Publications (27) View all
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Article: A facile synthesis, in vitro and in vivo MR studies of d-glucuronic acid-coated ultrasmall Ln₂O₃ (Ln = Eu, Gd, Dy, Ho, and Er) nanoparticles as a new potential MRI contrast agent.
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ABSTRACT: A facile one-pot synthesis of d-glucuronic acid-coated ultrasmall Ln(2)O(3) (Ln = Eu, Gd, Dy, Ho, and Er) nanoparticles is presented. Their water proton relaxivities were studied to address their possibility as a new potential MRI contrast agent. We focused on the d-glucuronic acid-coated ultrasmall Dy(2)O(3) nanoparticle because it showed the highest r(2) relaxivity among studied nanoparticles. Its performance as a T(2) MRI contrast agent was for the first time proved in vivo through its 3 T T(2) MR images of a mouse, showing that it can be further exploited for the rational design of a new T(2) MRI contrast agent at high MR fields.ACS Applied Materials & Interfaces 08/2011; 3(9):3325-34. · 4.53 Impact Factor -
Article: Neural correlates of motor imagery for elite archers.
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ABSTRACT: Motor imagery is a mental rehearsal of simple or complex motor acts without overt body movement. It has been proposed that the association between performance and the mental rehearsal period that precedes the voluntary movement is an important point of difference between highly trained athletes and beginners. We compared the activation maps of elite archers and nonarchers during mental rehearsal of archery to test whether the neural correlates of elite archers were more focused and efficiently organised than those of nonarchers. Brain activation was measured using functional MRI in 18 right-handed elite archers and 18 right-handed nonarchers. During the active functional MRI imagery task, the participants were instructed to mentally rehearse their archery shooting from a first-person perspective. The active imagery condition was tested against the nonmotor imagery task as a control condition. The results showed that the premotor and supplementary motor areas, and the inferior frontal region, basal ganglia and cerebellum, were active in nonarchers, whereas elite archers showed activation primarily in the supplementary motor areas. In particular, our result of higher cerebellar activity in nonarchers indicates the increased participation of the cerebellum in nonarchers when learning an unfamiliar archery task. Therefore, the difference in cerebellar activation between archers and nonarchers provides evidence of the expertise effect in the mental rehearsal of archery. In conclusion, the relative economy in the cortical processes of elite archers could contribute to greater consistency in performing the specific challenge in which they are highly practised.NMR in Biomedicine 05/2011; 24(4):366-72. · 3.21 Impact Factor -
Article: The differences in neural network activity between methamphetamine abusers and healthy subjects performing an emotion-matching task: functional MRI study.
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ABSTRACT: Methamphetamine (MA) abusers commonly exhibit socially problematic behaviors, such as diminished empathy, decreased emotional regulation and interpersonal violence, which may be attributable to alterations in emotional experience. However, few studies have used functional MRI to examine directly the emotional experience of threatening or fearful non-face images in MA abusers. In this study, we investigated possible differences in neural correlates of negative emotional experiences between abstinent MA abusers and healthy subjects using complex visual scenes depicting fear or threat derived from the International Affective Picture System. In within-group analyses, healthy subjects and MA abusers activated a similarly distributed cortical network, prominently including the amygdala, fusiform gyrus, parahippocampal gyrus, ventrolateral prefrontal cortex and inferior frontal cortex. In between-group analyses, however, MA abusers showed a reduced activation in the bilateral dorsolateral prefrontal cortex and insula, and increased activation in the fusiform gyrus, hippocampus, parahippocampal gyrus and posterior cingulate cortex, relative to healthy subjects. Hypoactivation of the insula in MA abusers relative to healthy subjects suggests that the ability to have an emotional response to threatening scenes and empathy for another's pain could be compromised in MA abusers. Hyperactivity in the fusiform gyrus, parahippocampal gyrus and posterior cingulate cortex in MA abusers relative to healthy subjects indicates that threatening and fearful images from the International Affective Picture System may remind MA abusers of episodic memory related to similar experiences. Therefore, functional impairment of these neural networks in MA abusers may contribute to altered emotional experience in social interactions, which could lead to increased negative mood and stress in interpersonal communication.NMR in Biomedicine 04/2011; 24(10):1392-400. · 3.21 Impact Factor -
Article: Anti-inflammatory Activity of 1-docosanoyl Cafferate Isolated from Rhus verniciflua in LPS-stimulated BV2 Microglial Cells.
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ABSTRACT: Although various derivatives of caffeic acid have been reported to possess a wide variety of biological activities such as protection of neuronal cells against excitotoxicity, the biological activity of 1-docosanoyl cafferate (DC) has not been examined. The objective of the present study was to evaluate the anti-inflammatory effects of DC, isolated from the stem bark of Rhus verniciflua, on lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Pretreatment of cells with DC significantly attenuated LPS-induced NO production, and mRNA and protein expression of iNOS in a concentration-dependent manner. DC also significantly suppressed LPS-induced release of cytokines such as TNF-α and IL-1β . Consistent with the decrease in cytokine release, DC dose-dependently and significantly attenuated LPS-induced mRNA expression of these cytokines. Furthermore, DC significantly suppressed LPS-induced degradation of IKB, which retains NF-kB in the cytoplasm. Therefore, nuclear translocation of NF-kB induced by LPS stimulation was significantly suppressed with DC pretreatment. Taken together, the present study suggests that DC exerts its anti-inflammatory activity through the suppression of NF-kB translocation to the nucleus.Korean Journal of Physiology and Pharmacology 02/2011; 15(1):9-15. · 0.96 Impact Factor -
Article: Altered white matter microstructural integrity revealed by voxel-wise analysis of diffusion tensor imaging in welders with manganese exposure.
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ABSTRACT: Chronic exposure to manganese (Mn), which can be an occupational hazard or can result from liver failure, is associated with adverse motor and cognitive outcomes. Evidence from previous neuroimaging and magnetic resonance spectroscopy studies suggested alteration of function in Mn-exposed brains. However, the effect of chronic exposure of the human brain to Mn on white matter (WM) structure has not yet been determined. In the present study, we used diffusion tensor imaging (DTI) to investigate whether welders exposed to Mn demonstrate differences in WM integrity, compared with control subjects. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were measured on a voxel-wise basis in 30 male welders with exposure to Mn and in 19 age- and gender-matched control subjects. Direct comparison between welders and controls using investigator-independent Statistical Parametric Mapping (SPM) voxel-wise analysis of DTI metrics revealed a reduction of FA in the corpus callosum (CC) and frontal WM in Mn-exposed welders. Further, marked increases in RD and negligible changes in AD suggested that the microstructural changes in the CC and frontal WM result from compromised radial directionality of fibers in these areas, caused primarily by demyelination. Correlation analysis with neurobehavioral performance also suggested that the microstructural abnormalities were associated with subtle motor and cognitive differences in welders.NeuroToxicology 01/2011; 32(1):100-9. · 3.10 Impact Factor
