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S Mizukami

Publications and source records attributed to S Mizukami.

At least 19 recordsLinked to original sources
PubMed2002

Widespread activation of the brainstem preceding the recruiting rhythm in human epilepsies.

The excitability change of the brainstem was investigated before and during the conspicuous epileptic discharge in six patients with generalized convulsive seizures. The discharge consisted of a short duration of recruiting rhythm, which was considered equivalent to the seizure discharge on electroencephalogram. The excitability of the brainstem was measured with the parameters (amplitude and area) of component waves (wave-III and -V) of brainstem auditory evoked potentials. The theoretical background of the analysis is that brainstem auditory evoked potentials are 'far-field' potentials, by which they convey the information on the activity change of the brainstem even during the paroxysmal discharge within the cortex. The excitability of both the ventral (parameters of wave-III) and the dorsal brainstem (parameters of wave-V) exhibited a synchronized change (activation-inactivation). They were enhanced from -2.4+/-0.4 s, reaching the maxima before the onset of the seizure discharge, and decayed corresponding to the emergence of the recruiting rhythm. The results suggest the possibility that the widespread (ventral and dorsal) and synchronized activation of the brainstem triggers the seizure discharge in human generalized epilepsy. During the widespread activation of the brainstem, both the thalamus and the cortex probably undergo a suppressed inhibitory state through the cholinergic activation, precipitating the seizure discharge.

Acoustic Stimulation↗
PubMed2001

Brainstem activates paroxysmal discharge in human generalized epilepsy.

In nine patients with generalized epilepsy of convulsive seizures, the excitability change of the brainstem was evaluated over the course of the interictal paroxysmal discharge (poly spike-and-wave complex, poly SWC). The evaluation was carried out by a sequential analysis of brainstem auditory evoked potentials (BAEPs) before and during one sequence of poly SWC. The characteristics of BAEPs, i.e. far-field evoked potentials, allowed the evaluation of the excitability change in the brainstem, which was not influenced by the cortical activity. The excitability in the ventral brainstem, measured with the parameters of wave-III, showed a biphasic fluctuation (deceleration--acceleration) before the onset of poly SWC (minima at -0.7+/-0.4 s). On the other hand, the excitability in the dorsal brainstem, measured with the parameters of wave-V, showed no significant difference over the course of poly SWC. The results suggest that the biphasic excitability change in the ventral brainstem is conveyed to the cortex through the ascending activating system. The excitability acceleration preceded by deceleration in the ventral brainstem probably synchronizes the cortical activity profoundly enough to produce poly SWC through the activation of intralaminar thalamic neurons.

Adolescent↗
PubMed2000

Development of a time-resolved fluorometric detection system using diffusion-enhanced energy transfer

A novel detection system using both emission energy transfer and time-resolved fluorometry (TRF) was developed, with a europium chelate as the energy donor and a novel fluorophore SNR1, excitable with long-wavelength light corresponding to europium emission, as the energy acceptor. When the donor and acceptor molecules were mixed in solution, energy transfer was observed without direct attachment of the donor and the acceptor, via a diffusion-enhanced energy-transfer mechanism. Thus, the acceptor emission can be detected as a long-lifetime fluorescence in TRF. When the fluorescence properties of the acceptor molecule are changed by interaction with an enzyme or other bioactive molecule, the change can be detected as a long-lived sensitized emission. If we develop or select suitable acceptor molecules, this simple and convenient system should be applicable to a wide variety of bioactive molecules. Since it is based on TRF, it can be used for high-resolution assay.

Journal Article↗
PubMed2000

Time-course changes of eosinophil counts in premature infants: no effects of medical manipulation, except erythropoietin treatment, on eosinophilia.

In order to determine the factors responsible for eosinophilia during the neonatal period, we counted the eosinophils of premature infants every week and compared the medical profiles of infants with eosinophil counts above the 95th percentile and those below that percentile during the course of study. Medical treatments such as mechanical ventilation, antibiotics administration and intravenous catheterization had no significant effects on the increase of eosinophils. Furthermore, the incidence of eosinophil counts above the 95th percentile was not different between breast-fed and formula-fed infants. The infants treated with erythropoietin had greater eosinophil counts than those with no treatment. It is probable that medical manipulation using foreign bodies such as intratracheal tube, intravenous catheter, antibiotics and artificial formula had no significant effects on the increase of eosinophil counts, except for exogenous erythropoietin.

Disease Progression↗
PubMed2000

Are high barometric pressure, low humidity and diurnal change of temperature related to the onset of asthmatic symptoms?

