Virtual mono-energetic images and iterative image reconstruction: abdominal vessel imaging in the era of spectral detector CT.

AIM: To compare the quality of virtual mono-energetic (VMI) and polychromatic images reconstructed with hybrid iterative (PCIHIR) or model-based reconstruction (PCIMBR) derived from dual-layer spectral detector computed tomography (SDCT) in arterial phase images to visualise the aorta and abdominal main branches. MATERIAL AND METHODS: A retrospective review of 50 patients with abdominal arterial phase scans was undertaken. Attenuation, intraluminal noise, and signal-/contrast-to-noise ratio (S-/CNR) were assessed in the PCIHIR, PCIMBR and VMI40keV, VMI70keV, and VMI100keV images. Contrast, noise, and visualization of soft-plaque, and macro-/micro-calcifications were scored in a blinded reading by two radiologists. RESULTS: VMI40keV yielded highest S-/CNR (p≤0.001). VMI70keV and PCIMBR showed comparable SNR (p≥0.999) and yielded higher SNR than PCIHIR. VMI70keV yielded higher CNR than PCIHIR (p<0.001) and PCIMBR (p<0.045). VMI100keV yielded lowest CNR (p≤0.001) and SNR (p≥0.104). In the subjective analysis, VMI40keV outperformed PCIMBR for contrast and noise, PCIMBR scored better than VMI70keV, and the latter scored better than PCIHIR for these categories (all p<0.001). PCIMBR was superior for depiction of soft-plaque and micro-calcifications (p<0.001). VMI100keV visualized micro-calcifications second best (p<0.001) and matched PCIMBR for the depiction of macro-calcifications (p>0.999), while VMI40keV scored second best for depiction of soft-plaque (p<0.020). CONCLUSIONS: VMI40keV and VMI70keV yield better S-/CNR than PCIHIR and PCIMBR; however, PCIMBR visualized arteriosclerotic plaques best, followed by VMI40keV for depiction of soft-plaque and VMI100keV for macro- and micro-calcification. Based on the present findings, PCIMBR on conventional CT and VMI40keV supplemented by VMI100keV on SDCT are recommended for the diagnostic assessment of abdominal arteries.

A member of a novel Arabidopsis thaliana gene family of candidate Mg2+ ion transporters complements a yeast mitochondrial group II intron-splicing mutant.

Autocatalytic activity of some group II introns has been demonstrated in vitro, but helper functions such as the yeast MRS2 protein are essential for splicing in vivo. In our search for such helper factors in plants, we pursued the cloning of two Arabidopsis thaliana homologues, atmrs2-1 and atmrs2-2. Atmrs2-1, but not atmrs2-2, complements the yeast deletion mutant of mrs2, and this is congruent with the prediction of two adjacent transmembrane stretches in AtMRS2-1 and yeast MRS2 but not in AtMRS2-2. This complementation depends on fusion of the native yeast mitochondrial import sequence to atmrs2-1. A differing, non-mitochondrial, cellular targeting in Arabidopsis is supported by the analysis of green fluorescent protein fusion constructs after transient transformation into plant protoplasts. Further members of what now appears to be a family of 10 mrs2 homologues are identified in the Arabidopsis genome. Similarity searches with the PSI-BLAST algorithm in the protein database fail to identify homologues of this novel gene family in any eukaryotes other than yeasts, but do identify its distant relatedness to the corA group of bacterial magnesium transporters. In line with this observation, intramitochondrial magnesium concentrations are indeed restored to wild-type levels in the yeast mutant on complementation with atmrs2-1.

Hydration-dependent far-infrared absorption in lysozyme detected using synchrotron radiation.

Using the National Synchrotron Light Source (NSLS) at Brookhaven far-infrared absorption in the frequency range 15-45 cm-1 was detected in samples of lysozyme at different hydrations and in water. The absorption is due to the presence of low-frequency (picosecond timescale) motion in the samples, such as are calculated in molecular dynamics simulations. The form of the transmission profile is temperature independent but varies significantly with the degree of hydration of the protein. At higher hydrations the profile resembles closely that of pure water in the region 20-45 cm-1. At a low hydration marked differences are seen with, in particular, the appearance of a transmission minimum at 19 cm-1. The possible origins of the hydration dependence are discussed. The results demonstrate the usefulness of long-wavelength synchrotron radiation for the characterisation of biologically-important low-frequency motions in protein samples.

[Complete remission of cutaneous satellite and in-transit metastases. After intralesional therapy with interleukin-2 in 2 patients with malignant melanoma]. / Komplette Remission kutaner Satelliten- und In-transit-Filiae. Nach intraläsionaler Interleukin-2-Applikation bei 2 Patienten mit malignem Melanom.

Multiple cutaneous satellite and in-transit metastases of melanoma without involvement of lymph nodes or other organs are a challenge especially when they occur in elderly inoperable patients with multiple internal diseases. In this particular situation, intralesional application of interleukin-2 may represent an effective alternative to systemic chemo- or immunotherapy as it can be performed on an out-patient basis and has few side effects. We treated two elderly female patients with multiple cutaneous metastases of malignant melanoma with intra- and perilesional application of interleukin-2 (3 x 6-12 Mio IE) over 12 weeks and achieved a complete remission of these metastases. In follow-up biopsies, no viable tumor cells were found. Despite a slight burning at the injection side and a transient local inflammatory reaction, the therapy was well tolerated in both cases after premedication with paracetamol 500 mg orally and pretreatment of the injection site with a cream containing lidocaine and prilocaine. No systemic side effects were observed.

Plant mitochondrial RNA editing.

RNA editing affects messenger RNAs and transfer RNAs in plant mitochondria by site-specific exchange of cytidine and uridine bases in both seed and nonseed plants. Distribution of the phenomenon among bryophytes has been unclear since RNA editing has been detected in some but not all liverworts and mosses. A more detailed understanding of RNA editing in plants required extended data sets for taxa and sequences investigated. Toward this aim an internal region of the mitochondrial nad5 gene (1104 nt) was analyzed in a large collection of bryophytes and green algae (Charles). The genomic nad5 sequences predict editing in 30 mosses, 2 hornworts, and 7 simple thalloid and leafy liverworts (Jungermanniidae). No editing is, however, required in seven species of the complex thalloid liverworts (Marchantiidae) and the algae. RNA editing among the Jungermanniidae, on the other hand, reaches frequencies of up to 6% of codons being modified. Predictability of RNA editing from the genomic sequences was confirmed by cDNA analysis in the mosses Schistostega pennata and Rhodobryum roseum, the hornworts Anthoceros husnotii and A. punctatus, and the liverworts Metzgeria conjugata and Moerckia flotoviana. All C-to-U nucleotide exchanges predicted to reestablish conserved codons were confirmed. Editing in the hornworts includes the removal of genomic stop codons by frequent reverse U-to-C edits. Expectedly, no RNA editing events were identified by cDNA analysis in the marchantiid liverworts Ricciocarpos natans, Corsinia coriandra, and Lunularia cruciata. The findings are discussed in relation to models on the phylogeny of land plants.