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Biomedical subjects

T Otori

Publications and source records attributed to T Otori.

At least 19 recordsLinked to original sources
PubMed1999

[Photostimulation that induces flattening of photopic electroretinograms--first report. An apparatus for slope photostimulation].

PURPOSE: We developed a new photostimulation system for electroretinograms (ERGs). This apparatus is capable of varying the transients during stimulus on and off (up-slope and down-slope times, respectively) as well as the stimulus and background intensities. We applied this system to evaluate the photopic ERG in human eyes. CASES AND METHODS: Seven normal volunteers and a 43-year-old patient with pre-proliferative diabetic retinopathy served as test subjects. We recorded ERGs with relatively long intervals of up-slope and down-slope times for photostimulation. RESULTS: As the up-slope and down-slope times were increased, the amplitude was reduced and the peak latency was prolonged for both the on and off responses. When the normal subjects' retinas were stimulated with a 341-msec up-slope time and a 34.1-msec down-slope time, the ERG waves showed complete flattening in both on and off responses. The ERGs of a patient with pre-proliferative diabetic retinopathy showed much longer peak latency than that of the normal volunteers as the up-slope time was prolonged. When the patient's retina was stimulated for a prolonged up-slope time, the average of the amplitude of ERG waves was similar to that of the normal volunteers. CONCLUSION: These results suggest that this new type of photostimulation might potentially uncover some novel aspect of clinical ERGs and might be useful for testing retinal functions of patients with diabetic retinopathy.

Adult↗
PubMed1998

[Basic and clinical aspects of modern perimetry].

Clinical perimetry has made a remarkable advance in the last 40 years and many new automated perimeters and sophisticated techniques are now available. We developed a Central Field Screener, O-II, an automated perimeter, ATS-85, and a central critical fusion frequency (CFF)-meter. First, reappraisal of the clinical significance of manual kinetic perimetry was made in comparison with automated light threshold perimetry in the diagnosis of retinitis pigmentosa and chiasmal tumors. We concluded that manual kinetic perimetry was the basis of clinical perimetry and superior to automated static light threshold perimetry in some cases. Secondly, automated static flicker perimetry was performed with Octopus 1-2-3 and a software package developed by us. We found that automated static flicker perimetry was far superior to automated static light threshold perimetry in the detection of early changes of glaucomatous field defects, especially in cases of immature senile cataract. We also confirmed that measurement of CFF was essential in the diagnosis of optic neuritis and diseases of chiasmal syndrome. Dissociation of central vision and central CFF was observed in many cases of optic neuritis and inverse dissociation of central vision and central CFF was seen in some cases of Leber's disease.

Adult↗
PubMed1998

SPARC from corneal epithelial cells modulates collagen contraction by keratocytes.

PURPOSE: Contraction of the scar tissue during corneal wound healing changes the shape of the cornea and corneal refraction. In a previous study, it was found that corneal epithelial cells secrete the factor that stimulates collagen gel contraction by keratocytes in vitro. The purpose of the present study was to purify and identify the contraction-stimulating factor derived from corneal epithelial cells. METHODS: The cultured medium of rabbit corneal epithelial cells was collected and used as an epithelial cell-conditioned medium (ECCM). Subcultured rabbit keratocytes were embedded in a collagen gel, and collagen gel contraction was investigated. The contraction-stimulating factor in the ECCM was purified through acetone precipitation, affinity chromatography (heparin Sepharose), gel filtration, and reversed-phase chromatography. The amino acid sequence of a contraction-stimulating factor was analyzed. RESULTS: Collagen gel contraction by keratocytes was enhanced by the addition of ECCM in a dose-dependent manner. The amino acids sequence of the contraction-stimulating factor was homologous to a 32-kDa glycoprotein, a secreted protein that is acidic and rich in cysteine (SPARC). Western blot analysis confirmed that SPARC was contained in the ECCM. Collagen gel contraction by keratocytes was enhanced by the addition of purified SPARC in a dose-dependent manner. SPARC was found in the basal layer of the migrating epithelium and activated keratocytes adjacent to the wound 3 days and 1 week after perforating injury in rabbit corneas. CONCLUSIONS: Epithelial cells secrete SPARC, which modulates the contraction of scar tissue in the corneal stroma.

Animals↗
PubMed1997

[Measurement of regional cerebral blood flow and glucose utilization in rat brain under chronic hypoperfusion conditions following bilateral carotid artery occlusion. Analyzed by autoradiographical methods].

