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Biomedical subjects

M Shibagaki

Publications and source records attributed to M Shibagaki.

At least 55 records · Page 3Linked to original sources
PubMed1982

Effects of environmentally differential rearing upon maze performance in prenatally irradiated microcephalic rats.

Pregnant rats received 100 rads of X-irradiation on day 17 of gestation. Control pregnant rats were sham-irradiated on the same gestation day. The male offspring were reared under environmentally enriched, standard colony, and impoverished conditions for 30 days after weaning. Then the Hebb-Williams maze test was carried out. All the prenatally X-irradiated rats were microcephalic: their mean cerebral wet weight was 15.5% less than controls. The effect of X-irradiation was not significant in error scores and running times, whereas the effect of environment was significant in these items; initial and total error scores and running times were decreased in enriched groups compared to impoverished groups in controls as well as in X-irradiated animals.

Animals↗
PubMed1982

Concurrent occurrence of rapid eye movement with spindle burst during nocturnal sleep in mentally retarded children.

Concurrence of REM and sleep spindle in 45 mentally retarded children (from 4 months to 8 years of age) was studied throughout nocturnal sleep, and the following results were obtained. (1) Twenty-five cases showed a single or burst of REMs during stage NREM with sleep spindles. (2) Twenty-nine cases showed sleep spindles at the beginning or toward the end of stage REM sleep. (3) No significant difference in DQ was found between the subjects with and without REMs during stage NREM sleep. The former subjects, however, had more normal clinical EEGs than the latter. (4) No significant difference in DQ or clinical EEG classification was revealed between the subjects with REMs during stage NREM sleep and those with spindles during stage REM sleep. (5) It was concluded that the concurrence of REM and sleep spindle during stage NREM is a useful sign for early diagnosis of mental retardation.

Child↗
PubMed1982

Spindle evolution in normal and mentally retarded children: a review.

In neonates and infants, sleep-wake parameters indicate characteristic ontogenetic features. Sleep spindle activity also changes with maturation in terms of frequency, amplitude, and amount. For this reason, spindles are one of the useful indices of cerebral function in infants. The literature on the development of spindles in normal and mentally retarded children is reviewed.

Cerebral Cortex↗
PubMed1982

Developmental studies on EEG spectral analysis in mentally retarded children.

The EEG developmental characteristics of 36 mentally retarded infants were investigated by auto-power spectrum analysis. A significant positive correlation with age was found in the dominant frequency in all of the three regions, occipital, central, and frontal. A tendency for the generalized component to increase was found in 3- to 5-year-old subjects as compared with those aged 6 months to 1 year and 7 months. Developmental coherence characteristics could not be found. The peak components tended to show higher coherence values in the frontal-central relation than in the central-occipital and occipital-frontal ones.

Cerebral Cortex↗
PubMed1980

Sleep-waking cycle in microencephalic rats induced by prenatal methylazoxymethanol application.

Sleep-wakefulness cycle of adult microencephalic rats due to prenatal administration of methylazoxymethanol (MAM) acetate at the dose of 20 mg/kg on the 15th day of gestation showed no difference from the normal control group, whereas at the dose of 25 mg/kg, %PS and PS/TS decreased significantly. MAM-induced microencephalic rats revealed a significant increase of spindle bursts during PS, suggesting that their PS is less deep than that of the controls.

Animals↗
PubMed1980

Nocturnal sleep in severely mentally retarded children: abnormal EEG patterns in sleep cycle.

Sleep EEG patterns in 43 mentally retarded children (from 4 months to 80 years of age) were studied throughout nocturnal sleep and the following results were obtained. (1) Twenty-two cases evidenced normal sleep patterns that could be classified into 6 stages. (2) The 21 other cases showed some abnormal sleep EEG patterns as follows: (a) absence of sleep spindles (n = 18) which included cases of high voltage fast activity (n = 2) and cases of low voltage activity throughout nocturnal sleep (n = 3); (b) indistinguishable delta and theta activities (n = 1), extreme spindle-like pattern (n = 1), absence of REM sleep (n = 1). (3) The severely mentally retarded children under 18 months had definitely decreased spindle activity in comparison to the values obtained by other authors from normal children. (4) The majority of the abnormal sleep EEG patterns occurred during light sleep. (5) A significant decrease in DQ was found in children with abnormal sleep patterns throughout NREM sleep as compared with those in whom abnormal EEGs occurred only during stages 1 and 2. (6) It was concluded that the EEG recorded in nocturnal sleep may serve as a useful indicator of abnormality in mentally retarded children.

Cerebral Cortex↗
PubMed1977

The pathogenesis of Bartter's syndrome. Functional and histologic studies.

We describe a patient with Bartter's snyndrome. In addition to the well-known characteristic findings by light microscopy, electron micrograms confirmed the presence of juxtaglomerular cell hyperplasia with polymorphous renin secretory granules and dense multivesicular bodies. Volume expansion by albumin infusion decreased plasma renin activity and aldosterone excretion, and improved the pressor response to exogenous angiotensin, suggesting that the renin-angiotensin-aldosterone system was not autonomous but that a decreased extracellular volume might be a major defect in this patient. During hypotonic saline diuresis, moreover, fractional free water clearance per fractional distal sodium delivery, CH2O/CH2O + CNa, was markedly depressed in the patient when compared with the value in the controls. Evidence presented suggests that chronic extracellular volume depletion exists as a consequence of an impaired sodium transport in the ascending limb of Henle's loop.

Adult↗