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Biomedical subjects

M Osawa

Publications and source records attributed to M Osawa.

At least 37 records · Page 2Linked to original sources
PubMed2001

Acquired epileptiform opercular syndrome: a case report and results of single photon emission computed tomography and computer-assisted electroencephalographic analysis.

We report here a girl aged 5 years 3 months with cryptogenic localization-related epilepsy who showed a prolonged episode characterized by dysarthria, dysphagia, drooling and paresis of the right arm associated with almost continuous diffuse sharp-slow wave complexes during sleep. These symptoms were not directly related to seizures or to each sharp-slow wave complex revealed by examination during the video electroencephalographic (EEG) recording. The interictal single photon emission compute tomography showed a localized high perfusion area in the left posterior frontal region. The introduction of clonazepam completely controlled the clinical symptoms as well as the EEG abnormality within 2 weeks. After 4 months of remission, a similar episode recurred which was associated with aggravation of EEG. The clinical and EEG characteristics of this patient were identical to those of acquired epileptiform opercular syndrome (AEOS), a newly proposed epileptic syndrome, in which a transient operculum syndrome develops in association with continuous spike-and-wave activity during slow sleep (CSWS). Computer-assisted EEG analysis demonstrated that the epileptic EEG focus was located in the left sylvian fissure, and produced secondary bilateral synchronous sharp-slow complexes. The present study further supports the hypothesis that the electrical interference by CSWS creates bilateral opercular dysfunction through the mechanism of secondary bilateral synchrony, thus producing AEOS.

Child, Preschool↗
PubMed2001

Long-term effect of flunarizine on patients with alternating hemiplegia of childhood in Japan.

To determine the effect of flunarizine therapy on patients with alternating hemiplegia of childhood (AHC), we sent a questionnaire by mail to council members of the Japanese Society of Child Neurology. We collected 28 AHC patients, and studied their clinical courses and the effects of drug therapy. All of the patients had received flunarizine. In 18 of the 28 patients, flunarizine reduced the severity, duration, or frequency of the hemiplegic attacks. No other drug was more effective than flunarizine. Some flunarizine non-effective patients were severely deteriorated, for example, they had dementia or were ventilator-assisted. Flunarizine had not only a short-term effect, i.e. it reduced the hemiplegic attacks, but also a long-term effect on the motor and intellectual development in some patients with AHC. Flunarizine is still an essential drug for treating AHC.

Adolescent↗
PubMed2001

Severe myoclonic epilepsy in infants--a review based on the Tokyo Women's Medical University series of 84 cases.

Severe myoclonic epilepsy in infants (SME) is one of the most malignant epileptic syndromes recognized in the latest classification of epileptic syndromes. The clinical details and electroencephalographic (EEG) characteristics have been elucidated by Dravet et al. The diagnosis of SME depends largely on the combination of clinical and EEG manifestations at different ages, of which the presence of myoclonic seizures appears to be the most important. However, because of the inclusion of different types of myoclonic attack and the lack of strict criteria for diagnosing SME, there has been some confusion as to whether patients without myoclonic seizures or myoclonus should be classified as SME, despite other identical clinical symptoms (SME borderlands (SMEB) group). Among the various clinical manifestations characterizing SME, special attention has been paid to seizures easily precipitated by fever and hot baths in Japan. We have demonstrated that the onset of myoclonic attack in these patients is very sensitive to the elevation of body temperature itself rather than its etiology. Using simultaneous EEG and rectal temperature monitoring during hot water immersion, we showed that epileptic discharges increased in frequency, and eventually developed into seizures at temperatures over 38 degrees C. We believe that the unique fever sensitivity observed in SME is similar to, but more intense than that of febrile convulsions. We have also identified a group of cases who have had innumerous myoclonic and atypical absence seizures daily which were sensitive to the constant bright light illumination. In these cases, spike discharges increased or decreased depending on the intensity of constant light illumination. Although these cases form the most resistant SME group, they lost the constant light sensitivity with increasing age, leaving only relatively common types of fever-sensitive grand mal seizures (FSGM) at the age of around 5 years. In the long run, only convulsive seizures continue, while myoclonic or absence seizures and photosensitivity disappear with advancing age, thus it is conceivable that SMEB constitutes a basic epileptic condition underlying SME. There is a clinical continuum that extends from the mildest end of SMEB to the severest end of SME with constant light sensitivity, with intermediates of frequent or infrequent myoclonic and absence seizures in-between. This spectrum concept appropriately explains the clinical variabilities between SME and SMEB during early childhood.

