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Biomedical subjects

I Akiyama

Publications and source records attributed to I Akiyama.

At least 19 recordsLinked to original sources
PubMed2001

Short term effect of silicon carbide whisker to the rat lung.

We studied the short-term effect of silicon carbide whisker (SiCW) in vivo by instillation and inhalation to the rat lung. SiCW was instilled low dose (2 mg/0.5 ml saline) or high dose (10 mg/ 0.5 ml) intratracheally into the lungs of 25 rats. SiCW was also inhaled to another 25 rats at the average concentration of 10.4 mg/m3 for 1 month. In instillation study, the lung had focal alveolitis with the destruction of alveolar wall especially at 3 days after the instillation, and the lesion remained as an aggregated foci of SiCW at 6 months. The 'inflammation-score' of the instilled group by point counting method of the specimen correspondingly decreased gradually. In inhalation group, a minimum inflammatory change was observed. Collagen deposition in the aggregated foci of SiCW with accumulated alveolar macrophages and neutrophils was not progressive during the observed period. These findings suggest that SiCW may cause a minor effect to the rat lung in 6 months after exposure.

Administration, Inhalation↗
PubMed1998

[A case of video-assisted thoracic surgery for congenital esophago-bronchial fistula].

A 42-year-old male was admitted to our hospital because barium esophagograpm showed an esophago-bronchial fistula with an esophageal deverticulum. He has had frequent episodes of cough at drinking water since childhood. A chest CT scan showed mild inflammatory change and bronchiectasis in the right S6. Division of the fistula by video-assisted thoracoscopic surgery (VATS) was performed. There was no evidence of inflammation and adherent lymph nodes around the fistula. This case was diagnosed as a congenital esophago-bronchial fistula by operative findings and clinical course. The fistula was dissected easily and divided by an auto-suturing instrument. The affected lung could be preserved. The patient was discharged on the 10th postoperative day. VATS is an effective treatment for the patients of congenital esophago-bronchial fistula (Braimbrige type I and II), if they are not accompanied with pulmonary abscess or pleural empyema.

Adult↗
PubMed1990

Disorders of gaze during head rotation.

We investigated gaze functions during sinusoidal head rotation in patients with peripheral and central vestibular lesions. Various kinds of gaze disturbance appeared in relation to deficient compensation (labyrinthine lesions), inaccurate gain regulation (cerebellar lesions), impaired gaze-induced suppression (cerebellar lesions), and inadequate visual correction (brain stem lesions). Analysis of gaze during head rotation may help to understand the regulation system of the vestibulo-ocular reflex as well as to detect gaze disturbances in patients with vestibular disorders, which cannot be attained by conventional vestibular examinations.

Adult↗
PubMed1989

The effect of alcohol on the vestibulo-ocular reflex and gaze regulation.

To clarify the effect of the temporary decline in cerebellar function on the vestibulo-ocular reflex (VOR) and gaze functions, we examined 12 normal adults under passive rotations before and after they drank alcohol at dosages of 0.43 and 0.65 g/kg. Whereas spatial gaze fixation was maintained accurately with 0.65 g/kg administration (0.06% blood alcohol level), gaze fixation on a head-fixed target and smooth pursuit were impaired by the higher dosage of 0.43 g/kg (0.03% blood alcohol). The magnitude of the alteration in the VOR gain after drinking was correlated significantly with the VOR gain before drinking: while small values were enhanced by drinking, large values were suppressed. The present study indicates that the VOR in the dark is regulated by the balance between the amplifying and suppressing forces controlled by the cerebellum.

Adult↗
PubMed1989

Brain aromatase activity and behavioral consequences in the male rat treated in utero with 4-hydroxy-androstenedione.

