Spectrum of glutamate dehydrogenase mutations in Japanese patients with congenital hyperinsulinism and hyperammonemia syndrome.

INTRODUCTION: Congenital hyperinsulinism and hyperammonemia (CHH) is caused by gain of function of glutamate dehydrogenase (GDH). The genetic abnormalities are known to be located in three specific regions on the GDH protein. We describe here three different missense mutations identified in five new Japanese patients with CHH. And to study the genotype-phenotype correlations in patients with GLUD1 mutations, we analyzed previously reported Japanese cases. METHODS: An Epstein-Barr virus-transformed lymphoblastoid cell line was established from the 5 patients and control subjects, and was used for enzymatic and molecular analyses. RESULTS: All patients developed seizures with loss of consciousness associated with hypoglycemia and had persistent hyperammonemia. All patients had similar basal GDH activity of lymphoblasts and insensitivity to GTP inhibition. Genetic studies identified heterozygous I444M mutation in Patient 11, S217C mutation in Patient 1, and H262Y mutation in Patients 2, 3, and 4. Patients 3 and 4 were child and father, respectively. COS cell expression study confirmed that I444M and H262Y mutations were disease-causing genes. CONCLUSIONS: We identified three mutations (I444M, H262Y, and S217C), and the former is a newly described mutation. A summary of 17 reported Japanese patients (10 boys and 7 girls) with GDH mutations showed 8 patients had mutation at the site of the GTP-binding region, 2 at the site of the antenna-like structure, and 7 at the site of the hinge region. Analysis of the reported cases showed no clear association between clinical phenotype and mutation sites. However, G446D mutation seems to be associated with serious abnormalities.

Enzyme replacement therapy in a patient with Fabry disease and the development of IgE antibodies against agalsidase beta but not agalsidase alpha.

Fabry disease is an X-linked inherited lysosomal storage disorder caused by an inborn deficiency of the enzyme α-galactosidase A. Enzyme replacement therapy (ERT) with agalsidase alpha or beta isozymes is an effective treatment. Cross-reactivity of immunoglobulin G (IgG) antibodies with agalsidase alpha and beta has been reported, but no such reaction has been recorded for IgE antibodies. We present the case of a patient with Fabry disease who developed antiagalsidase beta IgE antibodies without cross-reactivity to agalsidase alpha. A 17-year-old boy with Fabry disease had suffered from severe atopic dermatitis since infancy, and he complained for several years of peripheral pain during the summer months and when exercising. Fabry disease was confirmed by family history and a positive enzyme test, and ERT was commenced. Following infusion of agalsidase beta (1.0 mg/kg), the patient complained of a high temperature in his hands and feet, and purulent eczema developed. The infusion dose was reduced to 0.2 mg/kg, but the hyperthermia did not change, although its duration decreased. After three infusions, eosinophilia developed (9.4%; 573 cells/µl blood) and remained unresolved after four infusions with agalsidase beta. Treatment with this enzyme was discontinued, and agalsidase alpha (0.2 mg/kg) started. This produced immediate resolution of the eosinophilia, which has been maintained during follow-up. In conclusion, this patient developed IgE antibodies against agalsidase beta, which demonstrated no cross-reactivity to agalsidase alpha. These findings emphasize the importance of analyzing IgE antibodies against both enzymes when patients exhibit severe infusion-related events.

Calpain inhibition induces activation of the distinct signalling pathways and cell migration in human monocytes.