Electroencephalography↗
PubMed2001

Myoclonic-astatic epilepsy of early childhood--clinical and EEG analysis of myoclonic-astatic seizures, and discussions on the nosology of the syndrome.

PURPOSE: The aim of this study is to elucidate the clinical and neurophysiological characteristics of the myoclonic, myoclonic-astatic, or astatic seizures in patients with myoclonic-astatic epilepsy (MAE) of early childhood, and to discuss on the nosology of this unique epileptic syndrome. SUBJECTS: The subjects included 30 patients, who fulfilled the following modified International League Against Epilepsy (ILAE) criteria for MAE, and whose main seizures were captured by video-electroencephalographs (EEG) or polygraphs. The modified ILAE criteria includes: (1) normal development before onset of epilepsy and absence of organic cerebral abnormalities; (2) onset of myoclonic, myoclonic-astatic or astatic seizures between 7 months and 6 years of age; (3) presence of generalized spike- or polyspike-wave EEG discharges at 2-3 Hz, without focal spike discharges; and (4) exclusion of severe and benign myoclonic epilepsy (SME, BME) in infants and cryptogenic Lennox-Gastaut syndrome based on the ILAE definitions. RESULTS: The seizures were investigated precisely by video-EEG (n=5), polygraph (n=2), and video-polygraph (n=23), which identified myoclonic seizures in 16 cases (myoclonic group), atonic seizures, with or without preceding minor myoclonus, in 11 cases (atonic group), and myoclonic-atonic seizures in three cases. All patients had a history of drop attacks, apart from ten patients with myoclonic seizures. Myoclonic seizures, involving mainly the axial muscles were classified into those with mild intensity not sufficient to cause the patients to fall (n=10) and those that are stronger and sufficient to cause astatic falling due to flexion of the waist or extension of the trunk (n=6). Patients in the atonic group fell straight downward, landed on their buttocks, and recovered immediately. Analysis of the ictal EEGs showed that all attacks corresponded to the generalized spike or polyspikes-and-wave complexes. In the atonic form, the spike-and-wave morphology was characterized by a positive-negative-deep-positive wave followed by a large negative slow wave. In two patients, the intensity of the atonia appeared to correspond to the depth of the positive component of the spike-and-wave complexes. We did not detect any significant differences in the clinical and EEG features and prognosis, between the atonic and myoclonic groups. CONCLUSIONS: Although the determination of exact seizure type is a prerequisite for diagnosing an epileptic syndrome, the strict differentiation of seizure type into either a myoclonic or atonic form, does not appear to have a significant impact on the outcome or in delineating this unique epileptic syndrome. At present, we consider it better to follow the current International Classification of Epileptic Syndromes and Epilepsies until a more appropriate system than the clinico-electrical approach for classifying patients with MAE is available.

Child, Preschool↗
PubMed2001

Study on early-onset benign occipital seizure susceptibility syndrome.

