Masayuki Yamaguchi

A major quantitative trait locus for increasing cadmium-specific concentration in rice grain is located on the short arm of chromosome 7

Large phenotypic variations in the cadmium (Cd) concentration of rice grains and shoots have been observed. However, the genetic control of Cd accumulation remains poorly understood. Quantitative trait loci (QTLs) determining the grain Cd concentration of rice grown in a Cd-polluted paddy field were identified. Using a mapping population consisting of 85 backcross inbred lines derived from a cross between the low-Cd-accumulating cultivar Sasanishiki (japonica) and high-Cd-accumulating cultivar Habataki (indica), two QTLs for increasing grain Cd concentration were found on chromosomes 2 and 7. A major-effect QTL, qGCd7 (QTL for grain Cd on chromosome 7), was detected on the short arm of chromosome 7. It accounted for 35.5% of all phenotypic variance in backcross inbred lines. qGCd7 was not genetically related to any QTLs for concentrations of essential trace metals (Cu, Fe, Mn, and Zn) or those for agronomic traits such as heading date, suggesting that this QTL is specific to Cd. Furthermore, the existence of qGCd7 was confirmed using chromosome segment substitution lines (CSSLs) and an F2 population from a cross between the target CSSL and Sasanishiki grown in a Cd-polluted paddy soil. To our knowledge, qGCd7 is a novel QTL with major effects for increasing grain Cd concentrations.

Double arterial phase dynamic MRI with sensitivity encoding (SENSE) for hypervascular hepatocellular carcinomas.

To investigate the efficacy of SENSE MRI, including the double arterial phase dynamic study, to detect hypervascular hepatocellular carcinomas (HCCs).

Contrast-enhanced CT with saline flush technique using two automated injectors: how much contrast medium does it save?

Purpose The purpose of this work was to investigate the volume of contrast medium saved by the saline flush technique. Method Thoracic helical CT was performed by injecting 75 ml of contrast material (Ioversol 320) only (n = 25; Group A) or 75 ml of contrast medium pushed with 6 ml (n = 25; Group B), 12 ml (n = 25; Group C), 25 ml (n = 25; Group D), or 50 ml (n = 25; Group E) of saline at a rate of 2 ml/s. The aortic CT numbers were measured from 30 to 55 s after the beginning of injection. We compared the time to peak aortic enhancement (TPAE) among Groups A–E. Results The TPAEs of the Groups A–E were 42.6, 45.2, 48.6, 48.4, and 48.3 s, respectively, and there was a statistically significant difference among them (p < 0.0001, analysis of variance). Post hoc test revealed statistically significant differences in TPAE between Groups A and B, C, D, and E and between Groups B and C, D, and E but no differences among Groups C, D, and E. Conclusion The saline flush technique prolongs TPAE by 6 s and saves 12 ml of contrast medium.

Variation in heading date conceals quantitative trait loci for other traits of importance in breeding selection of rice

To identify quantitative trait loci (QTLs) associated with the primary target traits for selection in practical rice breeding programs, backcross inbred lines (BILs) derived from crosses between temperate japonica rice cultivars Nipponbare and Koshihikari were evaluated for 50 agronomic traits at six experimental fields located throughout Japan. Thirty-three of the 50 traits were significantly correlated with heading date. Using a linkage map including 647 single-nucleotide polymorphisms (SNPs), a total of 122 QTLs for 38 traits were mapped on all rice chromosomes except chromosomes 5 and 9. Fifty-eight of the 122 QTLs were detected near the heading date QTLs Hd16 and Hd17 and the remaining 64 QTLs were found in other chromosome regions. QTL analysis of 51 BILs having homozygous for the Koshihikari chromosome segments around Hd16 and Hd17 allowed us to detect 40 QTLs associated with 27 traits; 23 of these QTLs had not been detected in the original analysis. Among the 97 QTLs for the 30 traits measured in multiple environments, the genotype-by-environment interaction was significant for 44 QTLs and not significant for 53 QTLs. These results led us to propose a new selection strategy to improve agronomic performance in temperate japonica rice cultivars.

Splenic Artery Aneurysm of the Anomalous Splenomesenteric Trunk: Successful Treatment by Transcatheter Embolization Using Detachable Coils

A splenomesenteric trunk, which involves replacing the splenic artery from the superior mesenteric artery (SMA), is rare and occurs in less than 1% of patients. We report a case of an aneurysm involving the origin of the splenic artery that anomalously arose from the SMA, and which was successfully treated using Guglielmi detachable coils.

Accelerated dynamic MR imaging with a parallel imaging technique for hypervascular hepatocellular carcinomas: usefulness of a test bolus in examination and subtraction imaging.

To assess the impact of the accelerated dynamic MR imaging (ADMRI) approach using parallel imaging for detecting hypervascular hepatocellular carcinomas (HCCs) and to evaluate the usefulness of a test bolus in examination and subtraction imaging in this setting.

