Publications by authors named "Tokito Yamaguchi"

18 Publications

  • Page 1 of 1

Characteristics of internalization of NMDA-type GluRs with antibodies to GluN1 and GluN2B.

J Neuroimmunol 2020 12 15;349:577427. Epub 2020 Oct 15.

Department of Molecular Neuroscience, Graduate Schools of Innovative Life Science and Medicine, University of Toyama, Toyama, Japan. Electronic address:

To characterize internalization of NMDA-type glutamate receptors (GluRs) by antibodies to NMDA-type GluRs, we produced rabbit antibodies to N-terminals of human GluN1 and GluN2B, and examined internalization of NMDA-type GluRs in HEK293T cells using confocal microscopy. Internalization of NMDA-type GluRs occurred from at least 10 min after incubation with antibodies to GluN1 and or GluN2B and was temperature-dependent. These findings confirm that antibodies to N-terminals of GluN1 and GluN2B present in the cerebrospinal fluid of patients with NMDAR encephalitis can mediate prompt internalization of NMDA-type GluR complexes.
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http://dx.doi.org/10.1016/j.jneuroim.2020.577427DOI Listing
December 2020

Methylprednisolone pulse therapy in 31 patients with refractory epilepsy: A single-center retrospective analysis.

Epilepsy Behav 2020 08 6;109:107116. Epub 2020 May 6.

National Epilepsy Center, NHO, Shizuoka Institute of Epilepsy and Neurological Disorders, Japan.

Purpose: We investigated the efficacy of methylprednisolone pulse therapy (MP) and responder characteristics in patients with refractory epilepsy.

Methods: We reviewed medical records of our center to identify patients with refractory epilepsy treated with MP other than continuous spikes and waves during slow sleep (CSWS), Landau-Kleffner syndrome (LKS), or Rasmussen's syndrome (RS) between 2004 and 2015. A course of MP consisted of intravenous methylprednisolone (30 mg/kg/day) on three consecutive days. Patients received multiple courses at intervals of four weeks. We examined seizure outcome, developmental outcome, antibodies to N-methyl-d-aspartate (NMDA)-type glutamate receptors (GluRs), cerebral spinal fluid (CSF)-albumin/serum-albumin ratio, and interictal electroencephalograms (EEGs). Responder to MP was defined as maintaining seizure reduction rate (SRR) ≥50% for three months after the first course of MP.

Results: Thirty-one consecutive patients treated with MP at our center were studied. Seizure types were focal onset impaired awareness seizure (FIAS) only (n = 23), FIAS with epileptic spasms (ES) (n = 7), and ES only (n = 1). Responder rate was 32.2% (10/31 patients), and seizure-free rate was 9.7% (3/31). Responders constituted 43.5% of patients without ES. No patient with ES was responder. Behavior and cognition also improved in 6 of 10 responders. History of seizure aggravation after inactivated vaccine before MP was found significantly higher rate in responder patients, comparing with nonresponder patients (p = 0.01).

Conclusion: Methylprednisolone pulse therapy may be considered for possible treatment in patients with focal epilepsy with drug-resistant seizures without ES, and it may improve cognitive function and behavioral comorbidities.
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http://dx.doi.org/10.1016/j.yebeh.2020.107116DOI Listing
August 2020

Corrigendum to "Efficacy and tolerability of perampanel in pediatric patients with Dravet syndrome" [Epilepsy Res. 154 (2019) 34-38].

Epilepsy Res 2019 Oct 27;156:106158. Epub 2019 Jun 27.

NHO Shizuoka Institute of Epilepsy and Neurological Disorders, 886 Urushiyama, Aoi-ku, Shizuoka-shi, Shizuoka 420-8688, Japan.

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http://dx.doi.org/10.1016/j.eplepsyres.2019.106158DOI Listing
October 2019

Comprehensive analysis of coding variants highlights genetic complexity in developmental and epileptic encephalopathy.

Nat Commun 2019 06 7;10(1):2506. Epub 2019 Jun 7.

Department of Human Genetics, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.

