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  • Author or Editor: Takayuki Amano x
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Daiki Uchida, Yuki Amano, Hirokazu Nakatogawa, Takayuki Masui, Naoto Ando, Teiji Nakayama, Haruhiko Sato, Tetsuro Sameshima and Tokutaro Tanaka

OBJECTIVE

Adjustable shunt valves that have been developed for the management of hydrocephalus all rely on intrinsically magnetic components, and artifacts with these valves on MRI are thus inevitable. The authors have previously reported that the shapes of shunt artifacts differ under different valve pressures with the proGAV 2.0 valve. In the present study the authors compared the size and shape of artifacts at different pressure settings with 4 new-model shunt valves.

METHODS

The authors attached 4 new models of MRI-resistant shunt valve to the temporal scalp of a healthy volunteer: the proGAV 2.0; Codman Certas Plus; Polaris; and Strata MR. They set 3 different scales of pressures for each valve, depending on magnet orientation to the body axis. Artifacts were evaluated and compared among all valves on a 3.0-T GE scanner and 2 valves were also evaluated on a Philips scanner and a Siemens scanner. In-plane artifact sizes were evaluated as the maximum distance of the artifact from the expected scalp.

RESULTS

The sizes and shapes of artifacts changed depending on valve pressure for all valves on the 3 different MRI scanners. Artifacts were less prominent on spin echo sequences than on gradient echo sequences. For diffusion-weighted imaging and time-of-flight MR angiography, the authors matched image numbers within the same sequence and compared appearances of artifacts. For all valves, the number of images affected by artifacts and the image number showing the largest artifact differed among valve settings.

CONCLUSIONS

Artifacts of all adjustable shunt valves showed gross changes corresponding to pressure setting. Not only the maximum distance of artifacts but also the shape changed significantly. The authors suggest that changing pressure settings offers one of the easiest ways to minimize artifacts on MRI.

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Yoshihiko Maeda, Koichi Yoshikawa, Koji Kajiwara, Makoto Ideguchi, Takayuki Amano, Makoto Saka, Sadahiro Nomura, Masami Fujii and Michiyasu Suzuki

The authors report a rare case of intracranial yolk sac tumor in a 13-year-old boy with Down syndrome who presented with left hemiparesis. Admission MR imaging revealed a tumor in the right basal ganglia. Serum α-fetoprotein was markedly elevated. Yolk sac tumor was diagnosed radiologically and serologically. The standard therapy for intracranial yolk sac tumor is platinum-based chemotherapy with concomitant radiotherapy. However, the authors used reduced-dose chemotherapy and asynchronized radiotherapy because of the well-known low tolerance of patients with Down syndrome to chemotherapy. This treatment was successful with no complications. Blood cancers are frequently associated with Down syndrome, whereas solid tumors occur less frequently in these patients, and the risk of chemoradiotherapy is unclear. The results indicate that dose-reduction therapy can be effective for treatment of a brain tumor in a patient with Down syndrome.

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Takayuki Amano, Koji Kajiwara, Koichi Yoshikawa, Jun Morioka, Sadahiro Nomura, Hirosuke Fujisawa, Shoichi Kato, Masami Fujii, Mikiko Fukui, Yuji Hinoda and Michiyasu Suzuki

Object

The receptor for hyaluronan-mediated motility (RHAMM) is frequently overexpressed in brain tumors and was recently identified as an immunogenic antigen by using serological screening of cDNA expression libraries. In this study, which was conducted using a mouse glioma model, the authors tested the hypothesis that vaccination with dendritic cells transfected with RHAMM mRNA induces strong immunological antitumor effects.

Methods

The authors constructed a plasmid for transduction of the mRNAs transcribed in vitro into dendritic cells, which were then used to transport the intracellular protein RHAMM efficiently into major histocompatibility complex class II compartments by adding a late endosomal–lysosomal sorting signal to the RHAMM gene. The dendritic cells transfected with this RHAMM mRNA were injected intraperitoneally into the mouse glioma model 3 and 10 days after tumor cell implantation. The antitumor effects of the vaccine were estimated by the survival rate, histological analysis, and immunohistochemical findings for immune cells.

Mice in the group treated by vaccination therapy with dendritic cells transfected with RHAMM mRNA survived significantly longer than those in the control groups. Immunohistochemical analysis revealed that greater numbers of T lymphocytes containing T cells activated by CD4+, CD8+, and CD25+ were found in the group vaccinated with dendritic cells transfected with RHAMM mRNA.

Conclusions

These results demonstrate the therapeutic potential of vaccination with dendritic cells transfected with RHAMM mRNA for the treatment of malignant glioma.

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Makoto Saka, Takayuki Amano, Koji Kajiwara, Koichi Yoshikawa, Makoto Ideguchi, Sadahiro Nomura, Hirosuke Fujisawa, Shoichi Kato, Masami Fujii, Koji Ueno, Yuji Hinoda and Michiyasu Suzuki

Object

The Il13ra2 gene is often overexpressed in brain tumors, making Il13ra2 one of the vaccine targets for immunotherapy of glioma. In this study, using a mouse glioma model, the authors tested the hypothesis that vaccination using dendritic cells transfected with Il13ra2 mRNA induces strong immunological antitumor effects.

Methods

A plasmid was constructed for transduction of the mRNAs transcribed in vitro into dendritic cells. This was done to transport the intracellular protein efficiently into major histocompatibility complex class II compartments by adding a late endosomal/lysosomal sorting signal to the Il13ra2 gene. The dendritic cells transfected with this Il13ra2 mRNA were injected intraperitoneally into the mouse glioma model at 3 and 10 days after tumor cell implantation. The antitumor effects were estimated based on the survival rate, results of histological analysis, and immunohistochemical findings for immune cells.

Results

The group treated by vaccination therapy with dendritic cells transfected with Il13ra2 mRNA survived significantly longer than did the control groups. Immunohistochemical analysis revealed that greater numbers of T lymphocytes containing CD4+ and CD8+ T cells were found in the group vaccinated with dendritic cells transfected with Il13ra2 mRNA.

Conclusions

These results demonstrate the therapeutic potential of vaccination with dendritic cells transfected with Il13ra2 mRNA for the treatment of malignant glioma.