In vivo localized 1H MR spectroscopy of rat testes: Stimulated echo acquisition mode (STEAM) combined with short TI inversion recovery (STIR) improves the detection of metabolite signals

A noninvasive NMR technique for evaluating testicular function was explored in this study. Localized in vivo 1H NMR spectroscopy was performed on rat testes using a stimulated echo acquisition mode (STEAM) sequence with a short echo time (TE). In the 1H spectra, large lipid signals dominated the chemical shift range of 0.89–2.78 ppm, which prevented the observation of metabolite signals in this region. To suppress these lipid signals, short inversion time (TI) inversion recovery (STIR) was combined with STEAM (STIR‐STEAM). The optimal TI was typically 320 ms. STIR‐STEAM with a TE of 15 ms allowed successful suppression of the lipid signals and the sensitive detection of several new metabolite signals. In normal testes, choline, creatine, glutamate, and glycine signals were identified. In addition to these metabolites, a lactate signal was observed in ischemic testes. To our knowledge, the signals of glutamate, glycine, and lactate have not been previously assigned in 1H MR spectra of testes in vivo. Lipid suppression by STIR aided in the detection of these metabolites, which would otherwise have been masked by the lipid signals. Magn Reson Med, 2006.

Artifact‐reduced simultaneous MRI of multiple rats with liver cancer using PROPELLER

To explore simultaneous magnetic resonance imaging (MRI) for multiple hepatoma‐bearing rats in a single session suppressing motion‐ and flow‐related artifacts to conduct preclinical cancer research efficiently.

In Vivo Visualization of Heterogeneous Intratumoral Distributionof Hypoxia-Inducible Factor-1α Activity by the Fusion of High-Resolution SPECT and Morphological Imaging Tests

Purpose. We aimed to clearly visualize heterogeneous distribution of hypoxia-inducible factor 1α (HIF) activity in tumor tissues in vivo. Methods. We synthesized of 125I-IPOS, a 125I labeled chimeric protein probe, that would visualize HIF activity. The biodistribution of 125I-IPOS in FM3A tumor-bearing mice was evaluated. Then, the intratumoral localization of this probe was observed by autoradiography, and it was compared with histopathological findings. The distribution of 125I-IPOS in tumors was imaged by a small animal SPECT/CT scanner. The obtained in vivo SPECT-CT fusion images were compared with ex vivo images of excised tumors. Fusion imaging with MRI was also examined. Results. 125I-IPOS well accumulated in FM3A tumors. The intratumoral distribution of 125I-IPOS by autoradiography was quite heterogeneous, and it partially overlapped with that of pimonidazole. High-resolution SPECT-CT fusion images successfully demonstrated the heterogeneity of 125I-IPOS distribution inside tumors. SPECT-MRI fusion images could give more detailed information about the intratumoral distribution of 125I-IPOS. Conclusion. High-resolution SPECT images successfully demonstrated heterogeneous intratumoral distribution of 125I-IPOS. SPECT-CT fusion images, more favorably SPECT-MRI fusion images, would be useful to understand the features of heterogeneous intratumoral expression of HIF activity in vivo.

Delayed hepatic signal recovery on ferucarbotran-enhanced magnetic resonance images: an experimental study in rat livers with gadolinium chloride-induced Kupffer cell damage

ObjectiveHepatic signal recovery, rather than reduction, in ferucarbotran-enhanced magnetic resonance imaging (MRI) is a potential diagnostic marker of liver damage. We investigated hepatic signal recovery in rats with gadolinium chloride (GdCl3)-induced Kupffer cell (KC) damage.Materials and methodsTwelve rats received 8xa0μmol iron/kg of ferucarbotran 1xa0day after 0–7.5xa0mg/kg GdCl3 injection (experiment A). Another 12 rats received ferucarbotran followed by GdCl3 injection 6xa0h later (experiment B). In each experiment, three rats without GdCl3 (“no injury group”) served as control. Another six rats received GdCl3 alone without ferucarbotran. Hepatic signals were assessed on T2*-weighted images for up to 29xa0days. Iron deposits were histologically examined on day 29.ResultsHepatic signal recovery was delayed in a GdCl3 dose-dependent manner in experiment A. Gadolinium chloride alone reduced hepatic signal 15xa0% during this experiment. Hepatic signal recovery was delayed only in rats that received 7.5xa0mg/kg GdCl3 in experiment B. Hepatic signals negatively correlated with iron deposits in KCs and hepatocytes.ConclusionHepatic signal recovery on ferucarbotran-enhanced MRI was delayed in the context of GdCl3-induced KC damage due to increased hepatic iron deposits. Hepatic signal recovery may be used as a clinical marker of KC damage in liver disorders, including radiation-induced hepatitis.