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Biomedical subjects

E Adachi-Usami

Publications and source records attributed to E Adachi-Usami.

At least 37 records · Page 2Linked to original sources
PubMed1999

Glial cells in degenerating and regenerating optic nerve of the adult rat.

The glial cell reaction both in degenerating and regenerating adult rat optic nerve was studied by immunohistochemistry and electron microscopy. Degeneration in the optic nerve was achieved by complete transection, and the retinal stump was then analyzed. The regeneration was observed by autotransplantation of a sciatic nerve segment to the transected retinal stump. In both cases, optic nerve axons were labeled anterogradely with rhodamine, followed by immunohistochemical staining. Glial fibrillary acidic protein-positive astrocytes covered the transected end of degenerating optic nerve, whereas in the regenerating optic nerve they enwrapped axonal bundles emerging from the optic nerve stump and migrated together into the transitional zone intervening between the retinal stump and graft. In electron microscopy, direct attachment of astrocyte and Schwann cell was found within the transitional zone, whereby these cells were holding axons between them. Decrease of 04 immunoreactivity, which labels oligodendrocytes, was apparent in the transected end of retinal stump during the regeneration. The ED1 -positivity, which labels microglia/macrophages, was found in cells accumulated in the transitional zone of degenerating optic nerve, whereas during regeneration, ED1-immunoreactive cells were also distributed in the retinal stump. These results suggest that astrocytes, usually considered to interfere with optic nerve regeneration, change their characteristics in the presence of peripheral nerve graft and guide the regenerating axons in cooperation with Schwann cells. The response of oligodendrocytes and microglia/macrophages may also be modulated by peripheral nerve.

Animals↗
PubMed1999

An amplitude ratio of pattern visually evoked cortical potentials.

PURPOSE: We evaluated the amplitude of steady state pattern visually evoked cortical potentials (St PVECP) by comparing the amplitude ratio to transient PVECP (Tr PVECP) with the latency of Tr PVECP in macular, optic nerve, and chiasmal lesions. METHODS: PVECPs were obtained by pattern reversal stimulation of both 3 times and 12 times per second from normal subjects and patients. The peak latency of the P100 component of Tr PVECP and the amplitude ratio (St PVECP/ Tr PVECP) were studied. RESULTS: Ratio abnormalities were specifically found in patients with optic and chiasmal lesions who had normal Tr PVECP latency, but not in those with macular lesions. The ratio increased with visual improvement in optic nerve disease and chiasmal lesions. CONCLUSION: The amplitude ratio was useful in detecting and monitoring optic nerve and chiasmal lesions, and in differentiating optic nerve and chiasmal lesions from macular lesions.

Adolescent↗
PubMed1999

An electrophysiological follow-up study on acquired unilateral nyctalopia.

PURPOSE: To describe the clinical picture and electrophysiological findings in acquired unilateral nyctalopia. METHODS: A patient who had acquired unilateral visual loss with normal fundus was followed for a period of 2.5 years with basic ophthalmological examinations including standard electroretinogram and photopic on and off responses. RESULTS: A 46-year-old woman suffered from acquired unilateral nyctalopia. She complained of photopsia and blurred vision in her left eye. The initial examination of the left eye showed 1+ cells in the anterior chamber and a granular appearance in the fovea. After 1 month of treatment she still complained of photopsia in her left eye. Ophthalmoscopy and fluorescein angiography revealed no abnormality in either eye. A bright flash electroretinogram (ERG) in the left eye was a negative shape. Photopic ERG elicited by a 150 ms stimulus showed a depressed b-wave and enhanced a- and d-waves in the left eye. CONCLUSIONS: This ERG waveform suggested that the transmission between photoreceptor and on-bipolar cell might be affected by idiopathic retinal disease.

Electroretinography↗
PubMed1999

Optic nerve blindness due to paranasal sinus disease.

Patients with total blindness caused by paranasal sinus disease have rarely been reported. We retrospectively studied the prognosis of patients who had optic nerve blindness due to paranasal sinus disease. During the past 10 years, we identified 17 patients with optic nerve disease and posterior paranasal sinus disease. Seven of the 17 patients with optic nerve disease and paranasal sinus disease had no light perception. Five of these 7 patients with paranasal sinus disease had a final visual acuity of 20/200 or better. Two patients showed dramatic visual improvement after endonasal surgery. Because immediate surgery to correct paranasal sinus disease is required in affected patients, computed tomography should be done at the patient's first visit.

Adult↗
PubMed1999

Effects of intravitreal injection of botulinum toxin on the electroretinogram of rats.

