A proposed combination of flat-panel detector and mobile X-ray systems for low-dose image-guided central venous catheter insertion.

A central venous catheter (CVC) should be inserted at the optimum position to infuse medicines, blood products, nutrients, or fluids. Positioning of the catheter tip is commonly performed under landmark or fluoroscopic guidance. However, Japanese regulations do not allow the performing of fluoroscopy-guided procedures outside of the fluoroscopy room. We hypothesized that a new image-guided CVC placement technique by combining a wireless flat-panel detector (FPD) and a mobile X-ray system could be applied at the bedside to support CVC insertion. A CVC attached to a chest phantom in conjunction with the polymethyl methacrylate (PMMA) phantom was imaged, contrast-to-noise ratio (CNR) was measured with images, and radiologists and emergency physicians rated the catheter images using a Likert scale for visual evaluation. The minimum dose of the FPD and mobile X-ray system was reduced by at least 98% compared with that of the X-ray fluoroscopy system. The CNR decreased with the increasing PMMA phantom thickness. However, results of the visual evaluation were maintained at the clinically usable score with low-dose imaging up to a 6-cm thickness of the PMMA phantom. In conclusion, the combination of FPD and mobile X-ray systems is particularly effective in the emergency room setting where such procedures are required to be performed with urgency.

Measurement of the half-value layer for CT systems in a single-rotation technique: Reduction of stray radiation with lead apertures.

PURPOSE: This study aimed to compare two methods of assessing the half-value layer (HVL) for computed tomography scanners in a single-rotation technique with and without lead apertures (SRTLA / SRT). METHODS: A 0.6 cc real-time ionization chamber was suspended freely in the air at the isocenter, and six sheets of lead (130 × 170 × 2 mm) were placed at the bottom of the gantry cover, forming five apertures each having a width of 16 mm (SRTLA geometry). Four aluminum plates (100 × 100 mm2; 2.0, 4.0, 6.0, and 8.0 mm thick) were placed on these apertures. Air-kerma rate profiles (K̇air) in the spiral mode were measured at tube potentials of 80, 100, 120, and 135 kVp, a tube current of 100 mA, a nominal beam width of 32.0 mm, and a rotation time of 1.5 s. Thereafter, all lead sheets were removed, and these same measurements were taken to investigate the errors of the HVLs (SRT geometry). HVLs using the SRTLA and SRT were compared with those obtained through a conventional localization technique. RESULTS: The HVLs measured in the SRTLA/SRT at 80, 100, 120, and 135 kVp were 3.37/3.50, 4.24/4.47, 5.22/5.44, and 5.90/6.17 mm, respectively. The differences between these values and those obtained through the conventional technique were 0.09/0.22, 0.02/0.25, 0.05/0.27, and -0.01/0.26 mm, respectively. CONCLUSIONS: The accuracies of the HVLs of the SRTLA were similar to those of the conventional technique. The lead apertures under the aluminum plates would help reduce the number of inaccurate HVL measurements.

Expression profile of ribosomal protein L10a throughout gonadal development in rainbow trout (Oncorhynchus mykiss).

Ribosomal protein L10a (RpL10A) has been previously established as a stimulator during the early stages of ovarian development in both the banana prawn and the fruit fly. In order to develop a greater understanding of the role of this protein in vertebrates, the present study aimed to characterize the expression profile of rpl10a during gonadal development in fish. It was determined that the expression of rpl10a within genital ridges increased during embryonic development. Although rpl10a expression was observed in both gonadal somatic cells and primordial germ cells, higher levels of both transcript and protein expression were detected in somatic cells. rpl10a transcripts were observed in all of the adult tissues examined. Cellular level expression of rpl10a was subsequently characterized across various maturational stages using in situ hybridization and immunohistochemistry of both testes and ovaries. Analysis of tissue derived from the testis showed high levels of rpl10a expression within spermatogonia and the Sertoli cells attached to them. In ovarian tissue, rpl10a was strongly expressed in chromatin-nucleolus-stage and peri-nucleolus-stage oocytes. The relationship between rpl10a expression and regulation of gonadal development was confirmed using real-time PCR, which was performed in order to analyze rpl10a expression in testicular and ovarian tissues subsequent to incubation with salmon pituitary extract and various sex steroids for 24 h. Among them, 11-ketotestosterone at 100 ng/mL effectively up-regulated expression of rpl10a in testicular tissues, while 17ß-estradiol down-regulated rpl10a expression in ovarian tissues. These results suggested that rpl10a played a role in the regulation of gonadal development in fish.

Combining next-generation sequencing with microarray for transcriptome analysis in rainbow trout gonads.

Microarray technology is a powerful tool for studying genome-wide gene expression. As the genome of many fish has not yet been determined, however, cDNA microarrays can only be designed from limited expressed sequence tag data. In this study, we designed a microarray based on the sequencing data (337,466 reads) obtained by next-generation sequencing of RNA extracted from rainbow trout (Oncorhynchus mykiss) embryonic genital ridge, testis, and ovary. These data (307,264 reads) were assembled into 28,668 contigs; 3,298 reads could not be assembled and 26,904 reads were unique sequences that did not cluster with other reads. Based on this information, 55,928 microarray probes were designed for a microarray, which was validated by hybridization experiments with RNA extracted from type A spermatogonia (A-SG) and testicular somatic cells. Expression of known spermatogonial markers was confirmed to be higher in A-SG than in testicular somatic cells whereas supporting-cell markers were expressed at higher levels in testicular somatic cells. This microarray analysis revealed that 8,068 transcripts showed at least fourfold higher signal in A-SG than testicular somatic cells. Fourteen of 17 randomly selected transcripts were expressed at significantly higher-levels in A-SG than somatic cells, by quantitative RT-PCR. In addition, three transcripts analyzed with in situ hybridization showed A-SG-specific signals in immature trout testis, with one of them exhibiting a heterogeneous expression pattern in A-SG. The rainbow trout gonad microarray developed in this study therefore appears to be a useful tool to understand gametogenesis in rainbow trout.

Flow-cytometric isolation and enrichment of teleost type A spermatogonia based on light-scattering properties.

The transplantation of germ cells is a powerful tool both for studying their development and for reproductive biotechnology. An intraperitoneal germ cell transplantation system was recently developed for use in several teleost species. Donor germ cells transplanted into the peritoneal cavity of hatchlings migrated toward and were incorporated into the recipient's genital ridges, where they underwent gametogenesis. Among male germ cells, only type A spermatogonia were capable of colonizing the recipient gonads, unlike those at more advanced stages. The enrichment of type A spermatogonia is therefore important to achieve efficient donor-cell incorporation and subsequent donor-derived gametogenesis. Here we established a simple and rapid system of isolation and enrichment for fish type A spermatogonia, using flow cytometry. Type A spermatogonia were found to have distinctive forward and side light scatter properties compared to that with other types of testicular cell. Based on these characteristics, we were able to isolate and enrich type A spermatogonia by using flow cytometry. After intraperitoneal transplantation, the enriched type A spermatogonia could be successfully incorporated into the recipient genital ridges. This flow cytometry approach using forward and side light scatter was also found to be applicable to other salmonid and sciaenid species, suggesting that it could be a powerful tool for isolating and enriching transplantable type A spermatogonia in a wide range of teleosts. We expect this method to contribute significantly to germ cell biology and biotechnology.