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Biomedical subjects

G E Jones

Publications and source records attributed to G E Jones.

At least 91 records · Page 5Linked to original sources
PubMed1990

Protection of sheep against Chlamydia psittaci infection with a subcellular vaccine containing the major outer membrane protein.

An outer membrane (OM) preparation from elementary bodies (EBs) of Chlamydia psittaci (ovine abortion strain) was used to vaccinate pregnant ewes in a single subcutaneous dose and was found to achieve protection after subcutaneous challenge with infectious organisms. Inactivated purified EBs used as a single-dose vaccine also gave protection. The ratio of live to dead lambs was significantly higher in the vaccinated groups (16:1 and 15:1, respectively) than in the placebo group (8:9). Polyacrylamide gel electrophoresis and immunoblotting showed that a 40-kilodalton protein was the main protein constituent of the OM preparation, and this was positively identified as the major outer membrane protein by protein microsequencing. Electron microscopy revealed that fine particulate structures on the outermost surface of the EB were also present in the OM preparation. The findings suggest that the major outer membrane protein is an important immunoprotective determinant in ovine abortion vaccines.

Amino Acid Sequence↗
PubMed1990

Segregation of the myogenic cell lineage in mouse muscle development.

With increasing interest in the idea of therapeutic implantation of normal muscle precursor cells into muscle lacking the protein product of the dystrophin gene, it has become important to obtain enriched populations of myogenic cells from biopsied muscle sources. Myogenic cells for implantation are highly favoured as they are the only cells that will fuse readily with host muscle fibres into which they are implanted, thus carrying the introduced gene into the target fibre with the maximum of efficiency. Second, myogenic cells appear less immunogenic than those of a non-myogenic nature; and third, the use of mononuclear myogenic cells may permit the introduction of multiple copies of a deficient gene into the patient's own cells. From a mixed population of cells obtained by the enzymic disaggregation of neonatal murine muscle we have selected, utilising a modification of the panning technique, for a cell population rich in myogenic cells. Segregation was accomplished using Mab H28, an antibody to the mouse neuronal cell adhesion molecule (N-CAM), derived from mouse/rat hybridoma cells. Following incubation with Mab H28, disaggregated muscle was applied to the surface of a bacteriological grade dish previously coated with anti-rat immunoglobulin. Cells segregated into two populations; those bearing N-CAM, and hence labelled with Mab H28, were adherent to the dish, whereas those not expressing N-CAM remained in suspension. Use of this technique, which involves minimal cell loss, resulted in the segregation of prefusion myogenic cells together with fibroblasts in the 'non-adherent' fraction, whereas cells in the adherent fraction consisted of a highly enriched population of actively dividing myogenic cells.

Animals↗
PubMed1990

Do the 'Baby Doe' rules discriminate against infants?

This essay consists of a critical examination of the 'Baby Doe' rules with respect to their proscription of references to quality of life considerations as a basis for treatment decisions. It is argued that the rules cannot and should not obviate references to the infant's quality of life. Further, it is argued that there are not sufficient differences between infants and adult incompetent patients to justify the use of quality of life assessments with regard to the latter and not the former.

Humans↗
PubMed1989

Reticuloendothelial function and plasma fibronectin in a murine model of intra-abdominal sepsis.

The lung is the target organ most frequently involved in the early phase of multiple organ failure. Microembolisation of the pulmonary vasculature by bacterial and non-bacterial particles and debris with failure of the clearance mechanism of the reticuloendothelial system (RES) and depletion of plasma fibronectin have been implicated in the pathogenesis. The present study examined the concurrent changes in plasma fibronectin, RES phagocytic function, organ localisation of bacterial and non-bacterial particles and the levels of circulating endotoxin and fibrin degradation products in a clinically relevant murine model of severe intra-abdominal infection. Progressive sepsis was associated with deteriorating RES phagocytic function to 45% of control values within 48 h of sepsis induction. There was decreased hepatosplenic uptake and increased pulmonary localisation of bacterial and lipid emulsion particles. Plasma fibronectin increased in septic animals within 48 h suggesting increased fibronectin production. These changes would support the hypothesis that altered RES function may facilitate pulmonary microembolisation in the pathogenesis of septic multiple organ failure.

Abdomen↗
PubMed1989

Protection of lambs against experimental pneumonic pasteurellosis by transfer of immune serum.

Passive protection of specific pathogen-free lambs against experimental pasteurellosis was achieved using antisera from conventionally reared sheep which were either convalescent from experimental pneumonia or inoculated with Pasteurella haemolytica A2 vaccines. The complete immune sera, or immunoglobulin-rich fractions prepared from them, when administered separately or together provided 94-100% protection of recipients compared to control lambs. Antibodies to P. haemolytica in donor sera were quantified by anti-sodium salicylate extract (SSE) and anti-lipopolysaccharide (LPS) ELISA, bactericidal assay, cytotoxin neutralization and indirect haemagglutination. The anti-SSE ELISA titres correlated best with protective efficacy and could be used to measure antibody in recipient lambs immediately before challenge. The degree of protection was unaffected by prior infection with parainfluenza virus Type 3, suggesting that such exposure did not enhance exudation of circulating immunoglobulin into the respiratory tract. It was concluded that systemic humoral immunity alone can prevent pasteurellosis.

