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Biomedical subjects

Tomiki Sumiyoshi

Publications and source records attributed to Tomiki Sumiyoshi.

33 records · Page 2Linked to original sources
PubMed2004

Inhibition of dopamine synthesis with alpha-methyl-p-tyrosine abolishes the enhancement of methamphetamine-induced extracellular dopamine levels in the amygdala of rats with excitotoxic lesions of the entorhinal cortex.

This study was performed to investigate the mechanisms underlying the augmentation of methamphetamine (MAP)-induced dopamine (DA) release in the entorhinal cortex-lesioned rats. Quinolinic acid or phosphate buffered saline was infused into the left entorhinal cortex of adolescent rats (postnatal day 7 weeks). After 4 weeks of lesioning, acute MAP (2 mg/kg, i.p.)-induced DA release in the amygdala was significantly enhanced in lesioned rats compared to sham operated rats. Inhibition of DA synthesis by alpha-methyl-p-tyrosine, an inhibitor of catecholamine synthesis, resulted in abolishment of the enhancement of MAP (2 or 5 mg/kg, i.p.)-induced DA release in the amygdala of lesioned rats. These results suggest that excessive DA pool in nerve terminals underlies the augmentation of MAP-induced DA release in the amygdala of the lesioned rats.

Amygdala↗
PubMed2004

Plasma glycine and serine levels in schizophrenia compared to normal controls and major depression: relation to negative symptoms.

Previous studies have suggested decreased N-methyl-D-aspartate (NMDA)-type glutamate receptor function may contribute to increased negative symptoms in patients with schizophrenia. Consistent with this hypothesis, glycine, a co-agonist at NMDA receptors, has been reported to improve negative symptoms associated with the illness. This study was performed to determine if plasma levels of glycine or its ratio to serine, a precursor of glycine, are decreased in patients with schizophrenia compared to normal control subjects or patients with major depression. We also tested the hypothesis that these amino acids were correlated with negative symptoms in subjects with schizophrenia. Plasma levels of glycine, serine, and their ratio, were compared in 144 patients with schizophrenia, 44 patients with major depression, and 49 normal control subjects. All subjects were medication-free. Psychopathology was evaluated using the Brief Psychiatric Rating Scale (BPRS). Plasma glycine levels and glycine/serine ratios were decreased in patients with schizophrenia relative to control subjects and patients with major depression. By contrast, serine levels were increased in patients with schizophrenia compared to normal subjects but not compared to major depression. Patients with major depression also had increased plasma serine levels and decreased glycine/serine ratios compared to normal controls, but glycine levels were not different from those of normal controls. In subjects with schizophrenia, glycine levels predicted the Withdrawal-Retardation score (BPRS), whereas no such correlation was found in subjects with major depression. These results provide additional evidence that decreased availability of glycine may be related to the pathophysiology of negative symptoms. The decreases in plasma glycine levels support the evidence for an abnormality in the glutamatergic system in schizophrenia, and provide additional support for efforts to improve negative symptoms by augmentation of antipsychotic drugs with agonists at the glycine site of the NMDA receptor.

Adult↗
PubMed2004

Neuropsychological profile in patients with schizotypal personality disorder or schizophrenia.

Neuropsychological impairments have been consistently reported in patients with schizophrenia. As little is known whether subjects with schizotypal personality disorder exhibit neurocognitive dysfunction similar to that in schizophrenia, we assessed the neuropsychological profile of 15 subjects with schizotypal personality disorder and compared it with that for 15 patients with schizophrenia and for 15 psychiatrically normal volunteers. All participants were administered a standard neuropsychological battery assessing language ability, spatial ability, visuomotor function, verbal memory, visual memory, auditory attention, visual attention, and executive function. Performance on most of the cognitive domains was impaired in patients with schizotypal personality disorder but less than patients with schizophrenia. Specifically, impairment in verbal memory and visuomotor ability in patients with schizotypal personality disorder and patients with schizophrenia were comparable, while patients with schizophrenia performed worse on the test of executive function than did patients with schizotypal personality disorder. As a whole, cognitive deficits in patients with schizotypal personality disorder were qualitatively similar to, but quantitatively milder than, those for patients with schizophrenia. The results suggest that cognitive abilities related to frontotemporal lobe function are disturbed across these schizophrenia-spectrum disorders.

Adult↗
PubMed2003

Subchronic phencyclidine administration alters central vasopressin receptor binding and social interaction in the rat.

