Biomedical subjects

D Thiele

Publications and source records attributed to D Thiele.

At least 19 recordsLinked to original sources

PubMed2005

Periodic variability in cetacean strandings: links to large-scale climate events.

Cetacean strandings elicit much community and scientific interest, but few quantitative analyses have successfully identified environmental correlates to these phenomena. Data spanning 1920-2002, involving a total of 639 stranding events and 39 taxa groups from southeast Australia, were found to demonstrate a clear 11-13- year periodicity in the number of events through time. These data positively correlated with the regional persistence of both zonal (westerly) and meridional (southerly) winds, reflecting general long-term and large-scale shifts in sea-level pressure gradients. Periods of persistent zonal and meridional winds result in colder and presumably nutrient-rich waters being driven closer to southern Australia, resulting in increased biological activity in the water column during the spring months. These observations suggest that large-scale climatic events provide a powerful distal influence on the propensity for whales to strand in this region. These patterns provide a powerful quantitative framework for testing hypotheses regarding environmental links to strandings and provide managers with a potential predictive tool to prepare for years of peak stranding activity.

Animals↗

PubMed2005

A method for benchmarking CT scanners.

This study involved the development of an objective method to compare the performance of five CT scanners for the purpose of benchmarking. The method used to assess the scanners was to determine the dose-normalised noise at a spatial resolution of 5.5 cm(-1). This gave a dose-normalised percent noise between 0.37% and 0.76%. The scanners were also assessed for radiation dose to patients undergoing abdomen and head CT examinations. Patients' dose-length product (DLP) for the abdomen clinical examinations varied from 305 to 685 mGy-cm, and for the head clinical examinations from 333 to 900 mGy-cm. The study results demonstrated that the comparison of dose and spatial resolution normalised percent noise levels is a useful method of comparing CT scanner performance.

Australia↗

PubMed2000

Ocean circulation off east Antarctica affects ecosystem structure and sea-ice extent.

Sea ice and oceanic boundaries have a dominant effect in structuring Antarctic marine ecosystems. Satellite imagery and historical data have identified the southern boundary of the Antarctic Circumpolar Current as a site of enhanced biological productivity. Meso-scale surveys off the Antarctic peninsula have related the abundances of Antarctic krill (Euphausia superba) and salps (Salpa thompsoni) to inter-annual variations in sea-ice extent. Here we have examined the ecosystem structure and oceanography spanning 3,500 km of the east Antarctic coastline, linking the scales of local surveys and global observations. Between 80 degrees and 150 degrees E there is a threefold variation in the extent of annual sea-ice cover, enabling us to examine the regional effects of sea ice and ocean circulation on biological productivity. Phytoplankton, primary productivity, Antarctic krill, whales and seabirds were concentrated where winter sea-ice extent is maximal, whereas salps were located where the sea-ice extent is minimal. We found enhanced biological activity south of the southern boundary of the Antarctic Circumpolar Current rather than in association with it. We propose that along this coastline ocean circulation determines both the sea-ice conditions and the level of biological productivity at all trophic levels.

Animals↗

PubMed1999

Tumor necrosis factor inhibitor ameliorates murine intestinal graft-versus-host disease.

BACKGROUND & AIMS: Transfer of T helper cells from DBA/2 mice to irradiated allogeneic B6D2F1 mice leads to development of colonic graft-versus-host disease with pathological features of inflammatory bowel disease. To examine the role of tumor necrosis factor (TNF) in graft-versus-host disease enteropathy, an adenoviral vector encoding a TNF inhibitor protein was administered. METHODS: Irradiated B6D2F1 mice were infused with DBA/2 bone marrow and spleen cells. Mice then received either a control beta-galactosidase-encoding adenovirus or an adenovirus encoding a TNF inhibitor, composed of the extracellular domain of the human 55-kilodalton TNF receptor linked to the murine immunoglobulin G1 heavy chain. Mucosal permeability to sucralose and colonic histology were assessed 14 and 25 days after transplantation. RESULTS: Less diarrhea was observed in DBA/2 --> B6D2F1 mice expressing the TNF inhibitor, and colonic sections from these mice had significantly less inflammation and epithelial cell abnormalities. In TNF inhibitor recipients, mucosal permeability to sucralose was similar to that in nonirradiated control mice and significantly less than in recipients of the control adenovirus. CONCLUSIONS: TNF inhibition decreases the severity of enteropathy in the DBA/2 --> B6D2F1 murine model of colonic graft-versus-host disease.

Animals↗

PubMed1998

Anti-CD3 activation of human CD4+ T cells increases expression of the intracellular beta-endorphin endopeptidase (IDE/gamma-EpGE).

