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Biomedical subjects

Y Ichimaru

Publications and source records attributed to Y Ichimaru.

At least 37 records · Page 2Linked to original sources
PubMed1992

Identification and isolation of endogenous insect phenoloxidase inhibitors.

Inhibitors of phenoloxidase were identified in pupae of the housefly, Musca domestica L. The phenoloxidase inhibitors were purified from final instar pupae of the housefly by a combination of ammonium sulfate fractionation, ion-exchange chromatography, gel filtration and reverse-phase high performance liquid chromatography. The potent phenoloxidase inhibitors were heat-stable low molecular weight peptides with an inhibition constant of nM range. To the best of our knowledge, this is the first time that endogenous phenoloxidase inhibitors have been identified among the insects, and probably also among the invertebrates. It is likely that the inhibitors play a central role in regulating the action of active phenoloxidases and will also serve as important tools for understanding the structures and functions of phenoloxidases, as well as their role in insect metamorphosis.

Amino Acid Sequence↗
PubMed1992

[Heart rate variability].

Heart rate variability (HRV) has become a useful parameter for the quantification of autonomic nervous function. HRV has been quantified, either by time domain or frequency domain analysis. Time domain measures, such as CVRR and RR50, are easy to calculate but they only provide information related to parasympathetic activity. The spectral analyses, on the other hand, give us information concerning 3 oscillatory components. The high frequency band (the frequency between 0.15-0.5 Hz) is known as the respiratory sinus arrhythmia (RSA), and the middle frequency band (0.88-0.15 Hz) is attributed to baroreflex components. The low frequency band (0.01-0.08 Hz) may be of various origins, such as blood flow rhythm, periodic respiration (including Cheyne-Stokes respiration), renin-angiotensin, and thermal regulation. The efferent nerve to the high frequency band is totally operated by the parasympathetic system. The low frequency band is regulated by both sympathetic and parasympathetic nervous systems. We demonstrated that the diurnal variation of HRV may afford additional information, such as ultradian changes of autonomic activity, possibly due to REM/NREM cycles. It is believed that simultaneous monitoring of other physiological parameters such as EEG, EOG, respiration, and blood pressures, might give us information concerning the dynamic nature of autonomic nervous function.

Autonomic Nervous System Diseases↗
PubMed1991

Effects of anxiolytic drugs on escape behavior induced by dorsal central gray stimulation in rats.

Each animal was chronically implanted with bipolar electrodes in dorsal central gray matter (DCG) and was trained to press a lever to decrease the DCG-stimulation current. Chlordiazepoxide (5-20 mg/kg, PO), diazepam (2-10 mg/kg, PO) and bromazepam (1-5 mg/kg, PO) produced dose-dependent increases in the DCG-stimulation threshold 1-4 h after administration without affecting motor performance. Meprobamate (200 mg/kg, PO) and pentobarbital (10 mg/kg, PO) also slightly increased the stimulation threshold. Their potency was in the order of bromazepam greater than diazepam greater than chlordiazepoxide greater than pentobarbital greater than meprobamate. The increase in the threshold induced by diazepam (10 mg/kg, PO) was inhibited by the GABA antagonists, bicuculline (1 mg/kg, IP) and picrotoxin (0.1 mg/kg, IP). These results suggest that decreased susceptibility to brain stimulation is involved in suppressing effects of anxiolytic drugs on the escape behavior, and also that the antiaversive action of benzodiazepines may be related to a GABAergic mechanism.

Animals↗
PubMed1991

Differential effects of morphine on operant escape behavior and averse symptom induced by dorsal central gray stimulation in rats.

The involvement of a central opiate mechanism in the operant escape behavior induced by dorsal central gray (DCG) stimulation was investigated in rats. Morphine (2-10 mg/kg, i.p.) produced a rise in the DCG-stimulation threshold, but did not suppress rapid running as an averse symptom. Naloxone alone affected neither the threshold nor the averse symptom. Nevertheless, naloxone counteracted morphine-induced increments in the threshold. These results suggest that the opiate system may be indirectly involved in certain aspects of the operant escape behavior induced by the DCG-stimulation.

Animals↗
PubMed1990

Behavioral effects of HR-592, a new derivative of indole.