Although there are many known Mendelian genes linked to epileptic or developmental and epileptic encephalopathy (EE/DEE), its genetic architecture is not fully explained. Here, we address this incompleteness by analyzing exomes of 743 EE/DEE cases and 2366 controls. We observe that damaging ultra-rare variants (dURVs) unique to an individual are significantly overrepresented in EE/DEE, both in known EE/DEE genes and the other non-EE/DEE genes. Importantly, enrichment of dURVs in non-EE/DEE genes is significant, even in the subset of cases with diagnostic dURVs (P = 0.000215), suggesting oligogenic contribution of non-EE/DEE gene dURVs. Gene-based analysis identifies exome-wide significant (P = 2.04 × 10) enrichment of damaging de novo mutations in NF1, a gene primarily linked to neurofibromatosis, in infantile spasm. Together with accumulating evidence for roles of oligogenic or modifier variants in severe neurodevelopmental disorders, our results highlight genetic complexity in EE/DEE, and indicate that EE/DEE is not an aggregate of simple Mendelian disorders.
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http://dx.doi.org/10.1038/s41467-019-10482-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6555845PMC
June 2019

Genomic backgrounds of Japanese patients with undiagnosed neurodevelopmental disorders.

Brain Dev 2019 Oct 4;41(9):776-782. Epub 2019 Jun 4.

Department of Medical Genetics, Osaka Women's and Children's Hospital, Izumi, Japan.

Background: Recently, many genes related to neurodevelopmental disorders have been identified by high-throughput genomic analysis; however, a comprehensive understanding of the mechanism underlying neurodevelopmental disorders remains to be established. To further understand these underlying mechanisms, we performed a comprehensive genomic analysis of patients with undiagnosed neurodevelopmental disorders.

Methods: Genomic analysis using next-generation sequencing with a targeted panel was performed for a total of 133 Japanese patients (male/female, 81/52) with previously undiagnosed neurodevelopmental disorders, including developmental delay (DD), intellectual disability (ID), autism spectrum disorder (ASD), and epilepsy. Genomic copy numbers were also analyzed using the eXome Hidden Markov Model (XHMM).

Results: Thirty-nine patients (29.3%) exhibited pathogenic or likely pathogenic findings with single-gene variants or chromosomal aberrations. Among them, 20 patients were presented here. Pathogenic or likely pathogenic variants were identified in 18 genes, including ACTG1, CACNA1A, CHD2, CDKL5, DNMT3A, EHMT1, GABRB3, GABRG2, GRIN2B, KCNQ3, KDM5C, MED13L, SCN2A, SHANK3, SMARCA2, STXBP1, SYNGAP1, and TBL1XR1.

Conclusion: A diagnostic yield of 29.3% in this study was nearly the same as that previously reported from other countries. Thus, we suggest that there is no difference in genomic backgrounds in Japanese patients with undiagnosed neurodevelopmental disabilities. Although most of the patients possessed de novo variants, one of the patients showed an X-linked inheritance pattern. As X-linked recessive disorders exhibit the possibility of recurrent occurrence in the family, comprehensive molecular diagnosis is important for genetic counseling.
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http://dx.doi.org/10.1016/j.braindev.2019.05.007DOI Listing
October 2019

A novel de novo frameshift variant in SETD1B causes epilepsy.

J Hum Genet 2019 Aug 20;64(8):821-827. Epub 2019 May 20.

Department of Human Genetics, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.

We identified a de novo frameshift variant (NM_015048.1:c.5644_5647del:p.(Ile1882Serfs*118)) in the last exon of SETD1B in a Japanese patient with autistic behavior, developmental delay, intellectual disability, and myoclonic seizures. This variant is predicted to disrupt a well-conserved carboxyl-terminus SET domain, which is known to modulate gene activities and/or chromatin structure. Previously, two de novo missense mutations in SETD1B were reported in two patients with epilepsy. All three patients including the current patient share similar clinical features. Herein, we report a first epilepsy patient with a frameshift variant in SETD1B, emphasizing a possible pathomechanistic association of SETD1B abnormality with neurodevelopmental delay with epilepsy.
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http://dx.doi.org/10.1038/s10038-019-0617-1DOI Listing
August 2019

Efficacy and tolerability of perampanel in pediatric patients with Dravet syndrome.

