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Biomedical subjects

T Koeda

Publications and source records attributed to T Koeda.

At least 19 recordsLinked to original sources
PubMed2001

A functional magnetic resonance imaging study during sentence reading in Japanese dyslexic children.

A functional magnetic resonance imaging (fMRI) study during Japanese 'kana' readings was performed on Japanese dyslexic children. Five dyslexic children (aged 9-12 years) and five healthy children (aged 9-11 years) were investigated. The fMRI examination was performed by getting these children to read sentences constructed from Japanese phonograms, 'kana', compared with staring at meaningless figures as a control task. All control subjects showed activation of the left middle temporal gyrus. In the dyslexic children, the activation of the middle temporal gyrus was rather vague. However, other distinctively activated regions were detected as follows: the bilateral occipital cortex in two dyslexics, the inferior part of the frontal regions in two other dyslexics, and both the bilateral occipital cortex and the inferior part of precentral gyrus in the remaining one. These results indicate compensatory management processes for the unskilled reading ability of dyslexic children. The present results were similar to previous ones for adult dyslexia with the Roman alphabet, and suggest that brain malfunction in dyslexia during the task of reading must be common despite differences in languages.

Cerebral Cortex↗
PubMed2000

Cognitive and neurophysiological evaluation of Japanese dyslexia.

Seven Japanese dyslexic boys were evaluated as to their pedagogic performance on the pupil rating scale (PRS), and psychological and neurophysiological characteristics. One of them suffered from severe English dyslexia despite that his Japanese dyslexia was feeble. PRS did not successfully reveal their reading difficulties. Psychological examination (WISC-R and K-ABC) revealed their cognitive dysfunction, but the results were heterogeneous. The Token test was most useful for detecting their poor reading comprehension. Electroencephalogram (EEG) coherence analysis showed high inter- and intra-hemispheric values. These findings may imply hyperconnectivity of the cerebral white matter in dyslexia. We assumed that the Token test demonstrates the discrepancy between reading and hearing comprehension best of all among these psychological tests and that connectivity between non-functional cortical lesions remains in dyslexic children.

Adolescent↗
PubMed2000

Effects of prestimulus respiratory levels on inhibitory respiratory response by nociceptive muscular afferents.

We have previously shown that the inhibitory respiratory response, which we call post-stimulus suppression, is induced by nociceptive muscular afferents. This phenomenon is thought to be caused by a negative feedback induced by excessive afferent inputs. In the present study, we investigated whether augmented levels of prestimulus respiration would influence the magnitude of poststimulus suppression by recording the phrenic nerve discharges in chloralose-urethane anesthetized, vagotomized, paralyzed and artificially ventilated cats. The respiratory level was augmented by means of either hypercapnia, hypoxia or naloxone administration, all of which markedly facilitated the peak amplitude (PK) of integrated phrenic discharges, neural tidal volume. When the electrical stimulation of thin-fiber muscular afferents was performed at these augmented PK levels, the magnitude of poststimulus suppression in the PK was markedly attenuated without consistently altering the facilitatory response during the stimulation period. It seems that the facilitatory component of the augmented level of resting respiration may reduce the inhibitory component of poststimulus suppression. The results indicate that prestimulus respiratory activity is an important factor in determining the magnitude of poststimulus suppression.

Animals↗
PubMed2000

[Distribution in normal subjects of performance in Token test: a basic study for the diagnosis of learning disabilities].

For the diagnosis of specific reading disorder (SRD) we studied the distribution in 187 elementary school children of the scores of Token test. Token test was performed under two conditions: listening and reading by presenting the same sentences. The diagnosis required a normal score under the listening condition, an abnormally low score under the reading condition and significantly large discrepancy between them. This test is valid and convenient for the diagnosis of SRD.

Acoustic Stimulation↗
PubMed1999

Screening of urine by one-dimensional and pulsed-field gradient two-dimensional 1H NMR spectroscopy: intoxication by propylene glycol in an infant patient.