We have recently reported that constitutively active calpain negatively regulates activation of the distinct signalling pathways and cell migration in human neutrophils. Here, we report that a similar regulatory system is also functioning in human monocytes, but not lymphocytes. Calpain was constitutively active in resting human monocytes, but not lymphocytes. Mitogen-activated protein kinases, including extracellular signal-regulated kinase (ERK), p38 and c-Jun N-terminal kinase (JNK), phosphatidylinositol 3-kinase (PI3K)/Akt and p21-activated kinase (PAK, an effector molecule of Rac) were rapidly (within 1 min) activated in monocytes, but not lymphocytes, upon exposure to calpain inhibitors (PD150606 and N-acetyl-Leu-Leu-Nle-CHO), but not PD145305 (the inactive analogue of PD150606). Following activation of these signalling pathways, monocytes displayed active migration within 5 min after exposure to calpain inhibitors, and active migration was sustained for more than 45 min. The micropipette method revealed that calpain inhibition-mediated monocyte migration was chemotaxis, not random migration. The studies with pharmacological inhibitors suggest that calpain inhibition-mediated monocyte migration is mediated by activation of ERK, p38, JNK, PI3K/Akt and Rac. NSC23766 (Rac inhibitor) and pertussis toxin (PTX) suppressed calpain inhibitor-induced phosphorylation of distinct signalling molecules (PAK, ERK, p38, JNK and Akt) as well as cell migration, suggesting that the PTX-sensitive G protein and Rac axis may be a possible key target of calpain inhibitors. These findings suggest that constitutively active calpain negatively regulates activation of the distinct signalling pathways and cell migration in resting monocytes, but not lymphocytes.

Expression of estrogen receptor alpha and beta in reactive astrocytes at the male rat hippocampus after status epilepticus.

Estrogen is neuroprotective against status epilepticus (SE)-induced hippocampal damage in female animals. In male animals, estrogen is converted from testosterone via aromatization the activity of which is upregulated by brain damage. However, it is controversial whether estrogen is neuroprotective or neuroinvasive against male hippocampal damage after SE. In order to understand the role of estrogen, it is important to elucidate the distribution manner of estrogen receptor (ER)alpha and beta as the targets of estrogen. In this study, we examined the time course changes of ERs in adult male rat hippocampus after SE using anti-ERalpha antibodies (MC-20 and PA1-309) and anti-ERbeta antibodies (PA1-310B and PA1-311). In control rats, both ERalpha and beta were expressed in the pyramidal cells predominantly at CA1 and CA3. ERalpha was expressed in the cytoplasm and the nucleus, whereas ERbeta was expressed in the cytoplasm of the pyramidal cells. After SE, according to the pyramidal cell loss at CA1, the number of ERalpha- and beta-immunoreactive pyramidal cells decreased up to day 21. On the other hand, reactive astrocytes, which newly appeared after SE and formed gliosis at CA1, were confirmed to express both ERs in the nucleus, cytoplasm, and process. There were no differences in immunoreactivity between antibodies. Our results indicate that endogenous estrogen affects the pyramidal cells through ERalpha and beta under normal circumstances in adult male rats, whereas the targets of estrogen shift to the reactive astrocytes through ERalpha and beta after SE.

Aristaless-related homeobox gene disruption leads to abnormal distribution of GABAergic interneurons in human neocortex: evidence based on a case of X-linked lissencephaly with abnormal genitalia (XLAG).

X-linked lissencephaly with abnormal genitalia (XLAG) is a rare disorder caused by mutations in the aristaless-related homeobox (ARX) gene, located on Xp22.13. Arx-null mice show loss of tangential migration of GABAergic interneurons, presumably being related to caudal ganglionic eminence tangential migration. In the present study, we investigated a subpopulation of GABAergic interneurons in the brain of an infant with XLAG, who had a novel nonsense mutation of the ARX gene, compared with those of age-matched normal controls and Miller-Dieker syndrome. We performed immunocytochemistry for interneuron and migration markers. We found that glutamic acid decarboxylase (GAD)- and calretinin (CR)-containing cells were significantly reduced in the neocortex and located in the white matter and neocortical subventricular zone, while neuropeptide Y- or cholecystokinin-containing cells were normally distributed. Moreover, in the neocortical subventricular region, the GAD- and CR-containing cells expressed the radial migration marker Mash-1 as well as nestin. Our findings suggest that ARX protein controls not only the tangential migration of GABAergic interneurons from the ganglionic eminence, but also may serve to induce radial migration from the neocortical subventricular zone.

Biopterin in the acute phase of hypoxia-ischemia in a neonatal pig model.