Effects of HR-592 on various behaviors were investigated in rats and mice. 1) HR-592 at doses of 10-100 mg/kg, p.o., and chlorpromazine at doses of 2.5-20 mg/kg, p.o., suppressed dose-dependently spontaneous activities of mice. 2) In the mice treated with HR-592, 10 and 30 mg/kg, p.o., and with chlorpromazine, 1.25-5 mg/kg, p.o., the durations of loss of the righting reflex induced by thiopental-Na were extended in a dose-dependent manner. 3) In the mice and rats when HR-592 was administered at doses of 3-100 mg/kg, p.o., catalepsy was induced in a dose-dependent manner. 4) The incidence of catalepsy induced by haloperidol in mice was reduced dose-dependently after HR-592 administration (10-100 mg/kg, p.o.). 5) Dose-dependent suppressions of the slant of screen at which the mice slipped down were observed by HR-592 at 3-100 mg/kg, p.o., and chlorpromazine at 5-20 mg/kg, p.o. 6) The rotarod performance in mice was suppressed dose-dependently by HR-592, 3-100 mg/kg, p.o., and chlorpromazine, 5-20 mg/kg, p.o. 7) HR-592 at doses of 0.3-3 mg/kg, i.p., suppressed dose-dependently the turning behavior induced by methamphetamine in unilateral substantia nigra-lesioned rats. From these results and our previous data, it is considered that HR-592 has pharmacological properties as a major tranquilizer, although its behavioral effect is slightly weaker than that of chlorpromazine. Furthermore, these results imply that HR-592 has anti-cataleptogenic activity and might thereby alleviate the adverse effect of neuroleptics such as haloperidol.

Anesthetics↗
PubMed1990

Effects of methamphetamine on regional cerebral glucose utilization in rats with unilateral lesion of substantia nigra.

In rats with electrocoagulation of the unilateral substantia nigra (SN), methamphetamine at doses of 2.5 and 5 mg/kg, i.p., induced ipsilateral turning towards the lesioned side and caused an imbalance of the regional cerebral glucose utilization (CGU) in the caudate-putamen (CP), frontal cortex (FC) and ventromedial thalamic nucleus (VMT); i.e., showing a higher contralateral CGU as compared with the SN lesioned side. These results induced in unilateral SN-lesioned rats may be accompanied by an imbalance of neural activity in CP, FC and VMT of these rats.

Animals↗
PubMed1990

Effects of HR-592, a new derivative of indole, on conditioned behavior.

Effects of HR-592, a new derivative of indole, on conditioned avoidance and intracranial self-stimulation behavior were investigated in rats using a shuttle box and a Skinner box, respectively. The oral administration of HR-592 at doses of 3-10 mg/kg caused a dose-dependent suppression of the conditioned avoidance response. Even the escape response was slightly suppressed in the group administered 10 mg/kg of HR-592. The self-stimulation behavior was suppressed dose-dependently from 1 to 8 h after the administration of 6-10 mg/kg of HR-592. These results indicate that the action of HR-592 on conditioned avoidance response and intracranial self-stimulation behavior is similar to the action of neuroleptics.

Animals↗
PubMed1989

Frequency characteristics of the heart rate variability produced by Cheyne-Stokes respiration during 24-hr ambulatory electrocardiographic monitoring.

Spectral analysis of heart rates during 24-hr ambulatory electrocardiographic monitoring has been carried out to characterize the heart rate spectral components of Cheyne-Stokes respiration (CSR) by using fast Fourier transformation (FFT). Eight patients with congestive heart failure were selected for the study. FFT analyses have been performed for 614.4 sec. Out of the power spectrum, five parameters were extracted to characterize the CSR. The low peak frequencies in eight subjects were between 0.0179 Hz (56 sec) and 0.0081 Hz (123 sec). The algorithms used to detect CSR are the followings: (i) if the LFPA/ULFA ratios were above the absolute value of 1.0, and (ii) the LFPP/MLFP ratios were above the absolute values of 4.0, then the power spectrum is suggestive of CSR. We conclude that the automatic detection of CSR by heart rate spectral analysis during ambulatory ECG monitoring may afford a tool for the evaluation of the patients with congestive heart failure.

Aged↗
PubMed1989

[Analysis of EEG, respiration, and ECG by 24-hour polygraphic study in a case of aortitis syndrome associated with epilepsy].

The relationships between electroencephalographic changes and cardio-respiratory responses were analysed by using 24 hour ambulatory simultaneous monitoring of EEG, respiration, ECG in a patient with aortitis syndrome. Circadian changes of "absence" attacks, effects of anti-convulsive drugs on epileptic attacks, and respiratory arrest and abnormalities of the cardiorespiratory integration were clarified.

Adult↗
PubMed1988

Neural systems activated by the aversive stimulation of dorsal central gray.

Neural effects of aversive stimulation of dorsal central gray (DCG) were studied by [14C] 2-deoxyglucose (2-DG) autoradiography in rats. After training the animals to escape DCG stimulation by pressing a lever, they were injected i.p. with [14C] 2-DG and then allowed to resume the escape lever pressing for DCG stimulation. Reliable effects of the brain stimulation on the autoradiogram were found in the dorsal fasciculus of Schütz, periventricular gray and superior colliculus. Moderate effects were found in the reticular formation near the periventricular gray and in the claustrum. These data indicate that the neural signal activated by DCG stimulation is transmitted through an ascending nerve pathway over the superior colliculus via the dorsal Schütz bundle and reaches the periventricular system in the diencephalon.

Afferent Pathways↗
PubMed1987

A new screening method for anti-ulcer agents: psychological stress produced by intraspecies emotional communication.