In this study, increased expression of an endopeptidase hydrolyzing beta-endorphin (beta-Ep) to gamma-endorphin (gamma-Ep, beta-Ep1-17) was observed upon immobilized anti-CD3 stimulated activation of human peripheral blood CD4+ T cells (hCD4+ T cells). Although freshly isolated hCD4+ T cells are devoid of significant beta-Ep endopeptidase activity ( < 0.1 nmol h(-1) 10(6) cells (-1)), activation of these cells with immobilized anti-CD3 results in a time dependent appearance of beta-Ep endopeptidase activity which reaches a maximal value of 17.4+/-0.48 nmol h(-1) 10(6) cells(-1) after 48 h of culture. Significant up-regulation of both mRNA encoding IDE/gamma-EpGE and immunoreactive protein are observed in anti-CD3 stimulated hCD4+ T cells, indicating transcription and translation of IDE/gamma-EpGE may be elevated. No significant hydrolysis of exogenous beta-Ep is observed with intact hCD4+ T cells whether quiescent or activated or from preparations of hCD4+ T cell membranes. Therefore, this activity appears to be intracellular. Immunoreactive IDE/gamma-EpGE is detected inside activated hCD4+ T cells. Analysis of metabolites generated upon hydrolysis of beta-Ep with lysed activated hCD4+ T cell preparations identified the presence of: beta-Ep1-18, beta-Ep2-18, beta-Ep1-17, beta-Ep2-17, beta-Ep18-31, beta-Ep19-31, beta-Ep1-13, beta-Ep2-13, beta-Ep18-26, and beta-Ep20-31 as major metabolites and the majority of these are consistent with beta-Ep hydrolytic activity attributable to IDE/gamma-EpGE.

CD3 Complex↗

PubMed1998

Molecular characterization of Coxiella burnetii isolates.

Restriction fragment length polymorphism (RFLP) was used for the differentiation of 80 Coxiella burnetii isolates derived from animals and humans in Europe, USA, Africa and Asia. After NotI restriction of total C. burnetii DNA and pulsed field gel electrophoresis (PFGE) 20 different restriction patterns were distinguished. The index of discrimination for this typing system was 0.86. Comparison and phylogenetic analysis of the different RFLP patterns revealed evolutionary relationships among groups that corresponded to the geographical origin of the isolates. This finding was confirmed by genetic mapping. No correlation between restriction group and virulence of isolates was detected.

Animals↗

PubMed1997

Increased expression of an endopeptidase (gamma-EGE/IDE) hydrolyzing beta-endorphin during differentiation and maturation of bone marrow macrophages.

The presence and regulated expression of peptidase activity is a powerful mechanism with the potential to terminate or alter receptor recognition, cell membrane signal transduction, and physiological responses of immune cells to exogenous opioid peptides. In this study, the expression of an endopeptidase that hydrolyzes beta-endorphin to gamma-endorphin and other peptide products was investigated during in vitro differentiation and maturation of recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF) -derived, bone marrow-derived macrophages. In freshly isolated intact isolated mouse bone marrow cells the rate of beta-endorphin hydrolysis is undetectable (<0.1 nmol beta-endorphin hydrolyzed/h/10[6] cells). However, total intracellular beta-endorphin hydrolytic activity was increased significantly to 20.0 +/- 1.7 nmol/h/10(6) cells in the mature mouse macrophages derived in vitro by culture with rGM-CSF. rGM-CSF-derived macrophages expressed significantly higher levels of both protein and mRNA for the major beta-endorphin endopeptidase, gamma-endorphin-generating enzyme/insulin-degrading enzyme (gamma-EGE/IDE). Moreover, this enzymatic activity appears to be responsible for cleavage of exogenous beta-endorphin by intact rGM-CSF-derived macrophages or peritoneal macrophages to generate gamma-endorphin and other peptide products.

Animals↗

PubMed1997

Plasmid-homologous sequences in the chromosome of plasmidless Coxiella burnetii Scurry Q217.

Chromosomal DNA from Coxiella burnetii Scurry Q217 was screened for the presence of plasmid-homologous sequences. Total DNA from Scurry Q217 was digested with NotI, and the resulting DNA fragments were separated by contour-clamped homogeneous electric field pulsed-field gel electrophoresis (CHEF-PFGE). Following hybridization with biotin-labeled QpH1 plasmid as a probe, two DNA fragments of 40 and 170 kb were identified as targets. These fragments were cloned, and subclones containing QpH1-homologous sequences were completely sequenced. The physical mapping of DNA fragments was achieved by PCR with primers derived from adjacent fragments, and a total of 18,360 bp was sequenced. Within the QpH1-homologous region spanning 16,624 bp, homology was as high as 99%. Deletions were identified within EcoRI fragments A(H)-C(H)-K(H)-B(H) (13,490 bp) and J(H)-G(H)-E(H)-L+-D(H) (6,509 bp) and in fragment A(H) alone (619 bp). An insertion of 744 bp was identified within the JDc region of Scurry Q217. A search for putative coding regions identified a total of 17 open reading frames (ORFs). Compared to plasmid QpH1, 6 ORFs were identical, 5 ORFs were different in size, 6 ORFs were newly generated, and 25 ORFs were lost. It was found that plasmid-homologous sequences in Scurry Q217 were of chromosomal origin.