Animals↗
PubMed1989

A crude cytotoxin vaccine protects sheep against experimental Pasteurella haemolytica serotype A2 infection.

Three vaccines containing Pasteurella haemolytica serotype A2 antigens were tested for their ability to protect sheep against a homologous challenge. A crude cytotoxin preparation in combination with a sodium salicylate extract (SSE) or crude cytotoxin alone were highly protective (98 and 86%, respectively), whereas SSE alone was poorly (47%) protective. These findings indicated that the crude cytotoxin was an essential component of a protective vaccine. Protection correlated with serum cytotoxin-neutralising (CN) titres and bactericidal activity, which were stimulated by antigens in the crude cytotoxin preparation.

Animals↗
PubMed1989

Rapid, random evolution of the genetic structure of replicating tobacco mosaic virus populations.

The effects of temperature and type of host on the evolution of variants in replicating populations of tobacco mosaic virus (TMV) originating from an in vitro RNA transcript of a cDNA clone were studied. The phenotypic markers measured were temperature-sensitive (ts) replication and induction of necrotic local lesions (nl) on Nicotiana sylvestris. The proportions of ts variants were about the same under all conditions tested, but changes in temperature or host had strong effects on proportions of nl variants. During replication at elevated temperatures in tobacco or tomato, percentages of nl variants were reduced rapidly to about one tenth their initial values. In contrast, when virus replicated at 25 degrees in tobacco, little change in the average proportion of nl variants was observed, and in tomato, only a slight average reduction occurred. Virus replicating at 25 degrees in Solanum nigrum or Petunia hybrida suffered effects similar to those observed in tobacco or tomato, respectively. However, at 25 degrees in Physalis floridana, there was strong selection against nl variants, which eventually reduced them to essentially undetectable levels. In all hosts tested at 25 degrees, surprisingly large, apparently random changes in the proportion of nl variants occurred in individual plants. These experiments showed that virus populations can evolve rapidly on a time scale of days, and that an element of randomness is an important component in the initiation of change.

Biological Evolution↗
PubMed1989

The kinetics of cell-substratum detachment mediated by trypsin: a comparison of normal and Duchenne fibroblasts.

In previous studies of cell-cell and cell-substratum adhesion, we have identified differences in the behaviour between human skin fibroblasts cultured from normal individuals and patients with Duchenne muscular dystrophy (DMD). In these studies, monolayer cultures were dissociated by trypsinization and no detectable difference was noted in the efficiency of cell dissociation between normal and DMD fibroblast cultures. However, a detailed study by Kent has suggested that Duchenne fibroblasts exhibit increased sensitivity to trypsin. We have re-investigated this finding using an assay that directly measures the number of cells remaining attached to a substratum following trypsinization. In a series of experiments using cultures derived from five normal and five DMD individuals, we can detect no significant difference in the trypsin-induced detachment rates between normal and DMD skin fibroblasts. This observation applies to both growth-phase and stationary-phase cell cultures. This inconsistency with previously reported data on the trypsin-sensitivity of DMD cells is considered in terms of the different assays used and the effects of trypsin on cell-cell and cell-substratum adhesion. The relationship between abnormalities in the behaviour of DMD cells and the localization and primary structure of the DMD gene product are also discussed.

Cell Adhesion↗
PubMed1989

Colony-stimulating factor-1 induces rapid behavioural responses in the mouse macrophage cell line, BAC1.2F5.

The cloned, SV40-immortalized mouse macrophage cell line, BAC1.2F5, resembles primary macrophages in its dependence on colony-stimulating factor-1 (CSF-1) for both viability and proliferation. Re-addition of CSF-1 stimulates rapid, transient behavioural changes in starved cells, which are rounded, with diffusely organized F-actin and few intracellular vesicles. Within 1 min, cells begin to spread, forming prominent, F-actin-rich ruffles. Small vesicles (0.5-1.0 microns), formed throughout extending lamellar processes, move centripetally and, after 3-5 min, fuse to form larger vesicles (2.0-4.0 microns), clustered around the nucleus. Immunofluorescence demonstrates that CSF-1, bound to cell-surface receptors, is internalized via these vesicles. Cell spreading and ruffling peak about 5 min after restimulation. Interference reflection microscopy indicates no corresponding change in the mode of cell-substratum adhesion: a single area of close adhesion underlies most of the cell and simply broadens during spreading. Analysis of cell aggregation kinetics shows no effect of CSF-1 on intercellular adhesiveness. Measurement of cell areas after starvation and restimulation demonstrates quantitatively the time-course and concentration-dependence of cell spreading. Mean area doubles within 5 min and, after a transient peak, decreases within 30 min to the value measured before starvation. This time-course corresponds to that of CSF-1 internalization and of the phosphorylation and subsequent degradation of CSF-1 receptors. The concentration-dependence of the spreading response resembles that of CSF-1-dependent survival and proliferation. The minimum detectable stimulation of spreading occurs at the concentration (22 pM) that supports survival without proliferation. Increasing stimulation of spreading occurs over the range of concentrations that elicit increasing proliferation.