OBJECTIVE: Although the pathology of chronic hypoperfusion in rat following bilateral carotid artery occlusion has been documented, long term changes in cerebral blood flow and metabolism have not been reported. In this study regional cerebral blood flow (rCBF) and regional glucose utilization (rCGU) were analyzed by autoradiographical methods, pathological observation of the brains was also conducted. METHODS: Male Wistar rats aged 12 weeks were anesthetized and the bilateral carotid arteries were occluded. Physiological parameters, ABG, MABP, and rectal temperature were measured before and through occlusion. After 2 days, 1, 4, and 8 weeks and controls of rCBF (Sakurada) and rCGU. (Sokoloff) were measured (n = 6). Evaluated regions included frontal cortex (Fcor), parietal cortex (Pcor), temporal cortex (Tcor), occipital cortex (Ocor), genu corpus callosum (gCC), corpus callosum (CC), splenium corpus callosum (sCC), caudate putamen (CPu), globus pallidus (GP), internal capsule (IC), thalamus (Thal), hippocampus CA 1 (CA 1), hypothalamus (HypoTh), amygdal (Amygd), and substantia nigra (SNR). In separate animals (n = 3) tissue sections were stained using Klüver-Barrera (KB) and Hematoxylin-Eosin (HE), and pathological changes were observed. RESULTS: After 2 days the rCBF values were significantly reduced to 33-58% of control values in the Fcor. Pcor, Tcor, Ocor, gCC, CC, sCC, CPu, GP, JC, and Amygd. The reductions were observed from the 2nd day to the 1st week. From the 1st week to the 4th week values began to recover to control levels. However, after 4 weeks they were still significantly reduced in the Ocor, gCC, CC, sCC, GP, IC, and SNR (51-63%). After 8 weeks, the rCBF values in the areas except white matter, CPu, GP, and Ocor, etc., recovered to approximately 90% of control levels. However, in the Ocor, gCC, CC, sCC, CPu, GP, and IC, they were still 70-89% of control levels. After 2 days the rCGU values were reduced to 56-95% (except Amygd) in the measured regions, although not as reduced as the rCBF levels. From the 2nd day to the 1st week, the rCGU values were reduced further and after 1 week the rCGU values were significantly reduced to 39-69% in the Fcor, Pcor, Tcor, Ocor, gCC, CC, sCC, CPu, GP, IC (Lt), Thal (Rt), Amygd, and SNR From the 1st week to the 4th week, the values began to recover to control levels. After 4 weeks, rCGU improved to approximately 90-100% of controls, and remained at that level through 8 weeks occlusion. Rarefaction of the myelinated fibers was observed in the white matter from the 1st week to the 4th week in the KB stained sections, while little change in cortex was observed throughout 1st to 8th week. CONCLUSION: In this chronic hypoperfusion model rCBF remained depressed after 8 weeks in the Ocor, white matter, and basal ganglia, and rarefaction of the white matter was observed. These results indicate that this model is suitable for the study of chronic cerebral hypoperfusion.

Animals↗
PubMed1996

Entactin modulates the attachment of rabbit corneal epithelial cells.

PURPOSE: To understand the biological activity of entactin, a component of the basement membrane of the corneal epithelium, we investigated the ability of rabbit corneal epithelial cells to attach to an entactin matrix and the effect of entactin on the cells' attachment to other corneal basement proteins. METHODS: Multiwell plastic plates were coated with bovine serum albumin (BSA), alone or with BSA and entactin, laminin, fibronectin or collagen type IV. Cultured rabbit corneal epithelial cells were seeded on the plates. After incubation (usually 90 min), the cells were fixed and stained with 1% crystal violet. The number of attached cells was counted under a light microscope. RESULTS: The numbers of attached cells increased in proportion to both the incubation period and the concentration of entactin coated. Furthermore, the number of cells attached to the entactin-coated plate was greater than the number attached to the BSA-coated plate for each incubation period (30 to 120 min). Likewise, when laminin-coated plates were treated with entactin, the number of the attached cells increased in proportion to the concentration of entactin. However, entactin did not affect the cellular attachment of fibronectin or type IV collagen. Cellular attachment to entactin was partially inhibited by the cells' preincubation with the synthetic peptide (GRGDSP). CONCLUSIONS: The present results showed that cultured corneal epithelial cells adhere to entactin and that entactin stimulated the attachment of these cells to the laminin matrix. These findings suggest that entactin plays a specific role in maintaining the normal integrity of the corneal epithelium.

Amino Acid Sequence↗
PubMed1995

Up-regulation of integrin alpha 5 beta 1 expression by interleukin-6 in rabbit corneal epithelial cells.

