophoresis. Bindings constants to dextran range from 1.52 X 10(5) to 4.43 X 10(5) ml/g for the five IgA monomers and from 1.70 X 10(3) to 6.10 X 10(4) ml/g for the seven IgM monomers. Antibody monomers containing both specific and nonspecific (derived from the myeloma cell that was used to generate the hybridomas) light chains are shown to have association constants with dextran 6 to 30-fold lower than monomers containing only specific light chain, suggesting that the association of specific heavy chain with nonspecific light chain does not result in an anti-dextran combining site. Binding constants with isomaltoheptaose range from 1.45 X 10(4) to 7.01 X 10(4)/M for the IgA proteins and from 6.46 X 10(3) to 7.70 X 10(4)/M for the IgM proteins. The binding constants with dextran and with isomaltoheptaose, and the electrophoretic, immunochemical and idiotypic characteristics of the hybridoma proteins are discussed.

Animals↗
PubMed1982

Isolation and characterization of a variant of mouse plasmacytoma J558 synthesizing a 110,000-dalton immunoglobulin heavy chain and of secondary variants synthesizing either a 55,000-dalton or an 80,000-dalton immunoglobulin heavy chain: possible implications.

A mutant has been isolated from the J558 (immunoglobulin A, lambda, anti-alpha 1 leads to 3 dextran) cell line which synthesizes a heavy-chain immunoglobulin twice the size of normal heavy chain. Secondary variants that synthesized heavy chains either 1.5 times as large as wild type or the same size as wild type were identified. All mutants were serologically immunoglobulin continued to bind antigen, and retained the individual idiotype of the parent. Northern blot analysis and in vitro synthesis studies showed that the large heavy chains were primary synthetic products and not the consequence of abnormal covalent bonds. Cleavage of genomic DNA with restriction endonucleases and molecular hybridization studies showed new fragments in the 2 X and 1.5 X mutants which disappeared in the 1 X revertant. These data cannot easily be reconciled with the mutants arising either by unequal recombination or gene conversion. Further molecular characterization of these mutants should give additional insight into immunoglobulin gene evolution.

Animals↗
PubMed1982

A cross-reactive idiotype, QUPC52 IdX, present on most but not all anti-alpha (1 replaced by 6) dextran-specific IgM and IgA hybridoma antibodies with combining sites of different sizes.

Seven BALB/c IgM, 4 BALB/c IgA, and 1 C57BL/6 IgA anti-alpha (1 replaced by 6) dextran hybridoma antibodies were characterized idiotypically. Five of the 7 IgM and all 4 BALB/c IgA proteins bear a cross-reactive idiotype present on the anti-alpha (1 replaced by 6) dextran BALB/c myeloma protein QUPC52 and on a majority of anti-alpha (1 replaced by 6) dextran antibodies in BALB/c mice. Of these 9 monoclonal antibodies, some have combining sites as large as 6 glucose residues, and some have combining sites as large as 7 glucose residues. Individual idiotypes present on QUPC52 are differentially expressed on the 9 hybridoma proteins that bear the cross-reactive idiotype. One BALB/c IgM hybridoma protein and the C57BL/6 IgA hybridoma protein did not react with anti-QUPC52 idiotypic antibodies; another BALB/c IgM hybridoma antibody showed only marginal reactivity.

Animals↗
PubMed1982

Biochemical characterization of a differentiation antigen shared by human epidermal langerhans cells and cortical thymocytes.

Previous immunofluorescent studies have shown that differentiation antigens recognized by the monoclonal antibody (OKT6) are present on the external membranes of human epidermal Langerhans cells, cortical thymocytes and some cultured T cell lines. In the present investigation, the biochemical characteristics of the OKT6 recognized antigens derived from these three sources were compared. Following immunoprecipitation with OKT6, a single band with an approximate molecular weight of 52,000 daltons was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (under both reducing and nonreducing conditions) in the detergent lysate of radioiodinated normal epidermal cells. A molecule with the same apparent molecular weight was immunoprecipitated from thymocytes and cultured MOLT-3 (T cell-acute lymphoblastic leukemia) cells. However, a low molecular weight protein of approximately 10,000 daltons was coprecipitated from these MOLT-3 cells. No electrophoretically identifiable antigens were precipitated from peripheral lymphocytes or monocytes with OKT6. These observations further distinguish Langerhans cells from classical monocytes, indicate that these cells express a membrane antigen otherwise characteristic of cortical thymocytes, and suggest the potential usefulness of the monoclonal antibody, OKT6, in further investigations of the functions and ontogeny of Langerhans cells.

Animals↗
PubMed1981

Somatically generated mouse myeloma variants synthesizing IgA half-molecules.

Whereas mouse myelomas that secrete IgA half-molecules have been shown to arise in vivo, their origin has not been definitely established. We show that somatic variants secreting phenotypically similar molecules can arise directly from the normal IgA-secreting myelomas S107 and W3082. In addition to being improperly assembled, the variant proteins have distinct carboxy-terminal deletions and an aberrant heavy-light chain disulfide bond. For at least one of the variants, variable region serology and affinity for hapten are both unaffected by these changes. Southern and Northern blot analyses indicate normal size DNA restriction fragments and mRNA, suggesting premature termination as the mechanism of deletion. These results are discussed in relation to possible mutational hot spots and long-range interdomain interactions.

