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Biomedical subjects

O Mimura

Publications and source records attributed to O Mimura.

At least 19 recordsLinked to original sources
PubMed2005

Effect of GDNF gene transfer into axotomized retinal ganglion cells using in vivo electroporation with a contact lens-type electrode.

We developed an in vivo electroporation method to introduce foreign genes into retinal ganglion cells (RGCs). After the intravitreous injection of the plasmid gene (20 mug), five electric pulses (6 V/cm, 100 ms duration) were each delivered twice with 5 min interval to the rat eye using a contact lens-type electrode (cathodal) attached to the cornea and a needle electrode (anodal) inserted to the middle of the forehead. The efficiency of the genetic introduction into RGCs and tissue damage to the eyeball was evaluated using a green fluorescent protein (GFP) gene, TUNEL and histological observation. DiI retrograde labeling revealed that 24.4 +/- 4.7% of all RGCs were electrointroduced with the GFP gene. TUNEL and histological analysis showed a few tissue damages in the cornea, lens and retina. To confirm whether this method can actually rescue damaged RGCs, glial cell line-derived neurotrophic factor (GDNF) was electrointroduced into RGCs after optic nerve transection. After the electrointroduction, a significant increase in the number of surviving RGCs was observed 2 and 4 weeks after the optic nerve transection, and the decrease of caspase 3 and 9 was detected by RT-PCR. These results suggest that this method may be useful for the delivery of genes into RGCs with simplicity and minimal tissue damage.

Animals↗
PubMed2001

Location of lesions in multiple evanescent white dot syndrome and the cause of the hypofluorescent spots observed by indocyanine green angiography.

PURPOSE: To determine the location of the lesions in the retina of a patient with multiple evanescent white dot syndrome (MEWDS) and to resolve the conflict in the cause of the hypofluorescent spots observed in the late phase of indocyanine green angiography (ICGA). CASE REPORT: A 27-year-old woman presented with a unilateral enlarged blind spot and a central scotoma. Fundus examination of the left eye showed many round, indistinctly circumscribed white dots extending from the posterior pole toward the periphery. Fluorescein angiography demonstrated hyperfluorescence due to staining at the location of the white dots. Staining was also observed on the venous wall which was consistent with periphlebitis. The location of the scotomas corresponded with the hypofluorescent spots observed around the optic disc and in the macula in the late phase of ICGA. The scotomas disappeared with the resolution of the hypofluorescent spots, and the sites of other hypofluorescent spots were in accord with the sites of periphlebitis. Visual evoked cortical potentials disclosed no laterality, and the critical fusion frequency was reduced but normalized with the disappearance of the scotoma. CONCLUSION: The initial lesions of MEWDS occur in the retinal pigment epithelium and photoreceptor cells, but when MEWDS is complicated by periphlebitis, the inflammatory lesions extend to the inner layers of the retina. The inflammatory changes involve the choroid and all layers of the retina, which then block the weak background fluorescence in the later phase of ICGA and cause the hypofluorescent spots. The visual field defects are probably caused by retinal dysfunction due to the inflammatory changes.

Adult↗
PubMed2000

Parameters for the preoperative evaluation of arteriosclerosis for free-flap transfers in head and neck surgery.

The microsurgical transfer of free tissue has become essential for reconstructive surgery in the head and neck, and arteriosclerosis is one of the risk factors for microvascular anastomosis. In order to detect severe arteriosclerosis and to determine the parameters useful for evaluating arteriosclerosis preoperatively, the grade of arteriosclerosis was investigated with respect to age, PWV (Aortic Pulse Wave Velocity), ocular fundus findings, and histopathological findings of the recipient arteries in 40 patients with malignant tumours. Severe arteriosclerosis was detected in 2/40 patients by the PWV, in the same 2/40 patients by the ocular fundus findings and in the same 2/40 patients by histopathological findings. The current observations indicate that the PWV and ocular fundus findings are useful parameters for the preoperative evaluation of the grade of arteriosclerosis.

Adult↗
PubMed1993

[Treatment and prognosis of diplopia].

