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Biomedical subjects

T Tadano

Publications and source records attributed to T Tadano.

124 records · Page 7Linked to original sources
PubMed1966

Development of resistance to various insecticides in Culex pipiens fatigans Wiedemann.

Since larvicidal treatment to reduce the numbers of Culex fatigans, the tropical house mosquito, offers a promising means of preventing the spread of filariasis, an assessment was made of the liability of C. fatigans to develop resistance to certain important insecticides. Strains of this mosquito from Burma, Cameroon, Sierra Leone and the USA (California) were submitted to larval selection for periods of seven to 23 generations. It was found that resistance to DDT or deutero-DDT rapidly developed to high levels and that to dieldrin or CP-47412 to moderate levels; dieldrin did not select for DDT-resistance.The organophosphorus compounds chosen developed only a modest tolerance-fivefold to sixfold with malathion or parathion, twofold to fourfold with fenthion or diazinon; the carbamate insecticide Hercules 5727 induced a threefold to fivefold tolerance. There was a general cross-tolerance from the selecting agent to all of the organophosphorus compounds tested and to the carbamate. A Rangoon strain that had already been made DDT-resistant subsequently developed a ninefold resistance to fenthion after 23 generations of selection with this organophosphorus compound, but this is still insufficient to annual the larvicidal effectiveness of fenthion.

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Persistent erection in thiamine-deficient rats.

Male Wistar rats, maintained on a thiamine-deficient diet, showed a significant weight loss, decrease in heart frequency, disturbance of urinary excretion, and symptoms of polyneuritis. Once persistent erection ocurred in these rats, it continued throughout the study and subsided in most cases after the administration of thiamine HCl.

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Changes of ejaculation due to suppression of noradrenaline biosynthesis by diethyldithiocarbamate.

The effects of diethyldithiocarbamate on manually induced erection and ejaculation and on monoamines in the brain and male reproductive organs were investigated in male mongrel dogs. From the results obtained in this study it was concluded that diethyldithiocarbamate suppresses ejaculation, although penile erection is maintained, and that the suppression is not mediated by the central nervous system but by the changes of the monoamine levels in the organs relating to sperm transport.

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Changes of ejaculation due to suppression of noradrenaline biosynthesis by diethyldithiocarbamate in dogs: a supplemental report with reference to changes of posterior urethral pressure.

In the preceding paper (Kimura et al.-1979) it was reported that diethyldithiocarbamate suppresses ejaculation, although penile erection is maintained, and that the suppression is not mediated by the central nervous system but by the decrease of catecholamine contents in the organs relating to sperm transport. In this paper, changes of ejaculation following administration of diethyldithiocarbamate was studied with the posterior urethrogram; measurement of the posterior urethral pressure during hypogastric nerve stimulation. From the results obtained in this study the above results were confirmed. It was also confirmed that both seminal emission and ejaculation are under the influence of an alpha-adrenergic receptor mechanism. Also, a dopamine receptor mechanism was suspected to be present in the male accessory sexual glands.

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On the brain monoaminergic systems relating to ejaculation. III) Further study by using a peripheral decarboxylase inhibitor.

In the previous papers it was reported that ejaculation is facilitated by the brain dopaminergic system, particularly by that in the anterior hypothalamus, and inhibited by the serotonergic system. In an attempt to clarify more precisely the results, a further study was done in dogs by using a peripheral cecarboxylase inhibitor, Ro 4-4602, in combination with tetrabenazine and L-dopa. As a result it was found that in addition to the brain dopaminergic system, the increase in 5-HT level in the limbic system and the decrease in 5-HT level in the brain stem facilitate ejaculation.

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The spinal monoaminergic systems relating to ejaculation. II. Ejaculation and serotonin.

The effects of Ro 4-4602 and L-5-hydroxytryptophan on manually induced ejaculation in dogs and on spinal monoamines in dogs were investigated. From the results obtained in the study it was concluded that the serotonergic system in the spinal cord is an intermediate mechanism which inhibits the occurrence of ejaculation. Both the results in this study and the results in our previous paper seem to indicate that ejaculation occurs with the reconciliation of the spinal dopaminergic and serotonergic system.

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On suppression of ejaculation by Alpha-methyldopa.

Alpha-methyldopa caused inhibition of ejaculation. The cerebral mechanism which induced the inhibition was pursued by determining changes of brain monoamines in dogs. As a result, suppression of the dopaminergic system in the brain by alpha-methyldopa is found to be the origin of the inhibition of ejaculation. This inhibition was recovered by L-dopa with pretreatment with a peripheral decarboxylase inhibitor.