To clarify the participation of inducible NOS (iNOS) in the hypoxia-ischemia, we examined iNOS and its tetrahydrobiopterin co-factor in the cerebral cortex and plasma in a newborn-piglet model. We also investigated the role of hypothermia in iNOS expression and biopterin production. Male newborn piglets were ventilated 6% oxygen for 45 min. Their common carotid arteries were clamped during hypoxia. Then they were resuscitated with 30% oxygen (HI group). Piglets of the hypothermia group were treated as the HI group and their body was cooled to 35.5 degrees C after hypoxic-ischemic insults. Sham-treated piglets were also reserved. In the HI group, iNOS was present in neurons and macrophages of the cerebral cortex 12h after the insult. The concentrations of nitrite and nitrate were elevated in the cerebral cortex 12h after hypoxic-ischemic insults but the biopterin level was unchanged. The plasma biopterin concentration after the insult (377.9+/-78.7 nM) was five times higher than before the insult (80.1+/-4.3 nM); this level peaked 4h after the insult (604.8+/-200.9 nM) and only slightly decreased after 12h (445.9+/-57.8 nM). In the hypothermia group, no iNOS expression was observed 12h after the insult. The plasma biopterin concentration after the insult (464.2+/-92.3 nM) was similar to that in the HI group, but was suppressed by 4h of hypothermia (229.3+/-106.8 nM). In this study, neuronal iNOS expression and increase of NO production were found in the acute phase of hypoxia-ischemia. Brain biopterin did not increase in hypoxia-ischemia although plasma biopterin was five-fold elevated. The discrepancy may also affect hypoxic-ischemic organ damage.

Effectiveness of lidocaine infusion for status epilepticus in childhood: a retrospective multi-institutional study in Japan.

We evaluated the usefulness of intravenous lidocaine therapy for managing of status epilepticus (SE) during childhood in a retrospective multi-institutional study. Questionnaires were sent to 28 hospitals concerning patients admitted for SE who were managed with lidocaine, assessing patient characteristics, treatment protocols and efficacy. In 279 treated patients, 261 SE occurrences at ages between 1 month and 15 years were analyzed. SE was classified as showing continuous, clustered, or frequently repeated seizures. Considering efficacy and side effects in combination, the usefulness of lidocaine was classified into six categories: extremely useful, useful, slightly useful, not useful, associated with deterioration, or unevaluated. In 148 SE cases (56.7%), lidocaine was rated as useful or extremely useful. Multivariate analysis indicated lidocaine was to be useful in SE with clustered and frequently repeated seizures, and SE attributable to certain acute illnesses, such as convulsions with mild gastroenteritis. Efficacy was poor when SE caused by central nervous system (CNS) infectious disease. Standard doses (approximately 2mg/kg as a bolus, 2mg/kg/h as maintenance) produced better outcomes than lower or higher doses. Poor responders to the initial bolus injection of lidocaine were less likely to respond to subsequent continuous infusion than good initial responders. We recommend lidocaine for use in SE with clustered or frequently repeated seizures, and in SE associated with benign infantile convulsion and convulsions with mild gastroenteritis. Lidocaine should be initiated with a bolus of 2mg/kg. If SE is arrested by the bolus, continuous maintenance infusion should follow; treatment should proceed to different measures when SE shows a poor response to the initial bolus of lidocaine.

Kainic acid dose affects delayed cell death mechanism after status epilepticus.

Kainic acid (KA)-induced status epilepticus (SE) produces hippocampal neuronal death, which varies from necrosis to apoptosis or programmed cell death (PCD). We examined whether the type of neuronal death was dependent on KA dose. Adult rats were induced SE by intraperitoneal injection of KA at 9 mg/kg (K9) or 12 mg/kg (K12). Hippocampal neuronal death was assessed by TUNEL staining, electron microscopy, and Western blotting of caspase-3 on days 1, 3 and 7 after SE induction. K12 rats showed higher a mortality rate and shorter latency to the onset of SE when compared with K9 rats. In both groups, acidophilic and pyknotic neurons were evident in CA1 at 24h after SE and neuronal loss developed from day 3. The degenerated neurons became TUNEL-positive on days 3 and 7 in K9 rats but not in K12 rats. Caspase-3 activation was detected on days 3 and 7 in K9 rats but was undetectable in K12 rats. Ultrastructural study revealed shrunken neurons exhibiting pyknotic nuclei containing small and dispersed chromatin clumps 24h after SE in CA1. No cells exhibited apoptosis. On days 3 and 7, the degenerated neurons were necrotic with high electron density and small chromatin clumps. There were no ultrastructural differences between the K9 and K12 groups. These results revealed that differences in KA dose affected the delayed cell death (3 and 7 days after SE); however, no effect was seen on the early cell death (24h after SE). Moderate-dose KA induced necrosis, while low-dose KA induced PCD.