Animals↗
PubMed1981

Heavy-chain mutants derived from gamma 2b mouse myeloma: characterization of heavy-chain messenger ribonucleic acid, proteins, and secretion in delection mutants and messenger ribonucleic acid in gamma2a mutant progeny.

Mouse myeloma mutants isolated from cell line 45.6 (gamma 2b) producing structurally altered immunoglobulin heavy (H) chains have been characterized. The mutant 10-1 synthesizes an H chain of 47 000 daltons containing a CH1 deletion; two mutants, G251 and I17, derived from 10-1 synthesize H chains of 40 000 and 35 000 daltons, respectively. The messenger ribonucleic acids (mRNAs) in these mutants have been shown to be smaller in molecular weight than mRNAs produced in 45.6 cells and lack a portion, but not all, of the CH1 domain. The H chains of G251 and I17 no longer express IgG subclass-specific determinants, are not secreted, and are structurally altered in the carboxyl-terminal portion of the molecule. In vitro the mRNAs of the mutants code for the synthesis of a polypeptide precursor characteristic of secreted proteins; the shortened proteins are apparently glycosylated intracellularly. Somatic cell hybrids between a structurally altered nonsecretor and a drug-marked wild-type myeloma cell secret only the wild-type protein. Reversion to secretion for G251 or I17 is accompanied by a change in the amino acid composition of the H chain such that gamma 2a subclass-specific determinants are expressed. Therefore, the primary structure of the H chain is an important factor in determining secretion. The gamma 2a-secreted chains from G251 and I17 fall into two classes: (1) those synthesizing proteins of approximately 47 000 daltons producing H-chain mRNAs of approximately 1.66 kilobases that are deleted for a portion, but not all, of CH1; (2) those synthesizing gamma2a proteins of approximately 55 000 daltons that are encoded in mRNAs of apparently wild-type size and that have regained CH1 sequences. The molecular explanations for the production of these alterations is discussed.

Animals↗
PubMed1981

ICR-191 and ethyl methanesulfonate induced mutagenesis at the immunoglobulin locus in the Y5606 cultured myeloma cell line.

The Y5606 mouse tumor synthesizing an IgG3, lambda immunoglobulin (Ig) was adapted to continuous growth in tissue culture. The spontaneous mutation rate at the Ig locus (approximately 3 X 10(-5)/cell/generation) in this cell line was found to be less than that in other cultured mouse myeloma lines. Treatment with either ICR-191 or ethyl methanesulfonate (EMS) increased the mutation rate approx. 100-fold. Spontaneous and ICR-191 induced mutants were synthetic variants that is they synthesized either heavy (H) or light (L) chains alone instead of the H and L chains synthesized by the parent. Following EMS treatment assembly variants which were synthesizing structurally altered H chains were isolated in addition to synthetic variants. The assembly variants appear to be a unique consequence of EMS mutagenesis.

Aminacrine↗
PubMed1981

Two alpha heavy chain disease proteins with different genomic deletions demonstrate that nonexpressed alpha heavy chain genes contain methylated bases.

Two independently arising alpha heavy chain mutants have been found to synthesize heavy chains with CH1 deletions of approximately equal extent. Both were isolated from heavy chain-producing variants of the mouse myeloma W3129 and demonstrate that it is possible to arrive at the heavy chain disease phenotype by the pathway H + L leads to H leads to delta H. Analysis of genomic DNA by digestion with restriction endonucleases followed by molecular hybridization showed that one mutant (delta 37) had a deletion of approximately 0.2 kilobase and the second mutant (delta 15) had a deletion of approximately 0.5 kilobase. Mouse myeloma cells contain several alpha chain alleles but only one is expressed; the presence of the deletion in delta 37 and delta 15 made it possible to identify the restriction fragments from the expressed allele. Analysis of the fragments produced after cleavage with an isoschizomeric pair of restriction enzymes, Msp I and Hpa II, indicated that, in the W3129 cell line and its variants, the unexpressed alpha alleles contain methylated bases. The influence of methylation on gene expression remains to be elucidated.

Alleles↗
PubMed1981

Production and characterization of monoclonal antibodies to the subunits of human phosphofructokinase: new tools for the immunochemical and genetic analyses of isozymes.