The retinal toxicity of botulinum toxin A (BTA) was electroretinographically studied in rats. Sixteen rats were injected intravitreally with 10 ng of BTA. A response-amplitude series was recorded before and 1, 6, 13 and 21 days after the injection of BTA. BTA did not alter the amplitude and the peak latency of the a-wave. The amplitude of the b-wave was not changed except for 2 rats, in which the b-wave was diminished. The peak latency of the b-wave was significantly prolonged after injection of 10 ng BTA (p < 0.05). Except for these latter 2 rats, the results indicated that the dosage used therapeutically appears to have no deleterious effect on retinal integrity or function at least in the short term, but multiple injections or higher doses of BTA could alter retinal function.

Animals↗
PubMed1999

Light-induced apoptosis in the neonatal mouse retina and superior colliculus.

UNLABELLED: PURPOSE. Apoptosis occurs naturally in the rodent retina and superior colliculus (SC) during the neonatal period. The authors used mice to demonstrate the dependency of this apoptosis on the light stimulation and the developmental period. METHODS: A number of apoptotic cells were counted in the retina and SC from a group of newborn mice reared in constant darkness (DD group), a group reared in normal light and dark conditions (LD group), and a group reared in constant darkness up to P7 and then transferred to normal condition (DD-to-LD group). Terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick end labeling (TUNEL) was used for visualization of the apoptotic cells. RESULTS: In the LD group, apoptotic cells significantly increased in the retinal nuclear layers, including both the outer and inner nuclear layers, the retinal ganglion cell layer, and SC at postnatal day 1 (P1) and postnatal day 2 (P2). The number of apoptotic cells in the ganglion cell layer and SC reached the maximum level at P1. In contrast, in the DD group, an increase in the number of apoptotic cells was not observed. At P9, no significant increase in the number of apoptotic cells was observed in the outer nuclear layer, ganglion cell layer, and SC either in the LD, DD, or DD-to-LD groups, but the LD and DD-to-LD groups showed a significant increase in the inner nuclear layer compared to the DD group. CONCLUSIONS: Apoptosis during the neonatal period in the mouse visual system is induced by a light stimulus. This apoptosis was not induced after P7 in the retinal ganglion cell layer and SC, even if excessive cells survived.

Animals↗
PubMed1998

Putative gap junctional communication between axon and regenerating Schwann cells during mammalian peripheral nerve regeneration.

Gap junctions are intercellular channels which mediate the traffic of ions and a variety of molecular messengers between contiguous cells. Here, we report on the possibility that atypical gap junctions develop between heterologous tissues, such as regenerating nerve axons and Schwann cells, during peripheral nerve regeneration in adult rats. After a complete transection and subsequent regeneration in the rat sciatic nerve distal segment, a small scale gap junction-like structure was observed between the regenerating axons and adjoining Schwann cells. Immunoelectron microscopy showed that one of the gap junctional proteins, connexin32, was located at a small region of contact between the axon and Schwann cells. Biocytin, a small molecular weight dye, was transported from regenerating axons into adjoining Schwann cells. The present findings suggest that regenerating axons communicate directly with adjacent Schwann cells through small gap junctions, which may play a role in the mechanism of regeneration following nerve transection.

Animals↗
PubMed1998

Steady-state PVECP is superior to transient PVECP in the diagnosis of optic neuritis.

PURPOSE: To compare the diagnostic value for optic neuritis between transient pattern visual evoked potentials (PVECP) and steady-state PVECP. SUBJECTS & METHODS: We retrospectively studied 86 eyes of 69 patients with optic neuritis who visited our clinic. PVECPs to 3 rev/sec stimulation (transient) and 12 rev/sec stimulation (steady-state), were recorded in all patients. RESULTS: All of the cases with non-recordable transient PVECP showed non recordable steady-state PVECP Conversely, the cases with non-recordable steady-state PVECP often showed measurable transient PVECP where the latency of the P100 component was delayed. In 51 cases with unilateral optic neuritis, the amplitude ratio of the P100; affected eye/non-affected eye was significantly smaller in the steady-state PVECP than in the transient PVECP CONCLUSION: To detect visual dysfunction in optic neuritis, a steady-state PVECP was more sensitive than a transient PVECP.

Adolescent↗
PubMed1998

Decreased amplitude of steady state pattern visually evoked cortical potentials in multiple sclerosis.

