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R A Cox

Publications and source records attributed to R A Cox.

At least 73 records · Page 4Linked to original sources
PubMed1992

The nucleotide sequence of the promoter, 16S rRNA and spacer region of the ribosomal RNA operon of Mycobacterium tuberculosis and comparison with Mycobacterium leprae precursor rRNA.

Mycobacterium tuberculosis H37Rv has a single rrn (ribosomal RNA) operon. The operon was cloned and a region of 1536 nucleotides was sequenced, starting 621 bp upstream from the 5'-end of the 16S rRNA coding region and continuing to the start of the 23S rRNA coding region. The 16S rRNA sequence inferred from the gene sequence was found to differ in one position from Mycobacterium bovis (nucleotide 1443) and from Mycobacterium microti (nucleotide 427). A single putative promoter was identified on the basis of similarities with the sequence of rrn operons of Bacillus subtilis and Escherichia coli. The regions of similarity include a -35 box, a -10 box, a stringent response element, antitermination signals, potential RNAase III processing sites and features of precursor rRNA secondary structure. Sequences upstream from the 5'-end of Mycobacterium leprae 16S rRNA were also investigated. Homologous schemes of secondary structure were deduced for precursor rRNA of both M. tuberculosis and M. leprae; although the principal features are common to both species there are notable differences.

Base Sequence↗
PubMed1992

Localization of the tube precipitin and complement fixation antigens of Coccidioides immitis by immunoelectron microscopy with murine monoclonal antibodies.

The cellular localization of the tube precipitin (TP) and complement fixation (CF) antigens of Coccidioides immitis was examined by immunoelectron microscopy with murine immunoglobulin G1 monoclonal antibodies directed against the TP and CF antigens, respectively. Immunoelectron microscopic analyses of saprobic- and parasitic-phase cells showed that the TP antigen is present at a high concentration within the inner cell wall layer and along the plasma membrane. The antigen was also detected, at a lesser concentration, within cytoplasmic vacuoles. In contrast to the predominant localization of the TP antigen in the cell walls, the CF antigen residues primarily within the cytoplasm, where it appears to be dispersed throughout the cytoplasm rather than associated with a specific cytoplasmic organelle. A sparse amount of the CF antigen within the inner cell walls was also demonstrable. The localization of the TP and CF antigens throughout the morphogenetic phases of C. immitis has important implications in antigen production and in analyses of host response in coccidioidomycosis.

Animals↗
PubMed1992

Differentiation of anchoring junctions in tracheal basal cells in the growing rat.

A function of airway basal cells is to attach ciliated and nonciliated columnar cells to the basal lamina. The significance of the basal cell in attachment is related to the height of the columnar epithelium. In taller epithelia, basal cells are more numerous and differentiated with respect to anchoring junctional adhesion mechanisms (desmosomes, hemidesmosomes, and the cytoskeleton) than in shorter epithelia. In this study, we determined if basal cell anchoring junctional adhesion mechanisms differentiated during growth of the airway. Tracheas from five 3-day-old, five 30-day-old, and five 90-day-old rats were prepared for electron microscopy and morphometrically studied by standard techniques. The circumference of the trachea increased from 2.5 +/- 0.2 to 7.5 +/- 0.4 mm during growth. The height of the columnar cell increased from 13.4 +/- 1.5 to 24.6 +/- 3.9 microns, and the number of basal cells per millimeter increased from 3.2 +/- 0.7 to 9.6 +/- 1.8 during growth. The number of desmosomes per basal cell profile increased significantly from 1.5 +/- 0.1 to 2.1 +/- 0.1, as did keratin filament volume density from 0.046 +/- 0.05 to 0.098 +/- 0.032. The amount of hemidesmosome attachment per basal cell did not increase significantly during growth of the airway. These data demonstrate that as tracheas grow in circumference, the columnar cells increase in height, basal cells increase in number, and anchoring junctional adhesion mechanisms differentiate in the basal cells. These changes are closely related to the height of the epithelium and result in maintaining a constant amount of attachment between the columnar epithelium and the basal lamina as the epithelium increases in height.

Aging↗
PubMed1992

Morphologic changes in basal cells during repair of tracheal epithelium.