The case notes of 341 patients who had consulted the Ocular Motility Clinic of Hyogo College of Medicine between 1986 to 1992 with a chief complaint of diplopia were studied. The recovery rates of diplopia from major causes were as follows: 72% of patients recovered from diplopia in oculomotor nerve palsy, 70% in trochlear nerve palsy and 71% in abducens nerve palsy. Various treatments were effective to eliminate the diplopia in 69% of patients with myasthenia gravis, 60% in Graves' ophthalmopathy, 78% in blowout fractures and orbital tumors. Pharmaceutical therapy was applied in 236 cases. In ocular motor nerve palsy oral prednisone gave a higher recovery rate than other medicines. The recovery rate of diplopia in medicinal therapy was 60% and it increased to 69% when combined with surgical treatment. We concluded that it is better to select the surgical treatment if the patient complains of diplopia after more than 6 months of conservative therapy.

Adolescent↗
PubMed1992

[Eye movements].

Explore the source record for details and available documents.

Electrooculography↗
PubMed1991

[Choroidal detachment associated with spontaneous carotid cavernous fistula].

A rare case is presented in which an 87-year-old woman with choroidal detachment was subsequently found to have an atypical carotid cavernous fistula (CCF). In this case, the intraocular pressure of the affected eye was higher than that of the contralateral eye. However, tonography showed no increased ocular pulse (amplitude of Schioetz reading) of the affected eye, which is characteristic of CCF. Choroidal detachment accompanied with CCF is thought to be a result of severe choroidal hemostasis and transudation caused by increased episcleral venous pressure. Furthermore, the enlarged perichoroidal space due to choroidal detachment reduced the ocular pulse of the affected eye. This combination may not be as rare as it has been previously reported. Attention to these symptoms can provide clues to the elucidation of the pathogenesis of choroidal detachment.

Aged↗
PubMed1990

Bilateral trochlear nerve palsies from a brainstem hematoma.

We present a case of bilateral superior oblique palsies after a spontaneous brainstem hematoma. A computerized tomographic scan of the brain revealed a high-density mass lesion consistent with bleeding in the area caudal to the inferior colliculi, where the trochlear nerves decussate and exit the dorsal brainstem. Subsequent studies showed resolution of the density and persistent failure to enhance. Bilateral trochlear nerve palsies due to the nontraumatic brainstem bleeding are extremely rare.

Brain Stem↗
PubMed1990

[Responses in extraocular muscles from magnetic stimulation of the cat brain].

In 12 adult cats, pulsed magnetic stimuli were applied to the scalp, with the center of the stimulating coil over the interparietal bone. Recordings were obtained from the superior rectus, lateral rectus and inferior oblique muscles with concentric needle electrodes. In all cats, single muscle action potentials were recorded easily in all the muscles examined with latencies of 3.2-37.5 ms (mean 15.6ms). These responses disappeared after intravenous administration of pancuronium bromide. Furthermore, the elicited action potentials in the inferior oblique muscles disappeared by amputation of the inferior oblique branch of the oculomotor nerve. In some motor units, stronger stimuli shortened the latency of the responses. In most units, however, stimulus intensity did not influence the latency of responses over a wide range. The mean latency (15.6ms) is coincident with the latency of cortical spike potentials preceding voluntary saccades. This remarkable coincidence suggests that our pulsed magnetic stimuli have a very strong possibility of generation of human saccades. Thus, magnetic stimulation of the scalp may provide further information relevant to the normal operation of the oculomotor system.

Animals↗
PubMed1988

[A study on the membrane Na+ efflux of pregnancy-induced hypertension (PIH)].

In order to elucidate the mechanism of pregnancy-induced hypertension (PIH) from the point of view of vascular resistance, we measured the intracellular Na+ concentrations and the membrane Na+ effluxes using red blood cells from normal pregnant females and patients with PIH. We also discussed the influences of hormones such as estrogen, progesterone, dehydroepiandrosterone sulfate (DHAS), hydrocortisol, human placental lactogen (hPL), human chorionic gonadotropin (hCG), and prolactin and parathyroid hormone (PTH) on the membrane Na+ effluxes. The intracellular Na+ concentrations were lower and the Na+-K+-ATPase activities were slightly higher both in the luteal phase and in the first trimester of normal pregnancy than those in the follicular phase, after which the former gradually increased and the latter gradually decreased until term to the mean values of those in the whole menstrual period. In mild PIH, the intracellular Na+ concentrations were not significantly increased, and the Na+-K+-ATPase activities were significantly increased compared to those in the third trimester of normal pregnancy, which suggests the compensatory increase of the Na+-K+-ATPase activities as opposed to the increase of the intracellular Na+ concentrations. In severe PIH, the intracellular Na+ concentrations were significantly increased compared with those in the third trimester of normal pregnancy and slightly increased compared with those in mild PIH, whereas the Na+-K+-ATPase activities were slightly decreased compared with those in mild PIH, which indicates a breakdown of the compensatory increase of the Na+-K+-ATPase activities. The intracellular Na+ concentrations in PIH are significantly correlated to diastolic pressure, systolic pressure and mean blood pressure. When the male red blood cells were incubated with the hormone, dose-dependently the Na+-K+-ATPase activities were significantly elevated by hydrocortisol and slightly elevated by progesterone and hPL, and they were significantly depressed by estrogen and prolactin and slightly depressed by PTH. These results suggest that the peripheral vascular resistance might be increased in the third trimester of normal pregnancy compared with that in the first trimester because the intracellular Na+ concentrations were elevated, and the Na+-K+-ATPase activities in the cell membrane were decreased along the course of pregnancy as a result of the effects of various hormones in the maternal blood.(ABSTRACT TRUNCATED AT 400 WORDS)