PURPOSE: We studied the amplitude of steady state (St) PVECP using the amplitude ratio to transient (Tr) PVECP clinically in patients with multiple sclerosis. METHODS: Case report. A 25-year-old woman had multiple sclerosis without optic neuritis. She had normal vision and visual fields. She was followed by both St and TrPVECP. Statistical analysis. Patients with multiple sclerosis and no optic neuritis were retrospectively studied for both Tr and StVECP. RESULTS: Six months later, she showed a decreased ratio in the left eye, corresponding to abnormalities in the center of the visual field. The peak latency of TrPVECP remained normal in both eyes. A decreased ratio was found in 27% of patients with multiple sclerosis and no optic neuritis. CONCLUSIONS: Not only Tr, but StPVECP should be recorded in patients with multiple sclerosis and normal vision to detect abnormalities in the visual pathway.

Adult↗
PubMed1998

Follow-up studies on pattern reversal visually evoked cortical potentials in a 2-year-old child with optic neuritis.

A 2-year and 7-month-old boy had sudden visual loss in both eyes and showed bilateral optic neuritis without systemic symptoms. Steroid therapy improved his visual acuity from 0.077 and 0.053 to 1.0 at 7 months after onset. Magnetic resonance imaging (MRI) of the brain showed high density in both optic nerves and multiple lesions in the white matter that were enhanced by gadolinium. We considered the diagnosis of demyelinating disease. Follow-up MRI showed no abnormal lesion. Both transient and steady-state pattern visually evoked cortical potentials were nondetectable at the onset, and the P100 component of the transient pattern reversed visually evoked cortical potential appeared to be delayed thereafter. It has since become shorter in parallel with visual acuity improvement.

Blindness↗
PubMed1997

Functional recovery of retina after sodium iodate injection in mice.

ERGs and the azide responses were recorded from mice before and periodically up to 6 weeks after retinal pigment epithelium (RPE) damage by iodate injection to follow the recovery of retinal pigment epithelium and retinal function. At 14 days postinjection, there was a partial recovery of the maximal b-wave amplitude and the azide response but no further recovery was found after 14 days. The retinal sensitivity showed a slow recovery, and at 6 weeks postinjection did not differ from the pre-iodate sensitivity. These findings correlated with histological observations. We concluded that the recovery in ERGs resulted from RPE recovery and the large patchy area of recovered retina functioned normally.

Animals↗
PubMed1997

How are macular changes reflected in pattern visually evoked cortical potentials?

To investigate the macular contribution to the amplitude and latency of pattern visual evoked cortical potentials (PVECPs), we recorded PVECPs in patients with unilateral macular disease (retinal diseases involving the macular region) and optic neuritis. We selected patients with visual acuities better than 0.3, which is thought to be the minimum acuity to provide clearly discernible responses. The visual stimulus was a checkerboard. We varied the check size in 4 steps as 7, 14, 28, and 56 min of arc, and the contrast was 20% or 80%. The amplitude of the sinusoidal wave of steady-state VECPs (12 Hz) and the P100 component of a transient VECP (3 Hz) were measured. Significant attenuation and delay of PVECPs in the affected eye were found in the macular disease group. Macular disease may cause an increase of VECP latency. However, VECP seemed to be a more sensitive test of optic nerve disease than of macular disease, when patients had similar visual acuities.

Adult↗
PubMed1997

The role of Schwann cells during retinal ganglion cell regeneration induced by peripheral nerve transplantation.

PURPOSE: To investigate the key role of Schwann cells in retinal ganglion cell regeneration elicited by peripheral nerve autotransplantation. METHODS: Three kinds of autografts, Schwann-cell graft (intact sciatic nerve, consisting of living Schwann cells and their basal laminae). Schwann-cell-eliminated graft (consisting mainly of Schwann cell basal laminae) and partial Schwann-cell graft (consisting of basal laminae and diffusible factors secreted by Schwann cells) were prepared and autotransplanted to the adult rat optic nerve. The membrane specialization between regenerating axons and Schwann cells was observed by electron microscopy. The expression of cell adhesion molecules was demonstrated by Western blot analysis and immunohistochemistry. RESULTS: Retinal ganglion cell axons were observed to regenerate into the Schwann-cell graft in contact with Schwann cells but not into the Schwann-cell-eliminated graft. The regeneration was not observed in the empty basal laminae of the partial Schwann-cell graft. Most of regenerating axons contacted astrocytes in the optic nerve segment, and Schwann cells in the graft. At the interface of regenerating axon and Schwann cell, in addition to immunoreactivity of N-CAM and LI, short focal tight junctions were observed. CONCLUSIONS: These results suggested that viable Schwann cells are good substrate for retinal ganglion cell regeneration, the intimate contact with viable Schwann cell surface plays an important role in retinal ganglion cell regeneration, tight junctions, and cell adhesion molecules (LI, N-CAM) are observed between the regenerating axon and Schwann cell.

Animals↗