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Biomedical subjects

W V Williams

Publications and source records attributed to W V Williams.

At least 109 records · Page 6Linked to original sources
PubMed1989

Development of biologically active peptides based on antibody structure.

Antibody molecules are composed of several functional domains, including a variable domain that contacts antigen and a constant domain. The hypervariable regions of antibody molecules play an integral role in determining their specificity. However, the delineation of specific residues most critical in binding is difficult. We have been studying a monoclonal antibody (87.92.6) that binds to the reovirus type 3 receptor on a number of cell types, down-modulates the receptor, and inhibits DNA synthesis in the cells. We have shown that a peptide derived from the second complementarity-determining region of the monoclonal antibody 87.92.6 light-chain variable region can reproduce both of these effects. We were also able to demonstrate specific amino acid residues and structural features involved in producing these effects. The study of antibody structure, coupled with molecular synthetic techniques, can lead to the development of biologically active substances with potential clinical use.

Amino Acid Sequence↗
PubMed1989

Three dimensional structure of a functional internal image.

An anti-idiotypic antibody has been characterized that forms a functional internal image of the cell-attachment site of reovirus type 3. This antibody shares sequence similarity with the reovirus type 3 cell attachment protein. Studies utilizing synthetic peptides have shown that the region of sequence similarity corresponds to the cell-attachment site of the virus and the antibody. Studies are described demonstrating that these peptides possess biological activity similar to that of the virus and the antibody. Three-dimensional models of the cell-attachment site of the virus are presented and compared to a similar model for the antibody. These studies indicate that anti-idiotypic antibodies can be utilized to understand the three-dimensional basis of ligand - receptor interactions, and can lead to the development of novel biologically active substances.

Amino Acid Sequence↗
PubMed1989

Subtype-selective immunoprecipitation of the beta 2-adrenergic receptor.

Most antibodies known to interact with beta-adrenergic receptors do not exhibit subtype selectivity, nor do they provide quantitative immunoprecipitation. A monoclonal antibody, G27.1 raised against a synthetic peptide corresponding to the C-terminus of the beta 2-adrenergic receptor of hamster, is selective for the beta 2 subtype. G27.1 provides nearly quantitative immunoprecipitation of the beta 2-adrenergic receptor from hamster lung that has been photoaffinity-labeled and solubilized with sodium dodecyl sulfate. Immunoprecipitation is completely blocked by nanomolar concentrations of the immunizing peptide. This antibody interacts with beta 2-adrenergic receptors from three rodent species, but not with those from humans. When C6 glioma cells, which contain both beta 1- and beta 2-adrenergic receptors, are photoaffinity-labeled in the absence or presence of subtype-selective antagonists, subtype-selective photoaffinity-labeling results. G27.1 can immunoprecipitate beta 2-, but not beta 1-, adrenergic receptors from these cells. Similar results were obtained following subtype-selective photoaffinity-labeling of membranes from rat cerebellum and cerebral cortex. The beta-adrenergic receptors from C6 glioma cells and rat cerebral cortex exist as a mixture of two molecular weight species. These species differ in glycosylation, as shown by endoglycosidase F digestion of crude and immunoprecipitated receptors.

Affinity Labels↗
PubMed1989

Expression pattern of the neu (NGL) gene-encoded growth factor receptor protein (p185neu) in normal and transformed epithelial tissues of the digestive tract.