Arginine vasopressin (AVP) is a peptide involved in social behaviors in rodents. To investigate the mechanism underlying the deficits in social behavior induced by blockade of N-methyl-D-aspartate (NMDA) receptors, this study examined the effect of noncompetitive NMDA antagonists on AVP receptor binding and social interaction in the rat. Subchronic phencyclidine (PCP) administration (2 mg/kg/day, 14 days, i.p.) significantly reduced the density of V1a receptor binding sites, labeled by an [125I]-Linear AVP antagonist, in several brain regions. Subchronic treatment with PCP or MK-801 (0.13 mg/kg/day, 14 days, i.p.) impaired social interactions in rats, as has been previously reported. These results suggest that NMDA antagonists have modulatory effects on the central vasopressinergic system and social interaction.

Animals↗
PubMed2003

Modulation of stress-induced dopamine release by excitotoxic damage of the entorhinal cortex in the rat.

In the sham-operated rats, exposure to either footshock or psychological stress induced similar biphasic alterations of dopamine (DA) release (an initial increase followed by a decrease below baseline levels) in the amygdala 4 weeks after the surgery. On the other hand, the left entorhinal cortex lesions abolished the late decrement phase of DA release below baseline levels. These results suggest that entorhinal cortex lesions modulate stress-induced dopaminergic transmissions in the lateral amygdala.

Amygdala↗
PubMed2003

A comparison of two doses of melperone, an atypical antipsychotic drug, in the treatment of schizophrenia.

Melperone at a dose of 300 mg/day has been reported to be as effective as thiothixene and superior to placebo in the treatment of schizophrenia. Limited ability to cause extrapyramidal side effects (EPS) and absence of an effect on plasma prolactin (pPRL) levels suggests that it is an atypical antipsychotic drug. The goal of this pilot study was to determine: (1). the ability of melperone 400 mg/day to produce greater improvement in psychopathology than melperone 100 mg/day; and (2). to compare side effects of these two doses of melperone. Melperone, 100 or 400 mg/day, was administered to 34 acutely hospitalized patients with schizophrenia for 6 weeks in a randomized, double-blind manner. Psychopathology, EPS, pPRL levels, and body mass index (BMI) were evaluated at baseline and 6 weeks. Twenty-seven completed the 6-week treatment. A last carried forward analysis revealed no significant difference in the ability of the two doses of melperone to improve psychopathology as measured by the Brief Psychiatric Rating Scale (BPRS)-Total and Positive subscale, the Scale for the Assessment of Negative Symptoms (SANS), the Schedule for Affective Disorders and Schizophrenia-Disorganization subscale, and the Global Assessment Scale (GAS). Treatment with melperone was not associated with exacerbation of EPS, or an increase in pPRL levels or BMI. The Abnormal Involuntary Movement Scale (AIMS) was not significantly changed by treatment with melperone. These results suggest that melperone was equally effective at doses 100 and 400 mg/day, for ameliorating psychopathology and improving overall psychiatric status in patients with schizophrenia. However, the lack of difference and a placebo control group, as well as modest degrees of change in psychopathology, require caution about assuming efficacy of either dose. The lack of significant side effects such as exacerbation of EPS, pPRL elevation, and weight gain indicates melperone is well tolerated.

Acute Disease↗
PubMed2003

Immobilization stress-induced increment of lactate metabolism in the basolateral amygdaloid nucleus is attenuated by diazepam in the rat.

Using in vivo microdialysis technique, extracellular lactate levels were measured in the basolateral amygdaloid nucleus of the rat under immobilization stress. Immobilization stress (40 min) led to a tetrodotoxin-reversible increase in dialysate lactate levels. Diazepam (1.0 mg/kg, i.p.) reduced the ability of immobilization stress to increase lactate levels. Furthermore, the attenuation of the immobilization stress-induced increase of lactate levels by diazepam was antagonized by pretreatment with flumazenil (15 mg/kg, i.p.), a selective antagonist at benzodiazepine receptors. These findings suggest that immobilization stress increases lactate levels in rat basolateral amygdaloid nuclei, which is attenuated by stimulation of benzodiazepine receptors.

Amygdala↗
PubMed2003

The effect of melperone, an atypical antipsychotic drug, on cognitive function in schizophrenia.