Actins↗
PubMed1989

Prawf Geiriau Caerdydd--a Welsh language speech test.

We have developed a set of six isophonemic word lists in Welsh, each comprising 16 vowel-consonant-vowel (VCV) words. They include the 20 commonest consonants and the 16 commonest vowel/diphthongs in Welsh, and all six lists give equivalent scores. Examination of error patterns indicates a number of differences from those found in English including a lack of voiced/voiceless confusions and an adherence to the phonotactic constraints of the Welsh language.

Humans↗
PubMed1988

Requirements for the Ca2+-independent component in the initial intercellular adhesion of C2 myoblasts.

Using a sensitive and quantitative adhesion assay, we have studied the initial stages of the intercellular adhesion of the C2 mouse myoblast line. After dissociation in low levels of trypsin in EDTA, C2 cells can rapidly reaggregate by Ca2+-independent mechanisms to form large multicellular aggregates. If cells are allowed to recover from dissociation by incubation in defined media, this adhesive system is augmented by a Ca2+-dependent mechanism with maximum recovery seen after 4 h incubation. The Ca2+-independent adhesion system is inhibited by preincubation of cell monolayers with cycloheximide before dissociation. Aggregation is also reduced after exposure to monensin, implicating a role for surface-translocated glycoproteins in this mechanism of adhesion. In coaggregation experiments using C2 myoblasts and 3T3 fibroblasts in which the Ca2+-dependent adhesion system was inactivated, no adhesive specificity between the two cell types was seen. Although synthetic peptides containing the RGD sequence are known to inhibit cell-substratum adhesion in various cell types, incubation of C2 myoblasts with the integrin-binding tetrapeptide, RGDS, greatly stimulated the Ca2+-independent aggregation of these cells while control analogs had no effect. These results show that a Ca2+-independent mechanism alone is sufficient to allow for the rapid formation of multicellular aggregates in a mouse myoblast line, and that many of the requirements and perturbants of the Ca2+-independent system of intercellular myoblast adhesion are similar to those of the Ca2+-dependent adhesion mechanisms.

Animals↗
PubMed1988

Two-stage mineralization of phenanthrene by estuarine enrichment cultures.

The polycyclic aromatic hydrocarbon phenanthrene was mineralized in two stages by soil, estuarine water, and sediment microbial populations. At high concentrations, phenanthrene was degraded, with the concomitant production of biomass and accumulation of Folin-Ciocalteau-reactive aromatic intermediates. Subsequent consumption of these intermediates resulted in a secondary increase in biomass. Analysis of intermediates by high-performance liquid chromatography, thin-layer chromatography, and UV absorption spectrometry showed 1-hydroxy-2-naphthoic acid (1H2NA) to be the predominant product. A less pronounced two-stage mineralization pattern was also observed by monitoring CO(2) production from low concentrations (0.5 mg liter) of radiolabeled phenanthrene. Here, mineralization of C-labeled 1H2NA could explain the incremental CO(2) produced during the later part of the incubations. Accumulation of 1H2NA by isolates obtained from enrichments was dependent on the initial phenanthrene concentration. The production of metabolites during polycyclic aromatic hydrocarbon biodegradation is discussed with regard to its possible adaptive significance and its methodological implications.

Journal Article↗
PubMed1988

Mineralization of phenanthrene by a Mycobacterium sp.

A Mycobacterium sp., designated strain BG1, able to utilize the polycyclic aromatic hydrocarbon phenanthrene as the sole carbon and energy source was isolated from estuarine sediment following enrichment with the hydrocarbon. Unlike other phenanthrene degraders, this bacterium degraded phenanthrene via 1-hydroxy-2-naphthoic acid without accumulating this or other aromatic intermediates, as shown by high-performance liquid chromatography. Degradation proceeded via meta cleavage of protocatechuic acid. Different nonionic surfactants (Tween compounds) solubilized the phenanthrene to different degrees and enhanced phenanthrene utilization. The order of enhancement, however, did not correlate perfectly with increased solubility, suggesting physiological as well as physicochemical effects of the surfactants. Plasmids of approximately 21, 58, and 77 megadaltons were detected in cells grown with phenanthrene but not in those which, after growth on nutrient media, lost the phenanthrene-degrading phenotype. Given that plasmid-mediated degradations of aromatic hydrocarbons generally occur via meta cleavages, it is of interest that the addition of pyruvate, a product of meta cleavage, supported rapid mineralization of phenanthrene in broth culture; succinate, a product of ortho cleavage, supported growth but completely repressed the utilization of phenanthrene. The involvement of plasmids may have given rise to the unusual degradation pattern that was observed.

Cell Wall↗