Yoshihisa Higuchi

Protective effect of aminoguanidine on hypoxic-ischemic brain damage and temporal profile of brain nitric oxide in neonatal rat

Nitric oxide (NO) produced by inducible NO synthase contributes to ischemic brain damage. However, the role of inducible NO synthase-derived NO on neonatal hypoxic-ischemic encephalopathy has not been clarified. We demonstrate here that aminoguanidine, a relatively selective inhibitor of inducible NO synthase, ameliorated neonatal hypoxic-ischemic brain damage and that temporal profiles of NO correlated with the neuroprotective effect of aminoguanidine. Seven-day-old Wister rat pups were subjected to left carotid artery occlusion followed by 2.5 h of hypoxic exposure (8% oxygen). Infarct volumes (cortical and striatal) were assessed 72 h after the onset of hypoxia-ischemia by planimetric analysis of coronal brain slices stained with hematoxylin-eosin. Aminoguanidine (300 mg/kg i.p.), administered once before the onset of hypoxia-ischemia and then three times daily, significantly ameliorated infarct volume (89% reduction in the cerebral cortex and 90% in the striatum;p < 0.001). NO metabolites were measured by means of chemiluminescence using an NO analyzer. In controls, there was a significant biphasic increase in NO metabolites in the ligated side at 1 h (during hypoxia) and at 72 h after the onset of hypoxia (p < 0.05). Aminoguanidine did not suppress the first peak but significantly reduced the second one (p < 0.05), and markedly reduced infarct size in a neonatal ischemic rat model. Suppression of NO production after reperfusion is a likely mechanism of this neuroprotection.

Increase in nitric oxide in the hypoxic–ischemic neonatal rat brain and suppression by 7-nitroindazole and aminoguanidine

We measured the changes in nitric oxide (NO) metabolites in the brains of neonatal rats with hypoxic-ischemic damage. There were two peaks of NO metabolites in the lesioned side of the cortex without treatment: one during hypoxia and the other during the re-oxygenation period. Prehypoxic treatment with 7-nitroindazole, a selective neuronal NO synthase inhibitor, suppressed both peaks of NO metabolites, whereas prehypoxic treatment with aminoguanidine, a selective inducible NO synthase inhibitor, partially suppressed only the peak in the re-oxygenation period. These data suggest different roles of neuronal and inducible NO synthases in the pathogenesis of hypoxic-ischemic encephalopathy.

Increased neurons containing neuronal nitric oxide synthase in the brain of a hypoxic-ischemic neonatal rat model.

We evaluated the temporal profile of the number of neurons containing neuronal nitric oxide synthase (nNOS neurons) in the brain of a neonatal hypoxic-ischemic rat model. Hypoxic-ischemic insults were produced in the brains of 7-day-old rat pups using a combination of unilateral carotid artery ligation and hypoxic (8% oxygen) exposure. Sections of brain from rats killed at 0-24 h after the onset of hypoxia were stained immunohistochemically using a polyclonal anti-nNOS antibody. Histological changes of neuronal injury were evaluated in the adjacent Nissl stained sections. The number of nNOS neurons in the hemisphere ipsilateral to the carotid ligation was significantly increased (P < 0.05) at 3 h, when the neuronal injury consisted of clusters of degenerating hyperchromic neurons. Neuronal degeneration and an increased number of nNOS neurons were seen only in the ipsilateral hemisphere and the increase was most prominent in the dorsolateral area of the striatum. The increase in the number of nNOS neurons continued at 6 h, when the area of neuronal injury continued to expand. At 24 h, the neuronal injury was diffuse, and the number of nNOS neurons on the ipsilateral side significantly decreased. The increase of the number of nNOS neurons in the early phase of neonatal neuronal injury suggests its possible involvement in the hypoxic-ischemic injury. The delineation of its role in neuronal injury may lead to an improvement in managing neonatal hypoxic-ischemic brain injury.

Zonisamide reduces hypoxic-ischemic brain damage in neonatal rats irrespective of its anticonvulsive effect.

The neuroprotective effect of a novel anticonvulsant, zonisamide, was investigated in neonatal rats with hypoxic-ischemic brain damage. Rats underwent left carotid ligation followed by hypoxic exposure (8% O2) for 2.5 h. When zonisamide (75 mg/kg) was administered i.p. 1 h before hypoxia, it reduced the cortical infarction volume to 6 +/- 5% (mean +/- S.E.M.) from 68 +/- 7% in vehicle-treated controls and the striatal volume to 8 +/- 4% from 78 +/- 7%. Zonisamide also reduced neuronal necrosis in 5 hippocampal regions (the dentate gyrus, CA4, CA3, CA1, and the subiculum). The plasma zonisamide concentration before and after hypoxia was 47.9 +/- 2.0 microgram/ml and 42.3 +/- 3.9 microgram/ml, respectively. Epidural electrodes were implanted in 6 pups one day before hypoxia-ischemia. Electroencephalograms were recorded during hypoxia-ischemia in rats given zonisamide or vehicle before the insult. The intensity of seizure activities was similar in the zonisamide-treated pups and the vehicle-treated controls. These findings demonstrate that zonisamide reduces neonatal hypoxic-ischemic brain damage and that this protective effect does not depend on its anticonvulsant action.