Pregnant female rats were given daily injections of a potent aromatase inhibitor, 4-hydroxy-delta 4-androstenedione (4OHA), throughout the latter half of the pregnancy (days 11 to 22; the day of insemination was designated as Day O) and male fetuses and pups were obtained. Control animals were male offspring of mothers treated with oil vehicle. When measured by the tritium-water method, significant reductions in the aromatase activity were detected in the hypothalamic and preoptic continuum (HPOA) of the male fetuses and pups, over a period from day 16 of the pregnancy until a day after birth. All parturitions in the experimental as well as control animals occurred on day 22 of the pregnancy. Behavioral and anatomical consequences of the prenatal treatment were examined in adulthood. When mounted by stud male rats, the male litters of the 4OHA-treated mother showed lordosis at a significantly higher frequency both in terms of the number of positive test sessions (each consisted of a 20-min period in which the subject showed lordosis at least once) and the lordosis quotient (percent lordosis occurrence per 10 mounts). When placed with receptive female rats, the experimental animals were no less active in mounting or ejaculating than the control. No significant difference existed between the experimental and control animals in the weight of the testes or the accessorial genitalia, or the serum testosterone levels. Partial but significant intervention of behavioral defeminization of the brain was associated with decreased HPOA aromatase activity during the prenatal period.

Androstenedione↗
PubMed1989

[The effect of alcohol on the control of the vestibulo-ocular reflex and gaze].

The effects of ethyl alcohol on vestibulo-ocular reflex (VOR) and gaze functions were investigated in normal adults. Twelve normal adults were administered whisky at the rate of 1.0ml/kg (ethyl alcohol 0.43g/kg), so that the mean peak concentration of breath alcohol amounted to 0.15mg/l. Before and after alcohol administration, the subjects underwent sinusoidal rotation tests with an amplitude of 40 degrees and frequencies of 0.2-0.85Hz and eye tracking tests of unidirectional motion at 30 degrees-70 degrees/sec. For the rotation test, 7 subjects were examined at the dose of 0.65g/kg ethyl alcohol. The following results were obtained. 1. The mean value of VOR gain under the condition of performing mental arithmetic in the dark was not significantly altered by alcohol. However, the magnitude of change in VOR gain showed a highly significant correlation with the gain before drinking; whereas small values were enlarged and large values were suppressed by alcohol. 2. The accuracy of spacial gaze fixation was scarcely affected by alcohol, even at the dose of 0.65g/kg. 3. Visual fixation on a head-fixed target (fixation-induced suppression of VOR) and smooth pursuit were significantly impaired by alcohol. 4. The present study indicated that VOR is regulated even in the dark by both gaze stabilizing functions, i.e., spacial gaze fixation and smooth pursuit.

Adult↗
PubMed1988

Vestibulo-ocular reflex and gaze functions in a patient with congenital inner ear anomalies.

We report on the vestibulo-ocular reflex (VOR) and gaze functions during horizontal rotations as well as upright locomotions in a fisherman with congenital inner ear anomalies. The finding of a marked gaze disturbance due to low VOR gain during passive rotations resembled that found in early acquired lesions. There was an improvement during active rotations, suggesting an intensified cervico-ocular reflex. Although head oscillations in the horizontal plane were abnormally large during stepping and running, they were compensated for visually even at high frequencies. The absence of complaints of oscillopsia as well as his ability to achieve proper balance seemed to be accomplished by his optokinetic ability, regularly transformed head oscillations and modified perceptive mechanisms at higher cortical levels.

Adult↗
PubMed1988

Pursuit and saccadic eye movements in response to unpredictable constant velocity targets.

Pursuit eye movements in response to unpredictable reversals of constant velocity target motion at 20 degrees, 40 degrees and 60 degrees/s were analysed in 20 normal subjects. The gain in smooth pursuit was originally determined by the preceding target duration; the shorter the preceding movement, the longer was the acceleration of pursuit velocity inhibited. The ongoing target duration secondarily affected the gain at faster target velocities by restricting time for eye velocity acceleration. Whereas the saccadic reaction time was around 200 ms, the intersaccadic interval shortened as target velocity increased. The saccadic amplitude increased in direct proportion to an increase in target velocity. The present study showed that, even under irregular stimulations, pursuit eye movement is regulated in a feedforward manner by the perceptual analysis of the preceding target motion, and that corrective saccades in pursuit eye movement correspond to those observed in step displacements, except for the programming on the basis of the changing rate of position error.

Adult↗