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Biomedical subjects

H Yamadera

Publications and source records attributed to H Yamadera.

35 records · Page 2Linked to original sources
PubMed1996

A multicenter study of sleep-wake rhythm disorders: therapeutic effects of vitamin B12, bright light therapy, chronotherapy and hypnotics.

One hundred and six subjects with primary sleep-wake rhythm disorders [13 non-24 hour sleep-wake syndrome (non-24), 76 delayed sleep phase syndrome (DSPS), 11 irregular sleep-wake pattern (irregular) and six long sleepers] were treated with vitamin B12, bright light, chronotherapy and/or hypnotics. These therapies caused moderate or remarkable improvement in 32% of the non-24, 42% of DSPS, 45% of irregular and 67% of long sleepers. A lack of adequate sleep, unpleasant feelings at waking and daytime drowsiness were also improved in DSPS.

Adolescent↗
PubMed1996

Zopiclone pharmacodynamics: by monitoring event-related potentials and psychometric scores.

To investigate the pharmacological effects of zopiclone in the central nervous system, we monitored event-related potentials (ERPs, N100 and P300), the reaction time and the scores for subjective mental and emotional state (by using the Polarity Profile Questionnaire, PPQ) on 10 healthy right-handed male volunteers between 21 and 32 years old. Subjects were randomly allocated to receive a single oral administration of zopiclone 7.5 mg or placebo at the first-session, and the drug was crossed over at the second session 1 week later. ERPs, the reaction time and the psychometric scores were monitored at pre-drug, and 1, 3 and 5 hours after drug administration. In the zopiclone group, the reaction time was prolonged significantly at 1 hour after drug administration, the amplitudes of the ERPs significantly decreased at 1 and 3 hours after, and the PPQ scores showed significant changes. Maximum effects on the psychometric scores appeared later than those on ERPs and reaction time. Zopiclone decreased the arousal level and sensory sensitivity, and induced sedation through changes in subjective mental and emotional states.

Administration, Oral↗
PubMed1995

Laparoscopic splenectomy in children. Preliminary results and comparison with the open technique.

To determine the safety and efficacy of laparoscopic splenectomy (LS) in children, a retrospective review of our preliminary experience using LS was compared to results in patients who previously underwent open splenectomy (OS). From July 1993 to January 1995, we performed eight LS procedures in six children with hereditary spherocytosis (HS) and two with immune thrombocytopenic purpura (ITP). Laparoscopic cholecystectomy was simultaneously done in one case with HS. There were 4 males and 4 females who ranged in age from 5 to 15 years--an average age of 8.8 years. Two cases in the early series required a counterincision because of bleeding. Eleven patients who previously underwent OS in our department were used to compare demographics, operative courses, and surgical outcomes. The ages, genders, diseases, body weights, and spleen weights were comparable between LS group and OS groups. The operative time for the LS group was statistically longer than for the OS group (226 +/- 24 min vs 101 +/- 8 min, P < 0.001). The estimated blood loss in the LS group was similar to that of the OS group (100 +/- 39 ml vs 73 +/- 11 ml. P = 0.97). There were no peri- or postoperative complications in two groups. The postoperative hospital stay of LS group was statistically shorter than that of the OS (6.8 +/- 0.6 days vs 10.4 +/- .05 days, P < 0.0001). LS provided better cosmesis and minimized trauma in children over OS. LS appears to be a safe and effective procedure in children, and is useful in the management of pediatric patients with HS or ITP.

Adolescent↗
PubMed1995

[Study of zopiclone with quantitative EEG analysis and topography].

Zopiclone is a cyclopyrrolone derivative which possesses hypnotic activity. This drug is known to increase the slow sleep stage compared to benzodiazepines in polysomnography. The subjects were 10 right-handed healthy male volunteers aged 21-23 years. Double-blind crossover trials with placebo control were conducted in a random sequence at intervals of 1 week. Zopiclone 7.5 mg and placebo were administered as single oral doses. Three-minute vigilance controlled EEGs at before and at 1, 3, and 5 h after drug administration, and the response times were recorded. One minute out of the 3-minute EEGs was analyzed with FFT and the power spectrum was obtained. Then the absolute amplitude power (microV) was calculated. These results were subjected to Student's t-test (double difference) and displayed with topographic maps (t statistic significance probability mapping). Zopiclone prolonged the latency of the response time, and increased the amount of delta absolute amplitude power over the right central region, beta 1 absolute amplitude power over the left central region and beta 2 absolute amplitude power over the right central area along with decreased alpha absolute amplitude power over the occipital region and theta power over the left frontal pole area after 1 h, when the peak pharmacological effect was expected. The EEG profiles of zopiclone were different from that of diazepam reported previously concerning the increase in delta activity.

Adult↗
PubMed1993

Pharmaco-EEG mapping of diazepam effects using different references and absolute and relative power.

The effects of diazepam on the EEG were studied by means of EEG topographic mapping, using recordings with four different references. Subjects were ten healthy, right-handed, male volunteers aged 21-25 years. Double-blind crossover trials with a single oral dose of 10 mg diazepam and placebo controls were conducted in random sequence at intervals of one week. Four referential derivations--ipsilateral earlobe (A1A2), average reference (AV), source derivation (SD), and balanced noncephalic electrode (BNE)--were used. One-minute vigilance-controlled EEGs before drug administration and two hours after drug administration were analyzed using Fourier transformation; absolute power and relative power were calculated for four frequency bands. Diazepam caused a widespread increase of beta-frequency relative power, and a widespread decrease of theta-frequency absolute power when A1A2 and SD were taken as references. From the comparison of different reference electrodes we conclude that the selection of the reference and of spectral parameters (absolute power or relative power) play an important role in pharmaco-EEG studies.