LIVING-RELATED LIVER TRANSPLANTATION AND NEUROLOGICAL OUTCOME IN CHILDREN WITH FULMINANT HEPATIC FAILURE

BACKGROUND Fulminant hepatic failure (FHF) in children is associated with high mortality under medical management. Living-related liver transplantation (LRLT) is an accepted measure to treat the children with end-stage liver disease. Reversibility of hepatic encephalopathy is crucial for the quality of life among the survivors after transplantation. METHODS A retrospective review was made of the records of children undergoing LRLT at this hospital between May 1992 and November 1996. RESULTS Eleven children with FHF underwent emergency LRLT. The mean age was 5 years (range, 2 months to 15 years). The indication for transplantation was persistent or worsening hepatic encephalopathy and severe coagulopathy, despite repeated plasma exchanges or exchange transfusions. The cause of FHF was non-A, non-B hepatitis in seven children, hepatitis B in two children, herpes simplex virus hepatitis in one child, and fulminant Wilsons disease with intravascular hemolysis in one child. The grade of hepatic encephalopathy was II in four children, III in two, and IV in five. The actuarial survival rate was 73% after a mean follow-up of 28 months (range, 13-67 months). Short-term neurological morbidity was present in two children with grade IV encephalopathy who also showed brain edema on cranial computed tomography. Eight survivors exhibited no long-term neurological deficit; the mean intelligence or developmental quotient was 97 (range, 86-110) at the end of the follow-up period. CONCLUSIONS LRLT is an effective option for the treatment of FHF in children. The long-term neurological status is satisfactory among survivors.

Benign Familial Neonatal Convulsions Followed by Benign Epilepsy with Centrotemporal Spikes in Two Siblings

Summary: Purpose: To report on sibling cases with benign familial neonatal convulsions (BFNC) followed by benign epilepsy with centrotemporal spikes (BECT).

Phenotypic Differences Between T → C and T → G Mutations at nt 8993 of Mitochondrial DNA in Leigh Syndrome

This study reports on a patient with Leigh syndrome with a T-to-C mutation at nucleotide 8993 of mitochondrial deoxyribonucleic acid (T8993C). The authors reviewed 10 Leigh syndrome patients, including ours, with T8993C. Compared with 18 reported patients with Leigh syndrome caused by a T-to-G mutation at nucleotide 8993 (T8993G), Leigh syndrome with T8993C was characterized by a significantly higher frequency of ataxia (P < 0.01). None of the reviewed T8993C-associated Leigh syndrome patients had retinitis pigmentosa, which is one of the characteristic findings in Leigh syndrome with T8993G. The milder symptoms of T8993C-Leigh syndrome can be explained by the milder complex V dysfunction; however, the higher frequency of ataxia in T8993C-Leigh syndrome requires more study.

Co-segregation of benign infantile convulsions and paroxysmal kinesigenic choreoathetosis

We report seven families and two sporadic cases in which benign infantile convulsions and paroxysmal kinesigenic choreoathetosis were co-segregated. Clinical investigations included physical and neurological examinations, blood electrolyte values, interictal and ictal electroencephalograms, and computed tomography or magnetic resonance imaging of the brain. The family pedigree was confirmed and the clinical history of the relatives was obtained. Seventeen individuals developed infantile convulsions followed by paroxysmal dyskinesias during childhood or adolescence. Six had only infantile convulsions, and two had only paroxysmal dyskinesias. The seizures never persisted into childhood or recurred in adulthood. The seizure type was a complex partial seizure, with or without secondary generalization, in nine of 14 patients. Paroxysmal dyskinesias, a subgroup of paroxysmal kinesigenic choreoathetosis, occurred for less than 5 min. The attacks of dyskinesias began at age 5-12 years in most patients, and tended to remit in adulthood. The mode of inheritance was apparently autosomal dominant in four of the families (17 affected individuals), who were diagnosed with ICCA syndrome (infantile convulsions and paroxysmal choreoathetosis). However, the condition occurred only among siblings in three families (six patients), and sporadically in two patients, suggesting genetic heterogeneity in this distinct co-segregation.

Long-term prognosis of epilepsies and related seizure disorders in fukuyama-type congenital muscular dystrophy

Fukuyama-type congenital muscular dystrophy is an autosomal recessive disorder prevalent in Japan that is characterized by congenital muscular dystrophy, cobblestone lissencephaly, and eye anomalies. We examined 46 patients with Fukuyama-type congenital muscular dystrophy and followed their progress for more than 3 years, with special reference to long-term prognosis of seizure disorders and the relationship between seizures and neuropathologic abnormalities. Seizures were observed in 37 patients (80%). The average age at onset was 3 years, 1 month. Initial seizures usually occurred after a febrile episode, although one third of patients had afebrile seizures from the onset. All patients had generalized tonic-clonic convulsions at febrile disorders, and these were followed by complex partial seizures or secondary generalized seizures. Later these seizures developed into Lennox-Gastaut syndrome in three patients. Electroencephalography (EEG) showed paroxysmal discharges in 22 of 37 patients with seizures (59%). The main focus was in the frontal, temporal, or central region. Lesions with marked cortical dysplasia detected by computed tomography, magnetic resonance imaging, or autopsy showed focal paroxysmal discharges on EEG. (J Child Neurol 2005;20:385—391).

Brain atrophy in congenital neuromuscular disease with uniform type 1 fibers

We report a patient with congenital neuromuscular disease with uniform type 1 fibers. The patient had manifested muscle weakness and running difficulty since early childhood. Ptosis and ophthalmoplegia were evident, in addition to facial and distal weakness. Her serum creatine kinase level was normal, and electromyography revealed low-amplitude and short duration of motor unit potentials. A muscle biopsy specimen demonstrated absolute predominance of type 1 fibers (> 98%) with no diagnostic structures. Her intelligence was borderline (IQ 80), and dilatation of the lateral ventricles was demonstrated by cranial CT. This is the first report of an abnormality in the central nervous system in congenital neuromuscular disease with uniform type 1 fibers.