Psychological stress produced by intraspecies emotional communication in a communication box was studied to see whether it could be applied to a new screening method for anti-ulcer agents. There were two groups of mice, the 'sender' mice that received electrical foot shocks and showed emotional responses such as piloerection, abnormal squealing and jumping, and the 'responder' mice that were affected by the sender's emotional responses without foot shock. The gastric lesions (erosions) produced by conditioned emotional stimuli were observed in both groups. The effects of the anti-ulcer drugs cetraxate, cimetidine and gefarnate were examined. In 'senders', the gastric lesions were significantly suppressed by the administration of cetraxate at a dose of 200 mg/kg (p.o.) or cimetidine at doses of 30 and 100 mg/kg (p.o.). The gastric lesions in 'responders' were significantly suppressed by two administrations of cetraxate at doses of 100 and 200 mg/kg (p.o.), cimetidine at doses of 10-100 mg/kg (p.o.) or gefarnate at a dose of 200 mg/kg (p.o.). The gastric lesions of 'responders' were more sensitive to anti-ulcer drugs. The present results indicate that the gastric erosions of 'responders' are useful for the evaluation of anti-ulcer agents.

Animal Communication↗
PubMed1987

Effects of clobazam on amygdaloid and hippocampal kindled seizures in rats.

The effect of clobazam, a 1,5-benzodiazepine, on kindling seizures was compared with the effects of 1,4-benzodiazepines, diazepam and bromazepam, in amygdaloid and hippocampal kindled rats. After kindled seizures were established (stage 5 seizure), the test drugs were administered intraperitoneally. In amygdaloid kindled rats, clobazam significantly suppressed the motor seizures (MS) at doses of 20 and 50 mg/kg and significantly shortened the duration of after-discharge (AD) at doses of 10 to 50 mg/kg. Diazepam at doses of 2 to 10 mg/kg and bromazepam at 1 to 5 mg/kg also significantly suppressed the MS and significantly shortened the duration of AD. Similar suppressive effects by these three benzodiazepines were observed in hippocampal kindled rats. From these results, clobazam was found to have a qualitatively similar but weaker anticonvulsive effect than those of 1,4-benzodiazepines.

Amygdala↗
PubMed1987

Effect of clotiazepam on gastric mucosal lesions produced by conditioned emotional stimuli in mice.

The anti-ulcer action of clotiazepam (a thienodiazepine derivative) was studied in mice subjected to non-physical and physical stimuli in a communication box. There were two groups of mice: the "sender" mice that received electric shocks on the feet and responded by squealing and jumping, and the "responder" mice that were affected by the senders' responses without receiving shocks on the feet. Gastric ulcers resulted in both groups. The effect of clotiazepam was compared with that of diazepam. The incidence of gastric ulcers was suppressed by clotiazepam at a dose of 3 mg/kg, per os, in "responder" and "sender" mice, and by diazepam at a dose of 1 mg/kg, per os, in "responder" mice. These results suggest that clotiazepam has a suppressive action against gastric ulcers produced by non-physical or physical stimuli, although its potency is slightly weaker than that of diazepam.

Animals↗
PubMed1986

Experimental study on the relationship between cardiac arrhythmias and sleep states by ambulatory ECG-EEC monitoring.

The relationship between cardiac arrhythmias and sleep states was investigated in rats using the ambulatory ECG-EEG monitoring system under the 14/10 light-dark illumination schedule. Records of 14 rats obtained over 94 days were analyzed. Bradyarrhythmias (SA block and AV block) and ventricular arrhythmias [ventricular premature contraction (VPC) and short run of VPCs (ventricular tachycardia, VT)] were observed. Average number of episodes of bradyarrhythmia per day was 7.5, and the ratio of SA block to AV block was 34.9% to 65.1%. Average VPC or VT occurrence per day was 0.9 or 0.1 times, respectively. Sleep states were divided into alertness, slow-wave sleep, and paradoxical sleep, and the relationship between sleep states and arrhythmias was investigated. Bradyarrhythmias appeared predominantly during paradoxical sleep, while ventricular arrhythmias appeared during alertness as well as paradoxical sleep. Bradyarrhythmic episodes decreased by right or left vagotomy 78% or 70%, respectively. Sinus bradyarrhythmias disappeared almost completely by the right vagotomy, while the occurrence of AV block decreased by the right or left vagotomy. Circadian rhythms in arrhythmias were also analyzed by the cosine-fitting technique, and significant circadian rhythms were demonstrated in both bradyarrhythmias and ventricular arrhythmias. Acrophases were 9:56 A.M. and 1:47 A.M., respectively. Occurrence of VT was rare, but the most frequent incidental time zone was immediately following transition from light effects (rest) to dark (activity). This knowledge of circadian rhythm effects in arrhythmias must be incorporated into improved treatment of arrhythmias.

Animals↗