The neu gene (also called NGL, erbB-2, and HER-2) encodes a 185-190 kDa transmembrane glycoprotein, p185neu, which has tyrosine-specific kinase activity and is homologous to but distinct from the epidermal growth factor receptor. The normal expression of neu mRNA and protein has been demonstrated in epithelial tissues of adult animals. Also, activation of the neu oncogene has been implicated in a variety of human adenocarcinomas. In the present study, we examined the expression of the p185neu protein in normal and transformed digestive tract tissues and in a panel of digestive tract-derived cell lines. By immunohistochemistry, strong reactivity was observed in the mucosal epithelium of the stomach, small intestine, and colon of both rodents and humans. In the small intestine, there was prominent p185neu expression by mucosal epithelium of the villus, with little or no staining in the crypts. Prominent expression was observed in the liver parenchyma, the endocrine and exocrine portions of the pancreas, and in the salivary gland. Immunoreactive p185neu was also demonstrated in fetal human intestinal epithelium. Tissue sections of selected benign and malignant colonic neoplasms were also examined. Immunoreactivity was consistently greater in adenomatous polyps than in adjacent normal colonic epithelium or areas showing malignant degeneration. By radioimmunoprecipitation, there was decreased expression in cell lines derived from more anaplastic colonic tumors. The p185neu protein is expressed widely in normal and transformed epithelial tissues of the digestive tract of the adult rat and human. This finding suggests that p185neu, a putative growth factor receptor, may play a role in the regulation of normal growth and function or in the malignant transformation of these cells.

Animals↗
PubMed1989

Linkage of tyrosine kinase activity with transforming ability of the p185neu oncoprotein.

The neu oncogene encodes a 185 kd glycoprotein (p185neu) with intrinsic tyrosine kinase activity. Sequencing data has demonstrated that oncogenic p185neu differs from c-neu by a single point mutation within the transmembrane region of the glycoprotein. This mutation results in the substitution of a glutamic acid residue for a nonpolar valine residue at amino acid position 664 of the rat neu gene product. Recent studies have demonstrated that this mutation results in specific aggregation of the p185neu oncoprotein mimicking ligand induced dimerization events. The cellular consequences of the aggregated phenotype may include the enzymatic activation of p185neu. We demonstrate that the oncoprotein p185neu possesses higher intrinsic tyrosine kinase activity and that this increase in enzymatic activity is apparent within the plasma membrane, manifesting itself through the increased tyrosine phosphorylation of substrates. Furthermore, the neu oncoprotein itself is also phosphorylated on tyrosine to a higher extent than the proto-oncoprotein. These results strongly link enzymatic activation of p185neu to cellular transformation events. To test directly the effect of p185neu tyrosine kinase activity on cellular transformation we constructed mutant p185neu devoid of ATP binding ability. This mutant protein is expressed at high levels, but is unable to induce the transforming phenotype. The point mutation within the transmembrane region of p185neu mimics aspects of ligand induced activation events including increases in the specific tyrosine kinase activity of the molecule leading to cellular transformation.

Adenosine Triphosphate↗
PubMed1988

The antigen-major histocompatibility complex-T cell receptor interaction. A structural analysis.

In summary, we wish to propose that regions on MHC molecules interact with complementary regions on processed peptide antigens, and that the resultant Ag-MHC complex forms a conformation with separate functional regions that are able to interact with similarly complementary areas on T cell receptors. It is the product of these interactions that determines whether a given peptide Ag is capable of binding the MHC molecule, and whether a given Ag-MHC complex is capable of stimulating a particular T cell. As more becomes known about the molecular aspects of MHC-restricted, Ag-specific T cell activation, it will become clear which amino acid residues on the Ag, MHC, and TCR are involved in these interactions.

Animals↗
PubMed1988

Reovirus type 1 and type 3 differ in their binding to isolated intestinal epithelial cells.

Binding of reovirus type 1 to dispersed villus cells from the small intestine was found to be specific for the basolateral membrane. Reovirus type 3 did not bind to any surface of small intestinal epithelial cells, but did bind to intra-epithelial lymphocytes. Using reovirus genetic reassortants, it was shown that the viral attachment polypeptide, encoded by the S1 genome segment of reovirus type 1 is essential for reovirus specific immunofluorescence to villus epithelial cells. In addition, the binding of reovirus type 1 to intestinal cells is saturable. Competition for the binding of 125I-labeled reovirus type 1 was demonstrated with unlabeled reovirus type 1 but not unlabeled reovirus type 3. This indicates that the intestinal epithelial receptor for reovirus is not shared by reovirus serotypes 1 and 3, and infection of intestinal epithelial cells by reovirus type 3 may be limited due to a failure of virus to bind.

