PubMed Health⌕ Search

Biomedical subjects

E S Miller

Publications and source records attributed to E S Miller.

At least 37 records · Page 2Linked to original sources
PubMed1993

The role of cytokines in immune changes induced by spaceflight.

It has become apparent that spaceflight alters many immune responses. Among the regulatory components of the immune response that have been shown to be affected by spaceflight is the cytokine network. Spaceflight, as well as model systems of spaceflight, have been shown to affect the production and action of various cytokines including interferons, interleukins, colony stimulating factors, and tumor necrosis factors. These changes have been shown not to involve a general shutdown of the cytokine network but, rather, to involve selective alterations of specific cytokine functions by spaceflight. The full breadth of changes in cytokines induced by spaceflight, as well as mechanisms, duration, adaptation, reversibility, and significance to resistance to infection and neoplastic diseases, remains to be established.

Animals↗
PubMed1993

Influence of suspension on the expression of protective immunological memory to murine Listeria monocytogenes infection.

Female BDF1 mice were immunized with virulent Listeria monocytogenes, which resulted in the generation of a long-lived state of protective immunological memory for this facultative intracellular bacterial pathogen. The influence of antiorthostatic suspension, a ground-based model employed to simulate certain aspects of weightlessness that occur during spaceflight, on the capacity of these mice to express memory immunity was evaluated. Memory-immune mice were suspended by the tail in the orthostatic or antiorthostatic position and were reinfected with a lethal dose of virulent L. monocytogenes. It was found that suspension did not influence the kinetics of bacterial growth in vivo when the rechallenge infection was started concurrently with the suspension. However, mice that were reinfected on day 2 or 4 of the suspension exhibited an enhanced capacity to eliminate the infection. Attenuation of this enhancing effect was observed when mice were infected on day 7 of the suspension. These results indicate that the stress of antiorthostatic suspension can influence the capacity of the murine host to express protective immunological memory to pathogenic bacteria.

Animals↗
PubMed1993

The metabolic stressor 2-deoxy-D-glucose (2-DG) enhances LPS-stimulated cytokine production in mice.

The present study was designed to evaluate the influence of metabolic stress on murine cytokine production in vivo. Female Swiss-Webster mice were exposed to a single or multiple injections of the metabolic stressor 2-deoxy-D-glucose (2-DG; 500 mg/kg body wt) once every 48 h and then were injected intravenously with 10 micrograms of bacterial lipopolysaccharide to stimulate macrophage-derived cytokine production. Plasma samples were harvested 2 h later and were assayed for interleukin (IL)-1, IL-3, and IL-6 activities using a panel of standardized bioassays. It was found that one, two, or three injections of 2-DG enhanced the production of all three cytokines. An attenuation of the enhancing effect was observed following the fourth and fifth injections. These results demonstrate that the metabolic stressor 2-DG can alter immune cell effector functions, including the enhancement of normal patterns of cytokine production in vivo.

Animals↗
PubMed1993

Space flight and humoral and cellular immunity of animals.

The use of animal surrogates for the study of the effects of space flight on immune responses is desirable for several reasons. First, animal models are very useful in conditions where the use of human subjects would be difficult. This is certainly true in the space flight environment, where the number of human subjects is small, the human subjects are often too occupied with space flight duties to serve as subjects, and where sampling could be difficult under adverse conditions. Second, because of the intense interest in the immune system, many animal models and reagents already exist that are readily adaptable to space flight studies. Therefore, animal models have been used for many years for space flight studies on immunity. The predominant model used has been the rat, although recently, development of a rhesus monkey model has begun. The focus of this paper will be a description of the results of ground-based and space flight animal models to determine the effects of space flight on immune responses.

Animals↗
PubMed1992

Regions of bacteriophage T4 and RB69 RegA translational repressor proteins that determine RNA-binding specificity.