Efficacy of intravenous midazolam for status epilepticus in childhood.

A retrospective multicenter study was conducted, designed to evaluate the efficacy and safety of midazolam for the treatment of status epilepticus. The subjects were 358 inpatients who received intravenous midazolam therapy for status epilepticus. The mean age was 48.6 +/- 46.5 months. The underlying disorder was epilepsy in 195 cases, and acute symptomatic diseases in 163 (encephalitis or encephalopathy in 88 cases). Midazolam was administered as a bolus dose (0.25 +/- 0.21 mg/kg), followed if necessary by continuous infusion (0.26 +/- 0.25 mg/kg/hr). The bolus injection was effective in 162 (56.6%) of the 286 cases. In the end, seizure suppression was obtained in 231 cases (64.5% of the total). The effectiveness of midazolam was lower in patients in whom midazolam was initiated more than 3 hours after seizure onset, and this tendency was particularly marked in the epilepsy group. During the treatment period, 10 patients died, but none of these deaths were associated with midazolam therapy. The incidence and types of adverse events were consistent with previously reported data. The present results indicate that midazolam is highly effective for the management of status epilepticus, if used sufficiently early after seizure onset.

Comments from the Developmental Neurotoxicology Committee of the Japanese Teratology Society on the OECD Guideline for the Testing of Chemicals, Proposal for a New Guideline 426, Developmental Neurotoxicity Study, Draft Document (October 2006 version), and on the Draft Document of the Retrospective Performance Assessment of the Draft Test Guideline 426 on Developmental Neurotoxicity.

In October 2006, a new revision of the draft guideline (OECD Guideline for the Testing of Chemicals, Proposal for a New Guideline 426. Developmental Neurotoxicity Study) and Draft Document of the Retrospective Performance Assessment (RPA) of the Draft Test Guideline 426 on Developmental Neurotoxicity were distributed following incorporation of the results of the Expert Consultation Meeting in Tokyo on May 24-26, 2005. The draft guideline consists of 50 paragraphs and an appendix with 102 references; and the draft RPA consists of 37 paragraphs with 109 references. National coordinators were requested to arrange for national expert reviews of these draft documents in their member countries. Members of the Developmental Neurotoxicology (DNT) Committee of the Japanese Teratology Society (JTS) reviewed, discussed, and commented on the draft Test Guideline Proposal. The DNT Committee of the JTS also commented on the draft document of the RPA. These comments were sent to the OECD Secretariat. The DNT Committee of the JTS expects the comments to be useful for the finalization of these draft documents.

Hippocampal BDNF and TrkB expression in young rats after status epilepticus.

BACKGROUND: The immature brain is more susceptible to seizures than mature brains but less vulnerable to seizure-induced neuronal loss. We studied age-related susceptibility and vulnerability to kainic acid-induced status epilepticus (KASE) in rats in terms of hippocampal expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B receptor (TrkB). METHODS: Immunohistochemical and Western analysis were performed after kainic acid (KA)-induced status epilepticus (SE). RESULTS: KA doses required to induce SE increased from 1.5 mg/kg in 1-week-old rats to 10 mg/kg at 4 weeks of older. After SE the older rats showed spontaneous seizures and hippocampal pyramidal neuronal loss-unlike rats under 4 weeks old. Hippocampal BDNF protein expression had increased fivefold in 1-week-old rats and threefold in 8-week-old rats 1 day after SE, returning to baseline 2 days after SE. TrkB expression showed little effect from KASE at either age. CONCLUSIONS: These results indicated that the critical period as for vulnerability to SE was the age of 4-week-old and older in the rat. Since the response patterns of BDNF and TrkB to SE were similar between neonatal and the adult rats, our study revealed that the observed transient upregulation of BDNF did not contribute to cause epilepsy in neonatal rats.

[Case of Sanfilippo syndrome type B and Wilson disease born to unrelated parents].