Base Composition↗

PubMed1996

Prevalence studies of GB virus-C infection using reverse transcriptase-polymerase chain reaction.

Among the three recently described GB viruses (GBV-A, GBV-B, and GBV-C), only GBV-C has been linked to cryptogenic hepatitis in man. Because of the limited utility of currently available research tests to determine antibody response to GBV-C proteins, the prevalence of GBV-C RNA in human sera was studied using reverse transcription-polymerase chain reaction (RT-PCR). The prevalence of GBV-C is higher among volunteer blood donors with elevated serum alanine aminotransferase (ALT) levels (3.9%) than among volunteer blood donors with normal ALT levels (0.8%). Higher rates were also noted among commercial blood donors (12.9%) and intravenous drug users (16.0%). GBV-C was frequently detected in residents of West Africa, where the prevalence was > 10% in most age groups. Approximately 20% of patients diagnosed with either acute or chronic hepatitis C virus (HCV) were found to be positive for GBV-C RNA. In addition, GBV-C RNA sequences were detected in individuals diagnosed with non-A-E hepatitis, with clinical courses ranging from mild disease to fulminant hepatitis. Fourteen of sixteen subjects with or without clinically apparent hepatitis were positive for GBV-C RNA more than 1 year after the initial positive result.

Flaviviridae↗

PubMed1996

A secreted peptidase involved in T cell beta-endorphin metabolism.

Beta-endorphin metabolism by CD4+ and CD8+ T cells, and the thymoma cell line, EL4, was investigated. In all three cell types, extracellular beta-endorphin was metabolized exclusively by a secreted, metal-dependent, thiol peptidase. The enzyme activity is expressed constitutively in EL4 cells and following activation of CD4+ and CD8+ T cells with anti-CD3 antibody. The enzyme is not one of the proteinases associated with cytolytic T cells and does not appear to be identical with any previously described beta-endorphin metabolizing enzyme. The enzyme cleaves beta-endorphin at approximately equal rates at either of two sites to yield beta-endorphin(1-17) (which is gamma-endorphin), beta-endorphin(1-18), beta-endorphin(18-31) and beta-endorphin(19-31). Evidence in the literature indicates that these N- and C-terminal peptides which contain, respectively, the opioid and non-opioid receptor binding domains of beta-endorphin, are biologically active. Thus, it is likely that this new T cell peptidase has important immunoregulatory activity.

Amino Acid Sequence↗

PubMed1996

Chlamydia trachomatis antibodies in serum and ejaculate of male patients without acute urethritis.

In a prospective study, the prevalence of specific antibodies against Chlamydia trachomatis in serum and seminal plasma evaluated by a genus specific immunofluorescence test in 101 men without acute urethritis was investigated. The results were compared to the clinical diagnosis, cell culture of urethral swabs, demonstration of DNA particles by Polymerase Chain Reaction (PCR) in the ejaculate and signs of genital inflammation by counting peroxidase-positive leukocytes and elastase level in semen. The objective was to evaluate the significance of chlamydial antibodies in genital infection. Serum specific IgG and IgA antibodies were found in 26% and 15%, respectively; seminal IgG and IgA antibodies were present in 6% and 7%, respectively. Serum specific antibodies were not associated with the clinical diagnosis of infection nor with C. trachomatis cell culture, PCR findings, peroxidase positive leukocytes or PMN-elastase level. It is concluded that serum antibodies are not useful in detecting a chlamydial infection. Seminal plasma antibodies were not correlated with the clinical diagnosis of infection, positive cell culture, PMN-elastase levels and leukocytes in semen. However, a significant correlation was found for positive PCR in the ejaculate (p < 0.001 for IgG, p < 0.05 for IgA, p < 0.001 when combined). Though seminal antibodies may be more useful in detecting ascended or occult chlamydial infection, their significance remains unclear, their absence does not exclude chlamydial infection. In particular, the biological significance of locally derived IgA needs further evaluation.

Acute Disease↗

PubMed1996

Monoclonal antibody based differentiation of Coxiella burnetii isolates.

Isolates of Coxiella burnetii from different geographic regions in Europe, USA, Japan and Africa were compared in their binding properties to the monoclonal antibody (MoAb) 1/4/H directed against the lipopolysaccharide (LPS) of C. burnetii strain Priscilla. Immunoblot analysis and enzyme-linked immunosorbent assay (ELISA) revealed different binding patterns of C. burnetii isolates under study. Most of the isolates tested did react with MoAb 1/4/H. Only four of 20 groups of isolates and one isolate of an otherwise positively reacting group did not react with MoAb 1/4/H. The results indicate a significant variation of LPS structure of the C. burnetii isolates studied.