Epilepsy Res 2019 08 21;154:34-38. Epub 2019 Apr 21.

NHO Shizuoka Institute of Epilepsy and Neurological Disorders, 886 Urushiyama, Aoi-ku, Shizuoka-shi, Shizuoka 420-8688, Japan.

Purpose: In the present study, we aimed to investigate the efficacy and tolerability of perampanel in patients with Dravet syndrome.

Methods: We retrospectively reviewed data regarding seizure frequency and adverse effects in 10 patients (four boys, six girls) with Dravet syndrome following treatment with perampanel. Perampanel treatment was considered effective when seizure frequency had been reduced by more than 50%.

Results: The mean age of patients at perampanel introduction was 11.5 ± 2.2 years. Seizure types were as follows: generalized tonic-clonic seizure (n = 8), unilateral clonic seizure (n = 6), myoclonic seizure (n = 3), atypical absence seizure (n = 3), and focal impaired awareness seizure (n = 1). The average number of concomitant anti-epileptic drugs (AEDs) was 3 ± 0.9. The mean duration of perampanel use was 11.1 ± 3.8 months. Seizure frequency was reduced by more than 50% in five patients (50%). The efficacy of perampanel for each seizure type was as follows: generalized tonic-clonic seizure: 50% (4/8), unilateral clonic seizure: 50% (3/6), myoclonic seizure: 33% (1/3), atypical absence seizure: 33% (1/3), and focal impaired awareness seizure: 100% (1/1). The effects of perampanel in each patient occurred between 3 and 6 months following the initiation of treatment. Seizure reduction was observed beginning at perampanel doses of 0.1 ± 0.07 mg/kg/day. Adverse events were observed in seven of 10 patients. Although somnolence was noted in 50% of patients, most events were mild.

Conclusions: The results of this retrospective observational study indicate that perampanel treatment may be promising in some patients with Dravet syndrome. Additional studies are necessary to verify the actual efficacy of perampanel for Dravet syndrome.
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http://dx.doi.org/10.1016/j.eplepsyres.2019.02.014DOI Listing
August 2019

Quinidine therapy and therapeutic drug monitoring in four patients with KCNT1 mutations.

Epileptic Disord 2019 Feb;21(1):48-54

National Epilepsy Center, NHO Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka.

Several recent studies have reported potassium sodium-activated channel subfamily T member 1 (KCNT1) mutations in epilepsy patients on quinidine therapy. The efficacy and safety of quinidine for epilepsy treatment, however, remains controversial. We herein report the cases of four patients with KCNT1 mutations treated with quinidine. A reduction in seizures of more than 50% after quinidine treatment was observed in one patient with epilepsy of infancy with migrating focal seizures (EIMFS), whereas two patients with EIMFS and one with focal epilepsy did not achieve apparent seizure reduction. The relationship between quinidine dose and serum quinidine concentration was inconsistent, particularly at high quinidine doses. One patient with EIMFS developed ventricular tachycardia the day after an increase in quinidine dose from 114 to 126 mg/kg/day. The serum trough quinidine concentration and the corrected QT interval (QTc) before arrhythmia onset were 2.4 μg/ml and 420 ms, respectively, and peak serum quinidine concentration after arrhythmia onset was 9.4 μg/ml. Another patient with EIMFS showed aberrant intraventricular conduction with a quinidine dose of 74.5 mg/kg/day and a serum trough concentration of 3.2 μg/ml. Given that serum quinidine levels may elevate sharply after a dose increase, careful monitoring of electrocardiographs and serum concentrations is required. Based on a review of previous reports and our experience with this case, quinidine should be considered as a promising drug for patients with EIMFS harbouring KCNT1 mutations, however, its efficacy remains controversial due to the limited number of cases, and more information on optimal serum concentrations and appropriate titration methods is required.
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http://dx.doi.org/10.1684/epd.2019.1026DOI Listing
February 2019

Chronic dysfunction of blood-brain barrier in patients with post-encephalitic/encephalopathic epilepsy.

