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Biomedical subjects

S L Warren

Publications and source records attributed to S L Warren.

At least 19 recordsLinked to original sources
PubMed1992

Autocrine angiotensin system regulation of bovine aortic endothelial cell migration and plasminogen activator involves modulation of proto-oncogene pp60c-src expression.

Rapid endothelial cell migration and inhibition of thrombosis are critical for the resolution of denudation injuries to the vessel wall. Inhibition of the endothelial cell autocrine angiotensin system, with either the angiotensin-converting enzyme inhibitor lisinopril or the angiotensin II receptor antagonist sar1, ile8-angiotensin II, leads to increased endothelial cell migration and urokinase-like plasminogen activator (u-PA) activity (Bell, L., and J. A. Madri. 1990. Am. J. Pathol. 137:7-12). Inhibition of the autocrine angiotensin system with the converting-enzyme inhibitor or the receptor antagonist also leads to increased expression of the proto-oncogene c-src: pp60c-src mRNA increased 7-11-fold, c-src protein 3-fold, and c-src kinase activity 2-3-fold. Endothelial cell expression of c-src was constitutively elevated after stable infection with a retroviral vector containing the c-src coding sequence. Constitutively increased c-src kinase activity reconstituted the increases in migration and u-PA observed with angiotensin system interruption. Antisera to bovine u-PA blocked the increase in migration associated with increased c-src expression. These data suggest that increases in endothelial cell migration and plasminogen activator after angiotensin system inhibition are at least partially pp60c-src mediated. Elevated c-src expression with angiotensin system inhibition may act to enhance intimal wound closure and to reduce luminal thrombogenicity in vivo.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1992

Cytostellin: a novel, highly conserved protein that undergoes continuous redistribution during the cell cycle.

Cytostellin, a 240 kDa protein, has been purified from mammalian cells by immunoaffinity chromatography using monoclonal antibody H5. Immunofluorescence microscopy shows diffuse and punctate cytostellin immunoreactivity in interphase nuclei. Nuclease digestion and salt extraction are not required to expose the epitope. The onset of prophase is marked by the appearance of multiple intensely immunofluorescent cytostellin-containing 'bodies' within the nucleus. Nuclear disassembly is heralded by the movement of cytostellin bodies from the nucleus to multiple positions throughout the cell. Cytostellin bodies in metaphase, anaphase and telophase cells are widely dispersed, including some in cell processes far removed from the mitotic spindle apparatus. However, a distinct subset of larger, more intensely staining bodies surrounds the mitotic spindle apparatus. Cytostellin bodies remain in the cytoplasm of the daughter cells and disappear after the appearance of nascent nuclei. Cytostellin is immunologically distinct from other nuclear and cytoplasmic proteins, and it has been detected by immunoblot analysis in all species tested from yeast to humans. Based upon these findings, we postulate that cytostellin has a cell cycle-dependent function which is conserved in higher and lower eukaryotic cells.

Animals↗
PubMed1991

Ankyrin binds to the 15th repetitive unit of erythroid and nonerythroid beta-spectrin.

Ankyrin mediates the attachment of spectrin to transmembrane integral proteins in both erythroid and nonerythroid cells by binding to the beta-subunit of spectrin. Previous studies using enzymatic digestion, 2-nitro-5-thiocyanobenzoic acid cleavage, and rotary shadowing techniques have placed the spectrin-ankyrin binding site in the COOH-terminal third of beta-spectrin, but the precise site is not known. We have used a glutathione S-transferase prokaryotic expression system to prepare recombinant erythroid and nonerythroid beta-spectrin from cDNA encoding approximately the carboxy-terminal half of these proteins. Recombinant spectrin competed on an equimolar basis with 125I-labeled native spectrin for binding to erythrocyte membrane vesicles (IOVs), and also bound ankyrin in vitro as measured by sedimentation velocity experiments. Although full length beta-spectrin could inhibit all spectrin binding to IOVs, recombinant beta-spectrin encompassing the complete ankyrin binding domain but lacking the amino-terminal half of the molecule failed to inhibit about 25% of the binding capacity of the IOVs, suggesting that the ankyrin-independent spectrin membrane binding site must lie in the amino-terminal half of beta-spectrin. A nested set of shortened recombinants was generated by nuclease digestion of beta-spectrin cDNAs from ankyrin binding constructs. These defined the ankyrin binding domain as encompassing the 15th repeat unit in both erythroid and nonerythroid beta-spectrin, amino acid residues 1,768-1,898 in erythroid beta-spectrin. The ankyrin binding repeat unit is atypical in that it lacks the conserved tryptophan at position 45 (1,811) within the repeat and contains a nonhomologous 43 residue segment in the terminal third of the repeat. It also appears that the first 30 residues of this repeat, which are highly conserved between the erythroid and nonerythroid beta-spectrins, are critical for ankyrin binding activity. We hypothesize that ankyrin binds directly to the nonhomologous segment in the 15th repeat unit of both erythroid and nonerythroid beta-spectrin, but that this sequence must be presented in the context of a properly folded spectrin "repeat unit" structure. Future studies will identify which residues within the repeat unit are essential for activity, and which residues determine the specificity of various spectrins for different forms of ankyrin.