Melperone, a butyrophenone, has been shown to possess atypical antipsychotic properties, i.e. ability to produce an antipsychotic effect in man at doses that cause minimal extrapyramidal side effects. In addition, melperone shares the following with other atypical antipsychotic drugs: (1) effectiveness for ameliorating negative symptoms; (2) no prolactin elevation; and (3) effectiveness in the treatment of some patients with neuroleptic-resistant schizophrenia. Other atypical antipsychotic drugs have been reported to improve cognitive function. This study was performed to investigate the effect of melperone on cognitive function. Nineteen patients with schizophrenia or schizoaffective disorder, including 11 neuroleptic-resistant patients, were treated with melperone for 6 weeks. A comprehensive neurocognitive test battery and psychopathological ratings (Brief Psychiatric Rating Scale, BPRS) were administered at baseline and after 6 weeks of melperone treatment. Treatment with melperone was associated with improvement in executive function, as measured by the Wisconsin Card Sorting Test (WCST)-Categories and WCST-Percent Perseveration. On the other hand, visuospatial manipulation, as measured by the Wechsler Intelligent Scale for Children-Revised (WISC-R) Maze, worsened during melperone treatment. There were no significant changes in other domains of cognition, i.e. verbal learning and memory, verbal working memory, verbal fluency and sustained attention. Scores of WCST-Categories and Perseveration at 6 weeks were predicted from the relevant cognitive test scores at baseline and the change in BPRS Total and Positive scores. These results suggest the usefulness of melperone for facilitating work and social function in patients with schizophrenia. The differences in the cognition-enhancing abilities between melperone and clozapine are discussed.

Analysis of Variance↗
PubMed2002

Lack of self-control as assessed by a personality inventory is related to reduced volume of supplementary motor area.

The present study was performed to examine the relationship between schizophrenia-related personality and brain morphometry. Magnetic resonance (MR) imaging and schizophrenia-related personality scales extracted from the Minnesota Multiphasic Personality Inventory (MMPI) were administered to 42 university students. Analysis of the relationships between the gray matter segmented from the MR images on a voxel-by-voxel basis through the use of the statistical parametric mapping technique and the schizophrenia-related personality subscale scores from the MMPI revealed that lack of self-control subscale scores were negatively related to the gray matter volume of the supplementary motor area (SMA). Furthermore, it was suggested that self-control including self-inhibition is associated with the density of the SMA, the precuneous and the cerebellar vermis, which govern voluntary movements and motor imagery. These results provide important clues to the neural basis for the disturbance of self commonly observed in schizophrenia spectrum disorders.

Adult↗
PubMed2002

Exploratory eye movements in schizophrenia: effects of figure size and the instruction on visual search.

It has been reported that patients with schizophrenia show restricted eye-scanning in comparison with normal controls; however, the precise mechanism underlying the limited eye movement pattern remains unknown. The purpose of this study was to determine the factors affecting restricted eye-scanning in schizophrenic patients by examining exploratory eye movements during demonstration of two different sizes of the S-shaped figure. The second purpose was to determine the effect of the instruction for performance on the restricted viewing pattern in patients with schizophrenia. Eye movements during demonstration of the S-shaped figure of the original or half size were examined in 15 patients with schizophrenia and 15 normal controls using an infrared eye-mark recorder. The patients showed lower search scores than control subjects for both sizes of the figure. The subjects were then instructed to compare a slightly modified figure with the original one. Lower responsive search scores were found for the patients when "fixation point" was defined as a point at which a gaze was held for at least 200 ms, while the patients and control subjects performed equally at the 100-ms setting. Direct instruction to scrutinize the S-shape abolished the difference in the search scores between patients and control subjects at both the 100-ms and 200-ms settings. These findings suggest that the size of the S-figure is not a factor of restricted eye movements, and that the direct instruction improves the visual performance in patients with schizophrenia.

Adult↗
PubMed2002

Minnesota Multiphasic Personality Inventory profile characteristics of schizotypal personality disorder.

The goal of the present study was to determine whether precursors for psychopathology can be found in personality dimensions of the general population. Two hundred and 62 university students were compared with 41 schizophrenic patients and 18 patients with schizotypal personality disorder (SPD) on the Minnesota Multiphasic Personality Inventory (MMPI). Schizotypal personality disorder patients showed significantly elevated Pt and Si scales compared with the schizophrenic patients. Schizophrenia and SPD groups generally produced two-point codetypes of 6-8/8-6, 2-6/6-2, 7-8/8-7, and 7-8/8-7, 2-7/7-2, 6-8/8-6. A total of 77.5% of students had no codetype with a T-value of > or = 70, although the frequency of codetypes of spike 5, spike 0 and 2-7/7-2 was relatively high in the student group compared with the general population. Discriminant function analysis of the MMPI profiles revealed significant variance among the three groups. The overall rate of correct classification of the subjects into schizophrenia, SPD or university students was 90.3%. The first coefficient, mainly defined by a negative weight on the Sc scale, best distinguished the patients with either schizophrenia or SPD from the students. The second coefficient, defined by negative weights on the Sc and Si scales, and positive weights on the F and Ma scales identified patients with schizophrenia and SPD patients. The Harris-Lingoes subscales, which are supposed to provide the profile patterns characteristic of schizotypy, well discriminated the three groups. These results suggest the usefulness of the MMPI subscales for the detection of subjects with the SPD trait.

Adolescent↗