Seizure 2018 Dec 13;63:85-90. Epub 2018 Nov 13.

Department of Pediatrics, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, NHO, Shizuoka, Japan.

Purpose: This study aimed to elucidate the characteristics and effects of chronic blood-brain barrier (BBB) dysfunction in patients with post-encephalitic/encephalopathic epilepsy (PEE), using brain images and the cerebral spinal fluid (CSF)/serum albumin ratio (albumin quotient, QAlb) as a marker of BBB function.

Methods: We examined the albumin levels in CSF and serum samples from 312 patients with refractory epilepsy in our center between 2004 and 2015. Sixty samples from patients with PEE and 97 samples from age- and sex-matched disease controls (DC) were evaluated. We classified PEE patients into a widespread lesion group and a focal lesion group by severity on brain magnetic resonance images in the chronic phase after acute encephalitis/encephalopathy.

Results: Median QAlb was higher in PEE than in DC [median (range) ×10: PEE 3.6 (1.0-10.3) versus DC 2.7 (1.0-6.7), p = 0.007]. In a linear regression analysis of the relationship between QAlb and patient's age at CSF examination or duration of epilepsy, the slope of the regression line was greater in PEE than in DC. Furthermore, in patients under ten years of age, linear regression analysis of QAlb versus seizure frequency showed a weak but positive correlation. Among PEE patients, seizure frequency was higher in the widespread lesion group than in the focal lesion group [300 (4-3000) versus 30 (1-1500) seizures/month, p <  0.001].

Conclusion: Our study suggests that patients with PEE have more severe BBB dysfunction, and that the BBB dysfunction is associated with refractory epilepsy.
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http://dx.doi.org/10.1016/j.seizure.2018.11.005DOI Listing
December 2018

Pyridoxal 5'-phosphate, pyridoxal, and 4-pyridoxic acid in the paired serum and cerebrospinal fluid of children.

Clin Chim Acta 2017 Sep 1;472:118-122. Epub 2017 Aug 1.

Department of Child Neurology, Okayama University Hospital, Okayama, Japan; Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.

Background: We quantified pyridoxal 5'-phosphate (PLP), pyridoxal (PL), and 4-pyridoxic acid (PA) in paired serum and cerebrospinal fluid (CSF) samples from children and investigated the effect of age on the concentrations and CSF-to-serum ratios of these vitamers.

Methods: Serum and CSF samples prospectively collected from 49 pediatric patients were analyzed. PLP, PL, and PA were measured using high-performance liquid chromatography with fluorescence detection, using pre-column derivatization by semicarbazide. Effects of age on these vitamers, the PLP-to-PL ratio, CSF-to-serum PLP ratio, and CSF-to-serum PL ratio were evaluated using correlation analysis.

Results: The PLP, PL, and PA concentrations in the serum and CSF were higher at younger ages, except for CSF PA concentrations that were mostly below the limit of detection (<1.2nmol/l). The PLP-to-PL ratios in the serum and CSF correlated positively with age. The CSF-to-serum PLP ratio and CSF-to-serum PL ratio were independent of age.

Conclusions: Age-related changes in PLP, PL, and PA in serum and in CSF from pediatric patients and CSF-to-serum ratios of PLP and PL demonstrated in this study will provide valuable information for evaluating PLP supply to the central nervous system from the peripheral blood.
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http://dx.doi.org/10.1016/j.cca.2017.07.032DOI Listing
September 2017

A case of early onset epileptic encephalopathy with de novo mutation in SLC35A2: Clinical features and treatment for epilepsy.

Brain Dev 2017 Mar 12;39(3):256-260. Epub 2016 Oct 12.

Department of Pediatrics, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, NHO, Japan.

Introduction: Mutations of SLC35A2 that encodes Golgi-localized Uridine diphosphate (UDP)-galactose transporter at Xp11.23 lead to congenital disorders of glycosylation (CDG). Although patients with CDG generally have diverse systemic symptoms, patients with a SLC35A2 mutation manifest predominantly disorders of the central nervous system (CNS).