Adult↗
PubMed1991

Effects of indeloxazine hydrochloride on sleep in normal humans.

The effects of 40 mg of indeloxazine hydrochloride, a cerebral metabolic enhancer, on sleep were investigated in 6 healthy male students. Polygraphic recordings were made for 8 consecutive nights on each subject. An inert placebo was given on the first 3 nights and on the 7th and 8th nights, and 40 mg of indeloxazine was administered on the 4th, 5th and 6th nights. Drug and placebo were administered orally at 21:30 h, and the recording of polysomnograms started at 22:00 h and ended at 8:00 h the next morning. The polysomnograms were evaluated by computerized automatic analysis using the interval histogram method. Indeloxazine prolonged both sleep latency and REM latency, and increased stage 1 sleep, but decreased stages 3, 4 and REM sleep. A significant increase of REM sleep was observed on the 7th and 8th recovery nights. No obvious changes were shown in the subjective assessments after administration of the drug. These results suggest that the effects of indeloxazine on sleep are similar to those of the tricyclic antidepressants. Furthermore, polysomnographic examinations might be useful in evaluating the pharmacological properties of cerebral metabolic enhancers.

Adult↗
PubMed1989

Adult pigment type (Peiffer) of sudanophilic leukodystrophy. Pathological and morphometrical studies on two autopsy cases of siblings.

Two autopsy cases of siblings with the adult pigment (Peiffer) type of sudanophilic leukodystrophy (SLD), which demonstrated the full-blown stage (case 1) and early stage (case 2) of demyelination, were examined. Numerous brown pigments deposited in demyelinated cerebral areas were characterized histochemically and ultrastructurally as lipofuscin and ceroid. Under the electron microscope formation of blebs due to myelin splitting associated with deposition of multilamellar myeloid bodies within them was a prominent feature in the demyelinated cerebral areas of case 2 as compared with case 1. However, various features of myelin degradation such as thinning, partial or complete circumferential myelin loss, and deposition of electron-dense material on the interperiodic lines were found in both cases. Blebs occurred in all layers of myelin, and axons were compressed by these blebs or the hydropically swollen inner lips of oligodendroglias. Oligodendroglias were relatively well preserved in the demyelinated and nondemyelinated areas in case 2, although the cytoplasm was hydropic. Many spheroids were present in demyelinated areas and were irregularly distributed in both cases. The peripheral nerves in case 1 presented essentially the same changes as those in the brain, although those in case 2 were not affected. Morphometrically, the results showed that hypomyelination was not the mechanism for this pigment type of SLD. One possible cause may be an accelerated ageing of the metabolic process of myelin turnover.

Astrocytes↗
PubMed1987

Quantitative pharmaco-electroencephalographic differentiation between the CNS effects of bromocriptine and imipramine, drugs with qualitatively different antidepressant properties.

Two double-blind, placebo-controlled studies were carried out at two different centers using the same protocol. Eight young healthy male volunteers were recruited for each of the studies, which were both undertaken to investigate the effect of single doses of 0.6, 1.25 and 2.5 mg bromocriptine (Parlodel) in comparison with 25 and 50 mg imipramine (Tofranil) on the electroencephalogram (EEG), subjective mental and emotional states, blood pressure, heart rate, and plasma prolactin levels. Side effects were also noted. The changes in the resting EEG power spectrum after imipramine were an increase in slow wave and fast beta activity and a decrease in alpha activity. At the same time imipramine depressed subjective mental and emotional states. Bromocriptine slowed the alpha activity of the resting EEG power spectrum, depressed subjective mental and emotional states, lowered blood pressure, and reduced prolactin secretion.

Adolescent↗
PubMed1985

Electroencephalographic and psychometric assessment of the CNS effects of single doses of guanfacine hydrochloride (Estulic) and clonidine (Catapres).

A double-blind, placebo-controlled study was carried out in 10 young healthy volunteers to investigate the effects of single doses of 1 and 2 mg guanfacine hydrochloride (Estulic) and 0.15 and 0.3 mg clonidine (Catapres) on the electroencephalogram (EEG), subjective mental and emotional state, blood pressure and heart rate. These doses are considered to be equipotent with regard to their antihypertensive effects, as shown in long-term therapeutic trials. Each subject received all five treatments in random sequence at intervals of 1 week. The EEG tracings were evaluated quantitatively by spectral analysis. Procedures were carried out before and at 1, 2, 4, 6 and 8 h after drug administration. After clonidine the EEG showed increased slow-wave activity and decreased alpha activity, these effects being dose-dependent. They were of the sedative type and did not clearly indicate specific psychotropic properties. The subjective mental and emotional state questionnaire indicated a decrease of alertness, extroversion, concentration and mood (in that order), changes which paralleled the EEG changes. The changes observed after guanfacine were qualitatively similar to those after clonidine, but were of considerably lower intensity. Our data suggest that guanfacine has less central nervous system-depressant activity than clonidine.

Adult↗