Stimulation of phospholipase C by a mutationally activated G protein alpha 16 subunit.

Alpha 16, a member of the alpha q subfamily of G protein alpha subunits, was recently identified in human hematopoietic cells. In order to elucidate the function of this novel alpha subunit, we cloned and mutagenized its cDNA to obtain a constitutively active protein. COS-1 cells were transfected with both wild-type and mutant cDNAs.

Does CD4 help to maintain the fidelity of T cell receptor specificity?

During antigen presentation, a close association between CD4 and the T cell receptor (TCR) occurs as a result of interacting with the same major histocompatibility complex class II molecule. The potential consequences of such an intimate interaction on TCR specificity was addressed using CD4 loss variants of four different murine T cell hybridomas specific for the immunodominant hen egg lysozyme (HEL) peptide 46-61. While all the CD4+ and CD4- variants tested possessed comparable surface expression of TCR, CD3, CD2 and LFA-1, and responded similarly to immobilized anti-TCR and anti-CD3 monoclonal antibodies, they differed dramatically in their responses to either the naturally processed HEL antigen, synthetic peptide 46-61 or staphylococcal enterotoxin superantigens.

Species-specific binding of CD4 to the beta 2 domain of major histocompatibility complex class II molecules.

Exon-shuffled constructs between mouse (IA beta b) and human (DR3 beta) class II beta chains were made to study the interaction sites between CD4 and major histocompatibility complex (MHC) class II molecules, and to determine whether a species barrier is involved. The overall structure and the peptide binding groove appeared to be unaffected by the exon shuffling procedure as determined by monoclonal antibody and peptide binding assays, respectively. While purified CD4+ BALB/c T cells responded strongly in a mixed leukocyte reaction to transfectants expressing the whole IA molecule, the response to IA molecules containing a DR beta 2 domain was substantially reduced.

Sequence analysis of cytoplasmic mRNA-binding proteins of Xenopus oocytes identifies a family of RNA-binding proteins.

Storage of maternal mRNAs as nontranslated ribonucleoprotein (RNP) complexes is an adaptive strategy in various vertebrate and invertebrate oocytes, for rapid translational recruitment during embryonic development. Previously, we showed that Xenopus laevis oocytes have a soluble cytoplasmic pool of mRNA-binding proteins and particles competent for messenger RNP assembly in vitro. Here we report the isolation of cDNAs for the most abundant messenger RNPs, the 54- and 56-kDa polypeptide (p54/p56) components of the approximately 6S mRNA-binding particle, from an ovarian expression library.

The current spectrum of peptic ulcer disease in the older age groups.

Not only has there been a relative increase in the prevalence of peptic ulcer disease (PUD) among America's older age groups, but the characteristics of PUD in these patients differ significantly from those of the general population. Seventy-two consecutive patients 60 years of age or older who underwent operation for PUD between 1984 and 1989 were studied. The unusual features in these patients were 1) 92 per cent required emergency operation, 2) 57 per cent with perforated PUD were female, 3) 85 per cent had duodenal pathology, 4) 28 per cent were currently taking nonsteroidal anti-inflammatory agents, and 5) over one half of all patients had serious postoperative complications.

Epidermal Langerhans' cells in elderly patients with decubital ulcers.

Langerhans' cells in the sacral epidermis 8-10 cm from the lesion of elderly patients (mean age 74 years) with decubital ulcers were studied ultrastructurally and compared with the patients' own normal epidermis from the upper leg, with age-matched normal controls, and with young normal controls (mean age 43 years). High percentages of Langerhans' cells (ranging between 30 and 50%) without dendrites were found in patient epidermis from the sacral region near the lesion and similar percentages in normal skin from the patients' upper leg. In both elderly and young controls, Langerhans' cells without dendrites found in the epidermis of the upper leg were fewer, ranging between 13 and 33%.

Identification of protein IT of the intestinal cytoskeleton as a novel type I cytokeratin with unusual properties and expression patterns.

A major cytoskeletal polypeptide (Mr approximately 46,000; protein IT) of human intestinal epithelium was characterized by biochemical and immunological methods. The polypeptide, which was identified as a specific and genuine mRNA product by translation in vitro, reacted, in immunoblotting after SDS-PAGE, only with one of numerous cytokeratin (CK) antisera tested but with none of many monoclonal CK antibodies. In vitro, it formed heterotypic complexes with the type II CK 8, as shown by blot binding assays and gel electrophoresis in 4 M urea, and these complexes assembled into intermediate filaments (IFs) under appropriate conditions.

Molecular cloning and amino acid sequence of human plakoglobin, the common junctional plaque protein.

Plakoglobin is a major cytoplasmic protein that occurs in a soluble and a membrane-associated form and is the only known constituent common to the submembranous plaques of both kinds of adhering junctions, the desmosomes and the intermediate junctions. Using a partial cDNA clone for bovine plakoglobin, we isolated cDNAs encoding human plakoglobin, determined its nucleotide sequence, and deduced the complete amino acid sequence. The polypeptide encoded by the cDNA was synthesized by in vitro transcription and translation and identified by its comigration with authentic plakoglobin in two-dimensional gel electrophoresis.

