PubMed Health⌕ Search

Biomedical subjects

G Rutter

Publications and source records attributed to G Rutter.

At least 37 records · Page 2Linked to original sources
PubMed1988

A preliminary study of the pharmacodynamics and pharmacokinetics of a novel enkephalin analogue [Tyr-D.Arg-Gly-Phe (4NO2).Pro.NH2 (BW443C)] in healthy volunteers.

We have studied 16 healthy men to evaluate preliminary pharmacodynamics and kinetics of BW443C given by i.v. infusions. Four volunteers received escalating doses at weekly intervals, starting at 0.1 microgram.kg-1 for 60 min and increasing to a maximum of 2.0 micrograms.kg-1.min-1 for 180 min. Subsequently 12 different subjects received single i.v. infusions of 10 micrograms.kg-1.min-1 for 20 min. Subjective effects were reported and objective measurements made of central nervous and cardiovascular effects. Blood was sampled at intervals on all occasions, plasma concentrations were determined by radioimmunoassay and pharmacokinetic profiles were analysed using NONLIN. Dry mouth and some nasal stuffiness were reported and postural hypotension occurred in 5/16 subjects at plasma concentrations greater than 0.8 microgram.ml-1. Supine blood pressure was well maintained in all subjects and hypotension resolved within 60-90 min of discontinuing the infusion. There was no evidence of sedation, mood change, nausea, vomiting, miosis, change in accommodation or respiratory depression. Rapid infusions produced transient feelings of warmth, heavy eyelids, heavy legs, and increased bowel sounds, which resolved despite increasing plasma concentrations. The disposition of the peptide was adequately described by a 2-compartment model with a mean +/- SD plasma clearance of 123 +/- 18 ml.min-1 and a half-life of 2.0 +/- 0.4 h.

Adult↗
PubMed1988

Demonstration of antigens at both sides of plasma membranes in one coincident electron microscopic image: a double-immunogold replica study of virus-infected cells.

We present here a procedure for obtaining high-resolution topographical information about the spatial distribution of antigens at both sides of isolated plasma membranes. HeLa cells grown on coverslips and infected with measles virus served as a model system. Virus glycoproteins appearing at the cell surface were demonstrated by tagging them with rabbit anti-measles antibodies and protein A-gold probes. Cells were stabilized with tannic acid, covered with a cationized coverslip, and then split in potassium-containing buffer. Membranes adherent to the cationized coverslip were fixed in formaldehyde-glutaraldehyde and reacted with mouse monoclonal antibodies against various structural proteins of measles virus. Antibody binding sites at the cytoplasmic surface were visualized either by the antibody bridge method, using normal mouse Ig coupled to gold colloid of different sizes, or by the peroxidase-antiperoxidase procedure. After osmication and critical point-drying, the cytoplasmic surfaces were replicated by platinum-carbon evaporation and examined by TEM without prior cleaning from biological material. This new method permits concomitant localization of antigens present at the inner and outer leaflets of the plasma membrane, and provides high-resolution information about the three-dimensional organization of the cytoplasmic surface.

Antibodies, Monoclonal↗
PubMed1987

Replica-immunogold technique applied to studies on measles virus morphogenesis.

The replica technique was applied to studies on the dynamic process of measles virus budding on infected HeLa cells. Virus structures were identified by labeling with anti-measles antibodies and protein A-gold. The combination of these two methods enabled us to characterize the sequence of virus budding at the plasma membrane, to localize virus structures on cytoskeletons of infected cells, and to study the influence of Ca2+ ions on virus structures at the plasma membrane. Studies on platinum carbon surface replicas suggest that the process of virus budding is similar to the genesis of cellular microvilli. Replicas prepared from cytoskeletons of infected cells reveal a close association of budding virus with actin filaments composing the outer parts of the networks. Replicas of apical plasma membranes isolated from infected cells show the attachment of viral nucleocapsids to the protoplasmic membrane face of infected cells. These nucleocapsids are not present on membranes prepared from cells treated with calcium and the ionophore A23187. In addition viral cell surface antigens become randomly distributed on these cells. The data suggest that measles virus morphogenesis at the plasma membrane of cultured cells is dependent on the function of the cytoskeleton and may be influenced by Ca2+ ions.

