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Biomedical subjects

M Wakakura

Publications and source records attributed to M Wakakura.

At least 73 records · Page 4Linked to original sources
PubMed1987

Distribution and orthograde axonal transport of HRP in feline eyes following intravitreal injection: an ultrastructural study.

The retina and optic nerve in the cat were examined by electron microscopy at five different time periods (1-, 3-, 8-, 16- and 24 hr) following the injection of horseradish peroxidase (HRP) into the vitreous cavity. Intra- and intercellular HRP was found in ganglion cells, Müller cells and horizontal cells even at 1 hr. Intra-axonal HRP in the retina and the retrolaminar optic nerve was seen most frequently at 3- and 8 hr. At 16- and 24 hr, many phagocytes containing HRP were noted in the nerve-fibre layer; subsequently HRP activity decreased throughout the retina. On the other hand, HRP activity in the intracanalicular optic nerve was significantly increased at 16 hr. Intra-axonal HRP appeared to be morphologically distributed in two forms: (i) HRP granules bound by a single-unit membrane mostly 0.1-0.4 micron in diameter; (ii) granules less than 0.05 micron which were occasionally hard to distinguish from artefacts such as stain deposit. The rate of orthograde axonal transport of HRP granules larger than 0.05 micron was examined on the basis of the frequency of HRP granules appearing in the retrolaminar and intracanalicular parts of the optic nerves. Though the rate seemed to be widely variable, the major velocity was calculated to be 45 mm per day, which is equal to intermediate axonal flow rates.

Animals↗
PubMed1987

Immunohistological localization of calmodulin in feline rod outer segments.

The calcium-binding regulatory protein, calmodulin, was immunohistologically examined in feline rod outer segments. The peroxidase antiperoxidase technique was used for the immunohistological analysis and protein A-gold, to localize calmodulin electron-microscopically. Calmodulin was found to be located in the distal position of the rod outer segments. Most of the gold particles could be seen on the disk membranes. The same observations were obtained for retinas in either a light or dark environment. Thus, there is the possibility that calmodulin may have some influence on enzyme activity in the rod outer segments, particularly in the distal portion.

Animals↗
PubMed1987

A simple clinical method of assessing patients with optic nerve hypoplasia. The disc-macula distance to disc diameter ratio (DM/DD).

The diagnosis of optic nerve hypoplasia may be difficult when the optic disc is only slightly reduced in size, or when central visual acuity is normal, or only minimally decreased. In these cases, measurement of the DM/DD ratio can provide a valuable tool in establishing the diagnosis. By means of fundus photographs the ratio of the distance between the centre of the optic disc and the fovea centralis, to the diameter of the optic disc (the DM/DD ratio) is measured. We have calculated the DM/DD ratio in 19 eyes of 11 patients with optic nerve hypoplasia and found it to be significantly higher than the ratios obtained for 58 eyes of 48 normal subjects, 22 eyes of 11 patients with primary open angle glaucoma and 25 eyes of 16 patients with optic atrophy. The DM/DD ratio is easily estimated and is recommended as a simple means of establishing the diagnosis of optic nerve hypoplasia.

Adolescent↗
PubMed1987

[The evaluation of cardiac function and the effect of therapy in acute myocardial infarction--comparison by radio nuclide method in acute and chronic phase].

The cardiac function and the effect of therapy in patients with acute myocardial infarction (AMI) were assessed in over 100 patients by analysis of 201Tl-scintigraphy and 99mTc-gated pool study in our ICU. The cardiac function and 201Tl-defect ratio were compared with the results obtained in chronic phase. Sixteen of them were treated with intravenous urokinase (UK) within 6 hours from onset. The other 18 patients without UK treatment served as a control group. Significant correlation was recognized between 201Tl-defect ratio and peak-CPK levels, peak-GOT levels, peak-LDH levels. Significant correlation (r = -0.655, r = -0.713) were found between 201Tl-defect ratio and LVEF in acute and chronic phase. The UK group showed a significant increase of LVEF as compared with the control group in patients with antero-septal (A/S) AMI. In inferior (INF) AMI, no significant differences were observed UK and control group in LVEF, RVEF and 201Tl-defect ratio. In chronic phase, improvements of LVEF and 201Tl-defect ratio were observed in patients with A/S AMI. But no significant differences of LVEF, RVEF and 201Tl-defect ratio were observed in A/S AMI in acute and chronic phase. The UK group showed a significant increase of LVEF (50.1%) as compared with the control group of A/S AMI in chronic phase. We have demonstrated that a combination of 201Tl-scintigraphy and 99mTc-gated pool study are useful techniques in ICU, to evaluate the cardiac function and the effect of thrombolysis therapy and thus greatly contribute to the primary care of AMI cases.

Female↗
PubMed1986

[Evaluation of the visualized left atrium by 201Tl myocardial scintigraphy].

201Tl myocardial scintigraphy was evaluated in patients with 18 mitral stenosis cases. Left atrium was to be seen in ANT (16.7%), LAO (16.7%), MLAO (16.7%) and L-LAT (11.1%), respectively. Furthermore, 201Tl uptake ratio of left atrium, right ventricle, pulmonary area tended significantly to increase in visible group compared with invisible group. PCW pressure was correlated with left atrial Tl uptake (r = 0.51, p less than 0.005), and it indicated some correlation between left atrial pressure and 201Tl uptake.