We prospectively studied the early-onset benign occipital seizure susceptibility syndrome to confirm the benign prognosis. The patients were 37 children followed for more than 2 years after meeting the following criteria on the first examination: (1) normal development before the onset of epilepsy, (2) onset between 1 and 8 years of age, (3) normal brain MRI and cranial CT findings, (4) partial seizures manifested both initial ictal vomiting and tonic eye-deviations, and (5) normal background activity with or without epileptic EEG foci regardless of location. The incidence and clinical characteristics of seizures, response to treatment, and EEG findings were analyzed. The total number of seizures ranged from one (n = 6) to 27 times, with a median of five times. Recurrent prolonged attacks resistant to antiepileptic drugs were recognized in 15 children, who had earlier onset of epilepsy and more frequent complications than the remaining 22 children. Interictal EEG revealed occipital foci in 26 children, 17 of whom later revealed a shift in predominant foci. At the final examinations, 28 patients had been seizure-free for at least 2 years. The clinical picture of this syndrome ranges from those with a few seizures to those with recurrent prolonged seizures initially resistant to antiepileptic drugs despite ultimate remission by 12 years of age.

Age Factors↗
PubMed2001

A case of MERRF associated with chronic pancreatitis.

We report the first case to our knowledge of chronic pancreatitis associated with mitochondrial encephalopathy with the A8344G mitochondrial DNA (mtDNA) mutation. This 10-year-old-girl had suffered from recurrent abdominal pain with elevated serum amylase and lipase since the age of 6, and easy fatigability, tremor and astatic seizures since the age of 8. A biopsy of quadriceps muscle revealed ragged-red-fibers and cytochrome c oxidase deficiency. Analysis of mtDNA in peripheral blood identified an A8344G mutation in the mitochondrial tRNA(Lys) gene. Taken together with physical signs of myoclonic seizures and cerebellar dysfunction, we diagnosed her as myoclonic epilepsy with ragged-red fibers associated with chronic pancreatitis. Although no association between mitochondrial disease and pancreatitis has yet been established, this case suggests it is necessary to consider the participation of mitochondrial abnormality in the pathogenesis of recurrent pancreatitis.

Brain↗
PubMed2001

Neurophysiological study of secondary synchronous occipito-frontopolar spikes in childhood.

OBJECTIVES: We conducted this latency study to clarify the neurophysiological mechanism underlying the synchronous appearance of independent occipital and frontopolar spike discharges in childhood epilepsies. METHODS: The subjects were 13 children with localization-related epilepsies (LRE) who showed apparently synchronous occipital and frontopolar EEG spike discharges. There was idiopathic LRE in 7 children, symptomatic LRE in 4, and cryptogenic LRE and a history of cryptogenic West syndrome in one patient each. Patient ages at the time of the study ranged from 4 years 3 months to 14 years 0 month with a mean of 9 years 4 months. The EEGs were digitized at 1024 samples/s. The latency was measured between the peak of the occipital and frontopolar spike discharges. The conduction velocity was calculated by dividing the distance between the occipital and frontopolar electrodes by the latencies. RESULTS: We studied 19 EEGs including 6 serial EEGs recorded longitudinally in 5 patients. The number of occipito-frontal spike discharges available for the study ranged from 12 to 70 with an average of 36+/-17 in each EEG record. Occipital spikes always preceded the frontopolar spikes by 11.1-31.6 ms (average 19.3+/-5.4 ms). The estimated conduction velocity ranged from 6.7 to 19.2 m/s with a mean of 12.2+/-3.7 m/s. CONCLUSIONS: The synchronizing spike phenomenon we showed in this study was in the posterior to anterior direction (intrahemispheric synchrony) in contrast to that of secondary bilateral interhemispheric synchrony through the corpus callosum. It is suggested that the long occipito-frontal association fibers play a role in synchronizing both spike discharges. This secondary occipito-frontopolar synchrony should be one of the developmental EEG phenomena related to the maturation of brain, and contribute to the multiplication or diffusion of the pre-existing localized spike discharges often seen in pediatric LRE regardless of etiology.

Action Potentials↗
PubMed2001

Culturally verified Mycoplasma pneumoniae pneumonia in Japan: a long-term observation from 1979-99.

We describe the prevalence of community-acquired M. pneumoniae pneumonia diagnosed by culture methods in a single institute in Japan from January 1979 to December 1999. Cultures were performed in 2971 pneumonia cases and yielded M. Pneumoniae in 508 cases. The epidemic peaks recurred regularly at 4-year intervals (1980, 84, 88 and 91-2). Although a large epidemic has not occurred since 1992, traces of epidemic periodicity have still persisted from 1992 to 1999 at 3-year intervals.