Calcimycin↗
PubMed1986

Involvement of actin filaments in budding of measles virus: studies on cytoskeletons of infected cells.

Cytoskeletons were prepared from measles virus infected HeLa cells to investigate the involvement of cytoskeletal filaments in virus budding at the plasma membrane. The cytoskeletons retained nearly 80% of measles virus hemagglutinin, the major viral polypeptides, including P, NP, and M, and 2 to 12% of the total cell bound infectivity. As demonstrated with platinum- and carbon-shadowed cytoskeletons, all stages of budding, i.e., virus specific strands, stub-like protrusions, and completely rounded virus particles, are associated with actin filaments composing the outer part of the cytoskeletal network. As shown with ultrathin sections of flat embedded extracted cells, actin filaments identified with heavy meromyosin almost exclusively protrude into virus particles with their barbed ends and are in close association with viral nucleocapsids. The data support previous suggestions that actin is involved in virus budding and show that budding itself is possibly the result of a vectorial growth of actin filaments.

Actins↗
PubMed1986

Preparation of apical plasma membranes from cells grown on coverslips. Electron microscopic investigations of the protoplasmic surface.

We introduce here a simple method which permits an efficient isolation of apical plasma membranes from tissue culture cells and the electron microscopic examination of their protoplasmic surfaces by use of the platinum/carbon replica technique. Different procedures were tested with regard to the efficiency of isolation and preservation of ultrastructure. Best results were obtained by prestabilization of cell surfaces with low concentrations of tannic acid prior to isolation. To demonstrate the possible applications and versatility of the method, studies were done on virus-infected cells in combination with immunocytochemical labeling. With this model system, we show that it is possible to correlate the structures seen on the cytoplasmic surface of the plasma membrane with the distribution of virus antigens at the cell surface labeled with immunogold markers prior to preparation.

Capsid↗
PubMed1985

Self-reactive B lymphocytes detected in young adults, children and newborns after in vitro infection with Epstein-Barr virus.

B-lymphocytes from healthy children and young adults who were seronegative for autoantibodies and B lymphocytes from umbilical cord blood of newborns were induced to secrete a variety of autoantibodies upon infection with Epstein-Barr virus. Such autoantibody-secreting clones were obtained from different lymphoid tissues and occurred at frequencies of 1 in 10(6)-10(7) mononuclear cells. The autoantibodies were exclusively of the IgM class. They recognized normal cellular components, such as cytoplasmic, nuclear and cytoskeletal antigens. The fact that self-reactive clones were not efficiently eliminated during ontogeny suggests that suppressor mechanisms might be responsible for normal self tolerance.

Adult↗
PubMed1984

Action of temperature-sensitive mutants of myeloproliferative sarcoma virus suggests that fibroblast-transforming and hematopoietic transforming viral properties are related.

The myeloproliferative sarcoma virus is molecularly related to the Moloney sarcoma virus (Pragnell et al., J. Virol. 38:952-957, 1981), but causes both fibroblast transformation in vitro and leukemic changes--including spleen focus formation--in adult mice. The fibroblast transforming properties of myeloproliferative sarcoma virus were used to select viral temperature-sensitive mutants at 39.5 degrees C, the nonpermissive temperature. These mutants are temperature sensitive in the maintenance of the transformed state. This was also shown by cytoskeletal changes of the infected cells at permissive and nonpermissive temperatures. Viruses released from cells maintained at both the permissive and nonpermissive temperature are temperature sensitive in fibroblast transformation functions. All temperature-sensitive mutants show only a low reversion rate to wild-type transforming function. The myeloproliferative sarcoma virus temperature-sensitive mutants are inefficient in causing leukemic transformation (spleen enlargement, focus formation) in mice at the normal temperature. A method to maintain a low body temperature (33 to 34 degrees C) in mice is described. One temperature-sensitive mutant was checked at low body temperature and did not induce leukemia. These data thus indicate that the same or related viral functions are responsible for hematopoietic and fibroblast transformation.

Animals↗
PubMed1984

Monoclonal antibodies reveal in blocking reactions the antigenicity and antibody response of poliovirus.