BACKGROUND: Meteorologic factors play a role in the expression of asthmatic symptoms; however, there are controversies about the causal relationship between meteorologic factors and asthma. The relationship between meteorologic parameters and emergency admissions for asthmatic symptoms in this hospital were analyzed. METHODS: A total of 205 patients (130 boys and 75 girls, 0.1-16.6 years of age) who were admitted to Hakodate Chuo General Hospital for asthmatic symptoms between 1 January and 31 December 1997 were submitted to our study. We divided a total of 365 days into two groups of days with and without any admissions. Meteorologic factors for the days with admissions and 1-3 days before hospitalization were compared with those of the days of no admissions. Statistical analysis was done with the Mann-Whitney U-test. RESULTS: On the days with admissions and 1 day before hospitalizations, barometric pressure was higher and relative humidity lower than on days with no admissions. The diurnal difference between maximum and minimum temperature for days 1 day before days with admissions was larger than that for 1 day before days with no admissions. CONCLUSIONS: It is thought that change in barometric pressure, relative humidity and temperature had some influence on the worsening of asthmatic symptoms.

Asthma↗
PubMed1999

Brainstem triggers absence seizures in human generalized epilepsy.

Simultaneous analysis of brainstem auditory evoked potentials (BAEPs) with reference to electroencephalography (EEG) was designed to examine the brainstem function corresponding to the EEG event. With this method, we investigated the brainstem function pre- and during the paroxysmal discharge in human absence seizures classified as primary generalized epilepsy (PGE). Two types of functional change in the lower brainstem were revealed as parameters of wave-III components (amplitude and area) of BAEPs without significant change in the upper brainstem. One was long-range biphasic fluctuation (acceleration followed by abrupt deceleration with the maximum -6.4+/-3.2 s before the seizure onset), and the other was rhythmic oscillation with 3 Hz. The latter, synchronized with the cortical spike-and-wave complex, imposed on the descending slope of the former. One important point is that both preceded the onset of cortical paroxysmal discharge. The results reappraise the classical hypothesis of "centrencephalic system" on seizure generating mechanism in human PGE. The results prove the primary triggering role of the lower brainstem that is independent of sleep-related synchronizations. The method is applicable to other types of EEG event for the investigation of brainstem involvement.

Adolescent↗
PubMed1999

Imaging of caspase-3 activation in HeLa cells stimulated with etoposide using a novel fluorescent probe.

Microscopic visualization of intracellular enzyme activity can provide information about the physiological role of the enzyme. Caspases are cysteine proteases that have critical roles in the execution of apoptosis. General fluorometric substrates of caspase-3, such as DEVD-MCA, are unsuitable for imaging because they are excited at short wavelength, so we designed and synthesized novel fluorescent probes that are excited at suitable wavelengths for detecting caspase-3 activity in living cells. Using one of these probes, we succeeded in microscopic visualization of caspase-3-like activity within HeLa cells treated with etoposide. The caspase-3-like activity was increased in the cytosol at first, then expanded to the whole cell.

Apoptosis↗
PubMed1999

[The effect of olprinone administered after cardio-pulmonary bypass during open heart surgery, evaluated by its plasma concentrations and hemodynamic changes].

Plasma concentrations and hemodynamic effects of olprinone were evaluated in seventeen patients undergoing open heart surgery. The patients were randomized into the bolus group (15 micrograms.kg-1 bolus dose +0.1 microgram.kg-1.min-1 infusion, n = 9) and the non-bolus group (0.1 microgram.kg-1.min-1 infusion, n = 8). Plasma concentrations and hemodynamic variables were measured before CPB (cardiopulmonary bypass; baseline), 5, 60 min after weaning from CPB, and 3, 6 hours after the end of surgery. Plasma concentrations in the non-bolus group were significantly lower than those of bolus group at any point except for 3 hours after the end of surgery. In the bolus group, increases in the cardiac index and stroke volume index were significantly higher compared with the non-bolus group. From these results we conclude that olprinone given in bolus (15 micrograms.kg-1) followed by continuous infusion (0.1 microgram.kg-1.min-1) is efficacious and safe during weaning from CPB.

Aged↗
PubMed1999

[Energy metabolism in the cerebrum and the brainstem-cerebellum of the rat brain under hypoxic conditions].

The relationship between neuronal activity, intracellular oxygenation and energy metabolism in the cerebrum and the brainstem-cerebellum of the rat brain in graded hypoxia was studied. Intracellular oxygenation was monitored by near-infrared measurement of the redox state of cytochrome oxidase (cyt.ox.). Neuronal activity was assessed by EEG (electroencephalography) and the evoked potentials (VEP; visual, BSR; brainstem, C-SEP; cortical-sensory, S-SEP; spinal-sensory evoked potentials). As hypoxia progressed, neuronal activities disappeared in the order of VEP, C-SEP, EEG, BSR, S-SEP. However, intracellular oxygenation at the disappearance of each neuronal activity was significantly lower in the brainstem-cerebellum than in the cerebrum. ATP (adenosine triphasphate), glucose, and lactate were measured in the cerebral cortex, subcortex, brainstem, and cerebellum 1-2 minutes after the disappearance of neuronal activities on EEG. Hypoxia caused decreases in ATP in each brain region. Marked increases in lactate were observed in each brain region, though the degree of increment was less in the cerebral cortex than the other brain regions. A decrease in glucose was observed only in the cerebral cortex. These results suggest that by the use of the energy generated via glycolysis, the brainstem functions even after oxygen supply has been significantly reduced, while the neuronal activity in the cerebrum is suppressed at the higher oxygenation level than that in the brainstem-cerebellum. It is, thus, supposed that these differential responses of brainstem and cortical neurons to oxygen deprivation are inherent, and critical for neuronal survival in severe hypoxia.