Adolescent↗
PubMed2001

Increased cell surface expression of C-terminal truncated erythropoietin receptors in polycythemia.

Primary familial and congenital polycythemia (PFCP) is a disorder characterized by an increased number of erythrocytes despite normal blood oxygen pressure and a normal serum erythropoietin (EPO) level. Recent studies revealed that erythroid progenitor cells from certain individuals with PFCP express various forms of EPO receptor (EPOR) truncated at the terminal carboxyl site (EPOR-TTC(PFCP)). EPOR-TTC(PFCP) can transmit EPO-mediated proliferative signals more efficiently than can full-length EPOR (EPOR-F), at least partly because of defective recruitment of SHP-1 phosphatase to these receptors. In agreement with previous studies, Ba/F3 transfectants expressing EPOR-TTC(PFCP) showed higher proliferative responses to EPO. In those transfectants, we found that EPOR-TTC(PFCP) was expressed more abundantly on the cell surface than was EPOR-F. This tendency was confirmed by a transient-expression experiment using COS7 cells. Since expression levels of EPOR protein were not significantly different among these transfectants, differences in cell surface expression were likely dependent on post-translational mechanism(s). In addition to defective recruitment of SHP-1 to EPOR-TTC(PFCP), more efficient transport and expression on the cell surface appear to serve as mechanisms responsible for increased EPO-responsiveness of erythroid progenitor cells in PFCP.

Amino Acid Sequence↗
PubMed2001

The ABC transporter Bcrp1/ABCG2 is expressed in a wide variety of stem cells and is a molecular determinant of the side-population phenotype.

Stem cells from bone marrow, skeletal muscle and possibly other tissues can be identified by the 'side-population' (SP) phenotype. Although it has been assumed that expression of ABC transporters is responsible for this phenotype, the specific molecules involved have not been defined. Here we show that expression of the Bcrp1 (also known as Abcg2 murine/ABCG2 human) gene is a conserved feature of stem cells from a wide variety of sources. Bcrp1 mRNA was expressed at high levels in primitive murine hematopoietic stem cells, and was sharply downregulated with differentiation. Enforced expression of the ABCG2 cDNA directly conferred the SP phenotype to bone-marrow cells and caused a reduction in maturing progeny both in vitro and in transplantation-based assays. These results show that expression of the Bcrp1/ABCG2 gene is an important determinant of the SP phenotype, and that it might serve as a marker for stem cells from various sources.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Anaesthetic management of 27 cases of boron neutron capture therapy for glioblastoma.

Twenty-seven patients received boron neutron capture therapy during craniotomy at our research reactor from 1991 to 1999. This is a form of intra-operative radiation therapy, which uses neutrons from a nuclear reactor. There are three additional major problems to anaesthetists: boron neutron capture therapy must be given beside the nuclear reactor, with no hospital facilities; neutrons cannot be shielded effectively by ordinary protectors; and neutrons are detrimental to metal devices and especially to electrical appliances. Boron neutron capture therapy has been adopted as an effective therapy for glioblastoma/astrocytoma, but special considerations are required for anaesthesia.

Anesthesia, General↗
PubMed2001

Amygdala kindling develops without mossy fiber sprouting and hippocampal neuronal degeneration in rats.

