Cardiac 4D phase-contrast CMR at 9.4 T using self-gated ultra-short echo time (UTE) imaging

Background: Time resolved 4D phase contrast (PC) cardiovascular magnetic resonance (CMR) in mice is challenging due to long scan times, small animal ECG-gating and the rapid blood flow and cardiac motion of small rodents. To overcome several of these technical challenges we implemented a retrospectively self-gated 4D PC radial ultra-short echo-time (UTE) acquisition scheme and assessed its performance in healthy mice by comparing the results with those obtained with an ECG-triggered 4D PC fast low angle shot (FLASH) sequence. Methods: Cardiac 4D PC CMR images were acquired at 9.4 T in healthy mice using the proposed self-gated radial center-out UTE acquisition scheme (TE/TR of 0.5 ms/3.1 ms) and a standard Cartesian 4D PC imaging sequence (TE/TR of 2.1 ms/5.0 ms) with a four-point Hadamard flow encoding scheme. To validate the proposed UTE flow imaging technique, experiments on a flow phantom with variable pump rates were performed. Results: The anatomical images and flow velocity maps of the proposed 4D PC UTE technique showed reduced artifacts and an improved SNR (left ventricular cavity (LV): 8.9 +/- 2.5, myocardium (MC): 15.7 +/- 1.9) compared to those obtained using a typical Cartesian FLASH sequence (LV: 5.6 +/- 1.2, MC: 10.1 +/- 1.4) that was used as a reference. With both sequences comparable flow velocities were obtained in the flow phantom as well as in the ascending aorta (UTE: 132.8 +/- 18.3 cm/s, FLASH: 134.7 +/- 13.4 cm/s) and pulmonary artery (UTE: 78.5 +/- 15.4 cm/s, FLASH: 86.6 +/- 6. 2 cm/s) of the animals. Self-gated navigator signals derived from information of the oversampled k-space center were successfully extracted for all animals with a higher gating efficiency of time spent on acquiring gated data versus total measurement time (UTE: 61.8 +/- 11.5%, FLASH: 48.5 +/- 4.9%). Conclusions: The proposed self-gated 4D PC UTE sequence enables robust and accurate flow velocity mapping of the mouse heart in vivo at high magnetic fields. At the same time SNR, gating efficiency, flow artifacts and image quality all improved compared to the images obtained using the well-established, ECG-triggered, 4D PC FLASH sequenc

Structure of the no-go mRNA decay complex Dom34-Hbs1 bound to a stalled 80S ribosome

No-go decay (NGD) is a mRNA quality-control mechanism in eukaryotic cells that leads to degradation of mRNAs stalled during translational elongation. The key factors triggering NGD are Dom34 and Hbs1. We used cryo-EM to visualize NGD intermediates resulting from binding of the Dom34-Hbs1 complex to stalled ribosomes. At subnanometer resolution, all domains of Dom34 and Hbs1 were identified, allowing the docking of crystal structures and homology models. Moreover, the close structural similarity of Dom34 and Hbs1 to eukaryotic release factors (eRFs) enabled us to propose a model for the ribosome-bound eRF1-eRF3 complex. Collectively, our data provide structural insights into how stalled mRNA is recognized on the ribosome and how the eRF complex can simultaneously recognize stop codons and catalyze peptide release

Preliminary

Phytochemical analysis of the methanolic and aqueous extracts of Faidherbia albida legumes indicated the presence of terpenes, cardiac glycosides, monosaccharides and carbohydrates type of compounds in both extracts. While alkaloids and saponins were found in aqueous extract only, flavonoids were found to be absent in both extracts. The aqueous and methanolic extracts exhibited a potent growth stimulation effect. Inhibition of both the rootlet and shoot showed a dose dependent response. Aqueous extract has a greater inhibitory effect on rootlet growth than shoot growth. The methanolic extract has a greater inhibitory effect than the aqueous extract. Both extracts and some fractions were tested against three pathogenic bacterial species; Staphylococcus aureus, Escherichia coli and Shigella dysenteriae, also tested against three pathogenic fungal species; Fusarium oxysporum, Alternaria alternate, and Aspergillus niger. Most of the plant extracts stimulate the studied fungal growth specially the aqueous extract. Meanwhile it shows interesting results by inhibiting the growth of the studied pathogenic bacterial species with most extracts and fractions

Evaluation of compressed sensing MRI for accelerated bowel motility imaging

BACKGROUND: To investigate the feasibility of compressed sensing and parallel imaging (CS-PI)-accelerated bowel motility magnetic resonance imaging (MRI) and to compare its image quality and diagnostic quality to conventional sensitivity encoding (SENSE) accelerated scans. METHODS: Bowel MRI was performed in six volunteers using a three-dimensional balanced fast field-echo sequence. Static scans were performed after the administration of a spasmolytic agent to prevent bowel motion artefacts. Fully sampled reference scans and multiple prospectively 3× to 7× undersampled CS-PI and SENSE scans were acquired. Additionally, fully sampled CS-PI and SENSE scans were retrospectively undersampled and reconstructed. Dynamic scans were performed using 5× to 7× accelerated scans in the presence of bowel motion. Retrospectively, undersampled scans were compared to fully sampled scans using structural similarity indices. All reconstructions were visually assessed for image quality and diagnostic quality by two radiologists. RESULTS: For static imaging, the performance of CS-PI was lower than that of fully sampled and SENSE scans: the diagnostic quality was assessed as adequate or good for 100% of fully sampled scans, 95% of SENSE, but only for 55% of CS-PI scans. For dynamic imaging, CS-PI image quality was scored similar to SENSE at high acceleration. Diagnostic quality of all scans was scored as adequate or good; 55% of CS-PI and 83% of SENSE scans were scored as good. CONCLUSION: Compared to SENSE, current implementation of CS-PI performed less or equally good in terms of image quality and diagnostic quality. CS-PI did not show advantages over SENSE for three-dimensional bowel motility imaging

Relationships between radiological and biochemical-evidence of rickets in asian schoolchildren

One hundred Asian schoolchildren provided evidence of the relationships between radiological and biochemical evidence of rickets in a vitamin D-deficient population. In a retrospective study of the X-rays of 56 children the variables serum alkaline phosphatase, inorganic phosphorus and age provided a discriminant function which correctly classified 10 of 11 children with radiological evidence of rickets and 44 of 45 children with negative or marginally abnormal X-rays. When the discriminant function was applied to a prospective study of 44 children, three children with radiological evidence of rickets were correctly classified together with 38 of the remaining 41 children with negative or marginally abnormal X-rays. Serum alkaline phosphatase was the most important variable in the discriminant analysis, followed by serum inorganic phosphorus and age. Low levels of serum 25-hydroxy vitamin D (25-OHD) are of little value in predicting the severity of radiological evidence of rachitic bone disease in a vitamin D-deficient population