Case Report: A female infant aged 12months was referred to our center because of intractable seizures. The patient was born with birth weight of 3228g after 40weeks of unremarkable gestation. At the age of 2months, she had partial seizures evolving to epileptic spasms. Her electroencephalogram showed hypsarrhythmia. Her seizures were refractory to antiepileptic drugs. At referral to our center at 12months, she had developmental delay (no head control), widely spaced inverted nipples, external strabismus, and bilateral heterochromia of irises. Blood examinations were normal. Brain magnetic resonance imaging findings included cerebral and cerebellar atrophy, thinning of the corpus callosum, and arachnoid pouch. Whole-exome sequencing detected a de novo frameshift mutation c.950delG (p.Gly317Alafs*32) at exon 4 in SLC35A2. Seizures subsided after the second adrenocorticotropic hormones (ACTH) therapy at 18months. At the age of 36months, although she had intellectual disability with no meaningful words, she was seizure-free and was able to sit without support and showed smiling face a lot.

Conclusion: This report reviewed the clinical features of patients with a SLC35A2 mutation. ACTH therapy may be effective for refractory epilepsy in these patients.
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http://dx.doi.org/10.1016/j.braindev.2016.09.009DOI Listing
March 2017

Antibodies against peptides of NMDA-type GluR in cerebrospinal fluid of patients with epileptic spasms.

Eur J Paediatr Neurol 2016 Nov 13;20(6):865-873. Epub 2016 Jul 13.

National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, NHO, 886 Urushiyama, Aoi-ku, Shizuoka 420-8688, Japan.

Objective: We investigated the contribution of antibodies against N-methyl-d-aspartate (NMDA)-type glutamate receptor (GluR) in cerebrospinal fluid (CSF) to the clinical features of patients with epileptic spasms (ES).

Methods: CSF samples were collected from 33 patients with ES with median (range) age 1.8 (0.2-8.5) years. Thirty patients without ES with 3.5 (0.5-7.0) years were also studied as disease controls. The CSF levels of antibodies against peptides of NMDA-type GluR subunits (GluN2B & GluN1) were measured by enzyme-linked immunosorbent assay.

Results: The levels of antibodies against the n-terminal of GluN2B (GluN2B-NT2), c-terminal of GluN2B (GluN2B-CT) and n-terminal of GluN1 (GluN1-NT), were significantly higher in patients with ES than in disease controls (p < 0.01, p < 0.01 & p = 0.03). Levels of antibodies to GluN2B-NT2 & CT were not related with ACTH therapy nor conventional CSF factors (cell counts, protein level, etc). Levels of antibodies to GluN2B-NT2 & CT showed evidence of correlation within a linear regression model with intervals from the onset to the examination of CSF until 25 months (p = 0.01 & p = 0.01). The correlation was significant in patients with unknown cause (p = 0.01). Five of 33 patients (four unknown cause & one chromosomal anomaly) had higher level of antibodies to GluN2B-NT2 exceeding mean + 1 SD of all ES patients, and they had poor motor (score 0) and cognitive outcomes (score 0 or 1).

Conclusion: The CSF level of antibodies against GluN2B in ES patients with unknown cause was estimated to increase after onset. We hypothesize that some ES patients may have immune process after the onset of ES.
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http://dx.doi.org/10.1016/j.ejpn.2016.07.006DOI Listing
November 2016

Three patients manifesting early infantile epileptic spasms associated with 2q24.3 microduplications.

Brain Dev 2015 Oct 3;37(9):874-9. Epub 2015 Apr 3.

Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan; Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan.

Background: Recent development of genetic analyses enabled us to reveal underlying genetic causes of the patients with epileptic encephalopathy in infancy. Mutations of voltage-gated sodium channel type I alpha subunit gene (SCN1A) are to be causally related with several phenotypes of epilepsy, generalized epilepsy with febrile seizure plus (GEFS+), Dravet syndrome, and other infantile epileptic encephalopathies. In addition to SCN1A, contiguous genes such as SCN2A and SCN3A in 2q24.3 are also reported to have contribution to epileptic seizures. Therefore, gene abnormality involving this region is reasonable to contribute to epilepsy manifestation.