RegA protein of T4 and related bacteriophages is a highly conserved RNA-binding protein that represses the translation of many phage mRNAs that encode enzymes involved in DNA metabolism. RB69, a T4-related bacteriophage, has a unique regA gene, which we have cloned, sequenced, and expressed. The predicted amino acid sequence of RB69 RegA is 78% identical to that of T4 RegA. Plasmid-encoded RB69 RegA expressed in vivo represses the translation of T4 early mRNAs, including those of rIIA, rIIB, 44, 45, rpbA, and regA. Nucleotide sequences were determined for several T4 and RB69 regA mutations, and their corresponding repressor properties were characterized. All of the 10 missense mutations affect residues conserved between RB69 and T4 RegA. Two regions of RegA are especially sensitive to mutation: one between Val-15 and Ala-25 and another between Arg-70 and Ser-73. Sequence alignments and mutational data suggest that the region from Val-15 to Ala-25 is similar to helix-turn-helix domains of DNA-binding proteins and confers RNA-binding specificity upon RegA. The RegA691 protein (Ile-24----Thr) has an in vivo phenotype that appears to distinguish site-specific and cooperative binding modes of hierarchical RegA-mediated translational repression.

Amino Acid Sequence↗
PubMed1992

T lymphocytes mediating protection and cellular cytolysis during the course of Mycobacterium tuberculosis infection. Evidence for different kinetics and recognition of a wide spectrum of protein antigens.

Recent evidence suggests the existence of at least two pathways of acquired specific resistance to Mycobacterium tuberculosis infection; the first consisting of cytokine-mediated activation of parasitized host cells by protective T cells, and the second involving the lysis of these cells by cytolytic T cells. Evidence presented in this report shows that both of the above mechanisms are operative in experimentally infected mice, but that they differ markedly in terms of their kinetics of emergence and loss. It was found that protective T cell activity was acquired very early during the course of the infection, and was temporally associated with the onset of bacterial elimination; however, cytolytic activity did not peak until 10 to 20 days later. This report shows further that the target Ag of these effector T cell populations were apparently numerous with no evidence for preferential recognition of a few immunodominant Ag. In view of the preponderance of target proteins in the bacterial filtrate, we present the hypothesis that such proteins secreted or otherwise leaked from the dividing mycobacterium are pinocytosed from the phagosome and used by the infected macrophage as the key protective Ag leading to T cell sensitization. This hypothesis thus explains the preferential requirement for the viable bacterium in the generation of specific resistance, and further explains why protective immunity is generated even while the organism is still multiplying in an apparently unrestrained manner.

Animals↗
PubMed1991

Physical properties of the complexes formed between heptakis(2,6-di-O-methyl)-beta-cyclodextrin, beta-cyclodextrin, and chlorambucil.

The solid complex of chlorambucil (CHL) and heptakis-(2,6-di-O-methyl)-beta-cyclodextrin (DIMEB) has been isolated from ethanol and analyzed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffractometry. The carbonyl stretching band of the complex, observed in the FTIR spectrum, was shifted to higher frequency, suggesting that intermolecular hydrogen bonds between CHL molecules are broken when the complex is formed. Since no melting endotherm was observed for CHL when the DSC thermogram of the complex was obtained, the crystal lattice of the compound must be disrupted upon complexation. X-ray diffraction patterns of the inclusion complex were different from those of the physical mixture and contained no peaks corresponding to free CHL, thus indicating the formation of a new crystalline material. The 1:1 CHL:beta-cyclodextrin (beta-CD) complex was isolated from aqueous solution at 3 degrees C. Results of analyses using FTIR and DSC were similar to those obtained with the CHL:DIMEB complex. The X-ray diffraction patterns of the complex suggest that its degree of crystallinity is higher than that of the CHL:DIMEB complex.

Calorimetry, Differential Scanning↗
PubMed1991

Description of the erythromycin-producing bacterium Arthrobacter sp. strain NRRL B-3381 as Aeromicrobium erythreum gen. nov., sp. nov.

Arthrobacter sp. strain NRRL B-3381T (T = type strain) is a nonmycelial, nonsporulating actinomycete that produces the macrolide antibiotic erythromycin. This bacterium differs in many ways from the type species of the genus Arthrobacter (Arthrobacter globiformis), suggesting that a taxonomic revision is appropriate. The G + C content of strain NRRL B-3381T DNA is 71 to 73 mol%, and the peptidoglycan of this organism contains LL-diaminopimelic acid. Evolutionary distance data obtained from 16S rRNA sequences identified NRRL B-3381T as the deepest branching member of the Nocardioides group of actinomycetes. The principal long-chain fatty acids which we identified that distinguished strain NRRL B-3381T from related G + C-rich bacteria were 10-methyloctadecanoic (tuberculosteric), octadecenoic, and hexadecanoic acids. These characteristics, together with phage typing and biochemical characteristics, form the basis for our recommendation that strain NRRL B-3381 should be the type strain of a new taxon, for which we propose the name Aeromicrobium erythreum.