Basal cells are differentiated with respect to junctional adhesion mechanisms and play a role in attachment of columnar epithelium to the basal lamina. Although much is known about nonciliated and ciliated cell differentiation during the repair process after injury, little is known about the basal cell. We studied the morphology of basal cells and quantitated junctional adhesion structures during repair of tracheal epithelium exposed to toxic cotton smoke. Ten adult ewes were given a smoke injury to a portion of the upper cervical trachea and were killed at 4, 6, 8, 10, and 18 days after injury for morphometric studies. At 4 days, there was a stratified reparative epithelium over the basal lamina, which was two to four cells in depth. The basal cells were identified by their hemidesmosome (HD) attachment to the basal lamina. Basal cells were about 69% larger than controls and flattened rather than columnar. The amount of HD attachment was 192% greater than controls. In contrast, volume density of cytokeratin filaments had decreased about 47%. Basal cells had returned to normal numbers and size and a columnar shape by day 18. The amount of desmosome (D) and HD attachment and volume density of cytokeratins had also reached control levels by day 18. These data indicate that morphology of basal cells changes during the initial stages of reparative regeneration but returns to normal by 18 days. Morphologic changes appear to reflect changes in size of the cell associated with cell division rather than differentiation of recently divided basal cells.

Animals↗
PubMed1991

The 16S ribosomal RNA of Mycobacterium leprae contains a unique sequence which can be used for identification by the polymerase chain reaction.

Nucleotide sequence data for bacterial 16S ribosomal RNA was used to identify oligodeoxyribonucleotide primers suitable for probing the rRNA gene of mycobacteria and related organisms, with the polymerase chain reaction. The method enabled us to distinguish mycobacteria from other closely related genera, and to differentiate between slow- and fast-growing mycobacteria. Mycobacterium leprae fell within the slow-growing group of mycobacteria but there are significant differences between the sequence of the M. leprae 16S rRNA gene and that of other slow-growing mycobacteria. These differences were used to devise a rapid, non-radioactive method for detecting M. leprae in infected tissue.

Animals↗
PubMed1991

Effect of a recombinant HIV gp160 vaccine on monokine production.

An investigation was undertaken to determine whether a recombinant gp160 envelope protein, which is currently being evaluated as a vaccine for AIDS, induces or modulates the production of tumour necrosis factor-alpha (TNF-alpha) or interleukin-1 beta (IL-1 beta). Incubation of monocytes from healthy, HIV-seronegative persons with 0.0001-1.0 micrograms of the recombinant vaccine did not result in the secretion of TNF-alpha or IL-1 beta, nor did the recombinant product augment or suppress monokine production by lipopolysaccharide (LPS) stimulated monocytes. The vaccine was also without a stimulatory or modulatory effect upon TNF-alpha or IL-1 beta secretion by monocytes from a patient with the AIDS-related complex (ARC) and from the monocytic THP-1 cell line. The lack of effect of gp160 on monokine production has important implications for its efficacy as a vaccine for AIDS.

Gene Products, env↗
PubMed1991

Production and characterization of a monoclonal antibody to the complement fixation antigen of Coccidioides immitis.

Detection of complement-fixing antibody to coccidioidin by using the complement fixation test or an immunodiffusion assay for complement-fixing antibody (IDCF) is widely viewed as the most useful immunodiagnostic test for coccidioidomycosis. In this investigation, we report the production of an immunoglobulin G subclass 1 (IgG1) monoclonal antibody (MAb) to the IDCF antigen for use as a biospecific ligand for purifying the IDCF antigen on solid-phase immunosorbents and for use as a reagent for screening genomic or cDNA expression libraries from Coccidioides immitis. BALB/c mice were immunized by intramuscular injections of coccidioidin in adjuvant, followed by an intrasplenic booster injection of coccidioidin in saline. The spleen cells were fused with SP2/0 Ag14 myeloma cells, and the fusion products were screened for IgG antibody to coccidiodin by using an enzyme-linked immunosorbent assay. Positive hybridomas were cloned and evaluated for reactivity to the IDCF antigen by two-dimensional immunoelectrophoresis and by immunoblotting. An IgG1 Mab was produced that was specific for the IDCF antigen when evaluated by two-dimensional immunoelectrophoresis and immunoblotting. The epitope recognized by the MAb was heat labile (60 degrees C, 30 min) and susceptible to enzymatic digestion with pronase but was resistant to treatment with lipase, alpha-mannosidase, glucose oxidase, and endoglycosidase H. This heat-labile peptide epitope appears to be specific to C. immitis, as judged by the fact that the MAb was not reactive in immunoblots or enzyme-linked immunosorbent assays of histoplasmin or blastomycin.

Animals↗
PubMed1990

Social knowledge and social competence: number and quality of strategies as predictors of peer behavior.

The purpose of this study was to examine the ability of two different measures of preschool children's social strategy knowledge to predict classroom behavior with peers. Thirty-two 4- and 5-year-old children attending a university sponsored preschool were administered the Preschool Interpersonal Problem-Solving Tests (PIPS) and an enactive assessment of strategy knowledge. Observational and teacher-rating measures of children's positive and aggressive peer behavior were also obtained. Significant correlations were obtained between (a) the number of strategies produced in the enactive measure and cooperative play ratings by teachers, (b) the number of strategies produced in the PIPS and observations of positive peer behavior, and (c) ratings of friendliness in the PIPS and teacher-rated cooperative play and aggression and observations of aggression. Results are discussed in terms of implications for social skill training.

