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Biomedical subjects

W Ludwig

Publications and source records attributed to W Ludwig.

At least 145 records · Page 8Linked to original sources
PubMed1989

The 23S ribosomal RNA higher-order structure of Pseudomonas cepacia and other prokaryotes.

A 23S ribosomal RNA gene of Pseudomonas cepacia has been cloned and sequenced. A general higher-order structure model based on earlier published models has been derived from comparative analysis of 23S-like rRNAs of eubacteria, archaebacteria, organelles and eukaryotes. Differences between the previous models were carefully analyzed and controversial regions evaluated. Moderately large insertions and deletions have been found at new points in the secondary structure. The analysis of 50 published as well as unpublished 23S rRNA sequences provide additional proof for six of the seven previously suggested tertiary interactions within the 23S rRNA. P. cepacia is the first representative of the beta subgroup of the Proteobacteria phylum whose 23S rRNA has been sequenced. A tree reflecting evolutionary relationships of prokaryotes was constructed. The topology of this tree is in good agreement with the 16S rRNA tree.

Base Sequence↗
PubMed1989

[Neutropenic enterocolitis].

In three patients with neutropenia who had died after a short period from their basic disease (myelodysplasia, medullary carcinoma, acute myeloic leukaemia), autopsy revealed segmental necrotising enterocolitis in the caecal region (neutropenic enterocolitis). Morphologically the enterocolitis was characterised by necrotized mucosa, marked oedema of the intestinal wall, intramural gas, the absence of pseudomembranes and a nearly complete absence of inflammatory cell infiltrates. In one case a palpable abdominal tumour had been produced by pseudotumorous thickening of the intestinal wall. The pathogenesis in these three cases might be a neutropenia-associated disturbance of the intestinal flora with selective proliferation of toxin-producing clostridia.

Aged↗
PubMed1988

Production of an antiserum against cyclic nucleotide phosphodiesterase and its use for the immunocytochemical demonstration of this enzyme in rat cerebellum.

A procedure for the separation of cyclic AMP phosphodiesterase from a commercially available preparation and for raising antibodies against this enzyme in rabbits is described. An antiserum thus obtained was used for the immunocytochemical detection of cyclic nucleotide phosphodiesterase in rat cerebellum. The molecular layer, the granular layer and the cerebellar white matter exhibited different degrees of immunoreactivity. Only a few cell bodies (possibly glial cells) were stained. Most of the antigenic sites were present in the neuropil of the molecular layer and around Purkinje cells. Cerebellar glomeruli, sites of synaptic interactions between mossy fibres, Golgi cells and granule cells, were also stained by this antiserum. Control reactions using preimmune serum were consistently negative.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

Beta-subunit of ATP-synthase: a useful marker for studying the phylogenetic relationship of eubacteria.

The genes encoding the beta-subunits of ATP-synthases (ATPases) from Bacteroides fragilis DSM 2151, Cytophaga lytica DSM 2039 and 'Taxeobacter ocellatus' were cloned. The nucleotide sequences were determined completely for the genes of the first two organisms and to a major part for that of 'T. ocellatus'. The predicted amino acid sequences were compared with previously published amino acid sequences of beta-subunits. Two characteristic insertions were found in genes from organisms belonging to the so-called bacteroides-cytophaga-flavo-bacterium group. The remaining structure shows a high degree of sequence similarity within this group. These data support the conclusions drawn from comparative 16S rRNA sequence analyses that organisms in this phenotypically heterogeneous group are phylogenetically related. A phylogenetic tree was constructed based on a distance matrix of optimally aligned amino acid sequences of beta-subunits of ATPases of various eubacteria, chloroplasts and mitochondria. It is in good agreement with a tree derived from 16S rRNA sequence analyses.

Adenosine Triphosphatases↗
PubMed1988

DNA probes with different specificities from a cloned 23S rRNA gene of Micrococcus luteus.

A 7500 bp PstI restriction fragment of chromosomal DNA from Micrococcus luteus containing a 23S rRNA gene was cloned in vector pHE3 in E. coli RR 28 (the recombinant plasmid was designated pAR1). A recombinant phage (pAR5) hybridizing to all eubacteria tested was constructed by shotgun subcloning of the PstI fragment in phage M13mp8. Further subcloning of the fragments of the 23S rRNA gene in the vectors pTZ18R and pTZ19R using selected restriction sites of the gene enabled us to select cloned fragments of the 23S rRNA gene representing different specificities. Probes specific for Micrococcus luteus-Micrococcus lylae (pAR28), for the Arthrobacter-Micrococcus group (pAR27), for eubacteria (pAR5), and for the detection of eu- and archaebacteria (the so-called universal probe pAR17) were constructed. The specificity of each probe was analysed by dot hybridization to the chromosomal DNAs of representatives of most of the main phyla of eu- and archaebacteria.

Base Sequence↗
PubMed1988

The venous pattern in femoral head necrosis. Digital subtraction angiography and phlebography in 5 patients.

According to digital subtraction angiography in 5 cases of idiopathic ischemic necrosis of the head of the femur, the arterial and venous circulation was normal. However, pertrochanteric phlebography showed stasis of contrast indicating venous obstruction. We suggest that this could be due to arteriovenous-venous shunting, possibly resulting from sympathetic dysfunction, as in the diabetic foot.

Aged↗