Amino Acids↗
PubMed1991

Cloning vectors, mutagenesis, and gene disruption (ermR) for the erythromycin-producing bacterium Aeromicrobium erythreum.

Genetic systems for study of Aeromicrobium erythreum, a gram-positive, G + C-rich (72%) bacterium with the capacity for erythromycin biosynthesis, are described. High-copy-number plasmids suitable as gene cloning vectors include derivatives of the Streptomyces plasmids pIJ101, pVE1, and pJV1. pIJ101 derivatives with missense substitutions at the rep gene BamHI site do not replicate in A. erythreum. Ethyl methanesulfonate treatment generated several amino acid auxotrophs and non-erythromycin-producing (Ery-) strains. Using the Ery- strain AR1807 as a recipient for plasmid-directed integrative recombination, the chromosomal ermR gene (encoding 23S rRNA methyltransferase) was disrupted. Phenotypic characterizations demonstrated that ermR is the sole determinant of macrolide antibiotic resistance in A. erythreum.

Amino Acids↗
PubMed1990

Anti-phosphotyrosine immunoprecipitation of phosphatidylinositol 3' kinase activity in different cell types after exposure to epidermal growth factor.

In previous studies from this laboratory, it was shown that mouse epidermal growth factor (mEGF) or insulin increased the labeling of phosphaditylinositol-3,4-bisphosphate (PI-3,4-P2) in MA-10 cells prelabeled with different radioactive precursors (Pignataro, O.P., and Ascoli, M. (1990) J. Biol. Chem. 265, 1718-1723 and Mol. Endocrinol. (1990) 4, 758-765). In order to further characterize this phenomenon we sought to determine if we could use anti-phosphotyrosine antibodies to immunoprecipitate a phosphatidylinositol (PI) kinase activity from MA-10 cells treated with mEGF or insulin. Our data indicate that this is indeed the case, and that the PI kinase precipitated is a PI-3' kinase. A second cell type, A431 cells, in which we were unable to detect an increase in PI-3,4-P2 labeling when stimulated with mEGF or insulin, was also studied. It was found that, as in MA-10 cells, A431 cells also contain an immunoprecipitable PI-3' kinase activity that is increased in response to mEGF or insulin.

Animals↗
PubMed1990

Sequence analysis of conserved regA and variable orf43.1 genes in T4-like bacteriophages.

Bacteriophage T4 RegA protein is a translational repressor of several phage mRNAs. In the T4-related phages examined, regA nucleotide sequences are highly conserved and the inferred amino acid sequences are identical. The exceptional phage, RB69, did not produce a RegA protein reproducibly identifiable by Western blots (immunoblots) nor did it produce mRNA that hybridized to T4 regA primers. Nucleotide sequences of either 223 or 250 base pairs were identified immediately 3' to regA in RB18 and RB51 that were absent in T-even phages. Open reading frames in these regions, designated orf43.1RB18 and orf43.1RB51, potentially encode related proteins of 8.5 and 9.2 kilodaltons, respectively. orf43.1 sequences, detected in 13 of 27 RB bacteriophage chromosomes analyzed by polymerase chain reaction, are either RB18- or RB51-like and have flanking repeat sequences that may promote orf43.1 deletion.

Amino Acid Sequence↗
PubMed1989

Patterns of IL-2 production and utilization in mice heavily infected with Mycobacterium bovis BCG reflect the phase of protective immunity being expressed.

The results shown here demonstrate that in mice heavily infected with Mycobacterium bovis BCG Pasteur, mitogen-induced levels of interleukin-2 (IL-2) correlate temporally with the state of immunity that is being expressed in the animal during the course of the infection. Active immunity, which is conferred by populations of both CD4+ (L3T4) and CD8+ (Lyt-2) T lymphocytes, and memory immunity, which is mediated by a population of CD4+ T lymphocytes, were identified and distinguished in terms of their sensitivity to cyclophosphamide therapy, their ability to passively transfer specific resistance to infection with virulent Mycobacterium tuberculosis, and their capacity to produce and/or absorb IL-2. In this regard, concanavalin A (Con A)-stimulated L3T4+ and Lyt-2+-enriched splenocytes exhibited an apparent depression in measurable levels of IL-2 when harvested during the first 40 days of the infection, which could be explained by the subsequent observation that these T cells were capable of rapidly absorbing a known quantity of recombinant IL-2 in vitro. Detectable levels of IL-2 in these mitogen-stimulated supernatants began to rise after Day 25, which was temporally associated with a gradual shift from active immunity, to immunity mediated by cyclophosphamide-resistant memory T cells, which did not absorb IL-2 in vitro. These data indicate that fluctuations in apparent IL-2 production reflect changes in the type of immunity being expressed, rather than than some form of defect in IL-2 production.

