Biomedical subjects

Tatsuya Sato

Publications and source records attributed to Tatsuya Sato.

7 recordsLinked to original sources

PubMed2026

Development and Crossover Evaluation of an Artificial Intelligence-Assisted System for Solid Pancreatic Lesion Detection and Pancreatic Parenchyma Recognition in Endoscopic Ultrasonography (With Video).

BACKGROUND AND STUDY AIMS: Pancreatobiliary endoscopic ultrasonography (EUS) is technically demanding, and supervised training opportunities are limited. We developed an artificial intelligence (AI) overlay system for detecting solid pancreatic lesions (SPL) and recognizing pancreatic parenchyma (PP) and evaluated its effect on reader performance. PATIENTS AND METHODS: Across six centers, two deep learning-based models were trained using expert-annotated EUS frames. We then conducted a randomized, two-sequence, two-period crossover reader study in which eight endosonographers (five novices and three experts) interpreted image sets with and without AI assistance. The primary endpoint was superiority of sensitivity for SPL detection among novices; key secondary endpoints included specificity and PP recognition. RESULTS: From 118 patients, 120 SPL-positive/negative image sets and 160 PP-positive/negative image sets were constructed. Among novices, AI assistance improved SPL detection sensitivity (88.7% vs. 76.8%, p < 0.001) and accuracy (86.4% vs. 78.7%), while specificity met the predefined noninferiority criterion (84.2% vs. 80.5%, p < 0.001). For PP recognition, sensitivity increased numerically (86.3% vs. 83.3%) but did not meet the predefined superiority criterion (p = 0.095); specificity met the noninferiority criterion (87.8% vs. 81.0%), and accuracy increased from 82.1% to 87.0%. Among experts, sensitivity was maintained for both tasks, whereas specificity increased with AI assistance. CONCLUSIONS: AI assistance improved SPL detection among novice endosonographers. For PP recognition, sensitivity increased without reaching statistical superiority, whereas specificity met the predefined noninferiority criterion. These findings support a potential adjunctive role for AI in EUS interpretation.

Humans↗

PubMed2005

Isthmus organizer for midbrain and hindbrain development.

Classical transplantation studies showed that the isthmus has an organizing activity upon the tectum and cerebellum. Since Fgf8 is expressed in the isthmus and mimics functionally isthmic grafts, it is accepted that Fgf8 plays pivotal role in the isthmic organizing activity. The fate of brain vesicles is determined by the combinations of transcription factors. The neural tube region where Otx2, Pax2, and En1 are expressed early on acquires midbrain identity. Pax3/7 forces the midbrain to differentiate into tectum. En1/2, Pax2/5, and Fgf8 form a positive feedback loop for their expression, thus misexpression of one of these molecules turns on the loop and forces presumptive diencephalon to differentiate into tectum. The isthmic organizer signal, Fgf8, stabilizes or changes the expression of the transcription factors in mid/hindbrain region. A strong Fgf8 signal activates the Ras-ERK signaling pathway, which in turn activates Irx2 in a rostrodorsal part of the hindbrain, and forces this tissue to differentiate into cerebellum.

Animals↗

PubMed2005

[A patient with Vibrio vulnificus meningoencephalitis].

A 76-year-old man with liver cirrhosis and diabetes mellitus was admitted to our hospital because of bacterial meningoencephalitis. He had eaten raw fish 2 days before onset. He also developed septic shock, disseminated intravascular coagulation, adult respiratory distress syndrome and panophthalmitis of the right eye. Vibrio vulnificus was isolated from the blood culture. Extensive therapy including antibiotics and nafamostat methylate, resulted in full recovery except for right blindness. The necrotizing fasciitis, which is common with Vibrio vulnificus infection, had not been complicated in this patient.

Aged↗

PubMed2004

Regulation of isthmic Fgf8 signal by sprouty2.