Animals↗

PubMed1995

Quantification of Coxiella burnetii by polymerase chain reaction (PCR) and a colorimetric microtiter plate hybridization assay (CMHA).

A colorimetric microtiter plate hybridization assay (CMHA) for the quantitative determination of Coxiella burnetii DNA after amplification by externally controlled polymerase chain reaction (PCR) is described. The quantification assay is based on an enzyme linked immunosorbent assay (ELISA) format. Cloned DNA, representing a sequence complementary to an internal part of the diagnostic amplicon, was noncovalently attached to the wells of a microtiter plate. Biotinylated PCR product was hybridized to the immobilized capture probe. Bound product was detected via streptavidin horse-radish peroxidase. The devised nonisotopic technique allows specific, rapid, and convenient quantification of C. burnetii DNA. Additionally, it is compatible with standard laboratory ELISA equipment, making this assay amenable to automation and permitting processing of large sample numbers.

Bacterial Proteins↗

PubMed1995

Sequencing and linkage analysis of a Coxiella burnetii 2.1 kb NotI fragment.

Most of the Coxiella burnetii isolates (72 of 80) available in our institute share a 2.1 kb NotI fragment. Sequence analysis revealed two incomplete open reading frames (ORF) for putative genes hemA and bcR coding for glutamyl-tRNA-reductase and bicyclomycin resistance protein, respectively. Upon completing the ORF for the hemA gene by sequencing the adjacent NotI/EcoRI fragment a third ORF for the putative prfA gene was determined coding for release factor 1, an enzyme catalysing the last step in protein biosynthesis.

Aldehyde Oxidoreductases↗

PubMed1994

Analysis of the entire nucleotide sequence of the cryptic plasmid QpH1 from Coxiella burnetti.

The complete plasmid QpH1 from Coxiella burnetti, isolate 'Nine Mile', phase I, was cloned as NotI fragment with a size of 37329 bp. The entire plasmid was sequenced by the chain termination method after EcoRI subcloning. 37 open reading frames coding for polypeptides larger than 100 amino acid residues were determined. The predicted polypeptide products of the open reading frames were compared by computer analysis with reported protein sequences. Homologies of predicted polypeptide products to analogous proteins are described.

Amino Acids↗

PubMed1994

The 16S/23S ribosomal spacer region of Coxiella burnetti.

The 16S/23S spacer region of Coxiella burnetti isolate Nine Nile, phase 1, was sequenced. Sequence analysis revealed two tRNA coding regions for tRNA(Ile) and tRNA(Ala). DNA sequence alignment demonstrated significant homology with tRNA species from Pseudomonas aeruginosa and Rhodobacter sphaeroides, respectively. The non-coding tRNA spacer region was unique to Coxiella burnetti, based on database alignment.

Cloning, Molecular↗

PubMed1994

Is plasmid based differentiation of Coxiella burnetii in 'acute' and 'chronic' isolates still valid?

Ten human Coxiella burnetii isolates from french patients with acute hepatitis or chronic endocarditis were characterized according to their polymorphism in DNA restriction patterns and differentiated by plasmid-specific PCR. The aim of this investigation was to clarify if the present classification of so called 'acute' and 'chronic' Coxiella burnetii isolates--based on plasmid profile of a so far limited number of partly ancient isolates--could be confirmed with lately isolated organisms of this agent. The data obtained in this investigation indicate that this classification based on C. burnetii plasmid content is no longer justified.

Acute Disease↗

PubMed1994

Comparison of dark-field microscopy, culture, and polymerase chain reaction (PCR) for detection of Borrelia burgdorferi in field-collected Ixodes ricinus ticks.

In a study based on 100 field-collected female Ixodes (I.) ricinus ticks from the surroundings of Giessen, dark-field microscopy (DFM), culture, and PCR were compared as procedures for detecting Lyme borreliosis spirochetes in ticks. By DFM, 16 ticks were found to be infected with spirochetes. From the midgut of 18 ticks (including 14 microscopically positive specimens), spirochetes were cultured in BSK II medium and in BSK II medium supplemented with either co-trimoxazole (500 micrograms/ml) or 5-fluorouracil and kanamycin (200 micrograms/ml and 8 micrograms/ml). Using these selective media, the isolation rate was increased by 50% compared to BSK II medium without additives. Midgut homogenates of 22 ticks (including 13 ticks positive by culture and 12 microscopically positive ticks) were found to contain Borrelia (B.) burgdorferi-specific DNA by PCR using a primer set based on sequences of the flagellin gene of B. burgdorferi.

Animals↗