Neutralizing monoclonal antibodies against infectious poliovirus particles, type 1, strain Mahoney, were produced in hybridomas obtained from primed Balb/c mouse lymphocytes fused with the P3/NS-1/1-Ag4-1 mouse myeloma cell line (NS-1). From eleven neutralizing monoclonal antibodies, belonging to four groups differing in their reaction patterns, we chose for our experiments mNt-Abs reacting equally well with infectious poliovirus particles and naturally occurring empty capsids (NEC). We characterized the epitopes of NEC reacting with mNt-Abs by a quantitative absorption (blocking) ELISA with the help of monospecific polyvalent rabbit antisera directed against individual structural poliovirus polypeptides, obtained by two different separation procedures. We ascribe the "neutralizing antigenicity" of NEC to reside in or near polypeptides VP1 and VPO. Furthermore, we were able to demonstrate for the first time for poliovirus, that isolated polypeptides induced blocking antibodies, which were able to prevent binding of neutralizing antibodies to poliovirus NEC.

Antibodies, Monoclonal↗
PubMed1983

Inhibition of measles virus budding by phenothiazines.

HeLa cells infected with measles virus show an accumulation of virus-specific strands at the plasma membrane after addition of the anticalmodulin drugs trifluoperazine (TFP) and chlorpromazine (CPZ), whereas spherical virus particles are almost completely absent. At low drug concentrations (10-15 microM TFP; 30-40 microM CPZ) the inhibitory effect is dependent on the presence of extracellular calcium. The strands complete the budding process after removal of the drugs. Restoration of virus budding is not sensitive to cycloheximide and immunoprecipitation experiments give evidence that the viral protein synthesis is not qualitatively altered in the presence of TFP. The data indicate that both drugs arrest the budding process at an intermediate stage at the plasma membrane. The inability of the strands to comigrate with cytochalasin B-induced actin patches suggests that the inhibition of budding is probably the result of an impaired interaction of viral structures with the cytoskeleton.

Antipsychotic Agents↗
PubMed1983

Evidence for several unrelated neutralization epitopes of poliovirus, type 1, strain Mahoney, provided by neutralization tests and quantitative enzyme-linked immunosorbent assay (ELISA).

With the aid of 11 neutralizing monoclonal antibodies which were investigated in four different neutralization tests, evidence was provided that several unrelated epitopes for neutralizing antibodies exist on the surface of poliovirus type 1. All monoclonal antibodies were able to neutralize poliovirus infectivity prior to and after virus adsorption to host cells. The quantitative enzyme-linked immunosorbent assay is introduced as a second independent system for the determination of antibody specificity. Antibodies could be divided into four groups according to their reaction patterns.

Antibodies, Monoclonal↗
PubMed1982

Protein-A gold particles as markers in replica immunocytochemistry: high resolution electron microscope investigations of plasma membrane surfaces.

Due to their high atomic number contrast in transmission electron microscopy, gold particles are ideal markers in surface replicas of cultured cells. The suitability of protein-A-coated gold particles in replica immunocytochemistry for labelling surface antigens is demonstrated using measles virus-infected cells as a model system. Labelled areas can easily be distinguished from unlabelled areas, and even markers positioned in the evaporation shadow of large structures can be accurately identified, which is a prerequisite for an exact quantification and mapping of antigen. In addition, the ultrastructure of labelled areas can still be visualized because of the small size of the marker.

Antigens, Surface↗
PubMed1980

Influenza A antibodies in Cervine animals.

In the haemagglutination inhibition (HI) test, 20 cervine sera, most of which came from Northern Germany, were treated with receptor destroying enzyme (RDE) and 11 sera were found to contain antibodies against the H1N1 (A/USSR 90/77) and H3N2 (A/Victoria 13/75, A/Texas 1/77) influenza viruses. Only two sera contained antibodies against H3N2 viruses, and seven sera were negative. Evidence of the specificity of influenza antibodies was provided by the following findings: 1) the IgG serum extracts showed the same inhibitory activity of haemagglutinin as the RDE treated sera; 2) addition of protein A led to an increase in the HI titers; 3) in the haemolysis in gel test, some of the HI positive sera formed haemolysis in gel test, some of the HI positive sera formed haemolysis rings of the same diameter as hyperimmune antiinfluenza A (H1N1) serum; and 4) the cervine sera reacted positively in the neuraminidase inhibition (NI) test. It is remarkable that influenza H1N1 antibodies were found in the serum of one cervine before this virus strain appeared in humans.

Animals↗