Fgf8 functions as an organizer at the mes/metencephalic boundary (isthmus). We showed that a strong Fgf8 signal activates the Ras-ERK signaling pathway to organize cerebellar differentiation. Sprouty2 is expressed in an overlapping manner to Fgf8, and is induced by Fgf8. Its function, however, is indicated to antagonize Ras-ERK signaling. Here, we show the regulation of Fgf8 signaling in relation to Sprouty2. sprouty2 expression was induced very rapidly by Fgf8b, but interfered with ERK activation. sprouty2 misexpression resulted in a fate change of the presumptive metencephalon to the mesencephalon. Misexpression of a dominant negative form of Sprouty2 augmented ERK activation, and resulted in anterior shift of the posterior border of the tectum. The results indicate that Fgf8 activates the Ras-ERK signaling pathway to differentiate the cerebellum, and that the hyper- or hypo-signaling of this pathway affects the fate of the brain vesicles. Sprouty2 may regulate the Fgf8-Ras-ERK signaling pathway for the proper regionalization of the metencephalon and mesencephalon.

Adaptor Proteins, Signal Transducing↗

PubMed2004

The Fgf8 signal causes cerebellar differentiation by activating the Ras-ERK signaling pathway.

The mes/metencephalic boundary (isthmus) is an organizing center for the optic tectum and cerebellum. Fgf8 is accepted as a crucial organizing signal. Previously, we reported that Fgf8b could induce cerebellum in the mesencephalon, while Fgf8a transformed the presumptive diencephalon into mesencephalon. Since lower doses of Fgf8b exerted similar effects to those of Fgf8a, the type difference could be attributed to the difference in the strength of the signal. It is of great interest to uncover mechanisms of signal transduction pathways downstream of the Fgf8 signal in tectal and cerebellar development, and in this report we have concentrated on the Ras-ERK pathway. In normal embryos, extracellular-signal-regulated kinase (ERK) is activated at the site where Fgf8 mRNA is expressed. Fgf8b activated ERK while Fgf8a or a lower dose of Fgf8b did not activate ERK in the mes/metencephalon. Disruption of the Ras-ERK signaling pathway by a dominant negative form of Ras (RasS17N) changed the fate of the metencephalic alar plate from cerebellum to tectum. RasS17N canceled the effects of Fgf8b, while co-transfection of Fgf8a and RasS17N exerted additive effects. Disruption of Fgf8b, not Fgf8a, by siRNA resulted in posterior extension of the Otx2 expression domain. Our results indicate that the presumptive metencephalon receives a strong Fgf8 signal that activates the Ras-ERK pathway and differentiates into the cerebellum.

Animals↗

PubMed2004

Gain- and loss-of-function in chick embryos by electroporation.

It remained very difficult to manipulate gene expression in chick embryos until the advent of in ovo electroporation which enabled the induction of both gain-of-function, and recently loss-of-function, of a gene of interest at a specific developmental stage. Gain-of-function by electroporation is so effective that it has become widely adopted in developmental studies in the chick. Recently, it became possible to induce loss-of-function by introducing an siRNA expression vector by electroporation. In this review, the methods of electroporation for gain-of-function and for loss-of-function by siRNA are discussed.

Animals↗

PubMed2004

How does Fgf signaling from the isthmic organizer induce midbrain and cerebellum development?

The mesencephalic/rhombomere 1 border (isthmus) is an organizing center for early development of midbrain and cerebellum. In this review, we summarize recent progress in studies of Fgf signaling in the isthmus and discuss how the isthmus instructs the differentiation of the midbrain versus cerebellum. Fgf8 is shown to play a pivotal role in isthmic organizer activity. Only a strong Fgf signal mediated by Fgf8b activates the Ras-extracellular signal-regulated kinase (ERK) pathway, and this is sufficient to induce cerebellar development. A lower level of signaling transduced by Fgf8a, Fgf17 and Fgf18 induce midbrain development. Numerous feedback loops then maintain appropriate mesencephalon/rhombomere1 and organizer gene expression.

Amino Acid Sequence↗