1H NMR spectroscopy is a promising method for the analysis of physiological fluids in clinical medicine. In the course of screening the urine of patients by 1D- and pulsed-field gradient 2D 1H NMR spectroscopy at 500 MHz, we encountered a case with a very high excretion of propylene glycol compared to others who received similar doses of the medication. In this case, the propylene glycol was scarcely metabolized by the patient. Propylene glycol is widely used as a safety material which is transformed into pyruvate and lactate in the healthy body. In this paper, we discuss how NMR spectroscopy can be a useful method for screening a patient intoxicated with propylene glycol.

Female↗
PubMed1999

A patient with cerebral palsy whose mother had a traffic accident during pregnancy: a diffuse axonal injury?

A 16-year-old girl had spastic cerebral palsy (CP) with triplegia and focal epilepsy. The patient's past history included her mother's lower abdominal trauma caused by a traffic accident at the 7th month of gestation. Brain examination with magnetic resonance imaging (MRI) revealed encephalomalacia at the bilateral parieto-temporal lobes and the left caudate nucleus, segmental narrowing of the splenium of the corpus callosum, dilatation of the left lateral ventricle and an abnormally high intensity at the right posterior portion of the internal capsule. These findings might indicate a diffuse axonal injury (DAI), but not an asphyxic brain damage. In this patient, CP might be caused by an intrauterine DAI when her mother was involved in the accident.

Accidents, Traffic↗
PubMed1999

Experimental actinomycosis caused by Actinomyces-like bacteria in mice and a sow.

The present experiment was performed to test the pathogenicity of Actinomyces-like bacteria in experimental animals and swine. Two rough (R) strains of Actinomyces-like bacteria isolated from a site of arthritis and from the tonsil in pigs were used as inocula. To investigate their susceptibility to Actinomyces-like bacteria, BALB/c, SS and ddY mice and guinea-pigs were inoculated intraperitoneally with the strains of Actinomyces-like bacteria. The ddY mice were used for the long-term observation of Actinomyces-like bacteria lesions and the mammary tissue of a sow was inoculated with Actinomyces-like bacteria isolated from swine tonsil. Macroscopic observation revealed many abscesses on the surfaces of the abdominal and/or thoracic organs in the mice, but not on those of the guinea-pigs. The sow developed firm nodules at the inoculation site in the mammary glands. Histopathologically, the lesions in the mice were characterized as actinomycotic abscesses in the early stage and as pus-forming granuloma (PFG) in the advanced stage; the lesions were accompanied by crystalloid particles. Actinomyces-like bacteria induced granulomatous mastitis in the sow, and the lesion was characterized as PFG. The characteristic actinomycotic lesions in swine mammary glands were reproduced by experimental infection.

Actinomyces↗
PubMed1999

Low interhemispheric and high intrahemispheric EEG coherence in migraine.

Twenty women with migraine were evaluated by EEG coherence analysis. In comparison with controls, the migrainous subjects showed lower interhemispheric coherence values at C3-C4 for the delta band (P=0.0030) and at F3-F4 (P=0.0055) and C3-C4 (P=0.0018) for the beta band frequency (Wilcoxon criterion). In contrast, 22 intrahemispheric coherence pairs were significantly higher in the migraine group than in the control group (P<0.01). The subjects with visual aura showed lower interhemispheric coherence at O1-O2 and T5-T6 for the alpha band than the subjects without the aura. Discriminant analysis revealed that 95% of the subjects with migraine and 85% of the controls were correctly classified into their proper groups. We suggest that EEG coherence analysis is a sensitive parameter in the detection of electrophysiological abnormalities in patients with migraine.

Adolescent↗
PubMed1999

Central motor reorganization in cerebral palsy patients with bilateral cerebral lesions.