Amino Acid Sequence↗
PubMed1988

Smooth muscle cells transiently express NCAM.

NCAM (neural cell adhesion molecule) polypeptides were first detected on neuronal cells and were subsequently found to be expressed at least transiently by a number of other cell types including skeletal and cardiac but not smooth muscle. We report here that rat smooth muscle expresses NCAM in vitro and transiently in vivo. Using a monoclonal antibody 3F4 which reacts with most rat NCAM polypeptides, NCAM was found on the surface of cultured rat aortic smooth muscle lines A10 and A7r5 and mouse smooth muscle like line BC3H1 in abundances equal to or greater than those of cardiac muscle, skeletal muscle, and neuronal cell lines. The major NCAM polypeptide of muscle cells was Mr = 140 kDa with lesser amounts of the 120 kDa form. Consistent with these results, a major NCAM mRNA of 6.7 kb was detected in Northern analyses with lesser amounts of the 4.3 and 2.9 kb mRNA size classes. The relative abundance of NCAM mRNA was similar in RNA prepared from smooth muscle A7r5 cells, L6 skeletal muscle cells, and 9-day-old rat brain. NCAM was distributed across the entire surface of cultured smooth muscle cells in a highly punctate manner. Cryostat sections of rat aorta, intestine and bladder were examined by immunofluorescence to determine if NCAM is also expressed on smooth muscle in vivo. In each case NCAM was found to be transiently expressed by the smooth muscle cells of these tissues. Highest NCAM levels were observed at embryonic day 17 which then declined to undetectable levels in tissues from adults. These results extend previous observations to indicate all muscle types transiently express NCAM in development.

Animals↗
PubMed1988

Elevated expression of pp60c-src alters a selective morphogenetic property of epithelial cells in vitro without a mitogenic effect.

Madin-Darby canine kidney (MDCK) cells are highly differentiated and have retained the morphogenetic properties necessary to form polarized, multicellular epithelial structures (cysts) in vitro that resemble epithelial tissues in vivo. We introduced the c-src gene into MDCK cells to elevate the level of the plasma membrane-associated cellular tyrosine kinase, pp60c-src, to levels two- to ninefold higher than that expressed in parent MDCK cells. Our results revealed a highly discriminatory biological action of pp60c-src on the morphogenetic properties of MDCK cells. Elevated expression of pp60c-src conferred on MDCK cells the ability to undergo dramatic changes of cell shape that includes the formation of long cell processes (100 to 200 microns), never observed in control MDCK cells. The morphogenesis of multicellular epithelial cysts was altered by elevated levels of pp60c-src and led to predictable distortions of their three-dimensional architecture. However, these cells established morphologically normal cell polarity, formed adhesive epithelial cell-cell contacts indistinguishable from those of control MDCK cells, and exhibited neither focus-forming ability or anchorage-independent growth potential. Finally, we showed that MDCK cells expressing elevated levels of pp60c-src exhibit increased phosphorylation of a more limited number of phosphotyrosine-containing proteins than MDCK cells expressing pp60v-src. We suggest that a natural function of pp60c-src is to regulate the morphogenetic properties which determine the shape of differentiated cells and multicellular structures.

Animals↗
PubMed1987

Nonmitogenic morphoregulatory action of pp60v-src on multicellular epithelial structures.

Madin-Darby canine kidney (MDCK) cells form polarized, multicellular epithelial structures in vitro. Low-level expression of pp60v-src in MDCK cells elicits plasticity in these multicellular structures. Plasticity was revealed by the displacement of cells from mechanically stressed regions of the epithelial monolayers; however, the two-dimensional relationship between the cells in the remainder of the monolayer was maintained. Electron microscopy of multicellular structures revealed abnormal separation of the lateral membranes of adjacent cells and selective uncoupling of the junctional complex; the zonula adherens was disrupted, but the zonula occludens and desmosomes were retained. Significantly, this result was not accompanied by transformation of the cells, as judged by the absence of anchorage-independent growth potential. These results demonstrate a nonmitogenic biological activity of pp60v-src which is experimentally dissociable from transformation. This morphoregulatory action on higher-order epithelial structures may reflect a function of related cellular tyrosine kinases.