A 5-year-old boy visited a hospital because of macrocephalus, mental retardation and hepatic dysfunction, and was suspected to have Wilson's disease since his father had this disease. The serum level of ceruloplasmin was low, but urinary copper excretion was not increased markedly. He was treated with D-penicillamine. He was then reffered to our hospital because of his facial features suggesting mucopolysaccharidosis. Based on mucopolysacchariduria and the deficiency of N-acetylglucosaminidase, the diagnosis of Sanfilippo syndrome type B was made. Molecular analyses identified him as a compound heterozygote for both the ATP7B (A844V/2659delG) and alpha-N-acetylglucosaminidase (V241M/R482W) genes, responsible for Wilson's disease and Sanfilippo syndrome type B, respectively. Although born to non-consanguineous parents, he had two rare autosomal recessive diseases. In this case, liver dysfunction was attributed to Wilson's disease, and mental retardation to Sanfilippo syndrome.

[A child with non-herpetic acute limbic encephalitis affecting the claustrum and hippocampus].

We experienced an 8-year-old-boy with non-herpetic acute limbic encephalitis (NHALE), who developed headache, convulsion, consciousness disturbance, and ataxia following cold like symptoms. Disturbance of short term memory and a change of character were recognized. Myoclonic seizures and generalized tonic clonic convulsions developed, that responded to antiepileptic agents. Although other symptoms resolved spontaneously, short term memory disturbance persisted. Brain MRI demonstrated the lesion involving the bilateral claustrum and right hippocampus. Three months later, the lesion in the claustrum disappeared, but the hippocampus still showed slight hyperintensity on FLAIR image of MRI. Autoantibodies against glutamine receptor were detected in the cerebrospinal fluid and plasma, which suggested the involvement of immunologic disturbances in this disease. In NHALE, many cases have been reported in adults but not in children, and the further attentions should be paid to childhood-onset NHALE.

An infant with idiopathic orbital myositis poorly responsive to steroid therapy: a case report.

A 9-month-old girl developed subacute limited adduction of the left eye, presenting with blepharoptosis. An orbital magnetic resonance imaging (MRI) 2 months after the onset revealed swelling of the left lateral rectus muscle, with increased intensity on T2-weighted images with fat saturation, which was enhanced with gadolinium. She was diagnosed with idiopathic orbital myositis based on history, physical examination, and MRI findings. Swelling of the left lateral rectus muscle was partially reduced by pulse steroid therapy. This is the first reported case of an infant orbital pseudotumor with clinical and MRI findings consistent with subacute orbital myositis. We propose that a fibrotic change of the orbital muscle may occur during a subacute course and would be incompletely responsive to steroid therapy.

Regulatory mechanisms and physiological relevance of a voltage-gated H+ channel in murine osteoclasts: phorbol myristate acetate induces cell acidosis and the channel activation.

UNLABELLED: The voltage-gated H+ channel is a powerful H+ extruding mechanism of osteoclasts, but its functional roles and regulatory mechanisms remain unclear. Electrophysiological recordings revealed that the H+ channel operated on activation of protein kinase C together with cell acidosis. INTRODUCTION: H+ is a key signaling ion in bone resorption. In addition to H+ pumps and exchangers, osteoclasts are equipped with H+ conductive pathways to compensate rapidly for pH imbalance. The H+ channel is distinct in its strong H+ extrusion ability and voltage-dependent gatings. METHODS: To investigate how and when the H+ channel is available in functional osteoclasts, the effects of phorbol 12-myristate 13-acetate (PMA), an activator for protein kinase C, on the H+ channel were examined in murine osteoclasts generated in the presence of soluble RANKL (sRANKL) and macrophage-colony stimulating factor (M-CSF). RESULTS AND CONCLUSIONS: Whole cell recordings clearly showed that the H+ current was enhanced by increasing the pH gradient across the plasma membrane (delta(pH)), indicating that the H+ channel changed its activity by sensing delta(pH). The reversal potential (V(rev)) was a valuable tool for the real-time monitoring of delta(pH) in clamped cells. In the permeabilized patch, PMA (10 nM-1.6 microM) increased the current density and the activation rate, slowed decay of tail currents, and shifted the threshold toward more negative voltages. In addition, PMA caused a negative shift of V(rev), suggesting that intracellular acidification occurred. The PMA-induced cell acidosis was confirmed using a fluorescent pH indicator (BCECF), which recovered quickly in a K(+)-rich alkaline solution, probably through the activated H+ channel. Both cell acidosis and activation of the H+ channel by PMA were inhibited by staurosporine. In approximately 80% of cells, the PMA-induced augmentation in the current activity remained after compensating for the delta(pH) changes, implying that both delta(pH)-dependent and -independent mechanisms mediated the channel activation. Activation of the H+ channel shifted the membrane potential toward V(rev). These data suggest that the H+ channel may contribute to regulation of the pH environments and the membrane potential in osteoclasts activated by protein kinase C.