Repeated electrical stimulation of limbic structures has been reported to produce the kindling effect together with morphological changes in the hippocampus such as mossy fiber sprouting and/or neuronal loss. However, to argue against a causal role of these neuropathological changes in the development of kindling-associated seizures, we examined mossy fiber sprouting in amygdala (AM)-kindled rats using Timm histochemical staining, and evaluated the hippocampal neuronal degeneration in AM-kindled rats by terminal deoxynucleotidyl transferase-mediated digoxigenin-11-dUTP nick end labelling (TUNEL). Amygdala kindling was established by 10.3 +/- 0.7 electrical stimulations, and no increase in Timm granules (neuronal sprouting) was observed up to the time of acquisition of a fully kindled state. However, the density and distribution of Timm granules increased significantly in the dentate gyrus compared with unkindled rats after 29 after-discharges or more than 10 kindled convulsions. In addition, no significant increase in TUNEL-positive cells was found in the hilar polymorphic neurons or in CA3 pyramidal neurons of the kindled rats that had fewer than 29 after-discharges. However, a significant increase of TUNEL-positive cells was found in the granule cell layer in the dentate gyrus of the stimulated side after 18 after-discharges or 10 kindled convulsions. Our result show that AM kindling develops without evidence of mossy fiber sprouting, and that mossy fiber sprouting may appear after repeated kindled convulsions, following death of the granule cells in the dentate gyrus.

Amygdala↗
PubMed2001

Haplotype analysis of the human alpha2-HS glycoprotein (fetuin) gene.

Alpha2-HS glycoprotein (AHSG), which is equivalent to fetuin in other species, is a protein found in human plasma. AHSG is polymorphic with two common alleles and many variants. To examine the intragenic haplotypes and their diversity at this locus, a contiguous genomic DNA sequence (10.3 kb) was analyzed in 20 samples (40 chromosomes), and haplotypes were determined for 309 subjects. Judging from the aligned nucleotide sequences and the conserved amino acid residues comparing human and chimpanzee AHSG, it was concluded that the type 1 allele is probably older and has evolved into four major suballeles. The type 2 allele was generated from one branch of the type 1 allele. AHSG*3 and *5 variants were each found to have a single nucleotide change in exon 7, resulting in the change of an amino acid residue from Arg299 to Cys and from Asp258 to Asn, respectively. It was noted that the AHSG*3 mutation gives rise to an additional cysteine residue, which possibly affects the conformation of the protein. The AHSG gene was found to have a low mutation rate and no apparent recombination events. Furthermore, the detected substitutions were nonhomogeneously distributed at this locus. In particular, four nonsynonymous substitutions were concentrated in the carboxyl-terminal domain.

Alleles↗
PubMed2001

A study of the effect of color photostimulation from a cathode-ray tube (CRT) display on photosensitive patients: the effect of alternating red-cyan flicker stimulation.

PURPOSE: In an attempt to establish evidence for developing better guidelines for the production of animation programs that would not induce photosensitive seizures in Japan, we evaluated the effects of red flicker, alternating red/cyan (complementary color to red) flicker stimuli, and of contrast between the red and cyan frames from a cathode-ray tube (CRT) display in photosensitive patients. METHODS: We studied 35 photosensitive patients. They were exposed to seven types of flicker. The first three types were alternating red/cyan flicker (R/C) with the luminance of cyan set at three different levels, high, equal, and low luminance (65, 20, and 16 cd/m2, respectively) relative to the red (20 cd/m2). The following four types were red, cyan, yellow, and magenta flicker stimuli. EEGs were recorded while the patients watched these stimuli on a CRT display. RESULTS: Rates of photoparoxysmal response (PPR) provocation were 11.4, 13.7, and 14.0% with high-, no- and low-contrast R/C flicker, respectively, and 3.7% with red flicker. The differences between red and each of the other R/C flicker stimuli were all statistically significant (p<0.05, 0.01, 0.01). No significant differences were found between the effects by each of the three levels of contrast in alternating R/C flicker (p > 0.05). CONCLUSIONS: These findings suggest that alternating R/C flicker is more provocative than simple red flicker, and that contrast between frames of different colors may play some role in the effects of alternating flicker stimuli from a CRT display in photosensitive patients. Therefore, caution against the use of the combination of red and cyan, in addition to the red flicker stimulus, should be included in any guidelines drawn up to prevent photosensitive seizures.

Adolescent↗
PubMed2001

Study on photo-pattern sensitivity in patients with electronic screen game-induced seizures (ESGS): effects of spatial resolution, brightness, and pattern movement.