Animals↗
PubMed1986

PC12 adhesion and neurite formation on selected substrates are inhibited by some glycosaminoglycans and a fibronectin-derived tetrapeptide.

The effects of added soluble glycosaminoglycans (GAGs) on adhesion and neurite formation by cultured PC12 pheochromocytoma cells on several substrates were tested. PC12 cells adhere more rapidly to Petri plastic coated with fibronectin, laminin, poly-L-lysine, or conA, than to either uncoated Petri plastic or tissue culture plastic. Adhesion to poly-L-lysine, fibronectin- and laminin-coated dishes was significantly inhibited by added dextran sulfate and to a lesser extent heparin--but not by chondroitin sulfate. PC12 adhesion to fibronectin could also be totally inhibited by the putative fibronectin cell binding tetrapeptide L-arginyl-glycyl-L-aspartyl-L-serine (Pierschbacher, MD & Ruoslahti, E, Nature 309 (1984) 30). The inhibitory effects of combinations of this tetrapeptide and heparin or dextran sulfate (but not chondroitin sulfate or hyaluronic acid) were additive. Nerve growth factor (NGF) pretreatment increased the percentage of PC12 cells adherent to all substrates and reduced the GAG inhibition of adhesion. PC12 cells previously treated with NGF to induce morphologic differentiation will rapidly re-extend neurites when plated on all four substrates. On fibronectin and poly-L-lysine-coated dishes this neurite growth is inhibited by added heparin and dextran sulfate, while on laminin it is not. Neurite formation on fibronectin-coated dishes was also inhibited by low concentrations of fibronectin tetrapeptide. In summary, PC12 adhesion and neurite formation can be inhibited by sulfated GAGs on some substrates, including fibronectin, but not other substrates, suggesting that these cells have at least two independent molecular adhesion mechanisms.

Animals↗
PubMed1984

Detection of a cell surface antigen found on rat peripheral nervous system neurons and multiple glia: astrocytes, oligodendrocytes, and Schwann cells.

A cell surface component has been identified that is found on cultured rat dorsal root ganglion neurons and Schwann cells and also cultured brain astrocytes and oligodendrocytes. This component was detected with a monoclonal antibody originally generated to the NG108 (N18 mouse neuroblastoma X C6 rat astrocytoma) hybrid cell line. The antibody, designated B2C11, binds to cultured peripheral nervous system cells: intact dorsal root ganglion and trigeminal neurons and cultured dorsal root ganglion and sciatic nerve Schwann cells. The binding of B2C11 to dorsal root ganglion neurons in vivo was confirmed by immunofluorescence analysis of cryostat sections. However, cultured embryonic rat central neurons showed no detectable binding of B2C11. Cultured brain cells containing glial fibrillary acidic protein (astrocytes) and also oligodendrocytes cultured from corpus collosum did bind B2C11 on their surfaces. B2C11 immunoprecipitation of detergent-solubilized membrane proteins from both lactoperoxidase iodinated C6 and PC12 rat pheochromocytoma cells indicated a single band with an apparent molecular weight of 21,000-23,000. Analysis of B2C11 binding to particulate protein preparations from adult rat organs showed highest specific activity in dorsal root ganglia. Other neural tissues had substantial binding. Some nonneural tissues (lung, kidney, and small intestine) expressed significant antigen levels, whereas others (heart, liver, and skeletal muscle) had a B2C11 antigen-specific activity less than 5% of that of dorsal root ganglia. Thus the B2C11 antigen is enriched in neural tissues, where it is found on the surfaces of a unique set of neuronal and glial cells.

Animals↗
PubMed1981

Interferon--a system of medium quantity production for therapeutic use.

A relatively detailed outline for the medium scale production and purification of interferon is presented in the hope that it will prove useful to those immunologically orientated physicians who desire to avail themselves of a course of interferon in therapeutic quantities for use in selected patients. A system for interferon assay is discussed and the reader is referred to the bibliography for further details of the process. This system has proved to be a reliable source of interferon in a therapeutic quantity. Pitfalls and support systems are discussed with the view of assisting the investigator in avoiding the many errors and disappointments encumbered in the process and are derived from experience in the field to date.

Blood Specimen Collection↗
PubMed1980

Inhibition of biological activity of mouse beta-nerve growth factor by monoclonal antibody.