Interleukin-6 (IL-6) has been shown to promote the attachment of rabbit corneal epithelial cells to fibronectin-coated substratum and ex vivo migration of the cells on the corneal stroma. To examine whether IL-6 promotes cell attachment through up-regulation of expression of integrin alpha 5 beta 1, i.e., the major cell surface fibronectin receptor, we quantified the levels of both alpha 5 and beta 1 subunit transcripts by reverse transcription-polymerase chain reaction in cultured rabbit corneal epithelial cells pretreated with various concentrations of IL-6. The levels of both alpha 5 and beta 1 mRNAs were dose-dependently elevated by IL-6, attaining 1.5- and 1.8-fold increases, respectively, at 10 ng/ml. The stimulatory effect of IL-6 was transient; the levels of both subunit mRNAs reached a maximum 1 h after the addition of IL-6 and returned to the basal levels after 6 h. The IL-6-induced up-regulation of integrin alpha 5 and beta 1 mRNAs was also confirmed by Northern blot analysis. These results indicate that the increased attachment of corneal epithelial cells to fibronectin and enhanced ex vivo migration on corneal stroma by IL-6 is, at least in part, due to the temporal up-regulation of integrin alpha 5 beta 1 expression in corneal epithelial cells.

Amino Acid Sequence↗
PubMed1995

Ocular fundus changes in malignant or precocious stroke-prone spontaneously hypertensive rats after administration of antihypertensive drugs.

1. Malignant or precocious stroke-prone spontaneously hypertensive rats (M-SHRSP) showed hypertensive ocular fundus changes with severe hypertension, but various anti-hypertensive drugs given over a proper period improved funduscopic findings. 2. We treated a M-SHRSP with SQ29,852 (an angiotensin converting enzyme inhibitor, ACEI) or manidipine (a calcium antagonist) and observed hypertensive vascular changes in the fundus. 3. The M-SHRSP treated with anti-hypertensive drugs lived longer and the hypertensive fundic changes improved in both groups. But there were some differences of histochemical staining reaction on the endothelial cell-surface and mucopolysaccharides accumulations between the treated group of ACEI and the group treated with the calcium antagonist. 4. In the treated group with calcium antagonist, the anionic ion functions of the endothelial cell-surface were impaired and organic retinal or choroidal damages appeared to have deteriorated.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

[The effect of corneal epithelial cells on the collagen gel contraction by keratocytes].

To understand the mechanism of corneal stromal wound contraction, we investigated the effect of corneal epithelial cells on the collagen gel contraction by keratocytes. Subcultured rabbit keratocytes embedded in type I collagen gel were cultured. Rabbit corneal epithelial cells were also cultured and the cultured medium was collected and used as an epithelial cell conditioned medium (ECCM). The collagen gel contraction by keratocytes was estimated by measuring the diameter of the collagen disc once a day for 5 days. The diameter of the collagen gel decreased in proportion to the number of keratocytes in the presence of fetal calf serum (FCS), but it decreased in inverse proportion to the concentration of collagen. The collagen gel contraction by keratocytes was enhanced by the addition of ECCM in a dose dependent manner. This stimulatory activity was found in ECCM obtained from 3 to 7 day cultivation of corneal epithelial cells. These findings demonstrated that keratocytes contracted collagen gel in the presence of FCS. It also appeared that corneal epithelial cells secrete a factor or factors that stimulate the collagen gel contraction by keratocytes.

Animals↗
PubMed1994

Binding of hyaluronan to plasma fibronectin increases the attachment of corneal epithelial cells to a fibronectin matrix.

We wished to determine whether hyaluronan would affect the attachment of epithelial cells to extracellular matrix proteins. Multiwell tissue culture plates were coated with human plasma fibronectin, laminin, or collagen type IV (0.01-10.0 micrograms/ml). Single-cell suspensions of rabbit corneal epithelial cells were placed in the wells, and after 45 minutes incubation the cells adhering to the matrix proteins were stained and counted. Cells attached to all three types of proteins. Preincubation of the matrix proteins with hyaluronan (0.1-1.0 mg/ml) significantly increased the number of cells attached to the fibronectin matrix, but it did not increase the numbers of cells attached to laminin or collagen type IV. Hyaluronidase inhibited this stimulatory effect. Glycosaminoglcyans other than hyaluronan (chondroitin sulfate, keratan sulfate, or heparan sulfate) failed to increase the numbers of attached cells. Treatment of the fibronectin matrix with monoclonal antibodies against the cell-binding domain of fibronectin (FN12-8 or FN30-8, 0.03-0.3 mg/ml, for 1 hour), before or after hyaluronan treatment, significantly decreased the numbers of attached cells. Monoclonal antibody against the fibrin- and heparin-binding domain at the N-terminal (FN9-1), however, significantly decreased the number of attached cells only when this antibody treatment preceded the hyaluronan treatment. Preincubation of the cells with hyaluronan had no effect; preincubation with GRGDSP (1 mg/ml), a synthetic peptide that blocks the cell surface receptor for fibronectin, significantly decreased cell attachment whether the fibronectin matrix was treated with hyaluronan or not. Further studies demonstrated that monoclonal antibody against the fibrin- and heparin-binding domain at the N-terminal of plasma fibronectin prevented radiolabeled hyaluronan from binding to fibronectin; likewise, the isolated N-terminal fragment, coupled with Sepharose 4B, bound to hyaluronan in columns. We conclude that hyaluronan binds to a fibrin- and heparin-binding domain at the N-terminal of plasma fibronectin and facilitates the attachment of epithelial cells.