PURPOSE: With the ever-increasing popularity of computers, electronic screen game-induced seizure (ESGS) is beginning to pose a serious social problem. To elucidate the pathophysiology of ESGS, with the ultimate goal of prevention, we have been studying photo-pattern sensitivity in detail with a pattern-stimulation test using a CRT (cathode ray tube) display. This method is referred to as the "CRT-pattern test." METHODS: We studied 17 patients brought to our department for evaluation of ESGS. EEG responses were recorded during exposure to various patterns consisting of three elements: spatial resolution, brightness perception, and pattern-movement recognition displayed on a CRT monitor. Photo-paroxysmal response (PPR) frequencies were compiled for each stimulation. RESULTS: PPR was induced by the CRT-pattern test in nine of the 17 cases. In four cases, PPR induction was obtained only after introducing CRT-pattern tests in addition to standard intermittent photic stimulation (IPS). The rate of PPR induction differed according to the type of pattern, spatial frequency, and pattern-reversal frequency. However, neither the clarity of the edges of a pattern nor changes in the brightness of a pattern element had any effect on the rate of PPR induction. With the exception of a few subjects, the stimulation caused by pattern movement was not effective in eliciting PPR. Six cases in whom spatial resolution was involved showed occipital dominance in PPR provocation, and three in whom brightness perception and pattern movement recognition was involved showed frontal dominance. CONCLUSIONS: The CRT-pattern test is useful for identifying patients with photosensitivity among patients considered to have incidental or nonphotosensitive seizures unresponsive to standard IPS. Patients with ESGS caused by photosensitivity can be divided into two groups: those with occipital dominance for PPR provocation, in whom spatial resolution is involved; and another group with frontal dominance, in whom brightness perception and pattern-movement recognition (or possibly perception of colors) are involved.

Adolescent↗
PubMed2001

Phenytoin-induced choreoathetosis in patients with severe myoclonic epilepsy in infancy.

We describe three patients with severe myoclonic epilepsy in infancy (SME) who suffer from choreoathetosis due to the adverse effect of phenytoin. Choreoathetosis appeared when these patients were 8, 19, and 21 years old, 2 days to 6 months after increasing the phenytoin dosage. Choreoathetosis disappeared when the phenytoin dosage was decreased. The two elder patients experienced episodic and rather paroxysmal onset of long-lasting choreoathetosis, requiring the differential diagnosis from degenerative disease. In one of the patients, an ictal SPECT revealed decreased perfusion in the basal ganglia contralateral to the unilateral choreoathetosis. Polypharmacy, including carbamazepine and zonisamide, may have facilitated the onset of choreoathetosis. Phenytoin-induced choreoathetosis in the patients with SME is an important differential diagnosis among degenerative disorders involving involuntary movements. The episodic and paroxysmal nature of this movement disorder can delay its diagnosis and effective treatment. Patients with SME appear to be particularly vulnerable to this side effect of phenytoin, indicating the possible involvement of basal ganglia in the pathophysiology of this type of epilepsy.

Adolescent↗
PubMed2001

Characteristics of breathing abnormality in Leigh and its overlap syndromes.

In this report we describe the respiratory patterns of six patients with Leigh syndrome, including two individual cases with accompanying clinical phenotypes of Alpers disease and mitochondrial encephalopathy with ragged red fibers. In five cases where sleep apnea was monitored, each one showed isolated or post-sigh central apnea, hiccup, apneusis-like breathing and obstructive apnea in various combinations. The remaining patient with Alpers/Leigh overlap syndrome showed an apneusis-like pattern of dyspnea. The sleep structure was examined in three patients. Two patients with brainstem lesions showed a decrease in the deep sleep stages and an absence of REM sleep. Medullary lesions were found in four patients by magnetic resonance imaging or at autopsy and involved predominantly the dorsal respiratory group (DRG) of medullary neurons. The role of DRG lesions in the pathophysiology of respiratory symptoms in Leigh syndrome is discussed.

Brain↗