Biomedical subjects

J Akiba

Publications and source records attributed to J Akiba.

81 records · Page 5Linked to original sources

PubMedDate not supplied

Cross-linking of vitreous collagen and degradation of hyaluronic acid induced by bilirubin-sensitized photochemical reaction.

To determine the mechanisms of vitreous liquefaction following vitreous hemorrhage, we investigated the effects of the free radicals produced by a bilirubin-sensitized photochemical reaction on collagen and hyaluronic acid (HA). Bovine vitreous collagen and HA were irradiated by visible light in the presence of bilirubin, which is produced from the degradation of hemoglobin, as a photosensitizer. Changes in molecular weight were monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the collagen, and high-performance liquid chromatography for the HA. We found that free radicals caused an increase in high-molecular-weight components and insolubilization of the vitreous collagen, and a decrease in the molecular weight of HA. The changed molecular properties of the vitreous collagen could be attributed to the extensive cross-linking of the molecules. This cross-linking and the degradation of HA, both induced by the bilirubin-sensitized photochemical reaction, may contribute to vitreous liquefaction following vitreous hemorrhage.

Animals↗

PubMedDate not supplied

Abnormal vitreous structure in optic nerve pit.

A 37-year-old man presented with an optic nerve pit and serous macular detachment of the left eye. Scanning laser ophthalmoscopy revealed a cyst-like structure terminating at the pit in the premacular vitreous. During ocular movement, this structure moved vigorously and seemed to exert traction on the pit. We believe that it is part of an anomalous Cloquet's canal, and that traction on the pit may be a significant factor in the development of serous macular detachment in this patient.

Adult↗

PubMedDate not supplied

Expression and localization of vascular endothelial growth factor receptors in human hepatocellular carcinoma and non-HCC tissues.

Flt-1 (VEGF receptor-1) and KDR/Flk-1 (VEGF receptor-2) are the high-affinity receptors for the angiogenesis factor, vascular endothelial growth factor (VEGF). VEGF expression has been confirmed in human hepatocellular carcinoma (HCC), and VEGF is thought to be involved in the angiogenesis within HCC tissues. However, expressions of VEGF receptors in HCC have not been reported. We immunohistochemically examined expressions and localizations of Flt-1 and KDR in 28 surgically resected HCC tissues. In non-cancerous area, Flt-1 and KDR were mainly found in macrophages including Kupffer cells; both receptors were found in vascular endothelial cells in the portal veins and arteries within portal tracts; and KDR was also found in some sinusoidal endothelial cells. In cancerous area, Flt-1 and KDR were found in some macrophages, and also in the endothelial cells of intratumoral blood vessels. In 25 moderately and/or poorly differentiated HCCs, KDR expression in the blood space endothelial cells was clear and continuous in 20 cases, and focal in 5 cases. These results suggest that there would be an angiogenesis mechanism via VEGF/Flt-1 or VEGF/KDR in HCC, and the VEGF/KDR system would take a more important role.

Carcinoma, Hepatocellular↗

PubMedDate not supplied

OCT in successful surgery of retinal detachment associated with optic nerve head pit.

The authors describe the course of a patient with retinal detachment associated with optic nerve head pit for whom optical coherence tomography (OCT) was performed before and after vitrectomy and gas tamponade. An 18-year-old woman presented with macular elevation and a lamellar macular hole associated with optic nerve head pit. OCT showed that the retinal elevation consisted of both separation of the inner and outer retinal layers and detachment of the outer layers from the retinal pigment epithelium. After vitreous surgery and postoperative intraocular gas tamponade, the macular elevation gradually resolved, and OCT showed that improvement in central vision corresponded with flattening of the outer layer detachment in the fovea. OCT is a useful tool for monitoring the therapeutic effect of vitrectomy and gas tamponade for retinal detachment associated with optic nerve head pit.

Adolescent↗

PubMedDate not supplied

Retinal detachment and retinoschisis detected by optical coherence tomography in a myopic eye with a macular hole.

