Biomedical subjects
Publications and source records attributed to M Sasa.
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Based on studies carried out by the author and his associates in areas of Japan and South Asia where malayan and bancroftian filariasis is endemic, this paper recommends methods for use in microfilaria surveys and in the analysis of data obtained in such surveys. The author recommends the use of measured blood samples of 30 mm(3), with which 3 linear smears are made on slides. The blood films are then stained with azure II and eosin. Microfilarial counts made with such smears are, it is claimed, simpler, less expensive, and more reliable than those made with round, thick smears. Furthermore, the use of 3 smears from each person permits the calculation of correction factors, by means of which the detection rates that would be obtained by the use of different volumes of blood may be calculated.Information obtained by the use of this method has proved to be of great use in epidemiological studies of filariasis in endemic areas, in comparing the prevalence of the disease in different populations, and in evaluating the results of control measures. Different ways of recording and classifying the results are described, and the frequency distribution of microfilarial densities is analysed.
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Studies were performed to elucidate reciprocal relationships between locus coeruleus (LC) and spinal trigeminal nucleus (STN) neurons responding to tooth pulp (TP) stimulation using rats anesthetized with alpha-chloralose. LC conditioning stimulation inhibited STN field potential as well as orthodromic spike generation of STN neurons produced by ipsilateral TP stimulation, confirming the previous findings in cats that LC neurons played an inhibitory role in the orthodromic transmission in STN neurons. Forty-one out of 56 LC neurons were activated by ipsilateral TP stimulation and 12 neurons by stimulation of both ipsi- and contralateral TP. STN stimulation usually excited LC neurons with a significantly shorter latency than did TP stimulation, including three LC neurons with a latency of less than 2.0 msec. These results indicate the existence of input from TP to LC neurons via multisynapses. In addition, neurons antidromically activated by STN stimulation were found in LC. It is highly probable, therefore, that there is a feedback loop between LC and STN, which might control input from TP to STN.
Electroencephalographic (EEG) studies were performed to examine the effects of several antiepileptic drugs (AEDS) on absence-like and tonic seizures in the spontaneously epileptic rat (SER: zi(zi), tm/tm,), a double mutant rat, which was obtained by mating the tremor heterozygous animals (tm/ +) with the zitter homozygous animals (zi/zi), and to determine whether the seizures in the SER correspond to human absence and tonic seizures. Spontaneous EEG was continuously recorded from the frontal cortex and hippocampus using implanted electrodes. The SER showed paroxysmal and synchronized 5-7-Hz spike-wave-like complexes in both cortical and hippocampal EEG during the absence-like state, which was characterized by immobility and staring. The animal also exhibited tonic convulsion without external stimulation concomitant with low-voltage fast waves on cortical and hippocampal EEG. In some animals, sporadic low-amplitude spikes appeared in the low-voltage fast waves during tonic convulsion. the absence-like seizures were inhibited by trimethadione (100 mg/kg intraperitoneally, i.p.) and ethosuximide 100 mg/kg i.p.), whereas the tonic convulsion was not affected by these drugs. In contrast, phenytoin (20 mg/kg i.p.) inhibited the tonic seizures without affecting the absence-like seizures. Phenobarbital (10 mg/kg i.p.) and valproate (200 mg/kg i.p.) inhibited both seizures to a similar degree. These results suggest that the SER, with both absence-like and tonic seizures, is a useful model for evaluation of AEDS.
Spontaneously epileptic rats (SER) are a double mutant (zi/zi, tm/tm) spontaneously exhibiting both tonic and absence-like seizures. We examined the long-term effects of continual intake of phenobarbital (PB) on SER as a method of assessing long-term evaluation of antiepileptic drugs (AEDs). Food pellets containing 0.1% PB were given ad libitum from 7 weeks of age. Plasma PB level was maintained at 30-70 micrograms/ml after age 11 weeks. Tonic seizures were inhibited markedly in rats that received PB until age 15-16 weeks, but thereafter the inhibitory effects of PB gradually decreased. An increase of body weight and prolongation of survival were also noted in SER that received PB. Cortical and hippocampal EEG of SER were recorded with chronically implanted electrodes from 11 weeks of age pre-PB and 3, 7, and 14 days post-PB intake. These animals exhibit absence-like seizures characterized by sudden appearance of 5-7-Hz spike-wave-like complexes on EEG concomitant with immobility and staring. The seizures were not affected until age 13 weeks (2 weeks after intake of PB), although tonic seizures were inhibited. SER are considered a useful model for evaluating the long-term effects of AEDs.
Dopamine (DA) and norepinephrine (NE) brain levels and turnover rate were examined in the spontaneously epileptic rat (SER: zi/zi, tm/tm), a double mutant rat obtained by mating tremor heterozygotes (tm/+) with zitter homozygotes associated with epileptic seizures composed of spontaneously occurring tonic convulsion and absence-like seizure. DA and NE levels were also determined in age-matched male zitter, tremor and Kyo: Wistar rats. DA levels in caudate nucleus were significantly lower in adult age (10-12 weeks) SER, which showed epileptic seizures, and zitter rats than in adult Kyo: Wistar and tremor rats. DA levels in other areas such as thalamus-hypothalamus, midbrain, and pons medulla were not different among SER, zitter, tremor, and Kyo: Wistar rats at age 10-12 weeks. Except in cerebral cortex and hippocampus, there were no differences in brain DA levels between young seizure-free SER (age 5 weeks) and young Kyo: Wistar rats. Furthermore, the turnover rate of DA was significantly lower in caudate nucleus of adult SER than of Kyo: Wistar rat, whereas in pons-medulla there was no difference between the two strains. In contrast, NE levels in the thalamus-hypothalamus, midbrain, cerebellum and pons-medulla were higher in SER and zitter rats at age 10-12 weeks than in age-matched tremor and Kyo: Wistar rats. Higher NE levels were also observed in midbrain, cerebellum, and pons-medulla of young SER as compared with young Kyo: Wistar rats. Turnover rates of NE were significantly lower in pons-medulla and cerebellum of the adult SER than in those of Kyo: Wistar rat.(ABSTRACT TRUNCATED AT 250 WORDS)
Monosynaptic spike generation of lateral vestibular nucleus (LVN) neurons with vestibular nerve stimulation in cats was inhibited by microiontophoretic atropine and gamma-aminobutyric acid (GABA). Spontaneous firing of the LVN monosynaptic neuron was increased by iontophoretic acetylcholine and glutamate. Atropine inhibited acetylcholine-induced firing without affecting glutamate-induced firing, while GABA blocked spike generation produced by acetylcholine and glutamate. Acetylcholine probably plays a role in transmission from the vestibular nerve to the LVN monosynaptic neurons.