Animals↗
PubMed1988

CT scanning in the management of intracranial abscess: a review of 100 cases.

One hundred cases of brain abscess presenting between 1974 and 1984 are reviewed. The overall mortality was 20%, 98 cases were actively treated with a peroperative mortality of 14%. The results are compared to Garfield's 1969 series, drawn from similar clinical material. Changes in presentation and outcome are described. A significant improvement in survival (p less than 0.001) has occurred following the introduction of computerised tomography (CT Scan) which permits the rapid diagnosis and accurate localisation of intracranial sepsis. As the basic therapeutic regime remains unchanged (burr hole aspiration and appropriate antibiotic treatment), other aspects of management have been examined, leading to the suggestion that CT Scanning has made a major contribution to the reduction in mortality.

Adolescent↗
PubMed1987

Translational repression: biological activity of plasmid-encoded bacteriophage T4 RegA protein.

The RegA protein of bacteriophage T4 is a translational repressor that regulates expression of several phage early mRNAs. We have cloned wild-type and mutant alleles of the T4 regA gene under control of the heat-inducible, plasmid-borne leftward promoter (PL) of phage lambda. Expression of the cloned regA+ gene resulted in the synthesis of a protein that closely resembled phage-encoded RegA protein in biological properties. It repressed its own synthesis (autogenous translational control) as well as the synthesis of specific T4-encoded proteins that are known from other studies to be under RegA-mediated translational control. Cloned mutant alleles of regA exhibited derepressed synthesis of the mutant regA gene products and were ineffective in trans against RegA-sensitive mRNA targets. The effects of plasmid-encoded RegA proteins were also demonstrated in experiments using two compatible plasmids in uninfected Escherichia coli. The two-plasmid assays confirm the sensitivities of several cloned T4 genes to RegA-mediated translational repression and are well-suited for genetic analysis of RegA target sites. Repression specificity in this system was demonstrated by using wild-type and operator-constitutive translational initiation sites of T4 rIIB fused to lacZ. The results show that no additional T4 products are required for RegA-mediated translational repression. Additional evidence is provided for the proposal that uridine-rich mRNA sequences are preferred targets for the repressor. Surprisingly, plasmid-generated RegA protein represses the synthesis of some E. coli proteins and appears to enhance selectively the synthesis of others. The RegA protein may have multiple functions, and its binding sites are not restricted to phage mRNAs.

Base Sequence↗
PubMed1987

Management of subdural empyema: a series of 24 cases.

Twenty four cases of subdural empyema are reviewed. The overall mortality was 17%, 18 patients were managed by burr hole and five by craniotomy or craniectomy. Antibiotic therapy was commenced once pus had been evacuated. Infection of the paranasal and mastoid sinuses was the commonest aetiological factor. Aspiration of pus through burr holes is the recommended surgical procedure with low mortality and morbidity, when combined with early diagnosis and aggressive chemotherapy.

Adult↗
PubMed1985

Bacteriophage T4 regA protein. Purification of a translational repressor.

The bacteriophage T4 regA protein translationally regulates its own synthesis and the synthesis of several other T4 early proteins. In order to study the mechanism of translational regulation, we have purified the regA protein. Initially a mutant protein, incapable of autogenous repression, was placed under lambda PL transcriptional control and amplified to approximately 10% of total cell protein. The membrane-associated mutant protein was extracted with organic solvent mixtures and purified by reverse phase-high performance liquid chromatography. Polyclonal antibodies prepared against the mutant protein were used in Western blot assays to monitor purification of the wild-type protein from T4-infected cells. Phosphocellulose and poly(U)-agarose chromatography were important steps in its purification. The binding properties of regA protein to polyribonucleotides are discussed in relation to the mechanism by which the protein recognizes its mRNA targets.

Amino Acid Sequence↗