Change of cytokeratin organization during development of Mallory bodies as revealed by a monoclonal antibody.

A monoclonal murine antibody (KM 54-5) was produced against Mallory body (MB) material isolated from liver tissue of griseofulvin treated mice. The antigen was identified by positive immunofluroescence microscopy of MBs and by the immunoblotting technique on polypeptides separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. In immunoblotting experiments, antibody KM 54-5 reacted with cytokeratins A (human no.

Patterns of expression and organization of cytokeratin intermediate filaments.

Cytokeratins are a large multigene family comprising two polypeptide types, i.e. acidic (type I) and basic (type II) ones, which are distinguished on the basis of immunological, peptide mapping, mRNA hybridization, and primary amino acid sequence data.

Comparison of intubating conditions with atracurium, vecuronium and pancuronium.

A blind trial, comparing time of onset of satisfactory conditions for tracheal intubation with atracurium 0.6 mg/kg, vecuronium 0.1 mg/kg and pancuronium 0.

Identification of two types of keratin polypeptides within the acidic cytokeratin subfamily I.

Cytoskeletal filaments of the alpha-keratin type (cytokeratins) are a characteristic of epithelial cells. In diverse mammals (man, cow and rodents) these cytokeratins consist of a family of approximately 20 polypeptides, which may be divided into the more acidic (I) and the more basic (II) subfamilies. These two subfamilies show only limited amino acid sequence homology.

Heterotypic tetramer (A2D2) complexes of non-epidermal keratins isolated from cytoskeletons of rat hepatocytes and hepatoma cells.

Cytoskeletal residues obtained after extraction of rat liver and cultured rat hepatoma cells (line MH1C1) were used to isolate cytokeratin subunit complexes by solubilization in low salt buffer containing 4 M-urea. Alternatively, the complexes were prepared by solubilization of total cytoskeletal proteins in 9.5 M-urea or 6 M-guanidinium hydrochloride (Gu .

Isolated right ventricular infarction: a diagnostic challenge.

Right ventricular involvement during myocardial infarction of the diaphragmatic and posterior wall of the left ventricle is not an infrequent complication, but isolated right ventricular infarction is rare. We report a case of rupture of the anterior wall of right ventricle and tamponade due to infarction at this site. The lack of characteristic clinical and electrocardiographic findings made the isolated right ventricular infarction a diagnostic challenge.

Protein complexes of intermediate-sized filaments: melting of cytokeratin complexes in urea reveals different polypeptide separation characteristics.

Subunit complexes of cytokeratin polypeptides from intermediate-sized filaments (IF) of various tissues and cultured cells from rat, cow, and man were solubilized in low-salt buffer containing 4 M urea and exposed to increasing concentrations of urea, followed by urea gradient electrophoresis or two-dimensional gel electrophoresis at different urea concentrations. Correspondingly, cytokeratin polypeptides dissociated in 9.5 or 10 M urea were dialyzed into lower concentrations of urea and allowed to reassociate into specific complexes.

Cessation of cytokeratin expression in a rat hepatoma cell line lacking differentiated functions.

Intermediate-sized filaments (IF) of diameter 7-11 nm occur in the cytoplasm of most cells of vertebrates and their constituent proteins are abundant in most cell types. Expression of IF proteins depends on the route of cell differentiation and five major subclasses of IF proteins have been distinguished: of these, cytokeratins are typical of epithelial cells whereas vimentin occurs in mesenchymally derived cells and some other non-epithelial cells. When epithelial cells are grown in culture this restriction of IF expression is often lost and they begin to synthesize vimentin in addition to cytokeratin, although examples of maintenance of the cell-type-specific expression of only cytokeratin have also been reported.

An epithelial cell line with elongated myoid morphology derived from bovine mammary gland. Expression of cytokeratins and desmosomal plaque proteins in unusual arrays.

Cells of a clonal line (BMGE + HM) selected from bovine mammary gland epithelial cell cultures are described which, after reaching confluence, do not assume typical epithelioid morphology, but form elongated cells with long slender processes extending over the surfaces of other cells. However, cells of this line which display non-epithelioid morphology and are exceptionally rich in actin microfilaments are identified as epithelial cells by their synthesis of cytokeratins and desmosomal plaque proteins, as demonstrated by immunofluorescence and immunoelectron microscopy and by gel electrophoresis of cytoskeletal proteins. The cells do not produce vimentin and desmin filaments.

Tissue type-specific expression of intermediate filament proteins in a cultured epithelial cell line from bovine mammary gland.

Different clonal cell lines have been isolated from cultures of mammary gland epithelium of lactating cow's udder and have been grown in culture media containing high concentrations of hydrocortisone, insulin, and prolactin. These cell (BMGE+H), which grow in monolayers of typical epithelial appearance, are not tightly packed, but leave intercellular spaces spanned by desmosomal bridges. The cells contain extended arrays of cytokeratin fibrils, arranged in bundles attached to desmosomes.