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Toru Nishikawa

Publications and source records attributed to Toru Nishikawa.

30 records · Page 2Linked to original sources
PubMed2003

D-cycloserine for the treatment of ataxia in spinocerebellar degeneration.

We studied the effects of D-cycloserine, a partial NMDA receptor allosteric agonist, on ataxia in patients with spinocerebellar degeneration. Fifteen Japanese ataxic patients enrolled in a 14-day single-blind trial of D-cycloserine (daily oral dose of 50 mg) following a 14-day single-blind placebo phase. At the end of the D-cycloserine administration, there was a significant reduction in the posture, gait and total score of the international cooperative ataxia rating scale and in the time for walking and speech tasks. D-Cycloserine was well-tolerated and no adverse effect was observed. D-Cycloserine may have therapeutic efficacy for spinocerebellar ataxia.

Adult↗
PubMed2003

Regional cerebral blood flow in depressed patients with white matter magnetic resonance hyperintensity.

BACKGROUND: Functional neuroimaging studies have consistently demonstrated decreased regional cerebral blood flow (rCBF) or metabolism in the frontal lobe, temporal lobe, or anterior cingulate gyrus of depressed patients. On the other hand, white matter hyperintensity as defined by magnetic resonance imaging (MRI) has been the most consistently replicated finding in structural neuroimaging studies on depression; however, these functional and structural neuroimaging findings of depression have not been well integrated. We aimed to clarify the possible associations of MRI-defined subcortical hyperintensities with rCBF changes in depressed patients. METHODS: Twelve depressed patients with subcortical hyperintensities defined by MRI, 11 depressed patients without MRI hyperintensities, and 25 healthy volunteers underwent 99mTc ECD SPECT. Group comparisons of their rCBF and correlation analysis between MRI hyperintensity and rCBF in patients were performed with a voxel-based analysis using statistical parametric mapping (SPM) software. RESULTS: Depressed patients showed decreased rCBF compared with control subjects in the frontal lobe, temporal lobe, and anterior cingulate gyrus whether subcortical hyperintensity existed or not; however, the patients with MRI hyperintensity showed decreased rCBF in the thalamus, basal ganglia, and brainstem in addition to cortical areas. Further, the score for white matter hyperintensity correlated negatively with rCBF in subcortical brain structures, including the thalamus and right basal ganglia. CONCLUSION: Our study indicates that depressed patients with MRI hyperintensities may have dysfunction in subcortical brain structures in addition to dysfunction in the fronto-temporal cortical structures.

Adult↗
PubMed2003

Effects of endogenous agonists, glycine and D-serine, on in vivo specific binding of [11C]L-703,717, a PET radioligand for the glycine-binding site of NMDA receptors.

A positron-emitter (carbon-11) labeled antagonist for the glycine-binding site of NMDA receptors, [(11)C]L-703,717, has a unique in vivo binding characteristic, in which it preferentially binds to cerebellar-specific NMDA receptors consisting of a GluRepsilon3 subunit and eventually accumulates in rodent cerebellum under in vivo conditions, but not under in vitro conditions. In order to understand the in vivo-specific site and subunit localization of this radioligand, we examined the effect of the endogenous glycine site agonists, glycine and D-serine, on in vivo [(11)C]L-703,717 binding. An increase in extracellular glycine concentration by treatment with a glycine transporter 1 (GlyT1)-selective inhibitor, NFPS ethyl ester, significantly decreased the cerebellar localization of [(11)C]L-703,717 in rats. D-serine is known to be concentrated in mammalian forebrain regions. The lack of D-serine detection in the cerebellum may be due to the fact that it has the highest enzymatic activity of D-amino acid oxidase (DAO). It was found that the cerebellar localization of [(11)C]L-703,717 is greatly diminished in mutant mice lacking DAO, in which D-serine content in the cerebellum is drastically increased from a nondetectable level in normal mice. These studies indicate that [(11)C]L-703,717 is susceptible to inhibition by glycine site agonists in its in vivo binding, and suggest that regional differences in inhibitions by endogenous agonists may be a crucial factor in the site- and subunit-specific binding of this glycine-site antagonist.

Amino Acid Transport Systems, Neutral↗
PubMed2003

Sleep spindles in human prefrontal cortex: an electrocorticographic study.

To investigate the sleep spindle activity of the human prefrontal cortex (PFC), we simultaneously recorded whole nights of polysomnographic and electrocorticographic (ECoG) activities during the natural sleep of epileptic patients. Subjects were nine patients with intractable epilepsy who had subdural electrodes surgically attached to the orbital (seven cases), medial (three cases), or dorsolateral (two cases) PFC, and in one case to the frontal pole. To examine spindle frequencies, fast Fourier transformation (FFT) and auto-correlation analyses were performed on the PFC ECoG and Cz EEG data, primarily on epochs of stage 2 sleep. Lower sigma band ECoG oscillations of about 12 Hz were widely distributed across all prefrontal cortical areas including the frontal limbic regions, but none of the PFC sigma frequency peaks coincided with the faster (about 14 Hz) Cz EEG sleep spindles. Combining our results with anatomical and electrophysiological facts, it is suggested that the thalamofrontal circuit involving the rostral reticular and the mediodorsal nucleus of the thalamus is responsible for the generation of 12 Hz frontal spindles in humans.