The authors describe a myopic patient with a full-thickness macular hole that was accompanied by both retinal detachment and retinoschisis. A 51-year-old woman presented with a localized retinal elevation of three disc diameters around the macular hole in a myopic eye. Optical coherence tomography (OCT) showed features of both retinal detachment and retinoschisis. After vitreous surgery and postoperative intraocular gas tamponade, the macular elevation resolved, and separation of the neurosensory retina from the retinal pigment epithelium band disappeared on the OCT images. OCT is a useful tool for examining macular conditions associated with a macular hole in myopic patients.

Diagnostic Techniques, Ophthalmological↗

PubMedDate not supplied

Three-dimensional characteristics of macular pseudoholes using confocal laser tomography.

BACKGROUND: Epiretinal membranes with macular pseudoholes are sometimes confused with full-thickness macular holes. Because both the natural course and clinical management of the two differ, an accurate differential diagnosis is needed. PATIENTS AND METHODS: We obtained three-dimensional images of macular pseudoholes in 12 eyes using the Heidelberg retina tomograph (HRT). Another 15 eyes with a full-thickness macular hole were also studied. In addition, we measured the area and the maximum depth of both types of holes. RESULTS: Irregular rippling undulations were frequently observed on the three-dimensional topographic maps around the pseudoholes, whereas elevated cuffs were observed around the full-thickness holes. The maximum depth of the macular pseudoholes (mean, 57 microm) was significantly shallower than that of the full-thickness macular holes (mean, 156 microm; P < 0.01). CONCLUSION: Three-dimensional images obtained by the HRT and the measurement of the maximum depth may be useful in differentiating macular pseudoholes from full-thickness macular holes.

Aged↗

PubMedDate not supplied

Three-dimensional analysis of macular diseases with a scanning retinal thickness analyzer and a confocal scanning laser ophthalmoscope.

OBJECTIVE: To compare three-dimensional analysis of macular diseases obtained using the scanning retinal thickness analyzer (RTA) with that obtained using the confocal scanning laser ophthalmoscope, Heidelberg Retina Tomograph (HRT). PATIENTS AND METHODS: Both the RTA and the HRT were used to examine 50 eyes of 36 patients with diabetic macular edema, macular edema following branch retinal vein occlusion, age-related macular degeneration, and idiopathic macular holes. RESULTS: In most macular diseases, the retinal thickness map constructed using the RTA agreed with the image obtained with the HRT. The two maps were not consistent with each other, however, in patients with dense retinal hemorrhages and with extrafoveal fixation. CONCLUSIONS: Although both the RTA and the HRT give additional information to clinically evaluate macular diseases, they do have limitations. The discrepancy between these two analyses in some specific macular pathologies might be caused by the different wavelengths of the laser beam and the different methodologies used to scan the retina.

Aged↗

PubMedDate not supplied

Prevalence of posterior vitreous detachment in retinitis pigmentosa.

To investigate the prevalene of posterior vitreous detachment (PVD) and PVD with collapse in relation to age in eyes with retinitis pigmentosa (RP), we retrospectively studied the vitreous condition in 218 eyes of 109 patients with RP. Two hundred thirty healthy eyes of 115 subjects served as controls. The prevalence of both PVD and PVD with collapse, respectively, in the first through the sixth decades of life, and the second through the seventh decades was significantly higher in the RP eyes than in the controls (P < .01). Our findings demonstrated the early onset and progression of PVD with age in the eyes with RP as compared with the control eyes.

Adolescent↗

PubMedDate not supplied

Comparison of the prevalence of posterior vitreous detachment in whites and Japanese.

The vitreous condition of healthy white (n = 551) and Japanese (n = 528) eyes were reviewed and compared with respect to the prevalence of posterior vitreous detachment (PVD) in the two groups. No white or Japanese patient 39 years of age or younger had PVD; the prevalence among those older than 39 increased with age in the fifth through the ninth decades, i.e., respectively, to 4%, 24%, 37% 59%, and 87% in the whites, and to 5%, 21%, 43%, 72%, and 82% in the Japanese. In none of these decades was there any significant difference between the prevalence of complete or partial PVD in the whites and the Japanese. This finding is significant because the vitreoretinal relationship influences the development and prognoses of the various vitreoretinal disorders.

Adolescent↗