A continuous hybrid cell line was derived that secretes monoclonal antibody capable of inhibiting the biological activity of mouse beta-nerve growth factor (beta-NGF). Results obtained with monovalent fragments indicate that the monoclonal antibody inhibits activity by interfering with the direct interaction between beta-NGF and the cell membrane receptor rather than by precipitating the dimeric form of beta-NGF. This monoclonal antibody binds to an antigenic determinant common to mouse beta-NGF, snake venom (Naja naja) beta-NGF, and human beta-NGF. These antibodies should provide specific molecular probes for a variety of studies of nerve growth factor including its tissue distribution and mechanism of action.

Animals↗
PubMed1980

A practitioner's guide to interferon.

The discovery and subsequent development of interferon as an anti-viral, ant-cancer therapeutic agent may well be a major milestone in the history of medical therapeutics. The results of the limited clinical trials available offer great promise for this biological agent. Only time, with large scale clinical trials, will serve to evaluate the true benefit of this modality of therapy. In the interim it is most desirable that the prcticing allergist-immunologist maintain an awareness of the use and mens of production of interferon so that he has available at his descretion a therapeutic modality for possible use in cases that have drastic, very poor or no therapeutic alternatives, remembering that each case add to the compendium of clinical knowledge.

Antineoplastic Agents↗
PubMed1979

Correlation of a bioassay with the clinical status of patients with rheumatoid arthritis.

Joint synovia and fluids taken from patients with various stages of rheumatoid arthritis (RA) were injected into embryonated chicken eggs, resulting in characteristic joint abnormalities ("crooked toes") in the extremities of the embryos and chicks. There was a direct correlation between the number of the induced lesions and the stages of the human RA disease. The percentage of abnormality of the bioassays was consistent with acute, subacute, chronic or remission phases in the clinical course of the RA disease. Specimens from chronic or remission RA joints produced few or no experimental abnormalities, suggesting few or no infectiojs RA particles available to the bioassay. Likewise, dilution of acute RA joint fluids of 1 : 100 by 0.15M NaCl resulted in a characteristic extinction of the bioassay test, suggesting that specimens could lose their reactivity in the bioassay because of too great dilution in the preparation of homogenates of the synovia. Numerical changes in the bioassay consistently followed the changes in the clinical courses of the RA during waning and waxing episodes. A useful numerical scale (0--100%) of the 10-day embryonated egg bioassay as an indication or measurement of the severity of the RA in the patient is proposed on the basis of these observations.

Adult↗
PubMed1977

Transfer factor for the practicing allergist-immunologist.

As continuing research elucidates the underlying mechanisms of immunological disease at the cellular level the need for the clinical allergist-immunologist to have available tools for the manipulation of cellular mechanics in the form of immunosuppression and immunostimulation becomes more apparent. An immunostimulant of perhaps wide application in the future is transfer factor derived from human lymphocytes. This presentation outlines in general the characteristics of transfer factor and a detailed method of production of transfer factor in a crude form is described. The procedure does not require specialized equipment and is simple enough so that interested clinical allergist-immunologists can produce transfer factor in their own laboratories and thus augment their armamentarium with an immunostimulant agent for use in selected cases.

Humans↗
PubMed1976

A systematic approach to the evaluation of immunological disease patterns.

An approach to the detection and investigation of immunological disease patterns is presented in the form of a relationship of etiology to disease and the major diagnostic procedures available to evaluate the etiological agents. The presentation is made in the form of a preamble which outlines the mechanisms of each class of dysfunction. Four tables are included which serve to amplify and detail the format of approach and the immune mechanisms.

Humans↗
PubMed1976

A new look at type I immediate hypersensitivity immune reactions.

The pathogenesis of type I disorders, particularly allergic asthma and urticaria, requires a critical review in the light of recent findings which indicate a second pathway for the release of granulocyte mediators. The isolation of enzyme activity of some of these released mediator establishes a direct link between the immunological system and bradykinin, as well as a system of self modulation of kinin activity. These findings open the door for a broader understanding of the asthmatic process and lay the foundation for integrating extrinsic and intrinsic asthma.

Asthma↗
PubMed1975

Thermal inactivation and gradient studies of the active agent in rheumatoid arthritis.

Ten day embryonated eggs have been used for testing supernatants of pooled RA synovial tissues for the presence of the RA-active agent. A high thermal resistance of the agent was observed up to 40 min of heating both at 100 and 121 degrees C with complete loss of infectivity only after 60 min at 121 degrees C. The high thermal resistance at 121 degrees C suggested that the active agent does not depend on a double-stranded DNA or RNA. It probably has no protein component and has a minimal number of subunits for replication. The CsC1 ultracentrifugation identified a concentration of high infectivity at densities in the range of 1.440-1.490 g/ml in five experiments.

Animals↗