Alterations and diversity in the cytoplasmic tail of the fusion protein of subacute sclerosing panencephalitis virus strains isolated in Osaka, Japan.

We determined the nucleotide sequence of the fusion (F) gene of three strains (Osaka-1, -2, and -3) of nonproductive variants of measles virus (MV). These viral strains were isolated in Osaka, Japan, from brain tissues of patients with subacute sclerosing panencephalitis (SSPE). Phylogenetic analysis revealed a close relationship among the three strains of SSPE virus. The cytoplasmic tail of the F protein, predicted from sequence analysis of the gene, is altered in all three SSPE strains when compared to the MV field strains. However, the extent and mode of alteration are different in each strain. The F protein of the Osaka-1 strain has six nonconservative amino acid substitutions and a 29-residue elongation of its cytoplasmic tail. The F protein of the Osaka-3 strain has two nonconservative substitutions and a 5-residue truncation of its C-terminus. Although the termination codon is not altered in the F protein of the Osaka-2 strain, five or six amino acids are changed in the cytoplasmic tail of the F protein of the two sibling viruses of this strain. The significance of the altered cytoplasmic domain of the SSPE viruses in the SSPE pathogenesis is discussed.

Decreased plasma tetrahydrobiopterin in pregnant women is caused by impaired 6-pyruvoyl tetrahydropterin synthase activity.

Tetrahydrobiopterin (BH4) is an essential cofactor of nitric oxide synthase as well as a cofactor of aromatic amino acid hydroxylases. However, its role in pregnancy is not yet understood. We evaluated the concentrations of BH4 throughout normal pregnancy and puerperium, and compared them with those of non-pregnant women by measuring its oxidation product biopterin. In addition, we also measured 6-pyruvoyl tetrahydropterin synthase (PTPS) activities, the rate-limiting enzyme in synthesizing BH4, in pregnant women at the 30th gestational week and non-pregnant women. Although the urinary biopterin levels did not remarkably change, plasma biopterin levels significantly decreased from the 10th gestational week to the 1st day of postpartum compared with those of non-pregnant women. There was no significant difference in PTPS activities between pregnant and non-pregnant women. However, the proportion of reticulocytes, which have been shown to possess high PTPS activity, is significantly higher in pregnant women than in non-pregnant women. Our results suggest that decreased plasma BH4 levels in pregnancy is caused by impaired PTPS activity.

Spontaneous improvement of intractable epileptic seizures following acute viral infections.

In general, epileptic seizures become more serious following infections. However, transient and permanent improvement of epileptic seizures has been observed following acute viral infections, without a recent change in anti-epileptic therapy. Questionnaires were sent to 73 institutions, throughout Japan, where pediatric neurologists care for children with epilepsy to characterize this phenomenon through clinician survey. Completed surveys were received from 11 institutions, and 21 cases were selected for the study. The age of the patients were 6 months to 17 years. The West syndrome or epilepsy subsequent to West syndrome cases were 16 out of 21. Two cases of symptomatic generalized epilepsy and one case each of symptomatic partial epilepsy, continuous spike-waves of slow sleep and severe myoclonic epilepsy in infancy were also reported. These seizures disappeared within 2 weeks subsequent to viral infections such as, exanthema subitum, rotavirus colitis, measles and mumps. The disappearance of intractable epileptic seizures following acute viral infections might be related to the inflammatory processes or the increased levels of antibodies after viral infections.