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Role of the spinal monoaminergic systems in suppression of ejaculation by alpha-methyldopa.

Alpha-methyldopa causes inhibition of ejaculation by suppressing the dopaminergic system in the brain. The spinal mechanism which works together with this brain inhibitory mechanism was persued by determining the changes of spinal monoamines in dogs. As a result, it was found that suppression of the dopaminergic system by alpha-methyldopa is caused also in the spinal cord just as in the brain and that this suppression can be a direct origin of the inhibition of ejaculation.

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The spinal monoaminergic systems relating to ejaculation ejaculation and monoamines after spinal cord transection.

The authors investigated the relationship between ejaculation and spinal monoamine levels by transecting the dog spinal cord at the various levels. From the results obtained in this study it was concluded that the lumbar and upper sacral segments of the spinal cord are important for ejaculation, and that the suppression of ejaculation by lower lumbar to upper sacral transection may be induced by increase in serotonin in the 5th lumbar-1st sacral segments.

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Diminution of ejaculatory capacity induced by frequent ejaculation in dogs: prevention and reversal by yohimbine.

The effect of yohimbine, an alpha-2 adrenoceptor antagonist, on diminished ejaculatory capacity induced by frequent ejaculation was investigated in dogs. Ejaculation was elicited by manual penile stimulation (for 5 min) 5-8 times every 30 min. The amount of ejaculate produced by the stimulation was drastically reduced during a period of frequent ejaculation in a frequency-dependent manner. When administered immediately after the first ejaculation, yohimbine (0.1 mg kg-1, i.p.) completely prevented the decrease in the amount of ejaculate produced in the succeeding ejaculation. Moreover, similar treatment with yohimbine immediately after the fifth ejaculation when the dogs displayed a greatly reduced ejaculatory capacity restored the capacity to the initial level. In addition, yohimbine increased the total number of sperm produced during a period of frequent ejaculation. These data corroborate our previous finding that yohimbine at a low dose has a stimulatory effect on ejaculatory function in dogs. The present study also indicates that an alpha-2 adrenergic mechanism may be involved in the diminution of ejaculatory capacity induced by frequent ejaculation.

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Central action of 9-methyl-7-bromoeudistomin D (MBED), a derivative of eudistomin D isolated from Eudistoma olivaceum.

The behavioral responses of mice following intracerebroventricular (i.c.v.) injection of 9-methyl-7-bromoeudistomin D (MBED) were studied. Head-twitches were produced 20-90 min after the injection of 2, 20 and 200 nmol/mouse but such twitches were not significantly induced by caffeine (1000 nmol/mouse). The locomotor activity, as assessed by the Animex autometer, increased 0-120 min after the injection with doses of 2, 20 and 200 nmol/mouse, whereas a large dose of caffeine (500 nmol/mouse also increased the activity counts. Simultaneous injection of picrotoxin (3 mg/kg, s.c.) and MBED (50, 100 and 200 nmol/mouse) produced clonic and tonic extensive convulsions, but caffeine (1000 nmol/mouse) in combination with picrotoxin did not cause any type of convulsion.

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[The diagnosis of severe disseminated paracoccidioidomycosis in a bone marrow aspirate: a case report].

Acute or chronic disseminated paracoccidioidomycosis can be associated with changes in blood and bone marrow cell counts, mainly in the severe forms of this disease. However, there are few reports about the microbiological confirmation of the mycosis in bone marrow tissue. The present report describes a case of an adult patient with severe chronic multifocal paracoccidioidomycosis, whose etiological diagnosis has been done by the microscopical exam and culture fo the bone marrow aspirate. The authors emphasize the importance of these exams as an alternative way for the diagnosis of suspected cases of severe paracoccidioidomycosis.

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On the brain monoaminergic systems relatint to ejaculation. II. Brain serotonin and ejaculation.

The effects of 5-HTP and pCPA on manually induced ejaculation in dogs and on brain monoamines in dogs and rats were investigated. From the results obtained in this study it was concluded that the serotonergic system in the brain is the mechanism which inhibits the occurrence of ejaculation. Considered together with the results obtained in our previous paper, it is though that ejaculation occurs with the reconciliation of the dopaminergic and serotonergic systems.

5-Hydroxytryptophan↗