Androgens↗
PubMed1986

Sirenoid monopodia with defects of right abdominal wall and lower limb associated with chromosome abnormality.

We have experienced a case of sirenoid monopodia with extreme deformity, which was studied pathoanatomically and genetically. The pathoanatomical studies revealed complicated deformities such as absence of the right abdominal wall, sacrum, right side of the os coxae and lower extremity, etc., and a chromosome study revealed 46XX, t (1 p-, Xq+), -8, +M. Various authors have discussed the genetic factors of anomaly of vascular development and concluded that all cases except for a few familial types would appear to be sporadic. In the present paper we report on an extreme type of sirenoid monopodia with right lower limb defect associated with chromosome abnormality. It is supposed that impoverished blood supply to the right lower portion of the body may have been the cause of this case, but the involvement of genetic factors is still unknown.

Abdominal Muscles↗
PubMed1986

Single fiber electromyography in cat extraocular muscles.

Single fiber electromyography (SFEMG) was carried out in the extraocular muscles (EOMs) of 40 adult cats, and the recordings were analyzed. The small fluctuations of the interpotential interval (IPI), so-called "jitter phenomenon", were represented quantitatively as a mean consecutive difference (MCD). The MCD and the IPI recorded from the orbital layer of the rectus muscles were similar among the 4 rectus muscles: the MCD and the mean IPI measured in 58 motor units from the 4 rectus muscles averaged 25.82 microseconds and 0.94 ms, respectively. These values were similar to those recorded from the oblique muscles. The MCD and IPI were 34.12 microseconds and 1.70 ms, respectively, in the retractor bulbi muscles and 45.54 microseconds and 1.23 ms, respectively, in the triceps muscles. The MCDs of the rectus and inferior oblique muscles were considerably smaller than those in the retractor bulbi and the skeletal muscles.

Animals↗
PubMed1984

Retinal sensitivity and spatial summation in amblyopia.

The retinal sensitivity and the spatial summation function in the foveal and parafoveal regions of unilaterally amblyopic patients with eccentric fixation were studied psychophysically by means of a refined fundus perimeter; the device made possible continuous and simultaneous monitoring of the subject's fundus, fixation behavior and location of the stimulus on the retina, and enabled us to obtain selectively reliable data. In 9 out of 10 amblyopic eyes, the retinal sensitivity was the highest at the subject's eccentric fixation locus, demonstrating central relative scotoma. In the fovea of amblyopic eyes, the spatial summation curve showed an abnormal gradient when tested with small stimuli, suggesting an enlarged spatial summation area at the amblyopic fovea. On the other hand, the spatial summation curve at the eccentric fixation locus was comparable to that at the corresponding eccentric locus of the nonamblyopic fellow eye, suggesting the spatial summation function at the peripheral retina was normal in the amblyopic eye.

Adolescent↗
PubMed1981

Retinal sensitivity and spatial summation in the foveal and parafoveal regions.

Retinal sensitivity and the critical area of the spatial summation in the foveal and parafoveal regions were investigated by using a fundus-controlled perimeter to monitor accurately a subject's fundus picture and target position on the retina. The first experiment showed that retinal sensitivity and the critical area change continuously from fovea to periphery and that the diameter of the critical area is a linear function of retinal eccentricity. In the second experiment, this linear relationship was verified by another method.

Adult↗