Influence of motion correction on the visual analysis of cardiac magnetic resonance stress perfusion imaging

Objective

Image post-processing corrects for cardiac and respiratory motion (MoCo) during cardiovascular magnetic resonance (CMR) stress perfusion. The study analyzed its influence on visual image evaluation.

Materials and methods

Sixty-two patients with (suspected) coronary artery disease underwent a standard CMR stress perfusion exam during free-breathing. Image post-processing was performed without (non-MoCo) and with MoCo (image intensity normalization; motion extraction with iterative non-rigid registration; motion warping with the combined displacement field). Images were evaluated regarding the perfusion pattern (perfusion deficit, dark rim artifact, uncertain signal loss, and normal perfusion), the general image quality (non-diagnostic, imperfect, good, and excellent), and the reader’s subjective confidence to assess the images (not confident, confident, very confident).

Results

Fifty-three (non-MoCo) and 52 (MoCo) myocardial segments were rated as ‘perfusion deficit’, 113 vs. 109 as ‘dark rim artifacts’, 9 vs. 7 as ‘uncertain signal loss’, and 817 vs. 824 as ‘normal’. Agreement between non-MoCo and MoCo was high with no diagnostic difference per-patient. The image quality of MoCo was rated more often as ‘good’ or ‘excellent’ (92 vs. 63%), and the diagnostic confidence more often as “very confident” (71 vs. 45%) compared to non-MoCo.

Conclusions

The comparison of perfusion images acquired during free-breathing and post-processed with and without motion correction demonstrated that both methods led to a consistent evaluation of the perfusion pattern, while the image quality and the reader’s subjective confidence to assess the images were rated more favorably for MoCo.

     

A POLE Splice Site Deletion Detected in a Patient with Biclonal CLL and Prostate Cancer: A Case Report

Chronic lymphocytic leukemia (CLL) is considered a clonal B cell malignancy. Sporadically, CLL cases with multiple productive heavy and light-chain rearrangements were detected, thus leading to a bi- or oligoclonal CLL disease with leukemic cells originating either from different B cells or otherwise descending from secondary immunoglobulin rearrangement events. This suggests a potential role of clonal hematopoiesis or germline predisposition in these cases. During the screening of 75 CLL cases for kappa and lambda light-chain rearrangements, we could detect a single case with CLL cells expressing two distinct kappa and lambda light chains paired with two separate immunoglobulin heavy-chain variable regions. Furthermore, this patient also developed a prostate carcinoma. Targeted genome sequencing of highly purified light-chain specific CLL clones from this patient and from the prostate carcinoma revealed the presence of a rare germline polymorphism in the POLE gene. Hence, our data suggest that the detected SNP may predispose for cancer, particularly for CLL.     

Effect of multiblock copolymers in polymer blends

The use of multiblock copolymers for the compatibilization of immiscible polymer blends is controversially discussed in the literature. Investigations have been carried out to estimate the effect of multiblock copolymers containing segments of a liquid crystalline polyester (LCP) and polysulfone (PSU) segments in blends of the based homopolymers. One goal was to determine whether multiblock copolymers provide an opportunity for compatibilizing PSU/LCP blends. By using PSU/LCP multiblock copolymers with different molecular weights of the blocks in the appropriate binary, solution-casted blends, it was shown that the interpenetration of the polysulfone phase of the block copolymer and the PSU matrix leads to an improved miscibility of the blend. This effect is retained in ternary blends of PSU, LCP, and the multiblock copolymer, assuming a certain critical molecular weight of the multiblock copolymer segments. In addition, some mechanical characteristics of PSU/LCP melt blends such as the E-modulus and fracture strength are improved by adding long-segmented multiblock copolymers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2293–2309, 1997     

Adsorbent Regeneration by Non‐thermal Plasma for Elimination of Odorous Compounds from Indoor Air

The non‐thermal plasma (NTP) technique was shown to be a method to improve indoor air quality. In particular in kitchens, odorous emissions can be removed by NTP. A combined concept of adsorption of volatile organic compounds (VOCs) and plasma regeneration of the adsorber was tested in adsorption‐regeneration‐adsorption cycles. As reference VOCs, 2‐methylthiophene, 2‐methylpyrazine, 2‐acetylthiazole, nonanal, and trans‐2‐nonenal were selected in humid air streams. These odorous compounds are emitted during cooking and frying processes. The adsorption‐regeneration concept was also tested during a simulated frying process with garlic in rape oil. A hydrophobic zeolite was chosen as adsorber material and placed directly into the discharge zone of a plasma reactor.     