Results: We encountered three patients with 2q24.3 microduplication diagnosed by Array comparative genomic hybridization array (aCGH). They developed partial seizures and epileptic spasms in their early infantile periods and showed remarkable developmental delay, although their seizures disappeared from 11 to 14 months of age. One of three patients had 2q24.3 microduplication which excludes SCN1A. Therefore, characteristics of epilepsy with 2q24.3 microduplication do not necessarily need duplication of SCN1A. This study suggested that 2q24.3 microduplication is one of the causes for early infantile epileptic spasms. Epileptic spasms associated with 2q24.3 microduplications may have better seizure outcome comparing with other etiologies.
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http://dx.doi.org/10.1016/j.braindev.2015.03.001DOI Listing
October 2015

Individualized phenytoin therapy for Japanese pediatric patients with epilepsy based on CYP2C9 and CYP2C19 genotypes.

Ther Drug Monit 2015 Apr;37(2):229-35

*Department of Clinical Research, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders; and †Department of Clinical Pharmaceutics, Graduate School of Pharmaceutical Sciences, University of Shizuoka, Japan.

Background: The aims of this study were to identify the target dose of phenytoin (PHT) and to compare the treatment continuation rate between patients receiving conventional therapy and patients receiving individualized therapy based on genotyping of the CYP2C9*3, CYP2C19*2, and CYP2C19*3 alleles. The operational definition for the target dose of PHT used in this study was the dose that yielded a steady-state PHT concentration within the range of 15-20 mcg/mL without dose-related adverse effects.

Methods: We investigated 394 samples from 170 Japanese pediatric patients aged 9 months to 15 years to identify factors that influenced the target dose of PHT. We also analyzed the clinical records of 156 patients who commenced PHT therapy at our hospital and retrospectively assessed the time to treatment failure within 1 year after starting PHT therapy. During the study period, 17 patients underwent genotyping at the start of PHT therapy. If the patients had the CYP2C9*3, CYP2C19*2, or CYP2C19*3 alleles, the initial dose of PHT was reduced by 10%-50% according to previous reports. The other 139 patients received conventional PHT therapy.

Results: According to multiple regression analysis, the body weight, concomitant use of sulthiame, and the CYP2C9*3, CYP2C19*2, and CYP2C19*3 alleles influenced the target dose of PHT. Our model explained 74% of the interindividual variability of the target dose of PHT. The total withdrawal rate in the individualized therapy group and the conventional therapy group was 23.5% and 33.1%, respectively. The adjusted hazard ratio for withdrawal of PHT therapy in the individualized therapy group was 0.37 (95% confidence interval; 0.12-1.10, P = 0.074).

Conclusions: These findings suggest that genotyping can help to estimate the optimum target dose of PHT and may contribute to avoid intoxication and concentration-dependent adverse effects.
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http://dx.doi.org/10.1097/FTD.0000000000000128DOI Listing
April 2015

[Adverse effects of antiepileptic drugs].

Nihon Rinsho 2014 May;72(5):908-19

Adverse effects of antiepileptic drugs are classified into idiosyncratic adverse effects, pharmacology-related adverse effects and biological effect after modification of seizure frequencies. Pharmacology-related adverse effects include those by administered AED and those by mutual interactions. Stevens-Johnson syndrome, one of the idiosyncratic adverse effects, may be predicted by the intrinsic HLA type (e.g., A*31:01 for CBZ). In epileptic patients after acute encephalitis, cutaneous adverse reactions usually occur in a month after encephalitis, but some patients will tolerate the causative AED by the extremely slow re-introduction. Prevention of pharmacology-related adverse effects needs therapeutic drug monitoring, and slow introduction considering dose-response curves for AEDs. Genotype examination of CYP2C9 and 2C19 can contribute to the safe introduction of PHT.
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May 2014

Influence of CYP2C19 polymorphism and concomitant antiepileptic drugs on serum clobazam and N-desmethyl clobazam concentrations in patients with epilepsy.