Adenosine Triphosphate↗
PubMed1998

Posterior sinus node artery and accessory atrioventricular node artery arising by a common origin: a case report.

We describe herein a rare and hitherto not reported variation, found in a Japanese male cadaver, in which a posterior sinus node (SN) artery and an accessory atrioventricular node (AN) artery originate from a common trunk branching from the posterior segment of the circumflex artery. After arising in this manner, the posterior SN artery passed in a clockwise direction around the posterior, lateral, and finally anterior wall of the left atrium to the sinus venosus, giving off a branch to the SN from posteriorly. The accessory AN artery coursed in a counterclockwise direction on the posterior wall of the left atrium as far as the crux of the heart, where it bent anterosuperiorly and continued within the interatrial septum. It entered the AN from superiorly and, crossing deep to the principal AN artery, reached the inferior and superficial portion of this node. It could be considered that the accessory AN artery in this study is a modified version of arteries entering and coursing in the interatrial septum, as exemplified by Kugel's anastomotic artery.

Aged↗
PubMed1998

Anomalous triad of a left-sided inferior vena cava, a retroesophageal right subclavian artery, and bilateral superficial brachial arteries in one individual.

We report a rare case of three major vascular variations in the same individual, two within the thorax and abdomen and one within the upper extremity. The observations were made in a cadaver of a 74-year-old Japanese woman. A single left-sided inferior vena cava was observed that began from the confluence of the left and right common iliac veins and ascended vertically to the left side of the abdominal aorta. After receiving the left renal vein, it passed obliquely upward anterior to the abdominal aorta, reaching the right side of the aorta, and then ascended vertically to the right atrium, following its normal course. The retroesophageal right subclavian artery was also present; it arose from the arch of the aorta as the last branch, passing obliquely between the esophagus and the vertebral column. Thus the right recurrent laryngeal nerve was not formed. Additionally, bilateral superficial brachial arteries were observed. They arose from the axillary artery, crossed over the medial root of the median nerve, coursed down the arm, and divided into the radial and ulnar arteries in the cubital fossa. Although each variation is not rare by itself, the triad of events is rare and important to clinicians, anatomists, and medical students.

Aged↗
PubMed1998

Bilateral four-headed biceps brachii muscles: the median nerve and brachial artery passing through a tunnel formed by a muscle slip from the accessory head.

Bilateral four-headed biceps brachii muscles were observed in the dissected cadaver of a 95-year-old Japanese woman. The third head on both sides originated from the humerus at the insertion of the coracobrachialis and inserted into the distal part of the biceps brachii and the proximal part of the common biceps tendon on the ipsilateral side. The fourth head on both sides arose from a thin fibrous origin from the intertubercular sulcus and the insertion of the pectoralis major, and inserted into the confluence of the biceps brachii and the third head. This anomaly is relatively rare. Moreover, the left third head gave off a muscle slip into the posterior fascia of the pronator teres, forming a tunnel. The median nerve and the brachial artery passed through the tunnel, where the nerve and artery seemed to be compressed. The possible production of clinical symptoms, given the anatomy, is discussed.

Aged↗
PubMed1998

Superficial ulnar artery originating from the brachial artery and its clinical importance.

We found a left superficial ulnar artery in the cadaver of a Japanese woman. This anomalous vessel originated from the brachial artery at a site 55 mm distal to the inferior border of the teres major muscle and medial to the median nerve, ran downward and medially superficial to the forearm flexor muscles, and then downward to enter the hand. It formed superficial and deep palmar arches with the radial artery. The clinical importance of the anomalous ulnar artery is discussed.

Aged↗
PubMed1998

Branches of the vagus nerve destined for the heart and the adjoining great vessels in the house shrew, Suncus murinus, with reference to the terminology of the vagal cardiac branches.

In order to help to organize the understanding of the bewildering complexities of the innervation of the mammalian heart by the vagus nerve and to clear up of confusions as regards the vagus cardiac branches, we scrutinized these branches in the adult house shrew, Suncus murinus, under a stereomicroscope. A number of branches were given off from the vagus nerve not only to the heart, but also to the adjoining great vessels, both outflowing and inflowing. When compared from the developmental viewpoint, the basic conformations of these branches on two sides were found not to differ from each other, but rather presented a symmetrical configuration, the feature which has been ascertained also in mammalian embryos. Relying on developmental criteria, we classified them into the arterial porta-related and the venous porta-related groups, formulating a new terminology by naming them on the basis of their destination. This version of terminology allowed us to define the vagus cardiac branches of the house shrew more accurately than the current terminology (e.g., Nomina Anatomica), and seems to provide us a clue for clearing up confusions concerning the terminology of the vagus cardiac branches in mammals.

Animals↗