Animals↗
PubMed1994

Combined effects of hyaluronan and fibronectin on corneal epithelial wound closure of rabbit in vivo.

We investigated the combined effects of hyaluronan and fibronectin on corneal epithelial wound closure in vivo. When fibronectin eye drops (1 mg/ml) were administered for the first 4 hours after chemical cautery and hyaluronan eye drops (1 mg/ml) were administered for following 32 hours, the mean healing rate was significantly higher than in control eyes treated with phosphate buffered saline instead of fibronectin or with initial fibronectin alone. These results demonstrated that hyaluronan and fibronectin have a synergistic effect, with fibronectin pretreatment augmenting hyaluronan-stimulated corneal epithelial wound closure.

Animals↗
PubMed1993

Role of urokinase type plasminogen activator (u-PA) in corneal epithelial migration.

The role of plasminogen activator (PA) in the migration of corneal reepithelialization was studied. Rabbit corneal blocks were cultured, and both the extent of epithelial migration over the exposed corneal stroma and the activity of PA released into the culture media were measured. A significant, direct correlation between epithelial migration and PA activity in the medium was observed, even when the migration was stimulated by fibronectin or EGF, or was inhibited by cytochalasin B or cycloheximide. Zymography confirmed that the PA released into the culture medium was of the urokinase type (u-PA). Immunohistochemical studies showed that u-PA and plasmin(ogen) were present at the leading edge of the migrating epithelium. Studies of corneal cell cultures indicated that epithelial cells rather than endothelial cells or fibroblasts were the source of the u-PA. The addition of antihuman u-PA IgG or protease inhibitors retarded the migration of the corneal epithelium in a dose-dependent manner, indicating that u-PA activity is essential for the migration of the corneal epithelium. These findings suggest that the migration of corneal epithelial cells requires not only cell attachment to the extracellular matrix through the fibronectin but also degradation of the fibronectin by the release of cellular u-PA.

Animals↗
PubMed1993

Effects of antimicrobials on corneal epithelial migration.

The slowed healing rates observed by some investigators may be caused by vehicles or preservatives in the antimicrobials preparations tested. To determine whether antimicrobials directly inhibit corneal epithelial wound healing, we cultured blocks of the rabbit cornea in media containing various concentrations of antibiotics or antimicrobials (at 1, 10, or 100 micrograms/ml); after 24 hours, we measured the distance of epithelium that had migrated down the side of each block. The higher concentrations of fluoroquinolones (ofloxacin; 74 +/- 5.8% of control at 100 micrograms/ml, p < 0.05, ciprofloxacin; 4.4 +/- 1.5% of control at 100 micrograms/ml, p < 0.01, or norfloxacin; 71 +/- 7.0% at 10 mu g/ml, p < 0.01, and 1.5 +/- 0.4% of control at 100 mu g/ml, p < 0.01) and the highest concentrations of peptides (polymyxin B; 64 +/- 3.0% of control at 100 micrograms/ml, p < 0.01, or colistin; 67 +/- 5.7% of control at 100 micrograms/ml, p < 0.01) or fosfomycin (79 +/- 6.2% of control at 100 micrograms/ml, p < 0.05) had an inhibitory effect on corneal epithelial migration. Among aminoglycosides tested, sisomicin (85 +/- 10.0% of control, not significant), dibekacin (76 +/- 11.6% of control, p < 0.05) and streptomycin (77 +/- 9.4% of control, not significant) were inhibitory at 100 micrograms/ml, but tobramycin had no effect. Penicillins (aspoxicillin, sulbenicillin or ampicillin), cephalosporins (cefmenoxime or cefminox), oxytetracycline, erythromycin and chloramphenicol did not affect epithelial migration at all. These results demonstrate that some antimicrobials are inhibitory at high concentrations, but penicillins, cephalosporins, oxytetracycline, erythromycin or chloramphenicol has no inhibitory effect on corneal epithelial migration.

