Effect of table height displacement and patient center deviation on size-specific dose estimates calculated from computed tomography localizer radiographs.

The aim of this study is to evaluate the effect of table height displacement and patient center deviation along the [Formula: see text]-axis on size-specific dose estimate (SSDE) calculations based on computed tomography (CT) localizer radiographs in pediatric and adult abdominal CT examinations. CT localizer radiographs and CT axial images were acquired with table heights of - 5.0, - 2.5, 0.0 (center), 2.5, and 5.0 cm using two acrylic self-made phantoms filled with water. Water-equivalent diameters ([Formula: see text]) were calculated from the CT localizer radiographs and CT axial images. Relative errors of SSDEs from the CT localizer radiographs to SSDEs from the CT axial images were calculated to evaluate the effect of table height displacement. Furthermore, patient center deviations and indices of SSDE overestimation were measured from the clinical data of 110 abdominal CT examinations. The relative errors of SSDEs in phantoms equivalent to 1-year-old and 20-year-old Japanese reference persons ranged from - 2.45% (table height of 50 mm) to + 1.88% (- 50 mm) and from - 4.22% (50 mm) to + 3.79% (- 50 mm), respectively. The largest center deviation in all patients ranged from - 43.1 to 21.5 mm (median: - 14.4 mm). The indices of SSDE overestimation for all patients ranged from - 16.2 to 6.9 mm (median: - 2.2 mm). We found that the effects of table height displacement and patient center deviation along the [Formula: see text]-axis on SSDEs calculated from CT localizer radiographs in pediatric phantoms were smaller compared to adult phantoms. In order to correct these patient center deviations, it is necessary to apply an appropriate correction technique in each section along the [Formula: see text]-axis.

Analysis of Image Gently Abdominal CT Protocol With the Use of Body Phantom Adapted to the Japanese Size.

OBJECTIVE: The purpose of this study was to analyze in detail the quality of abdominal CT images obtained using three protocols reported by Image Gently in 2014 (hereafter referred to as Image Gently 2014), with the use of a handmade body phantom adapted to typical body sizes of the Japanese population. Moreover, we converted the findings of Image Gently 2014 to match Japanese body sizes and referred to our converted findings as Image Gently Japan. MATERIALS AND METHODS: We scanned each phantom in a mechanical isocenter in accordance with the Image Gently 2014 abdominal imaging protocol. We changed the tube current-exposure time product per rotation from 25 to 250 mAs. The bowtie filter was set with a minimum FOV for the phantom size. We then analyzed the volume CT dose index (CTDIvol)-measured CT number curve. We then used this CT number curve to calculate the CT number recommended by Image Gently Japan for each of the designated patient ages. RESULTS: The CTDIvol-measured CT number curve showed that, as the CTDIvol increased with each age, image noise decreased. When we assumed that the CTDIvol value for adults was 20 mGy, the measured CT number was 12.5 HU. We then multiplied each reduction coefficient by age (neonate and 1, 5, 10, and 15 years). The measured CT numbers for Image Gently Japan performed to attain limited dose reduction were 3.0, 3.9, 4.9, 6.0, and 9.0 HU, respectively, whereas those for Image Gently Japan performed to achieve moderate dose reduction were 3.3, 4.3, 5.3, 6.3, and 9.3 HU, respectively, and those for Image Gently Japan performed to attain aggressive dose reduction were 4.1, 5.1, 5.8, 6.8, and 9.5 HU, respectively. CONCLUSION: We analyzed the abdominal image quality demanded by Image Gently 2014, and we were able to adapt the results to the Japanese population and present them as our own Image Gently Japan recommendations. If the results of the present study become a foundation for scanning parameters for Japanese patients, we believe that they will eventually lead to a reduction in medical radiation exposure for this patient population.

Ion-channel blocker sensitivity of voltage-gated calcium-channel homologue Cch1 in Saccharomyces cerevisiae.

The Cch1 protein of the yeast Saccharomyces cerevisiae is a homologue of the pore-forming alpha1 subunit of mammalian voltage-gated Ca2+ channels (VGCCs), and it constitutes a high-affinity Ca2+-influx system with the Mid1 protein in this organism. Here, we characterized the kinetic property of a putative Cch1-Mid1 Ca2+ channel overexpressed in S. cerevisiae cells, and showed that the L-type VGCC blockers nifedipine and verapamil partially inhibited Cch1-Mid1 activity, but typical P/Q-, N-, R- and T-type VGCC blockers did not inhibit activity. In contrast, a third L-type VGCC blocker, diltiazem, increased Cch1-Mid1 activity. Diltiazem did not increase Ca2+ uptake in the cch1Delta and mid1Delta single mutants and the cch1Delta mid1Delta double mutant, indicating that the diltiazem-induced increase in Ca2+ uptake is completely dependent on Cch1-Mid1. These results suggest that Cch1 is pharmacologically similar to L-type VGCCs, but the interactions between Cch1 and the L-type VGCC blockers are more complicated than expected.

A technique to enzymatically construct libraries which express short hairpin RNA of arbitrary stem length.

Short interfering RNAs (siRNAs) and short hairpin RNAs (shRNAs) usually used for RNA interference (RNAi) are double-stranded RNAs (dsRNAs) of 21 base pairs. However, siRNAs and shRNAs of longer stem length have been reported to show more potent gene silencing. Here, we report a new technique to enzymatically construct shRNA libraries containing clones from firefly luciferase cDNA and Jurkat cDNA. The technique allowed the efficacious generation of shRNAs of arbitrary stem length as desired, providing the clones which potently silenced the specified gene expression and presenting a high efficiency rate of gene silencing. Our results indicate that the technique permits the rapid, efficient, and low-cost preparation of genomewide shRNA expression libraries not only for humans and mice but also for sorts of biological species and that the relevant libraries are applicable for the search of genes related to phenotype changes and of new targets for drug discovery.