Biomedical subjects

N Yagi

Publications and source records attributed to N Yagi.

208 records · Page 12Linked to original sources

PubMedDate not supplied

Crocodile tears and thread test of lacrimation.

Patients with incomplete recovery from peripheral facial paralysis often complain of eye-watering while eating (crocodile tears or gustolacrimal reflex). In 55 patients (22 completely recovered from peripheral facial paralysis, 23 incompletely recovered, and ten with hemifacial spasm), lacrimation was monitored by the thread test (a modification of the Schirmer test) during taste stimulation. In the 22 patients with complete recovery, the results of the thread test did not differ before and after a sweet-sour candy was given (taste stimulation). All the patients with incomplete recovery showed either synkinesis or contracture. Lacrimation on the side of the lesion was high even before taste stimulation. After taste stimulation, a rapid and definite increase in lacrimation was observed. The results show that in patients with synkinesis and incomplete recovery after peripheral facial paralysis, the misdirected regeneration of the injured nerve fiber often occurs from the gustatory nerve to the lacrimal nerve, as well as between motor fibers.

Facial Nerve↗

PubMedDate not supplied

Stapedial electromyograms recorded by electrocochleography.

The stapedial reflex (SR) can be obtained by the impedance method only when the middle ear is intact. In order to examine the function of the stapedius muscle in diseased ears, the recording of the stapedial electromyogram by an electrocochleographic (ECoG) method was considered. The SR was recorded simultaneously by the impedance method in ten normal subjects for comparison. The outputs of ECoG were averaged by a signal processor up to 200 times under a longer sweep time, and a large biphasic wave with a latency of about 11 ms was obtained on the ECoG records. The amplitude increase of the biphasic wave caused by raising the intensity of the acoustic stimulation paralleled that of the SR. This means that the biphasic wave obtained by ECoG with a latency of about 11 ms originated from the stapedius muscle.

Audiometry, Evoked Response↗

PubMedDate not supplied

Response of single Purkinje neurons in the flocculus of albino rabbits to caloric stimulation.

The response of Purkinje neurons of the flocculus to caloric stimulation was investigated in the Urethane-chlorarose anesthetized rabbit. Twenty-five of 37 flocculus neurons which responded to ipsilateral caloric stimulation showed an increase in firing response, while 12 neurons showed a decrease. Fifteen of 28 flocculus neurons which responded to contralateral caloric stimulation showed an increase, while the firing of 13 neurons was decreased. Forty-one percent of flocculus neurons responded to ipsilateral caloric stimulation, and 41% responded to caloric stimulation of both sides. Eighteen percent of flocculus neurons responded only to contralateral stimulation. The ipsilateral flocculus may thus be responsible for the major control of the primary vestibular signal flow in the cerebellum.

Animals↗

PubMedDate not supplied

Effect of glycerol on the EP decrease caused by furosemide.

A change in endocochlear potential (EP) following furosemide injection was observed in regard to prior glycerol administration in two groups of guinea pigs. In one group, various doses of furosemide (20, 30, 40, 50 mg/kg) were injected, while in the other, glycerol (50 v/v %, 1 ml/kg) was injected prior to the furosemide (20, 30, 40 mg/kg) injection. In the glycerol-furosemide group, the decrease in EP was 40% greater than in the furosemide group. Therefore, glycerol was thought to potentiate the EP lowering action of furosemide. Such an effect of glycerol was assumed to be resulted by facilitating the access of furosemide to the site of action in the stria vascularis.

Action Potentials↗

PubMedDate not supplied

Perilymph oxygenation in sudden and progressive sensorineural hearing loss.

The perilymphatic oxygen tension of the vestibular perilymph of 34 patients with different inner ear losses were measured with the polarographic method before and after inhalation with carbogen. Two patterns of disturbed perilymphatic oxygenation were observed: 1) Characterized by low initial values of perilymphatic oxygenation and normal response to carbogen inhalation was present in sudden deafness and sudden cochleovestibular loss of inner ear function. 2) Characterized by normal initial values of perilymphatic oxygenation and a low response to carbogen, was found in presence of a slowly progressive sensorineural hearing loss. The significance of the obtained results in regard to the possible vascular pathology of the inner ear is discussed.

