Biomedical subjects

M Weizenegger

Publications and source records attributed to M Weizenegger.

7 recordsLinked to original sources

PubMed2000

Prevalence of hepatitis G in patients on chronic hemodialysis.

Hepatitis G virus (HGV) is a newly described RNA virus from the family of flaviviridae. It is closely related to the hepatitis C Virus (HCV) but is more common than HCV among healthy blood donors. The pathogenicity of HGV in immunosuppressed patients such as those undergoing hemodialysis is unclear. We measured the incidence of HGV in 105 patients undergoing hemodialysis in a chronic outpatient hemodialysis facility. HGV-RNA was detected using a RT-PCR method with primers directed against the 5' non-coding region and the NS5a gene of HGV. Nine (8.6%) patients were HGV RNA positive, eleven (10.5%) were anti-HCV positive, three (2.9%) were positive for hepatitis B surface antigen. Four patients were positive for both HGV and HCV; three of them had normal liver enzymes while one showed elevated ALT levels but no other signs of exacerbation of preexisting hepatitis. The prevalence of HGV among dialysis patients is comparable to that of HCV. The transmission route for HCV is nosocomial transmission during dialysis, whereas HGV shows both ways of transmission: blood transfusion mediated by a high prevalence of HGV among healthy blood donors and nosocomial transmission. HGV appears to play a minor role in acute hepatitis, even in immunosuppressed patients.

Adult↗

PubMed2000

A closer look at the insertion within helix 54 of the 23S-rRNA of the genus Corynebacterium (and related taxa).

Direct sequencing of the insertion in helix 54 of the 23S-rRNA of different strains of 8 species of the genus Corynebacterium was performed in order to determine the extent of variations of these strains. The results demonstrated that there is considerable variation within different strains of a single species. While this clearly jeopardizes the usefulness of the insertion with regard to species-specific diagnostic probes, the variations were found to concentrate within two clearly defined regions comprising the ascending and descending parts of the distal helix of a putative stemlike secondary structure. The remainder of the insertion sequences seem to be fairly constant within a single species while displaying considerable differences toward sequences of other species of the same genus.

Base Sequence↗

PubMed1998

Bacterial phylogeny based on comparative sequence analysis.

Comparative sequence analysis of small subunit rRNA is currently one of the most important methods for the elucidation of bacterial phylogeny as well as bacterial identification. Phylogenetic investigations targeting alternative phylogenetic markers such as large subunit rRNA, elongation factors, and ATPases have shown that 16S rRNA-based trees reflect the history of the corresponding organisms globally. However, in comparison with three to four billion years of evolution the phylogenetic information content of these markers is limited. Consequently, the limited resolution power of the marker molecules allows only a spot check of the evolutionary history of microorganisms. This is often indicated by locally different topologies of trees based on different markers, data sets or the application of different treeing approaches. Sequence peculiarities as well as methods and parameters for data analysis were studied with respect to their effects on the results of phylogenetic investigations. It is shown that only careful data analysis starting with a proper alignment, followed by the analysis of positional variability, rates and character of change, testing various data selections, applying alternative treeing methods and, finally, performing confidence tests, allows reasonable utilization of the limited phylogenetic information.

Bacteria↗

PubMed1992

Phylogenetic evidence for the transfer of Eubacterium suis to the genus Actinomyces as Actinomyces suis comb. nov.

The 16S rRNA primary structures of Eubacterium suis DSM 20639T (T = type strain) and Bifidobacterium bifidum DSM 20456T were determined by sequencing in vitro amplified rDNA. Sequence comparisons indicated that B. bifidum is moderately related to representatives of the genera Actinomyces and Mobiluncus. The closest relative of E. suis is Actinomyces pyogenes. E. suis and A. pyogenes are more closely related phylogenetically to one another than to the other Actinomyces species that have been investigated by using comparative 16S rRNA analysis. Therefore, we propose that E. suis should be transferred to the genus Actinomyces as Actinomyces suis comb. nov.

Actinomyces↗

PubMed1990

The phylogenetic position of Peptococcus niger based on 16S rRNA sequence studies.

A 1330 base-pair fragment of a 16S rRNA gene has been amplified, cloned and sequenced. Comparison to other 16S rRNA sequences of eubacteria showed that P. niger represents a deep branch within the subdivision "Gram-positive with Gram-negative cell walls". It is not related to peptostreptococci, representatives of this genus studied so far are more closely related to clostridia.

Base Composition↗

PubMed1990

Complete nucleotide sequences of seven eubacterial genes coding for the elongation factor Tu: functional, structural and phylogenetic evaluations.

The nucleotide sequences of cloned genes coding for the elongation factor Tu of seven eubacteria have been determined. These genes were from Anacystis nidulans, Bacillus subtilis, Bacteroides fragilis, "Deinonema" spec., Pseudomonas cepacia, Shewanella putrefaciens and Streptococcus oralis. The primary structures of the genes were compared to the available sequences of prokaryotic elongation factors Tu and eukaryotic elongation factors 1 alpha. A conservation profile was determined for homologous amino acid residues. Sites of known or putative functions are usually located at highly conserved positions or within highly conserved sequence stretches. The aligned 24 amino acid sequences were used as basis for a phylogenetic analysis. The phylogenetic tree corroborates the kingdom as well as phylum concept deduced from 16S rRNA data.

Amino Acid Sequence↗

PubMed1987

Comparative 16S rRNA oligonucleotide analyses and murein types of round-spore-forming bacilli and non-spore-forming relatives.

The phylogenetic incoherency of the genus Bacillus as presently described is demonstrated by analysis of both published and new data from comparative 16S rRNA cataloguing of nine Bacillus species and a number of related non-Bacillus taxa, i.e. Caryophanon latum, Filibacter limicola and Planococcus citreus. While the ellipsoidal-spore-forming bacilli, e.g. B. subtilis and allied species, formed a coherent cluster, the round-spore-forming bacilli showed a higher degree of relationship to the non-spore-forming organisms than these bacilli show among each other. Thus B. sphaericus clustered with C. latum, B. globisporus grouped with F. limicola, B. pasteurii with Sporosarcina ureae, and 'B. aminovorans' with P. citreus, respectively. These organisms formed two related subclusters which, in their phylogenetic depth, are comparable to that of the B. subtilis subline. With the exception of 'B. aminovorans', the 16S rRNA phylogeny was entirely consistent with the distribution of murein types. Even more distantly related to and grouping outside the main Bacillus cluster was B. stearothermophilus, which displayed a moderate relationship to Thermoactinomyces vulgaris. Taxonomic problems arising from the new insights into the intrageneric relationships of Bacillus are discussed.

Bacillus↗