Animals↗
PubMed1988

CD3-associated heterodimeric polypeptides on suppressor hybridomas define biologically active inhibitory cells.

We have investigated the relationship between CD3 expression and the suppressor T-cell function. We have isolated stable clonal cell lines of the F12.23 suppressor T-cell hybridoma that are either CD3+ or CD3-. These lines were subjected to functional assays including inhibition of in vivo hapten-specific delayed-type hypersensitivity responses, in vitro hapten-specific interleukin 2 responses, as well as hapten-specific cytotoxic T-lymphocyte assays. In all assays, the functional suppressor phenotype absolutely correlated with CD3 surface expression. Furthermore, we have immunoprecipitated heterodimeric proteins that share molecular features with some receptor polypeptides previously described. CD3 polypeptides found on the surface of suppressor T cells are phosphorylated after phorbol ester stimulation. Collectively these studies unambiguously define the suppressive supernatant function as a product of CD3+ receptor-bearing T cells.

Animals↗
PubMed1988

Sequences of the cell-attachment sites of reovirus type 3 and its anti-idiotypic/antireceptor antibody: modeling of their three-dimensional structures.

Previous studies have identified an area of amino acid sequence similarity shared by the reovirus type 3 cell-attachment protein sigma 1 and an anti-idiotypic/antireceptor monoclonal antibody (mAb) 87.92.6 that mimics reovirus type 3 by attaching to the same cell-surface receptor. We found that synthetic peptides corresponding to this area of primary sequence similarity bind a neutralizing mAb 9BG5 against which the mAb 87.92.6 is directed. The synthetic peptides compete with mAb 87.92.6 and reovirus type 3 for binding by mAb 9BG5 and displace mAb 87.92.6 and reovirus type 3 from binding to the cell-surface reovirus type 3 receptor. Such observations show that the shared primary structure between reovirus type 3 sigma 1 polypeptide and antireceptor mAb 87.92.6 defines the oligopeptide neutralizing/cell-attachment epitope of reovirus type 3. Computer modeling of this epitope, by use of sequence similarities of known immunoglobulin hypervariable loop conformations, permits an examination of the rudimentary three-dimensional structure of this epitope.

Amino Acid Sequence↗
PubMed1988

Molecular aspects of reovirus-host cell interaction.

Reovirus biology is defined, in the main, by the sigma 1 cell attachment protein located in the virion outer capsid. Interaction of the sigma 1 protein with serotype-specific receptor molecules located on the surface of target cells determines the tropism and virulence of the virus and mediates viral inhibition of target cell growth.

Amino Acid Sequence↗
PubMed1987

Augmentation of transfer of experimental autoimmune thyroiditis (EAT) in mice by irradiation of recipients.

Experimental autoimmune thyroiditis (EAT) can be adoptively transferred to normal syngeneic recipients using spleen cells from susceptible strains of mice primed in vivo with mouse thyroglobulin (MTg) and lipopolysaccharide (LPS) following in vitro activation of spleen cells by culture with MTg. Irradiation of recipient animals markedly augments the severity of thyroiditis induced in this system. Irradiation of recipients does not alter the time course of the development of thyroiditis, nor does it alter the requirement for both in vivo priming and in vitro activation of spleen cells for the development of EAT. Spleen cells from EAT-resistant strains of mice (e.g., Balb/c) do not induce EAT in irradiated recipients. Irradiated recipients develop significant levels of anti-MTg antibodies while unirradiated recipients have little detectable antibody response. The augmenting effect of irradiation can be substantially reversed by transferring naive spleen cells to recipients prior to the transfer of MTg/LPS-primed in vitro-activated spleen cells. In addition athymic CBA/Tufts nude mice develop more severe EAT than CBA/Tufts nude/+ littermates following transfer of activated CBA/J spleen cells. These data suggest that natural suppressor cells may regulate the development of EAT at the effector cell level.

