Hiroaki Kawasaki

Publications (15) View all

• Article: A placebo-controlled, double-blind study of the efficacy and safety of aripiprazole for the treatment of acute manic or mixed episodes in Asian patients with bipolar I disorder (the AMAZE study).

  Shigenobu Kanba, Hiroaki Kawasaki, Jun Ishigooka, Kaoru Sakamoto, Toshihiko Kinoshita, Toshihide Kuroki
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  ABSTRACT: Objective. To investigate the efficacy and safety of aripiprazole in Asian patients with manic or mixed episodes associated with bipolar I disorder. Methods. Subjects were randomised to aripiprazole (24 mg/day; reduced to 12 mg/day if needed for tolerability; n = 128) or placebo (n = 130) for 3 weeks in this multicentre, double-blind study. The primary efficacy measure was mean change from baseline in Young Mania Rating Scale (YMRS) Total score. Results. A total of 136 patients (aripiprazole 56.3%; placebo 49.2%) completed the study. The majority of patients (92.6%) received aripiprazole 24 mg/day. Aripiprazole produced statistically significant mean improvements in YMRS Total scores compared with placebo from Day 4 through to Week 3 (-11.3 vs. -5.3; P < 0.001). The most common adverse events (> 15% of patients; aripiprazole vs. placebo) were akathisia (22.0 vs. 5.6%) and insomnia (16.3 vs. 9.6%). Aripiprazole treatment resulted in no significant difference from placebo in change in mean body weight from baseline (-0.4 vs. -0.7 kg; P = 0.231). Aripiprazole was not associated with an elevated serum prolactin level. Conclusions. Aripiprazole had significantly greater efficacy than placebo for the treatment of acute manic or mixed episodes associated with bipolar I disorder in Asian patients. Treatment was generally safe and well tolerated.
  The World Journal of Biological Psychiatry 04/2012; · 2.38 Impact Factor
• Article: Association analysis of adenosine A1 receptor gene (ADORA1) polymorphisms with schizophrenia in a Japanese population.

  Leo Gotoh, Hiroshi Mitsuyasu, Yuki Kobayashi, Naoya Oribe, Atsushi Takata, Hideaki Ninomiya, Vincent P Stanton, Gregory M Springett, Hiroaki Kawasaki, Shigenobu Kanba
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  ABSTRACT: The human adenosine A1 receptor gene (ADORA1) localizes to chromosome 1q32 is 76.8 kbp in length and contains six exons. ADORA1 is ubiquitously expressed in the central nervous system and clinical and pharmacological evidence suggest the involvement of adenosine neurotransmission in the pathogenesis of schizophrenia. Therefore, we investigated the contribution of genetic variations of ADORA1 to the pathophysiological mechanisms of Japanese schizophrenia patients. We performed genetic analysis of 29 polymorphic markers in 200 schizophrenic patients and 210 healthy controls from the Kyushu region of Japan. In statistical analysis, we performed the univariate analysis with genotypes and allele frequencies, linkage disequilibrium (LD) analyses, multivariate analysis, haplotype analysis, and sliding window haplotype analysis. In univariate analysis, no statistical difference was shown, after Bonferroni correction. By LD analysis, however, we could not find any LD blocks. In haplotype analysis, a total of 359 haplotypes were estimated. In multivariate analysis, we found three statistically different markers. In sliding window haplotype analysis, there were four statistically different haplotypes. This is the first study describing the involvement of ADORA1 polymorphisms in the pathophysiological mechanisms of schizophrenia in a Japanese population. These results corroborate our previous pharmacological and neurochemical studies in the rat that have suggested an association between ADORA1 neurotransmission and the schizophrenic effects of the N-methyl-D-aspartate receptor antagonist phencyclidine. Thus, ADORA1 polymorphisms may represent good candidate markers for schizophrenia research and ADORA1 may be involved in the pathophysiological mechanisms of schizophrenia in Japanese populations.
  Psychiatric genetics 10/2009; 19(6):328-35. · 2.33 Impact Factor
• Article: Nominal association between a polymorphism in DGKH and bipolar disorder detected in a meta‐analysis of East Asian case–control samples