Adult↗
PubMed2003

Circadian fluctuation of time perception in healthy human subjects.

Previous studies suggested that various psychophysiological factors have influences on human time perception. In particular, working memory loads, time of day, body temperature, and mood were known as important modifiers of time perception. The purpose of this study is to elucidate factors affecting the short-term time perception under controlled condition. Fourteen healthy young male adults participated in this study. Time perception sessions (TPS) were conducted 4 times at 0900, 1300, 1700 and 2100 h. The TPS consisted of five 10-s time production trials under five different conditions (control trial, those with reward, and 3 different dual-load working memory tasks). Subjective status was assessed using visual analogue scales (VAS). To verify a participant's vigilance state, an alpha attenuation coefficient (AAC) was calculated. Two-way repeated measures ANOVA for produced time revealed a significant main effect of session, but no effect of task or interaction. Although produced time was not correlated with AACs or VAS scores, there was a significant negative correlation between produced time and core body temperature. These results suggest that human short-term time perception may be more influenced by circadian rhythm than working memory load or psychophysiological status.

Adult↗
PubMed2003

An MEG study of P300 activity during a color discrimination task 2: source localization study.

In this study, we described developmental changes in an event-related magnetic source of P300 activity during a visual oddball paradigm using magnetoencephalography. The maximum and minimum points of each peak of target P300 activity were scattered in a more anterior temporal area in children than in adults. The single dipole source analysis successfully estimated a dipole in the vicinity of the thalamus and the cingulate gyrus in adults. The location differed in children, although the dipole had overall greater moment in children than in adults. Our findings suggest that the thalamus plays an important role in generating P300 activity specific to color discrimination processing, and that in children the source is not consistent during development.

Adult↗
PubMed2003

Determining vulnerability to schizophrenia in methamphetamine psychosis using exploratory eye movements.

Patients with methamphetamine (MAP) psychosis whose psychotic symptoms continued after MAP withdrawal were observed at Saitama Prefecture Government Psychiatric Hospital. The purpose of the present study was to ascertain whether some of these MAP psychosis subjects have a vulnerability to schizophrenia. Forty-eight patients with MAP psychosis were divided into three groups based on clinical course: transient type, prolonged type and persistent type. Furthermore, the patients with the persistent type were divided into two groups: one group were moderately disturbed in social adaptive functioning and had Global Assessment Functioning scale (GAF) points >50, and the other group consisted of those who were severely disturbed in social adaptive functioning and who had GAF points of < or =50. These MAP patients were tested for exploratory eye movements, which are the vulnerability marker of schizophrenia, and were compared with 30 patients with schizophrenia and 30 healthy control subjects. The responsive search score of the severely disturbed group of patients of the persistent type was lowest, significantly lower than those of the transient type and the healthy controls. It did not differ from that of the schizophrenic subjects. These results suggest that the severely disturbed group of patients with the persistent type of MAP psychosis have a vulnerability to schizophrenia.

Adult↗
PubMed2002

Mammalian septins nomenclature.

There are 10 known mammalian septin genes, some of which produce multiple splice variants. The current nomenclature for the genes and gene products is very confusing, with several different names having been given to the same gene product and distinct names given to splice variants of the same gene. Moreover, some names are based on those of yeast or Drosophila septins that are not the closest homologues. Therefore, we suggest that the mammalian septin field adopt a common nomenclature system, based on that adopted by the Mouse Genomic Nomenclature Committee and accepted by the Human Genome Organization Gene Nomenclature Committee. The human and mouse septin genes will be named SEPT1-SEPT10 and Sept1-Sept10, respectively. Splice variants will be designated by an underscore followed by a lowercase "v" and a number, e.g., SEPT4_v1.

Alternative Splicing↗
PubMed2002

Decrease of serotonin and metabolite in the forebrain and facilitation of lordosis by dorsal raphe nucleus lesions in male rats.

In castrated male rats, a radiofrequency lesion was made in the dorsal raphe nucleus (DRL) and lordosis behavior was observed following treatment with estrogen. After the behavioral test, brains were removed and the contents of 5-HT and 5-HIAA in the forebrain were measured by high pressure liquid chromatography (HPLC). In the results, only 2 of 16 control males without brain surgery showed lordosis, and the mean lordosis quotient (LQ) was extremely low when compared to that in control females. In contrast, all male rats with DRL displayed lordosis and the mean LQ was higher than that of control males without brain surgery but lower than that in control females (P < 0.001). In the DRL males, 5-HT and 5-HIAA contents in the septum (SPT), the preoptic area (POA), the ventromedial hypothalamus (VMH) and the striatum (STM) were lower than those in control male and female groups (P < 0.001). These results suggest that the dorsal raphe nucleus prevents male rats from showing lordosis by serotonergic influence in the forebrain. In addition, HPLC results showed that levels of the 5-HT in the SPT, the POA and the VMH in the female group were higher than those in the control male group (P < 0.05). In female rats, the POA (P < 0.01) and the VMH (P < 0.05) contained larger 5-HT than those in the SPT and the STM, but there were no difference of 5-HT contents in the male rat.

Animals↗