Transcranial magnetic stimulation (TMS) has been used to describe cortical plasticity after unilateral cerebral lesions. The objective of this study was to find out whether cortical plasticity occurs after bilateral cerebral lesions. We investigated central motor reorganization for the arm and leg muscles in cerebral palsy (CP) patients with bilateral cerebral lesions using TMS. Seventeen patients (12 with spastic diplegia, 1 with spastic hemiplegia, and 4 with athetoid CP) and 10 normal subjects, were studied. On CT/MRI, bilateral periventricular leukomalacia was observed in all spastic patients with preterm birth. In two normal subjects, motor responses were induced in the ipsilateral tibialis anterior, but no responses were induced in any normal subject in the ipsilateral abductor pollicis brevis (APB) or biceps brachii (BB). Ipsilateral responses were more common among CP patients, especially in TMS of the less damaged hemisphere in patients with marked asymmetries in brain damage: in 3 abductor pollicis brevis, in 6 BBs, and in 15 tibialis anteriors. The cortical mapping of the sites of highest excitability demonstrated that the abductor pollicis brevis and BB sites in CP patients were nearly identical to those of the normal subjects. In patients with spastic CP born prematurely, a significant lateral shift was found for the excitability sites for the tibialis anterior. No similar lateral shift was observed in the other CP patients. These findings suggest that ipsilateral motor pathways are reinforced in both spastic and athetoid CP patients, and that a lateral shift of the motor cortical area for the leg muscle may occur in spastic CP patients with preterm birth.

Adolescent↗
PubMed1999

[What has medical science resolved learning disabilities (LD) into?: introductory remarks].

What can medicine contribute to learning disabled (LD) children? In this symposium, most distinguished speakers in Japan discuss the following issues: the incidence of LD in children with preterm birth, biochemical aspect in LD children neurophysiological examinations for LD and speech therapy for specific reading disorders. Brain dysfunctions in LD children should be clarified to facilitate remedial interventions. It is expected that medical insurance supports LD children and their family.

Child↗
PubMed1999

[Learning disabilities; toward adequate treatment and education].

The medical staff can serve learning disabled (LD) children by ruling out progressive and regressive diseases, and by treating concurrent disorders, such as attention deficit hyperactivity disorders (ADHD). Teachers and even some medical members in Japan have confused ADHD with LD. Although looking similar, these two disorders are completely different. We should further clarify the brain dysfunction in LD children, thereby contributing to remedial education.

Attention Deficit Disorder with Hyperactivity↗
PubMed1998

A case report of remarkable improvement of motor disturbances with L-dopa in a patient with post-diffuse axonal injury.

A 9-year-old girl with rigidospastic quadriplegia as post-traumatic sequela was reported. The distribution of lesions observed on a MRI implied diffuse axonal injury; involvement of the substantia nigra was also detected. L-Dopa administration was remarkably effective for relief of the rigidity. As a result, she became able to walk on her knees and communicate by writing letters. L-Dopa administration should be considered for patients who show rigidity as sequela of diffuse axonal injury with involvement of the substantia nigra.

Accidents, Traffic↗
PubMed1998

Slowly progressive cystic leukoencephalopathy with megalencephaly in a Japanese boy.

A Japanese boy with megalencephaly and leukoencephalopathy was reported. The clinical characteristics were as follows; slowly progressive megalencephaly starting at 8 months, and motor impairment with ataxia and spasticity, with relatively preserved intelligence and well-controlled epilepsy, and the following MRI findings; diffuse leukoencephalopathy in the supratentorial white matter with cystic subcortical white matter in the temporal tips and the fronto-parietal lobes. This corresponds to vacuolating leukoencephalopathy with megalencephaly, which was recently reported in European countries. In Japan, there were similar case reports previously, however, the patients were diagnosed as having Alexander's disease. It seems that this new leukoencephalopathy must also be seen among Japanese.

Brain↗
PubMed1998

Electroencephalographic coherence abnormalities in preterm diplegia.

Twelve patients with spastic diplegia (SD) and visuoperceptual impairments from preterm birth were evaluated for electroencephalogram (EEG) spectral power density, interhemispheric (ICoh) and intrahemispheric (HCoh) coherence, and asymmetry of coherence between the right and left hemispheres in and compared with normal children under resting conditions. There were no significant differences in EEG spectral power density. The SD group revealed lower ICoh at the occipital pair for the alpha band (P = .0034) and a higher value at the frontal pair for the theta band (P = .0047). Higher HCoh in SD was pronounced in the left hemisphere for the delta, theta, and beta bands (P < .01). There were no higher values in the control group. Higher HCoh asymmetry was exhibited in the left hemisphere in the control group, while very little asymmetry was found in the SD group. In both groups 91.7% were classified correctly by discriminant analysis. We suggest that these neurophysiologic abnormalities in preterm SD children correspond neuroanatomically to the callosal thinning and neuropsychologically to the visuoperceptual impairments.

Adolescent↗