Evaluation of bacterial RNase P RNA as a drug target

RNA has gained increasing importance as a therapeutic target. However, so far mRNAs rather than stable cellular RNAs have been considered in such studies. In bacteria, the tRNA-processing enzyme RNase P has a catalytic RNA subunit. Fundamental differences in structure and function between bacterial and eukaryotic RNase P, and its indispensability for cell viability make the bacterial enzyme an attractive drug target candidate. Herein we describe two approaches utilized to evaluate whether the catalytic RNA subunit of bacterial RNase P is amenable to inactivation by antisense-based strategies. In the first approach, we rationally designed RNA hairpin oligonucleotides targeted at the tRNA 3'-CCA binding site (P15 loop region) of bacterial RNase P RNA by attempting to include principles derived from the natural CopA-CopT antisense system. Substantial inactivation of RNase P RNA was observed for Type A RNase P RNA (such as that in Escherichia coli) but not for Type B (as in Mycoplasma hyopneumoniae). Moreover, only an RNA oligonucleotide (Eco 3') complementary to the CCA binding site and its 3' flanking sequences was shown to be an efficient inhibitor. Mutation of Eco 3' and analysis of other natural RNase P RNAs with sequence deviations in the P15 loop region showed that inhibition is due to interaction of Eco 3' with this region and occurs in a highly sequence-specific manner. A DNA version of Eco 3' was a less potent inhibitor. The potential of Eco 3' to form an initial kissing complex with the P15 loop did not prove advantageous. In a second approach, we tested a set of oligonucleotides against E. coli RNase P RNA which were designed by algorithms developed for the selection of suitable mRNA targets. This approach identified the P10/11-J11/12 region of bacterial RNase P RNA as another accessible region. In conclusion, both the P15 loop and P10/11-J11/12 regions of Type A RNase P RNAs seem to be promising antisense target sites since they are easily accessible and sufficiently interspersed with nonhelical sequence elements, and oligonucleotide binding directly interferes with substrate docking to these two regions.     

Iron(II)‐based catalysts for ethene oligomerization

The synthesis of iron(II) complexes with various tridentate di(imino)pyridine ligands and their potential as ethene oligomerization catalysts are described. The ligands are characterized by ¹H‐ and ¹³C‐NMR spectroscopy and the complexes only by mass spectrometry due to their paramagnetism. After activation either with methylalumoxane (MAO) or with a heterogeneous cocatalyst consisting of partially hydrolyzed trimethylaluminum and silica gel, the prepared complexes proved to be good catalysts for the oligomerization of ethene. 1‐Octene, 1‐hexene, and 1‐decene were the major products, formed in very high isomeric purity (99.9 %). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 476–482, 2003     

Destabilizing interactions between the partners of a bifunctional fusion protein

Hybrid MalE–GVP is a bifunctional protein in vitro sinceit binds maltose as protein MalE of Escherichia coli and sinceit is dimeric and specifically binds single-stranded DNA asprotein GVP of phage M13. The oxidation rate of a unique cysteineresidue was used to compare the stabilities of GVP in its freeand hybrid forms, under conditions where MalE was either foldedor unfolded by a denaturing agent. The results showed that boththe covalent link and tertiary non-covalent interactions betweenMalE and GVP destabilized GVP in MalE–GVP. To test whetherGVP had identical structures in its free and hybrid forms, mutationswere used as local conformational probes. The effects of thesemutations on the capabilities of MalE–GVP to dimerizeand to bind single-stranded DNA were assayed in vitro. Theywere compatible with the effects of the same mutations on theglobal activity of free GVP in vivo and with the effects thatcould be predicted from the known data on free GVP, in particularits crystal structure. Thus, one partner of a hybrid proteincan be destabilized by the other partner while maintaining itsstructural and functional characteristics.     

Ant and Mite Diversity Drives Toxin Variation in the Little Devil Poison Frog

Poison frogs sequester chemical defenses from arthropod prey, although the details of how arthropod diversity contributes to variation in poison frog toxins remains unclear. We characterized skin alkaloid profiles in the Little Devil poison frog, Oophaga sylvatica (Dendrobatidae), across three populations in northwestern Ecuador. Using gas chromatography/mass spectrometry, we identified histrionicotoxins, 3,5- and 5,8-disubstituted indolizidines, decahydroquinolines, and lehmizidines as the primary alkaloid toxins in these O. sylvatica populations. Frog skin alkaloid composition varied along a geographical gradient following population distribution in a principal component analysis. We also characterized diversity in arthropods isolated from frog stomach contents and confirmed that O. sylvatica specialize on ants and mites. To test the hypothesis that poison frog toxin variability reflects species and chemical diversity in arthropod prey, we (1) used sequencing of cytochrome oxidase 1 to identify individual prey specimens, and (2) used liquid chromatography/mass spectrometry to chemically profile consumed ants and mites. We identified 45 ants and 9 mites in frog stomachs, including several undescribed species. We also showed that chemical profiles of consumed ants and mites cluster by frog population, suggesting different frog populations have access to chemically distinct prey. Finally, by comparing chemical profiles of frog skin and isolated prey items, we traced the arthropod source of four poison frog alkaloids, including 3,5- and 5,8-disubstituted indolizidines and a lehmizidine alkaloid. Together, the data show that toxin variability in O. sylvatica reflects chemical diversity in arthropod prey.