  Atsushi Takata MD, PhD Hiroaki Kawasaki MD, Yoshimi Iwayama MS, PhD Kazuo Yamada MD, Leo Gotoh PhD, PhD Hiroshi Mitsuyasu MD, PhD Tomofumi Miura MD, PhD Tadafumi Kato MD, PhD Takeo Yoshikawa MD, PhD Shigenobu Kanba MD
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  ABSTRACT: Aim:  Recent genome-wide association studies (GWAS) of bipolar disorder (BD) have detected new candidate genes, including DGKH, DFNB31 and SORCS2. However, the results of these GWAS were not necessarily consistent, indicating the importance of replication studies. In this study, we tested the genetic association of DGKH, DFNB31 and SORCS2 with BD.Methods:  We genotyped 18 single-nucleotide polymorphisms (SNP) in DGKH, DFNB31 and SORCS2 using Japanese samples (366 cases and 370 controls). We also performed a meta-analysis of four SNP in DGKH, using the previously published allele frequency data of Han-Chinese case–control samples (1139 cases and 1138 controls).Results:  In the association analysis using Japanese samples, a SNP in SORCS2 (rs10937823) showed nominal genotypic association. However, we could not find any association in an additional analysis of tag SNP around rs10937823. In the meta-analysis of SNP in DGKH, rs9315897, which was not significantly associated with BD in the previous Chinese study, showed nominal association.Conclusion:  Although the association was not strong, the result of this study would support the association between DGKH and BD.
  Psychiatry and Clinical Neurosciences 04/2011; 65(3):280 - 285. · 2.13 Impact Factor
• Article: Guanine nucleotide exchange factors CalDAG-GEFI and CalDAG-GEFII are colocalized in striatal projection neurons.

  S Toki, H Kawasaki, N Tashiro, D E Housman, A M Graybiel
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  ABSTRACT: CalDAG-GEFI and CalDAG-GEFII (identical to RasGRP) are novel, brain-enriched guanine nucleotide exchange factors (GEFs) that can be stimulated by calcium and diacylglycerol and that can activate small GTPases, including Ras and Rap1, molecules increasingly recognized as having signaling functions in neurons. Here, we show that CalDAG-GEFI and CalDAG-GEFII mRNAs, detected by in situ hybridization analysis, have sharply contrasting forebrain-predominant distributions in the mature brain: CalDAG-GEFI is expressed mainly in the striatum and olfactory structures and deep cortical layers, whereas CalDAG-GEFII is expressed widely in the forebrain. Within the striatum, however, the two CalDAG-GEF mRNAs have nearly identical distributions: they are coexpressed in striatal projection neurons that give rise to the direct and indirect pathways of the basal ganglia. Subcellular fractionation analysis of the substantia nigra with monoclonal antibodies against CalDAG-GEFI suggests that CalDAG-GEFI protein is present not only in the cell bodies of striatal projection neurons but also in their axons and axon terminals. These results suggest that the CalDAG-GEFs may be key intracellular regulators whereby calcium and diacylglycerol signals can regulate cellular functions through small GTPases in the basal ganglia circuits.
  The Journal of Comparative Neurology 10/2001; 437(4):398-407. · 3.81 Impact Factor
• Article: Structure and polymorphisms of the human metabotropic glutamate receptor type 2 gene (GRM2): analysis of association with schizophrenia.

  A Joo, H Shibata, H Ninomiya, H Kawasaki, N Tashiro, Y Fukumaki
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  ABSTRACT: Metabotropic glutamate receptors (mGluRs) belong to the class of GTP-binding protein coupled receptors and consist of eight different subtypes. The subtype 2 metabotropic glutamate receptor (mGluR2) gene (GRM2) is one of the possible candidate genes for schizophrenia. Phencyclidine (PCP)-induced increase in glutamate efflux and schizophrenia-like behavioral abnormalities were reduced by pretreatment of the mGluRII agonist LY354740 in rats and its effects are mediated via mGluR2. To evaluate involvement of the mGluR2 gene in the pathogenesis of schizophrenia, we isolated the human mGluR2 gene and determined the transcription initiation site, the entire nucleotide sequence and the chromosomal localization. The hmGluR2 gene spans 13 kb with six exons, including one non-coding exon. The gene was mapped to chromosome 3 p12-p11 by Radiation Hybrid Panel analysis. We screened polymorphisms in the coding exons of the mGluR2 gene, using the SSCP procedure. The thirteen polymorphisms identified included ten missense, one silent mutation and two one-base substitutions in the 5'-untranslated region. We genotyped 213 Japanese schizophrenics and 220 controls to study the association of polymorphisms in the mGluR2 gene with schizophrenia. As we found no statistically significant differences in allele frequencies of each polymorphism, these polymorphisms apparently do not play a major role in schizophrenia.
  Molecular Psychiatry 04/2001; 6(2):186-92. · 13.67 Impact Factor