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888 results on '"Yamada, Takahiro"'

161. Diabetes mellitus impacts on expression of DNA mismatch repair protein PMS2 and tumor microenvironment in pancreatic ductal adenocarcinoma.

Author

Pan, Xuekai, Mizukami, Hiroki, Hara, Yutaro, Yamada, Takahiro, Yamazaki, Keisuke, Kudoh, Kazuhiro, Takeuchi, Yuki, Sasaki, Takanori, Kushibiki, Hanae, Igawa, Akiko, and Hakamada, Kenichi

Subjects
PALMITIC acid, PANCREATIC duct, DNA mismatch repair, PANCREATIC tumors, TUMOR proteins, TUMOR microenvironment, DIABETES, TYPE 2 diabetes
Abstract

Aims/Introduction: The mismatch repair (MMR) protein recognizes DNA replication errors and plays an important role in tumorigenesis, including pancreatic ductal adenocarcinoma (PDAC). Although PMS2, a MMR protein, is degraded under oxidative stress, the effects of diabetes are still unclear. Herein, we focused on whether diabetes affected MMR protein expression in PDAC. Materials and Methods: Tissues from 61 surgically resected PDAC subjects were clinicopathologically analyzed. Immunohistochemical analysis was performed for MMR protein expression, oxidative stress, and immune cell infiltration. The change of MMR protein expression was assessed in PDAC cell lines under stimulation with 25 mM glucose and 500 μM palmitic acid. Survival curves were analyzed by the Kaplan–Meier method with the log‐rank test. Results: Diabetes complicated with dyslipidemia significantly decreased the expression of PMS2 in PDAC tissues with an inverse correlation with the degree of oxidative stress. Palmitic acid combined with high glucose induced degradation of PMS2 protein, enhancing oxidative stress in vitro. CD8+ T‐cell infiltration was associated with a short duration of type 2 diabetes (≤4 years) and a low expression of PMS2 in PDAC tissues, while CD163+ tumor‐associated macrophage infiltration was increased with a long duration of diabetes (>4 years). A short duration of diabetes exhibited a better prognosis than nondiabetic subjects with PDAC (P < 0.05), while a long duration of diabetes had a worse prognosis (P < 0.05). Conclusions: The different phases of diabetes have a major impact on PDAC by altering PMS2 expression and the tumor immune microenvironment, which can be targeted by an immune checkpoint inhibitor. [ABSTRACT FROM AUTHOR]

Published
2023
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162. Catalytic RNA Oligomers Formed by Co-Oligomerization of a Pair of Bimolecular RNase P Ribozymes.

Author

Siddika, Mst. Ayesha, Yamada, Takahiro, Aoyama, Risako, Hidaka, Kumi, Sugiyama, Hiroshi, Endo, Masayuki, Matsumura, Shigeyoshi, and Ikawa, Yoshiya

Subjects
*CATALYTIC RNA, *ATOMIC force microscopy
Abstract

Naturally occurring ribozymes with a modular architecture are promising platforms for construction of RNA nanostructures because modular redesign enables their oligomerization. The resulting RNA nanostructures can exhibit the catalytic function of the parent ribozyme in an assembly dependent manner. In this study, we designed and constructed open-form oligomers of a bimolecular form of an RNase P ribozyme. The ribozyme oligomers were analyzed biochemically and by atomic force microscopy (AFM). [ABSTRACT FROM AUTHOR]

Published
2022
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163. Attenuation correction for phantom tests: an alternative to maximum-likelihood attenuation correction factor-based correction for clinical studies in time-of-flight PET.

Author

Mizuta, Tetsuro, Yamakawa, Yoshiyuki, Minagawa, Suzuka, Kobayashi, Tetsuya, Ohtani, Atsushi, Takenouchi, Shiho, Hanaoka, Kohei, Watanabe, Shota, Morimoto-Ishikawa, Daisuke, Yamada, Takahiro, Kaida, Hayato, and Ishii, Kazunari

Abstract

Objectives: This study evaluates the phantom attenuation correction (PAC) method as an alternative to maximum-likelihood attenuation correction factor (ML-ACF) correction in time-of-flight (TOF) brain positron emission tomography (PET) studies. Methods: In the PAC algorithm, a template emission image λ Ref and a template attenuation coefficient image μ Ref are prepared as a data set based on phantom geometry. Position-aligned attenuation coefficient image μ Acq is derived by aligning μ Ref using parameters that match the template emission image λ Ref to measured emission image λ Acq . Then, attenuation coefficient image μ Acq combined with a headrest image is used for scatter and attenuation correction in the image reconstruction. To evaluate the PAC algorithm as an alternative to ML-ACF, Hoffman 3D brain and cylindrical phantoms were measured to obtain the image quality indexes of contrast and uniformity. These phantoms were also wrapped with a radioactive sheet to obtain attenuation coefficient images using ML-ACF. Emission images were reconstructed with attenuation correction by PAC and ML-ACF, and the results were compared using contrast and uniformity as well as visual assessment. CT attenuation correction (CT-AC) was also applied as a reference. Results: The contrast obtained by ML-ACF was slightly overestimated due to its unique experimental condition for applying ML-ACF in Hoffman 3D brain phantom but the uniformity was almost equivalent among ML-ACF, CT-AC, and PAC. PAC showed reasonable result without overestimation compared to ML-ACF and CT-AC. Conclusions: PAC is an attenuation correction method that can ensure the performance in phantom test, and is considered to be a reasonable alternative to clinically used ML-ACF-based attenuation correction. [ABSTRACT FROM AUTHOR]

Published
2022
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180. Manual on the proper use of meta-[211At] astato-benzylguanidine ([211At] MABG) injections in clinical trials for targeted alpha therapy (1st edition).

Author

Ukon, Naoyuki, Higashi, Tatsuya, Hosono, Makoto, Kinuya, Seigo, Yamada, Takahiro, Yanagida, Sachiko, Namba, Masao, and Nakamura, Yoshihide

Abstract

In this manuscript, we present the guideline for use of meta-[211At] astatobenzylguanidine ([211At] MABG), a newly introduced alpha emitting radiopharmaceutical to the up-coming World's first clinical trial for targeted alpha therapy (TAT) at Fukushima Medical University in Japan, focusing on radiation safety issues in Japan. This guideline was prepared based on a study supported by the Ministry of Health, Labour, and Welfare, and approved by the Japanese Society of Nuclear Medicine on Oct. 5th, 2021. The study showed that patients receiving [211At] MABG do not need to be admitted to a radiotherapy room and that TAT using [211At] MABG is possible on an outpatient basis. The radiation exposure from the patient is within the safety standards of the ICRP and IAEA recommendations for the general public and caregivers or patient's family members. In this guideline, the following contents are also included: precautions for patients and their families, safety management associated with the use of [211At] MABG, education and training, and disposal of medical radioactive contaminants. TAT using [211At] MABG in Japan should be carried out according to this guideline. Although this guideline is based on the medical environment and laws and regulations in Japan, the issues for radiation protection and evaluation methodology presented in this guideline are useful and internationally acceptable as well. [ABSTRACT FROM AUTHOR]

Published
2022
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