Recently we have demonstrated that human phosphofructokinase (PFK; ATP: D-fructose-6-P, 1-phosphotransferase; EC.2.7.1.11) is under the control of three structural loci that code for M (muscle-type), L (liver-type), and P (platelet-type) subunits: random tetramerization of these subunits produces various isozymes. In this study, we have produced and characterized BALB/c hybridoma antibodies to the M- and L-type subunits of human PFK. The specific antibodies were detected by an enzyme-immunoprecipitation assay using Staphylococci-bearing protein A as an immunoadsorbent. Of the wells tested using red blood cell (RBC) PFK (M + L), 61% were positive. Only one M-specific hybridoma was identified. The one anti-M and 4 anti-L antibodies were characterized for their biochemical and immunochemical specificities. To define the combining specificities of these antibodies, we compared their reactivity and that of monospecific rabbit anti-M antiserum with muscle and liver PFKs from 15 different vertebrate species. The rabbit anti-M shows strong cross-reactivity with the muscle PFKs from all the species studied. In contrast, the monoclonal anti-M reacts exclusively with muscle PFKs from primates. Two of four anti-L antibodies react only with human L-PFK, whereas the other two react with that from a few other vertebrate species as well. Taken together, these data suggest that primate-specific antibodies recognize evolutionarily, recently acquired antigenic determinants, whereas the antibodies reactive with PFKs from distantly related species recognize conserved determinants. The differential immunoreactivities of muscle and liver PFKs strongly suggest the presence of distinct isozymes in all the vertebrate species studied. These studies demonstrate that it is feasible to produce and characterize monoclonal antibodies that distinguish among isozymes with structural and functional similarities. These antibodies provide sensitive tools in the analyses of isozyme structure, genetics, and related fields.

Animals↗
PubMed1981

Mutational events in mouse myeloma cells.

Cultured mouse myeloma cells frequently generate variants in immunoglobulin expression and structure. In this paper the authors will review the phenotypes of the variants which have been identified and discuss the mechanisms which may be responsible for the somatic instability of the immunoglobulin genes in mouse myeloma cells.

Amino Acids↗
PubMed1980

Policy for early discharge after acute myocardial infarction.

Simple criteria were used to select a low-risk group of patients after acute myocardial infarction. The criteria depended on the presence or absence of diabetes, pulmonary oedema, serious rhythm disorders, and recurrent cardiac pain. Patients in the low-risk category with a suitable home environment were discharged from hospital after five to seven days (mean 6.2 days); they constituted 47% of the 267 hospital survivors over 18 months. Mortality in the selected patients was 2.4% at six weeks and 7% at one year. Most complications preventing early discharge were identified on the first day. Provisional selection for a short hospital stay was made after two days, and 76% of those judged suitable at 48 hours remained free of complications. Early selection of a low-risk category is justifiable and of practical value, though subsequent events will delay discharge for some patients. All patients who died in hospital or within two weeks after infarction had developed overt complications by the end of the fourth day. The results suggest that a policy of hospital discharge after four days would be justifiable for a low-risk group selected by the present criteria.

Aged↗
PubMed1980

Formation of hybridoma clones in soft agarose: effect of pH and of medium.

Optimal conditions for the formation of hybridoma clones in soft agarose are described. The hybridization frequency is shown to be highly dependent on the pH of the polyethylene glycol (PEG) solution used for fusion and on the cloning medium. Maximal numbers of clones are obtained when the PEG solution used for fusion is at pH 8.0-8.2.

Animals↗
PubMed1979

A mouse myeloma variant with a defect in light chain synthesis.

A spontaneous assembly variant, B 50, has been isolated from the MPC-11 mouse myeloma cell line. This variant synthesizes fewer light chains per cell than the parent resulting the production of a slight molar excess of heavy chains. These changes are associated with a delay and change in the pathway of assembly and a delay in secretion. Spontaneous revertants of B 50 have been obtained, all of which synthesize normal amounts of light chains and assemble and secrete the immunoglobulin molecule through the same pathways and with the same kinetics as the parental cells. A comparison of the tryptic-chymotryptic peptides of the parental, variant and revertant heavy and light chains did not reveal any differences. These studies indicate that variants in mouse myeloma cells can arise with defects in the quantitative expression of the immunoglobulin gene and suggest that the presence of excess light chains facilitates the assembly and secretion of some immunoglobulin molecules.

Animals↗
PubMed1979

Detection of specific hybridoma clones by replica immunoadsorption of their secreted antibodies.

A sensitive and rapid method for the detection of monoclonal antibodies secreted by hybridomas is described. Mouse myeloma cells are fused with spleen cells from immunized mice and directly cloned in soft agarose containing selective medium; hybrid clones can be seen after a week. Nitro-cellulose filters that have been coated with a specific protein antigen, with antigen-coupled erythrocyte ghosts, or with other cells used as antigens are then placed on the agarose surface. After incubation to allow immunoadsorption of any secreted antibodies specific for the filter-bound antigen, the filter is removed and overlaid with a suspension of antigen-coupled erythrocytes that react with the adsorbed antibodies; after unbound erythrocytes are allowed to fall off the filter, red spots delineate the sites at which antibody-forming clones are present in the agarose. Alternatively, the filter may be treated with radiolabeled antigen followed by autoradiography. The reliability and sensitivity of the method are demonstrated with alpha-(1 leads to 3)-specific antidextran myeloma J558, and the method's applicability is established by detecting hybridomas with specificities for sheep erythrocytes and for alpha-(1 leads to 3) dextran.

Animals↗