Adult↗
PubMed1985

Orthograde axonal transport of optic nerve and injury--morphological study.

To investigate the effects of injury to the orthograde axonal transport in the optic nerve, horseradish peroxidase (HRP) was injected into the vitreous of the cat eye after various types of optic nerve injury, and the retina and optic nerve were examined with light and electron microscopes 8 hours after the injection. The optic nerve was sectioned in one eye at about 6 mm behind the eyeball and the optic nerve of the contralateral eye was used as the control. HRP reaction products were frequently observed within the retinal ganglion cells and their axons of the nerve fiber layer as well as in the retrolaminar optic nerve on the experimental side, and the findings were similar to those on the control side. The optic nerve was injured by cryocoagulation for 10 seconds or 30 seconds, and ischemic changes of various degrees were induced. Intracellular and intra-axonal HRP reaction products were markedly reduced at the retrolaminar portion, and the degree of reduction depended on the duration of cryocoagulation. The section of the optic nerve had, at least in the early stage, only minimal effects on the orthograde axonal transport, but the optic nerve injury accompanied by ischemic changes markedly blocked the axonal transport in both the inner part of the retina and the optic nerve.

Animals↗
PubMed1985

Junction scotoma and involvement of the optochiasmal junction.

In two patients, ipsilateral central scotoma and contralateral superior temporal hemianopic field defect indicated involvement of the junction of the optic nerve and chiasm, the optochiasmal junction. In both cases, computed tomography and carotid angiography confirmed mass lesions at this location. After surgical removal of a parasellar tumor in one case, we found that the optic nerve and the anterior part of the optic chiasm were compressed upwards. The previously reported examples of these perimetric findings are reviewed and compared with those of our cases. We concluded through this study that the characteristic combination of visual field defects, namely central or paracentral scotoma on the involved side and superior temporal field defect on the uninvolved side, should be termed junction scotoma.

Adult↗
PubMed1984

Central serous chorioretinopathy complicating systemic corticosteroid treatment.

Central serous chorioretinopathy developed in 2 cases of retrobulbar neuritis during systemic treatment with corticosteroids. Fluorescein angiography confirmed leakage surrounded by central serous detachment of the retina. In one case the central serous chorioretinopathy recurred 3 times during 3 separate courses of treatment. Spontaneous recovery accompanied a reduction in steroid treatment to a low level. It is suggested that high dosage corticosteroids may damage the posterior blood-ocular barrier.

Adult↗
PubMed1983

Circadian rhythm of human electroretinogram.

In order to ascertain the presence of circadian rhythm in the electrical responses of the retina, scotopic electroretinogram (ERG) evoked mainly by light flash stimulus was recorded consecutively in 14 normal healthy subjects during a 24-hour period. The ERGs were measured at 6, 12, 18 and 24 o'clock. Both a- and b-waves were analyzed. The a-wave amplitude of all subjects studied showed no circadian rhythm. By our criteria, the b-wave amplitude showed circadian rhythm in 8 of the 14 subjects. The minimum amplitude of the b-wave was seen at 6 o'clock. The amplitude of the b-wave was significantly higher at 12 o'clock when compared with the amplitude at 6, 18 and 24 o'clock. This tendency was repeatedly observed. The presence of circadian rhythm in the scotopic b-wave was, therefore, suggested. This rhythm had a good correlation with the circadian rhythm of dopamine beta-hydroxylase in the serum and no correlation with the corticosteroid level in the serum. The possibility of circadian rhythm in the human ERG should be taken into consideration for routine clinical application.

Adult↗
PubMed1982

Scanning electron microscopy of retinal ganglion cells by applying D,L-2-aminoadipic acid.

Retinal ganglion cells of the cat were clearly demonstrated in scanning electron microscopy. For identification of the cells, D,L-2-aminoadipic acid, a gliotoxic compound, was applied. Müller cells as well as astrocytes were destroyed by intravitreal injection of the aminoadipic acid prior to the enucleation. Balloon-shaped retinal ganglion cells with an axonal process were visualized in the normal cat retina. Flattened and sometimes indented ganglion cells were observed in the pathologic retina which was made 2 weeks after optic nerve transection. Pretreatment with the aminoadipic acid was a very effective method for the identification of the retinal ganglion cells by scanning electron microscopy.

2-Aminoadipic Acid↗
PubMed1982

Ultrastructural study on centrifugal fibers in the feline retina.

Morphological studies were carried out to elucidate whether centrifugal fibers are present in the cat retina. Unilateral optic nerve transection with the minimum vascular damage was performed at 6 mm behind the eyeball via the soft palate approach in adult specific pathogen free cats. Light and electron microscopic observations were performed at 40 and 96 hours after the optic nerve transection. At 40 hours, when there was no evidence of degenerative change in the retinal ganglion cells, degenerative changes were observed in the neuronal processes in the outer part of the inner plexiform layer. Two forms of degeneration occurred in close proximity to the cell bodies or the processes of amacrine cells: electron opaque and electron lucent degeneration. Since degeneration of the ganglion cells became manifest at 96 hours, the early neuronal changes in the inner plexiform layer were thought to represent degeneration of the centrifugal fibers.

Animals↗