Animals↗
PubMed1987

Metacarpophalangeal arthropathy associated with manual labor (Missouri metacarpal syndrome). Clinical radiographic, and pathologic characteristics of an unusual degeneration process.

We describe 7 manual laborers with painful, palpably enlarged metacarpophalangeal joints. Characteristic radiographic changes were joint space loss, prominent osteophytes, and cystic metacarpal heads most prominent in the second and third metacarpophalangeal joints. In 3 of 4 patients, joint biopsy specimens showed subsynovial fibrosis and villous hyperplasia. All 7 patients had similar backgrounds of heavy work demanding sustained gripping motions of both hands, for periods that exceeded 30 years. We designated their condition metacarpophalangeal arthropathy associated with manual labor.

Aged↗
PubMed1987

Effects of the adjuvants SGP and Quil A on the induction of experimental autoimmune thyroiditis in mice.

In the present study, two adjuvants, SGP and Quil A, were assessed for their ability to induce experimental autoimmune thyroiditis (EAT) in mice. SGP (a synthetic copolymer of starch, acrylamide, and sodium acrylate) and Quil A (a plant saponin) were compared with lipopolysaccharide (LPS) and complete Freund's adjuvant (CFA) given together with mouse thyroglobulin (MTg) for their ability to induce EAT in CBA/J mice. Immunization with MTg and LPS, MTg and CFA, or MTg with SGP was effective in inducing anti-MTg antibodies and histologic EAT, while MTg with Quil A was ineffective in inducing either anti-MTg antibodies or EAT. MTg with LPS was able to prime mice for the development of an in vitro spleen cell proliferative response to MTg while MTg with SGP or with Quil A was unable to prime spleen cells to proliferate detectably in response to MTg. MTg with LPS given in vivo primes CBA/J spleen cells for further activation by in vitro culture with MTg to transfer EAT to naive CBA/J recipients. MTg with SGP was also effective in priming CBA/J spleen cells for in vitro activation and transfer of EAT while MTg with Quil A was ineffective. The effective adjuvant activity of SGP and its lack of toxicity relative to LPS should make it a useful agent for further studies in murine models of EAT.

Acrylic Resins↗
PubMed1987

The cellular basis for the Ia restriction in murine experimental autoimmune thyroiditis.

Susceptibility to experimental autoimmune thyroiditis (EAT) in the mouse is linked to the I-A subregion of the major histocompatibility complex. EAT can be induced in susceptible strains of mice by immunization with mouse thyroglobulin (MTg) and adjuvant. We have described a cell transfer system wherein spleen cells from EAT-susceptible CBA/J mice primed in vivo with MTg and lipopolysaccharide (LPS) can be activated in vitro with MTg to transfer EAT to naive syngeneic recipients. This cell transfer system was used to elucidate the cellular basis for the I-A restriction in EAT. While the cell active in transferring EAT was Thy 1+ I-A-, depletion of I-A+ cells from the in vitro culture prevented the activation of EAT effector T cells. MTg-pulsed mitomycin C-treated naive syngeneic spleen cells as antigen-presenting cells (APCs) could replace the I-A+ cells in vitro. Allogeneic (Balb/c) APCs were ineffective. Using APCs from several recombinant inbred strains of mice, it was shown that C3H/HEN and B10.A(4R) APCs were effective in activating MTg/LPS-primed CBA/J spleen cells to transfer EAT while B10.A(5R) APCs were ineffective. This maps the H-2 restriction to the K or I-A subregions. Addition of polyclonal anti-Iak or monoclonal anti-I-Ak or anti-L3T4 during in vitro activation inhibited both the generation of EAT effector cells and the proliferative response to MTg. Irrelevant anti-Ia reagents, monoclonal anti-I-Ek, and monoclonal anti-I-Jk were ineffective. Thus the I-A restriction in murine EAT appears to result from an I-A restricted interaction between Ia+ APCs and Ia- EAT effector T cells.

Animals↗