Animals↗
PubMed1993

Diagnostic evaluation of diabetic retinopathy by 30-Hz flicker electroretinography.

The peak latency in 30-Hz flicker electroretinography (ERG) was determined in patients with diabetic retinopathy, using a newly developed contact lens electrode with built-in light-emitting diode. A good correlation was obtained between the peak latency of flicker ERG and that of oscillatory potentials of flash ERG. The peak latency of the flicker ERG was only slightly prolonged in background retinopathy, but markedly prolonged in proliferative retinopathy. The stage of pre-proliferative retinopathy with normal peak latency in flicker ERG may be a compensatory state of the retina, which is the most appropriate stage for laser treatment of diabetic retinopathy.

Adult↗
PubMed1993

[The influence of target blurring and simulated opacity of the ocular media on automated perimetric thresholds].

The influence of target blurring and simulated opacity of the ocular media on the sensitivity of the central visual field in quantitative static perimetry was studied using a SARGON program of the automated perimeter Octopus 201. Ten eyes of 10 normal subjects aged from 21 to 35 were examined with target sizes 1, 3, and 5; 4 spherical plus lenses of +1.0D, +2.0D, +3.0D, and +5.0D; 5 kinds of occlusion diffusers which corresponded to the visual acuities of 1.0, 0.8, 0.6, 0.4, and 0.1; and 4 neutral density filters of 0.1, 0.3, 0.6, and 1.0 log units. The studies suggested that there was little difference between the sensitivity for target size 1 and that for target size 3 in spite of slight blurring of the target and simulated opacity of the ocular media. We concluded that target size 1 was as useful as target size 3 in quantitative static perimetry.

Adult↗
PubMed1992

Interleukin 6 facilitates corneal epithelial wound closure in vivo.

Rapid corneal epithelial wound healing is essential to the maintenance of clear visual acuity. The cytokine interleukin 6 is thought to participate in the wound-healing process. We investigated the effect of interleukin 6 eye drops on the rate of corneal epithelial wound closure in rabbits in vivo. Recombinant human interleukin 6 in phosphate-buffered saline at concentrations of 0.1, 0.3, or 1 mg/L was administered immediately after the epithelium was débrided with the n-heptyl alcohol treatment and 2, 4, 6, 8, 10, 18, 20, 22, 24, 26, and 28 hours after débridement. The eyes were stained with fluorescein and photographed at baseline and at 7, 10, 18, 21, 24, 27, 30, and 43 hours after débridement. The rate of wound healing was calculated with a linear regression analysis based on the areas of the epithelial defects, which were recorded from hour 10 to hour 30. The mean (+/- SD) healing rate in the control group, which received phosphate-buffered saline alone, was 1.03 +/- 0.15 mm2/h. The administration of interleukin 6 at concentrations of 0.1, 0.3, or 1.0 mg/L increased the healing rate significantly (P less than .001) to 1.27, 1.39, or 1.44 mm2/h, respectively. Our results indicate that the administration of interleukin 6 might have clinical applications in the treatment of persistent corneal epithelial defects.

Alcohols↗
PubMed1992

Interleukin 6 promotes epithelial migration by a fibronectin-dependent mechanism.

We investigated the effect of interleukin 6 (IL-6) on the migration of rabbit corneal epithelium in vitro and on the attachment of dissociated corneal epithelial cells to a fibronectin matrix. When corneal blocks were cultured with IL-6 for 24 hours, the length of the path of epithelial migration over exposed corneal stroma increased significantly (p less than 0.005 at the concentration of 10 ng/ml) in proportion to the concentrations of IL-6 (0.1-10.0 ng/ml). The addition of antiserum against fibronectin or of GRGDSP abolished the stimulatory effect of IL-6 on epithelial migration. When corneal epithelial cells were cultured with various concentrations of IL-6, suspended, and plated on wells coated with fibronectin (10 micrograms/ml), the number of cells attached to the wells increased in a dose-dependent manner. The presence of antibody against fibronectin or of GRGDSP during the attachment assay decreased the number of cells attached to the fibronectin matrix, regardless of the fact that the cells had been cultured with IL-6 or not. IL-6 stimulated the attachment of corneal epithelial cells to collagen type IV and to laminin matrices. However, the presence of GRGDSP did not affect the cell attachment to collagen type IV and to laminin. These findings strongly indicate that IL-6 stimulates epithelial migration in the cornea by a fibronectin-dependent mechanism, presumably the increased expression of fibronectin receptors.

Amino Acid Sequence↗