Ther Drug Monit 2013 Jun;35(3):305-12

Department of Clinical Research, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Ulushiyama, Aoi-ku, Japan.

Objective: The aims of this study were to identify the factors influencing the metabolism of clobazam (CLB) and its active metabolite [N-desmethyl clobazam (NCLB)] and to evaluate the NCLB concentration as an indicator for CYP2C19 polymorphism in epileptic patients.

Methods: A total of 302 serum samples from 238 Japanese patients were evaluated. The ratios of the serum CLB and NCLB concentrations to the CLB dose (CD ratios) were calculated and compared with CYP2C19 phenotypes.

Results: The mean CD ratio of NCLB in extensive metabolizers (EM: *1/*1), intermediate metabolizers (IM: *1/*2 or *1/*3), and poor metabolizers (PM: *2/*2, *3/*3, or *2/*3) was 3.1, 4.9, and 21.6 (μg/mL)/(mg/kg), respectively. In the EM and IM groups, the concomitant use of hepatic enzyme inducers (phenytoin and carbamazepine) reduced the CD ratio of CLB and increased that of NCLB. In the PM group, these inducers also decreased the CD ratio for CLB but did not elevate the CD ratio for NCLB. Using multiple regression analysis, body weight showed a positive correlation with an increased CD ratio for NCLB. The concomitant use of zonisamide and stiripentol also elevated the CD ratio for NCLB in the EM and IM groups, but that of the PM group was almost unchanged. When the cut-off value of the CD ratio for NCLB was set as 10.0 (μg/mL)/(mg/kg) for predicting the CYP2C19 PM status, the sensitivity and specificity were 94.4% and 95.7%, respectively.

Conclusions: The interaction between NCLB and other antiepileptic drugs showed marked differences among CYP2C19 phenotypes. Measurement of the serum NCLB concentration is clinically useful for identifying the PM phenotype.
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http://dx.doi.org/10.1097/FTD.0b013e318283b49aDOI Listing
June 2013

[Antibodies to the glutamate receptor].

Brain Nerve 2013 Apr;65(4):345-53

National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Japan.

Glutamate receptors (GluRs) are classified into metabotropic GluRs and ionotropic GluRs. Ionotropic GluRs include the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) -type, kainate (KA)-type, and N-methyl-D-aspartate (NMDA)-type GluRs (NRs). Antibodies to the NRs have been detected using immunoblot, cell-based assays, and enzyme linked immunosorbent assay (ELISA). In patient with non-paraneoplastic, non-herpetic acute limbic encephalitis (NHALE), antibodies against GluN2B (GluRε2) and GluN1 (Gluζ1) are detected in the sera and CSF. In addition to the antibodies to NRs detected by ELISA, antibodies to an NR-complex detected by cell-based assay are found, not only in CSF from NHALE, but also in CSF from epilepsy, Creutzfeldt-Jakob disease (CJD), etc. Antibodies to NRs internalize mainly extra-synaptic NRs, and dissociate the connection between GluN2A and Ephrin-B2 receptor at the synapse. IgG fractions containing antibodies to NRs decrease apoptosis of cultured neurons. Antibodies to AMPA-type GluRs have been detected by immunoblot, cell-based assay and ELISA. In Rasmussen syndrome, antibodies against GluA3 (GluR3) were found to be the primary pathological factor. However the antibodies did not cause Rasmussen syndrome in mice models. These antibodies have been shown to cause excitotoxicity through GluA3, complement-dependent cytotoxicity, etc. Antibodies to GluA1/GluA2 in paraneoplastic limbic encephalitis modulate expression and localization of GluA1/GluA2 at the synapse. Antibodies to metabotropic GluRs have been detected using cell-based assays in patients with Hodgkin's lymphoma. Passive transfer of the IgG fraction from patients having antibodies to metabotropic GluR1 causes ataxia in mice.
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April 2013