Adult↗

PubMedDate not supplied

Effect of glycerol on furosemide-caused EP decrease in guinea pig neonates.

Furosemide, a loop diuretic, reduces the endocochlear potential in guinea pigs. In our previous experiment using adult guinea pigs, glycerol was thought to open the blood-cochlea barrier and to help furosemide to reach its site of action in the stria vascularis. The present study was designed to determine whether or not the same potentiation by glycerol occurs in neonate guinea pigs. In one group, furosemide (10-30 mg/kg) was administered, while in another group, 50 v/v% glycerol (1 ml/kg) was administered 15 minutes prior to the injection of furosemide. Furosemide reduced the EP significantly more in neonates than in adults. This effect was not potentiated in the glycerol-pretreated group. From these findings, it seemed conceivable that the neonate blood-cochlea barrier still remains immature in some functions.

Animals↗

PubMedDate not supplied

Thiamine deficiency induced by polychlorinated biphenyls (PCB) and dichlorodiphenyltrichloroethane (DDT) administration to rats.

To clarify the effect of polychlorinated biphenyls (PCB), and dichlorodiphenyltrichloroethane (DDT) and other organochloride compounds on thiamine metabolism, rats were separated into six groups and placed on different admixed diets. Group 1 was fed a normal diet; group 2, a PCB-supplemented diet; group 3, a DDT-supplemented diet; group 4, a benzenehexachloride-supplemented (BHC) diet. After 50 days of these dietary regimens all animals were sacrificed and various studies were done on the excised tissues. In PCB-treated rats, thiamine levels in blood, liver and sciatic nerve decreased, transketolase activity in erythrocytes and liver decreased and TPP effect in erythrocytes and liver increased. In DDT-treated rats, thiamine levels in blood, brain and liver decreased, transketolase activity in brain and liver decreased and TPP effect in brain and liver increased. In other groups, no significant changes were observed regarding thiamine metabolism. Our findings provide direct evidence that changes occur in thiamine metabolism in PCB- and DDT-poisoned rats.

Animals↗

PubMedDate not supplied

The effect of injection of high K+ solution into scala media.

Thirty guinea pig ears were studied to investigate the effect of endolymphatic hydrops on the cochlea. High K+ solution was injected into the scala media, and cochlear microphonics (CM) and endocochlear potential (EP) were observed before, during and after the injection. The CM amplitude decreased rapidly after injection, ending in a depressed plateau value. By contrast, EP remained almost unchanged. By changing the composition of the solution it was suggested that the effect of the injection was mechanical one, rather than biochemical. In three ears, spontaneous recovery of CM was observed during a relatively long interval after the injection. The meaning of these findings for the hearing loss in Meniere's disease is discussed.

Animals↗

PubMedDate not supplied

The validity of the thread test for evaluating nasal secretion in nasal allergy.

The volume of nasal secretion is so small that it is difficult to measure. We placed a thread on the anterior surface of the inferior turbinate to measure the volume of nasal secretion in normal subjects and patients with nasal allergy. In 24 normal subjects, the average nasal secretion amounted to 1.09 microliter/min. In 48 patients with nasal allergy, the volume of nasal secretion (1.94 microliter/min) decreased significantly after nasal spraying: the subjective symptoms of sneezing, rhinorrhea, nasal obstruction, inconvenience in daily life and the objective signs such as watery rhinorrhea abated. The thread test results showed a good correlation with the above items in a quantitative analysis. The thread test is a simple way to measure a small volume of nasal secretion, and a useful indicator of the severity of watery rhinorrhea in patients with nasal allergy.

Female↗

PubMedDate not supplied

Effect of subacute manganese feeding on serotonin metabolism in the rat.

To clarify the effect of subacute manganese feeding on serotonin and mineral metabolism, Wistar rats were separated into two groups and fed two different diets, one a normal diet and the another a manganese-supplemented diet. After three weeks on these dietary regimens, the rats on the manganese-supplemented diet manifested the following abnormalities: blood pressure was decreased; brain serotonin was decreased; L-aromatic amino acid decarboxylase activity in brain was decreased. Manganese levels in heart, lung, and kidney increased, whereas sodium, potassium, magnesium and calcium levels in the brainstem decreased.

Animals↗