Aggression↗
PubMed1990

Production of tumor necrosis factor-alpha and interleukin-1 by alveolar macrophages from HIV-1-infected persons.

Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) are potent immunomodulatory cytokines which are produced principally by cells of the macrophage-monocyte lineage. We conducted an investigation to assess the secretion of these cytokines by bronchoalveolar macrophages from patients with progressive stages of human immunodeficiency virus (HIV-1) infection. The mean level of TNF-alpha produced by macrophages from 9 patients with AIDS was significantly reduced compared with the responses of macrophages from 6 healthy HIV-1-seronegative persons, 6 patients with either asymptomatic HIV-1 infection or persistent generalized lymphadenopathy, and 6 patients with AIDS-related complex (ARC). The four study groups did not differ in their mean IL-1 beta responses. However, within the HIV-1-infected patient population, macrophages from 4 patients, 3 of whom had AIDS and 1 with ARC, failed to secrete detectable levels of IL-1 beta. All 4 patients were also nonresponsive in assays for TNF-alpha. These data establish that advanced HIV-1 infection may result in a pronounced dysfunction in the cytokine responses of alveolar macrophages.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Near fatal puerperal fever due to Mycoplasma hominis.

We describe a case of severe septicaemia caused by Mycoplasma hominis in a 23 year old patient following childbirth. She developed disseminated intravascular coagulation and acute respiratory distress syndrome which have not hitherto been described in association with septicaemia due to this organism. Investigation and treatment leading to full recovery is outlined.

Adult↗
PubMed1990

Inhalation injury to tracheal epithelium in an ovine model of cotton smoke exposure. Early phase (30 minutes).

The purpose of this study was to evaluate lung cell injury during the acute phase of smoke inhalation injury. A group of 10 sheep were anesthetized with halothane and pancuronium followed by endotracheal intubation. In the first experiment 5 sheep were given air (sham group) and 5 were insufflated with cooled cotton smoke with a modified bee smoker. In the second part of our study (Experiment 2) the animals were insufflated with the following number of smoke breaths: 1 x 12 (n = 3); 2 x 12 (n = 4); 3 x 12 (n = 4) 4 x 12 (n = 4); and sham control (n = 1). After 30 min the animals were killed with KCl and the trachea prepared for scanning, transmission electron, and light microscopy. Our initial observation with scanning electron microscopy revealed a large amount of mucus on the surface of the epithelia. Numerous ciliated cells had been sloughed from the epithelium and were observed on the surface of the remaining ciliated cells. The sloughed cells were intact, and the cilia remained on the apical cell surface. Light and transmission electron microscopy revealed that most goblet cells were in the process of extruding mucus. The cytoplasm of goblet and basal cells appeared normal. Ciliated cells had a slightly vesiculated cytoplasm, and many were in the process of being sloughed from the epithelial surface. In these cells desmosomal attachment had been separated. The light microscope evaluation of the tracheal epithelium showed there was no dose-dependent effect between the four treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Junctional adhesion mechanisms in airway basal cells.

The morphology of basal cells varies according to the height of the epithelium they are associated with. In taller epithelium, basal cells appear to have more tonofilaments (keratin filaments) than basal cells in shorter epithelium. We hypothesized that the changes in basal cell structure represent differentiation of junctional adhesion mechanisms related to the attachment strength necessary for the various-height epithelium. To evaluate this hypothesis, we used light- and electron-microscopic morphometry to quantitate junctional adhesion structures in basal cells from mice, rats, cats, rabbits, and sheep. The height of the tracheal columnar epithelium ranged from 12.0 microns in the mouse to 56.8 microns in the sheep. The volume density of basal cell keratin filaments ranged from 0.012 in the rat to 0.261 in the sheep and total desmosome length/basal cell profile (BCP) ranged from 0.08 microns to 1.77 microns, respectively. Total hemidesmosome length/BCP was similar in each airway sample. A close correlation was obtained between the height of the epithelium and the volume fraction of keratin filaments (r = 0.96) and total desmosome length/BCP (r = 0.94) in all airways studied. Total hemidesmosome length/BCP was not closely related to the height of the epithelium (r = 0.31). Based on these observations, we conclude that the basal cell is a differentiated cell with respect to junctional adhesion and a primary function of the airway basal cell is for attachment of columnar cells to the basal lamina.

Animals↗