[Sensitivity of MRI in detecting alveolar Infiltrates: Experimental studies]. / Sensitivität der MRT für alveoläre Infiltrate: Experimentelle Untersuchungen.

PURPOSE: An experimental study using porcine lung explants and a dedicated chest phantom to evaluate the signal intensity of artificial alveolar infiltrates with T 1 - and T 2 -weighted MRI sequences. MATERIAL AND METHODS: 10 porcine lung explants were intubated, transferred into the cavity of a MRI-compatible chest phantom and inflated by continuous evacuation of the artificial pleural space. All lungs were examined with MRI at 1.5 T before and after intra-tracheal instillation of either 100 or 200 ml gelatine-stabilised liquid to simulate alveolar infiltrates. MR-examination comprised gradient echo (2D- and 3D-GRE) and fast spin echo sequences (T 2 -TSE and T 2 -HASTE). The signal intensity of lung parenchyma was evaluated at representative cross sections using a standardised scheme. Control studies were acquired with helical CT. RESULTS: The instilled liquid caused patchy confluent alveolar infiltrates resembling the findings in patients with pneumonia or ARDS. CT revealed typical ground-glass opacities. Before the application of the liquid, only T 2 -HASTE and T 2 -TSE displayed lung parenchyma signals with a signal/noise ratio of 3.62 and 1.39, respectively. After application of the liquid, both T 2 -weighted sequences showed clearly visible infiltrates with an increase in signal intensity of approx. 30 % at 100 ml (p < 0.01) and 60 % at 200 ml (p < 0.01). With 2D- and 3D-GRE the infiltrates were not visible, although the lung parenchyma signal increase was statistically significant. On 2D-GRE the increase in signal intensity reached 0.74 % (p = 0.32) after 100 ml and 5.6 % (p < 0.01) after 200 ml (for 3D-GRE: 2.2 % [p = 0.02] at 100 ml and 4.4 % at 200 ml [p < 0.01]). The CT controls revealed a significant increase of lung density of 17 H.E. at 100 ml (p = 0.02) and 75 H.E. at 200 ml (p < 0.01). CONCLUSIONS: MRI with T 2 -weighted sequences detects artificial alveolar infiltrates with high signal intensity and may be a highly sensitive tool to detect pneumonia in patients.

Phylogenetic position of Rhynchopus sp. and Diplonema ambulator as indicated by analyses of euglenozoan small subunit ribosomal DNA.

The taxa Rhynchopus Skuja and Diplonema Griessmann were first described as remarkable protists with euglenid affinities. Later on, the placement of Diplonema within the Euglenozoa was confirmed by molecular data. For this study two new sequences were added to the euglenozoan data set. The uncertainly placed Rhynchopus can be identified as a close relative to Diplonema by small subunit ribosomal DNA (SSU rDNA) analysis. The new sequence of Diplonema ambulator is in close relationship to two other Diplonema species. Our molecular analyses clearly support the monophyly of the diplonemids comprising Rhynchopus and Diplonema. Yet the topology at the base of the euglenozoan tree remains unresolved, and especially the monophyly of the euglenids is arguable. SSU rDNA sequence analyses suggest that significantly different GC contents, high mutational saturation in the euglenids, and different evolutionary rates in the euglenozoan clades make it difficult to identify any sister group to the diplonemids.

Phylogenetic position and inter-relationships of the osmotrophic euglenids based on SSU rDNA data, with emphasis on the Rhabdomonadales (Euglenozoa).

In order to reconstruct the evolution of euglenid flagellates, euglenozoan SSU rDNA data have been used to investigate phylogenetic relationships with a focus on osmotrophic taxa and especially on the Rhabdomonadales. The dataset consisting of the SSU rDNAs of osmotrophic, phagotrophic and phototrophic taxa was used in parsimony, maximum-likelihood and distance analyses. Five genera make up the Rhabdomonadales, all of them osmotrophic: Gyropaigne, Menoidium, Parmidium, Rhabdomonas and Rhabdospira. According to our analyses they form a strongly supported monophyletic assemblage which is characterized by a low sequence divergence compared to the euglenids in general. Closest relatives are the members of the osmotrophic genus Distigma. All primary osmotrophic species constitute a larger monophyletic group with the phototrophic euglenids and the phagotroph Peranema trichophorum. The combination of three rhabdomonadalian species Rhabdomonas gibba, Rhabdomonas spiralis and Rhabdospira spiralis with nearly identical SSU rDNA sequences is strongly recommended. The phagotroph Petalomonas cantuscygni branches at the bottom of the euglenid subtree with significantly weaker support. The inter-relationship of the three distinct euglenozoan taxa (euglenids, kinetoplastids and diplonemids) could not be convincingly resolved by this study.