Publications by authors named "Yokokawa K"

To assess the interfractional anatomical range variations (ARVs) with beam directions and their impact on dose distribution in intensity modulated proton therapy, we analyzed water equivalent thickness (WET) from 10 patients with pancreatic cancer. The distributions of the interfractional WET difference ($\Delta{\mathrm{WET}}^{\theta }$) across 360° were visualized using polar histograms. Interfractional ARVs were evaluated using the mean absolute error and ΔWET pass rate, indicating the percentage of $\Delta \mathrm{WE}{\mathrm{T}}^{\theta }$ < thresholds.

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Stress fracture of the first rib is a rare but an important cause of brachial plexopathy. Here, we describe a patient with a unilateral brachial plexus injury presenting with involuntary neck movements. A 22-year-old man with cervical involuntary movements for 10 months was diagnosed with tardive dyskinesia.

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Real-time tumor-tracking volumetric modulated arc therapy (RT-VMAT) enabling beam-gating based on continuous X-ray tracking of the three-dimensional position of internal markers is relevant for moving tumors. Dose-volume characteristics and treatment time were evaluated in ten consecutive patients who underwent liver stereotactic body radiation therapy with RT-VMAT. Target dose conformity and sparing of the stomach and the intestine were improved comparing RT-VMAT with RT-3D conformal radiotherapy.

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Purpose: To demonstrate the possibility of using a lower imaging rate while maintaining acceptable accuracy by applying motion prediction to minimize the imaging dose in real-time image-guided radiation therapy.

Methods: Time-series of three-dimensional internal marker positions obtained from 98 patients in liver stereotactic body radiation therapy were used to train and test the long-short-term memory (LSTM) network. For real-time imaging, the root mean squared error (RMSE) of the prediction on three-dimensional marker position made by LSTM, the residual motion of the target under respiratory-gated irradiation, and irradiation efficiency were evaluated.

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We analyzed 20 patients diagnosed with autoimmune neurological diseases with seizure predominance. In these patients, we examined the usefulness of Antibody Prevalence in Epilepsy and Encephalopathy (APE) score and Antibodies Contributing to Focal Epilepsy Signs and Symptoms (ACES) score in autoimmune encephalitis (AE) for facilitating early treatment. APE score was positive in 19 of 20 patients.

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Background: Ionoacoustics is a promising approach to reduce the range uncertainty in proton therapy. A miniature-sized optical hydrophone (OH) was used as a measuring device to detect weak ionoacoustic signals with a high signal-to-noise ratio in water. However, further development is necessary to prevent wave distortion because of nearby acoustic impedance discontinuities while detection is conducted on the patient's skin.

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Objectives: We aimed to investigate whether daily computed tomography (CT) images could predict the daily gastroduodenal, small intestine, and large intestine doses of stereotactic body radiation therapy (SBRT) for pancreatic cancer based on the shortest distance between the gross tumor volume (GTV) and gastrointestinal (GI) tract.

Methods: Twelve patients with pancreatic cancer received SBRT of 40 Gy in five fractions. We recalculated the reference clinical SBRT plan (PLAN) using daily CT images and calculated the shortest distance from the GTV to each GI tract.

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Introduction: Cardiac arrest is a critical condition, and patients often experience postcardiac arrest syndrome (PCAS) even after the return of spontaneous circulation (ROSC). Administering a restricted amount of oxygen in the early phase after ROSC has been suggested as a potential therapy for PCAS; however, the optimal target for arterial partial pressure of oxygen or peripheral oxygen saturation (SpO) to safely and effectively reduce oxygen remains unclear. Therefore, we aimed to validate the efficacy of restricted oxygen treatment with 94%-95% of the target SpO during the initial 12 hours after ROSC for patients with PCAS.

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Background: The aim of this study is to quantify the short-term motion of the gastrointestinal tract (GI-tract) and its impact on dosimetric parameters in stereotactic body radiation therapy (SBRT) for pancreatic cancer.

Methods: The analyzed patients were eleven pancreatic cancer patients treated with SBRT or proton beam therapy. To ensure a fair analysis, the simulation SBRT plan was generated on the planning CT in all patients with the dose prescription of 40 Gy in 5 fractions.

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Purpose: To quantitatively evaluate the achievable performance of volumetric imaging based on lung motion modeling by principal component analysis (PCA).

Methods: In volumetric imaging based on PCA, internal deformation was represented as a linear combination of the eigenvectors derived by PCA of the deformation vector fields evaluated from patient-specific four-dimensional-computed tomography (4DCT) datasets. The volumetric image was synthesized by warping the reference CT image with a deformation vector field which was evaluated using optimal principal component coefficients (PCs).

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A 38-year-old man was taken to hospital with generalized clonic seizure. Brain magnetic resonance imaging (MRI) showed multiple ring-enhancing lesions centered in the left frontoparietal lobe. A histopathological examination of a brain biopsy sample revealed granulomatous lesions with caseous necrosis.

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Article Synopsis
  • A 26-year-old Japanese woman experienced fever, muscle pain, and difficulty walking the day after receiving her second dose of the mRNA COVID-19 vaccine.
  • A neurological exam showed muscle weakness in her legs, and lab tests indicated high levels of creatinine kinase.
  • MRI scans revealed issues in her thigh muscles, leading to a diagnosis of immune-mediated myopathy, after which she received immunotherapy and eventually regained her ability to walk steadily.
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The tendency to avoid punishment, called behavioral inhibition system, is an essential aspect of motivational behavior. Behavioral inhibition system is related to negative affect, such as anxiety, depression and pain, but its neural basis has not yet been clarified. To clarify the association between individual variations in behavioral inhibition system and brain 5-HT receptor availability and specify which brain networks were involved in healthy male subjects, using [F]altanserin positron emission tomography and resting-state functional magnetic resonance imaging.

