Biology subjects

Yukawa, H.

Publications and source records attributed to Yukawa, H..

4 recordsLinked to original sources

bioRxiv2026

Quantum Dot-Based Non-invasive Monitoring of Sinusoidal Endothelial Scavenger Function in Steatohepatitis

Metabolic dysfunction-associated steatotic liver disease (MASLD) and its progressive form, metabolic dysfunction-associated steatohepatitis (MASH), represent urgent medical challenges. Current non-invasive assessments rely on serum indices or tissue stiffness, and none visualizes functional changes within the liver, hindering drug discovery and patient management. In this study, we developed a non-invasive technique using semiconductor quantum dots, as blood-borne foreign particle mimics, to evaluate the scavenger function of liver sinusoidal endothelial cells (LSECs) via near-infrared optical imaging. Progression from MASLD to MASH induced a significant decline in the scavenger capability of LSECs, resulting in a marked reduction of intrahepatic quantum dot retention. Mechanistically, we demonstrated that quantum dots are recognized and internalized by scavenger receptor class A (SR-A) on LSECs, and that SR-A-mediated uptake progressively diminishes with increasing MASH severity. Crucially, quantum dot retention levels significantly correlated with both the progression and regression of MASH pathology. These findings demonstrate that quantum dot-based optical evaluation of LSEC scavenger function offers a highly sensitive, non-invasive diagnostic platform for staging MASH and assessing therapeutic efficacy.

bioengineering↗

bioRxiv2026

In vivo brain temperature measurement using quantum dot imaging temperature sensors

Temperature regulation in the brain is essential for maintaining neuronal function and preventing thermally induced damage. Here, we report the development and in vivo application of quantum dots (QDs) to high-resolution thermometry in the mouse brain using two-photon excitation microscopy. These QDs, via the red-to-green photoluminescence (PL) intensity ratios, enabled stable temperature measurements in both normal and chronically hypo-perfused cerebral tissue. Our findings show that localized neuronal activity leads to transient heat generation, which is rapidly dissipated by cerebrovascular responses. In a chronic hypoperfusion model, impaired vascular function resulted in exaggerated and prolonged brain temperature elevations. This thermometry system provides unprecedented insight into the mechanisms of cerebral thermoregulation and highlights the importance of vascular cooling in protecting the brain from heat-induced stress, particularly in pathological conditions such as stroke.

bioengineering↗

bioRxiv2025

In vivo deep-brain microscopy at submicrometer resolution with refractive index-matched prism interfaces

The mammalian brain is a thick and densely layered structure comprising a huge number of neurons that work together to process information and regulate brain functions. Although various optical methods have been developed to investigate deep brain dynamics, they are limited by technical constraints, invasiveness, suboptimal spatial resolution, and/or a restricted field of view. To overcome these limitations, we developed an implantable, optically optimized microprism interface with a refractive index matched to that of brain tissue and water, enabling minimally-invasive, wide-field two-photon imaging method with enhanced brightness and sub-micron resolution in deep prefrontal areas.

neuroscience↗

bioRxiv2024

Low-invasive, wide-field, and cellular resolution two-photon imaging of neural population activity in brainstem and nucleus tractus solitarii

Brain-viscera communication plays a crucial role in regulating mental health, with the vagus nerve being a key structure mediating this interaction. Clinically, artificial vagus nerve stimulation (VNS) is used to treat various neuropsychiatric disorders, highlighting the importance of vagal afferent fibers in regulating emotion. The nucleus tractus solitarii (NTS) is a brainstem structure proposed to receive signals from vagal afferents and relay them to brain networks for emotion regulation. However, due to the anatomical complexity and difficulty in accessing the deep-brain NTS region in living animals, the mechanisms remain unclear. Here, we developed a wide-field and deep-brain two-photon imaging method using a double-prism based optical interface. This approach enables the identification of cellular-resolution neural activities in the NTS while preserving the cerebellum, which covers the NTS and is important for emotion regulation, intact. We systematically evaluated how NTS neurons respond to VNS and a gastrointestinal hormone, suggesting the usefulness of this method for investigating the role of the vagus-NTS pathway in vivo.

neuroscience↗