Katsuaki Suzuki

In this paper, we propose a new formula to accurately estimate the output value on the real machine of the proposed mechanism as a part of the development concerning the high power joint mechanism. The previously proposed formula did not consider the energy loss when the slider translated. Considering the mass of the slider, we derived an expression that can estimate the angular velocity of the output link from the energy conservation law and the geometrical relationship. As a result of comparing the theoretical value and measured value, the performance of real machine could be more accurately estimated by using the proposed mathematical formula.

Evidence suggests neuroprotective effects of fluoxetine, a selective serotonin reuptake inhibitor (SSRI), on the developed neurons in the adult brain. In contrast, the drug may be deleterious to immature or undifferentiated neural cells, although the mechanism is unclear. Recent investigations have suggested that microRNAs (miRNA) may be critical for effectiveness of psychotropic drugs including SSRI. We investigated whether fluoxetine could modulate expressions of neurologically relevant miRNAs in two neuroblastoma SK-N-SH and SH-SY5Y cell lines. Initial screening results revealed that three (miR-489, miR-572 and miR-663a) and four (miR-320a, miR-489, miR-572 and miR-663a) miRNAs were up-regulated in SK-N-SH cells and SH-SY5Y cells, respectively, after 24 hours treatment of fluoxetine (1–25 μM). Cell viability was reduced according to the dose of fluoxetine. The upregulation of miR-572 and miR-663a was consistent in both the SH-SY5Y and SK-N-SH cells, confirmed by a larger scale culture condition. Our data is the first in vitro evidence that fluoxetine could increase the expression of miRNAs in undifferentiated neural cells, and that putative target genes of those miRNAs have been shown to be involved in fundamental neurodevelopmental processes.

The presence of activated microglia in the brains of healthy elderly people is a matter of debate. We aimed to clarify the degree of microglial activation in aging and dementia as revealed by different tracers by comparing the binding potential (BP_ND) in various brain regions using a first-generation translocator protein (TSPO) tracer [¹¹C]( R)PK11195 and a second-generation tracer [¹¹C]DPA713. The BP_ND levels, estimated using simplified reference tissue models, were compared among healthy young and elderly individuals and patients with Alzheimer’s disease (AD) and were correlated with clinical scores. An analysis of variance showed category-dependent elevation in levels of [¹¹C]DPA713 BP_ND in all brain regions and showed a significant increase in the AD group, whereas no significant changes among groups were found when [¹¹C]( R)PK11195 BP_ND was used. Cognito-mnemonic scores were significantly correlated with [¹¹C]DPA713 BP_ND levels in many brain regions, whereas [¹¹C]( R)PK11195 BP_ND failed to correlate with the scores. As mentioned elsewhere, the present results confirmed that the second-generation TSPO tracer [¹¹C]DPA713 has a greater sensitivity to TSPO in both aging and neuronal degeneration than [¹¹C]( R)PK11195. Positron emission tomography with [¹¹C]DPA713 is suitable for the delineation of in vivo microglial activation occurring globally over the cerebral cortex irrespective of aging and degeneration.

Objective: Neuroimaging studies of depression considered as a stress-related disorder have shown uncoupling in regional cerebral blood flow (rCBF) and regional cerebral metabolic rate for glucose (rCMRglc). We hypothesised that the mismatch change of rCBF and rCMRglc could be a stress-related phenomenon.Methods: We exposed male rats to 15-min period of forced swim (FS), followed by the measurement of rCBF using N-isopropyl-4-[¹²³I] iodoamphetamine (¹²³I-IMP) and rCMRglc using 2-deoxy-2-[¹⁸F] fluoro-D-glucose (¹⁸F-FDG).Results: The uptake rate of ¹⁸F-FDG in the FS group showed a significant decrease in the prefrontal cortex (0.86±0.20%ID/g, pp123I-IMP.Conclusions: The FS stress can cause mismatch change of rCBF and rCMRglc, which reflect a stress-related phenomenon.

Gaze abnormality is a diagnostic criterion for autism spectrum disorder (ASD). However, few easy-to-use clinical tools exist to evaluate the unique eye-gaze patterns of ASD. Recently, we developed Gazefinder, an all-in-one eye-tracking system for early detection of ASD in toddlers. Because abnormal gaze patterns have been documented in various ASD age groups, we predicted that Gazefinder might also detect gaze abnormality in adolescents and adults. In this study, we tested whether Gazefinder could identify unique gaze patterns in adolescents and adults with ASD. We measured the percentage of eye fixation time allocated to particular objects depicted in movies (i.e., eyes and mouth in human face movies, upright and inverted biological motion in movies that presented these stimuli simultaneously, and people and geometry in movies that presented these stimuli simultaneously) by male adolescents and adults with ASD (N = 26) and age-matched males with typical development (TD; N = 35). We compared these percentages between the two groups (ASD and TD) and with scores on the social responsiveness scale (SRS). Further, we conducted discriminant analyses to determine if fixation times allocated to particular objects could be used to discriminate between individuals with and without ASD. Compared with the TD group, the ASD group showed significantly less fixation time at locations of salient social information (i.e., eyes in the movie of human faces without lip movement and people in the movie of people and geometry), while there were no significant groupwise differences in the responses to movies of human faces with lip movement or biological motion. In a within-group correlation analysis, a few of the fixation-time items correlated with SRS, although most of them did not. No items significantly correlated with SRS in both ASD and TD groups. The percentage fixation times to eyes and people, which exhibited large effect sizes for the group difference, could differentiate ASD and TD with a sensitivity of 81.0 % and a specificity of 80.0 %. These findings suggest that Gazefinder is potentially a valuable and easy-to-use tool for objectively measuring unique gaze patterns and discriminating between ASD and TD in male adolescents and adults.