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Individual differences in positive memory recollection are of interest in mental health, as positive memories can help protect people against stress and depression. However, it is unclear how individual differences in positive memory recollection are reflected in brain activity in the resting state. Here, we investigate the resting-state functional connectivity (FC) associated with interindividual variations in positive memory by employing cluster-level inferences based on randomization/permutation region of interest (ROI)-to-ROI analyses.

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Purpose: To show the feasibility of real-time CT image generation technique utilizing internal fiducial markers that facilitate the evaluation of internal deformation.

Methods: In the proposed method, a linear regression model that can derive internal deformation from the displacement of fiducial markers is built for each voxel in the training process before the treatment session. Marker displacement and internal deformation are derived from the four-dimensional computed tomography (4DCT) dataset.

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SIRT1 is involved in the regulation of a variety of biological processes such as metabolism, stress response, autophagy and differentiation. Although progenitor cells of oligodendrocytes (OPCs) express high level of SIRT1, its function on differentiation is unknown. Because we have shown that SIRT1 plays a pivotal role in differentiation of neural precursor cells, we hypothesized that SIRT1 may also participate in the differentiation of oligodendrocytes (OLGs).

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Amyotrophic lateral sclerosis (ALS) due to a fused in sarcoma (FUS) P525L mutation is characterized by a rapidly progressive course. Multifocal motor neuropathy (MMN) may resemble ALS in early stage and is associated with anti-ganglioside antibodies. A 38-year-old woman was admitted to our hospital because of progressive muscle weakness in the right limbs.

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Spot-scanning particle therapy possesses advantages, such as high conformity to the target and efficient energy utilization compared with those of the passive scattering irradiation technique. However, this irradiation technique is sensitive to target motion. In the current clinical situation, some motion management techniques, such as respiratory-gated irradiation, which uses an external or internal surrogate, have been clinically applied.

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Article Synopsis
  • A new method for creating spread-out Bragg peaks (SOBPs) in low-energy proton therapy is proposed, which simplifies the process by using only one mini-ridge filter (MRF).
  • This method aims to maintain high dose uniformity while achieving a sharp distal falloff and significantly reducing the number of energy layers needed.
  • Results show that the dose uniformity is comparable to traditional methods, while the quick setup of the MRF at any facility enhances the efficiency of proton beam therapy.
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Mesenchymal stem cells (MSC) are increasingly being studied as a source of cell therapy for neurodegenerative diseases, and several groups have reported their beneficial effects on Alzheimer's disease (AD). In this study using AD model mice (APdE9), we found that transplantation of MSC via the tail vein improved spatial memory in the Morris water maze test. Using electron paramagnetic resonance imaging to evaluate the in vivo redox state of the brain, we found that MSC transplantation suppressed oxidative stress in AD model mice.

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Alzheimer's disease (AD) is a common neurodegenerative disease that progressively impairs memory and cognition. Deposition of amyloid-β (Aβ) peptides is the most important pathophysiological hallmark of AD. Oxidative stress induced by generation of reactive oxygen species (ROS) is a prominent phenomenon in AD and known to occur early in the course of AD.

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Article Synopsis
  • Microglia are crucial for clearing amyloid-β (Aβ) in Alzheimer's disease, and the study investigates how they take up Aβ through various receptors, specifically focusing on CD14 and Toll-like receptor 4 (TLR4).
  • The research demonstrates that CD14 and TLR4 interact to internalize a specific type of Aβ, and that this process is influenced by clathrin-mediated endocytosis (CME).
  • Findings indicate that both CD14 and TLR4 are not only involved in phagocytosis but also play a role in the clathrin-dependent uptake of Aβ, providing new insights that may inform potential Alzheimer's therapies.
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Article Synopsis
  • Alzheimer's disease (AD) is a leading cause of progressive dementia, primarily characterized by the accumulation of amyloid-β (Aβ) in the brain.
  • Research indicates that reactive oxygen species (ROS) from mitochondria play a role in worsening AD, prompting a hypothesis about the early accumulation of Aβ and oxidative stress in brain mitochondria of a specific mouse model, APdE9.
  • The study utilized electron paramagnetic resonance (EPR) and activity measurements of the antioxidant enzyme superoxide dismutase (SOD) to show that Aβ builds up in mitochondrial areas before non-mitochondrial areas, highlighting potential tools for understanding AD and developing treatments.
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Background: The histamine H receptor is regarded as a drug target for cognitive impairments in psychiatric disorders. H receptors are expressed in neocortical areas, including the prefrontal cortex, the key region of cognitive functions such as working memory. However, the role of prefrontal H receptors in working memory has not yet been clarified.

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Perceptual changes in shape, size, or color are observed in patients with derealization symptoms; however, the underlying neural and molecular mechanisms are not well understood. The current study explored the relationship between neural activity associated with altered colorfulness perception assessed by fMRI and striatal dopamine D receptor availability measured by [C]raclopride PET in healthy participants. Inside an fMRI scanner, participants performed the saturation adaptation task, where they rated how much vivid/faded visual objects looked like real/unreal ones using a visual analog scale.

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