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Biomedical subjects

Yukitaka Uji

Publications and source records attributed to Yukitaka Uji.

At least 19 recordsLinked to original sources

Changes in localization of amino acids in the detached cat retina.

PURPOSE: To investigate the distribution of amino acids (glutamate, aspartate, glutamine, GABA, glycine) in detached retinas with minimum postmortem artifact and to clarify the relation between amino acid distribution and histopathological change in the outer portion of detached retinas. METHODS: Unilateral retinal detachment was produced in cats by injecting 0.25% sodium hyaluronate into the subretinal space using a glass micropipet. The eyes were fixed by perfusion for 10 min, 1, 3, 6 and 24 h, 2, 3 and 7 days after detachment and then examined under conventional light- and electron-microscopic immunocytochemistry. RESULTS: For glutamate, aspartate and glutamine, the inner segments and perikarya of the photoreceptor cells, which were not immunopositive in the normal retinas, showed various degrees of immunoreactivity immediately after retinal detachment. Photoreceptor cells with the strong immunoreactivity developed necrosis. The staining pattern of GABA and glycine scarcely changed during the course of retinal detachment. CONCLUSIONS: Excess intracellular glutamate, aspartate and glutamine in photoreceptor cells may cause a part of neuronal death after retinal detachment.

Amino Acids↗

Effects of scleral buckling without encircling procedures on retrobulbar hemodynamics as measured by color Doppler imaging.

OBJECTIVE: To study the effects of segmental scleral buckling without encircling procedures on retrobulbar hemodynamic conditions using color Doppler imaging. METHODS: In 65 consecutive eyes of 65 patients with unilateral rhegmatogenous retinal detachment repaired by scleral buckling, we prospectively measured the blood flow velocities in the ophthalmic artery, central retinal artery, and short posterior ciliary artery using color Doppler imaging before and 2, 12, and 24 weeks after surgery. Peak systolic velocity (PSV) and end diastolic velocity (EDV) (calculated in centimeters per second) were measured using color Doppler imaging. RESULTS: The PSV and EDV in the ophthalmic artery were not changed significantly during follow-up. The PSV and EDV in the central retinal artery were reduced temporarily at 2 weeks after surgery, but at 12 weeks after surgery had returned to presurgery levels. The PSV and EDV in the short posterior ciliary artery on both sides continued to decrease postoperatively, and the reductions became statistically significant by 24 weeks after surgery (buckled side: P=.001 for PSV and P=.002 for EDV; unbuckled side: P<.001 for PSV and P=.004 for EDV). The decreases of PSV and EDV in the short posterior ciliary artery on the buckled side were positively correlated with the subject's age (R = 0.40, P = .001 for PSV; and R = 0.32, P = .008 for EDV). CONCLUSIONS: Scleral buckling procedures can cause subclinical disturbance of the choroidal circulation, even if encircling procedures are avoided. Aging is one of the risk factors for the disturbance.

Blood Flow Velocity↗

10-year follow-up of visual functions in patients who underwent scleral buckling.

PURPOSE: To study long-term visual functions in eyes that underwent scleral buckling for treatment of rhegmatogenous retinal detachment. METHODS: We retrospectively studied a nonconsecutive case series of 205 eyes with retinal detachment that underwent scleral buckling and were followed up for 10 years after surgery. Preoperatively, postoperatively, and 10 years after surgery, best-corrected visual acuities and visual fields were recorded. RESULTS: During the first postoperative year and during the next 9 years, there were significant increases in visual acuity (P<0.0001 and P<0.0001, respectively). Between the operation and 1 month postoperatively, there was a significant increase in the area size of visual field measured by Goldmann perimetry (V-4 isopter, P=0.0001; I-4 isopter, P=0.0001). Between 1 month and 10 years after surgery, there was no significant change of the area size of each isopter (V-4, P=0.786; I-4, P=0.211). CONCLUSION: Improvement in visual acuity after scleral buckling is possible over a long period. There may be a limit to long-term improvement of visual field after scleral buckling.

Adolescent↗

New gonioscopy system using only infrared light.

PURPOSE: To describe an infrared gonioscopy system designed to observe the anterior chamber angle under natural mydriasis in a completely darkened room. METHODS: An infrared light filter was used to modify the light source of the slit-lamp microscope. A television monitor connected to a CCD monochrome camera was used to indirectly observe the angle. RESULTS: Use of the infrared system enabled observation of the angle under natural mydriasis in a completely darkened room. CONCLUSION: Infrared gonioscopy is a useful procedure for the observation of the angle under natural mydriasis.

Anterior Chamber↗

Evaluation of eyes with relative pupillary block by indentation ultrasound biomicroscopy gonioscopy.

PURPOSE: To investigate changes in anterior chamber angle configuration with indentation ultrasound biomicroscopy gonioscopy of relative pupillary block (RPB). DESIGN: Cross-sectional study. METHODS: This study included 26 eyes of 26 patients with RPB. We determined angle opening distance 500 and angle recess area using indentation ultrasound biomicroscopy gonioscopy and compared a small-sized standard eye cup with a new eye cup with an area for inducing pressure. RESULTS: Indentation ultrasound biomicroscopy images documented concavity of the iris in eyes with RPB. Both the new and the small standard eye cups widened the anterior chamber angle significantly (P <.0001) without causing corneal damage. Angle changes were significantly greater for the new eye cup design. CONCLUSIONS: Indentation ultrasound biomicroscopy gonioscopy is a useful technique for observation and diagnosis of RPB. Using a small standard or the newly designed eye cup, the procedure can be performed easily and without causing corneal damage.

Aged↗

Evaluation and comparison of indentation ultrasound biomicroscopy gonioscopy in relative pupillary block, peripheral anterior synechia, and plateau iris configuration.

PURPOSE: To evaluate and compare the findings and changes of the anterior chamber angle configuration with indentation ultrasound biomicroscopy (UBM) gonioscopy in relative pupillary block (RPB), peripheral anterior synechia (PAS), and plateau iris configuration (PIC). METHODS: This study included 73 eyes of 52 patients with RPB (n = 26), PAS (n = 21), or PIC (n = 26). First, a conventional UBM scan was performed using a normal size standard eye cup before indentation. Then, for indentation UBM gonioscopy, scans were performed using a new eye cup that we designed. For evaluation of the angle, angle opening distance 500 and angle recess area were recorded and evaluated with regard to the effect of expansion on the anterior chamber angle. RESULTS: Indentation UBM gonioscopy showed the characteristic images in each of the eyes. The angle of all examined eyes was significantly widened with indentation (P < 0.01). The angle changes in eyes with RPB were significantly greater than in eyes with PAS or PIC (P < 0.01). CONCLUSION: Indentation UBM gonioscopy is a very useful method for observing the angle and diagnosis of RPB, PAS, and PIC.

Aged↗

Spermine induces cataract and 43-kDa protein that binds spermine possibly participates in the cataract formation.

Among polyamines (putrescine, spermidine, and spermine), spermine specifically induces cataract in an organ cultured lens. Spermine uptake nearly paralleled the cataract formation. When polyamines were added to lens soluble proteins, spermine specifically induced turbidity. When lens soluble proteins were separated by gel chromatography, heavy-molecular-weight protein (HMW, high molecular form of alpha-crystallin) and proteins between betaH- and betaL-crystallin fractions reacted with spermine and aggregated. SDS-polyacrylamide gel electrophoresis of the aggregated proteins showed that 43-kDa lens protein was commonly observed in both aggregates. Spermine-affinity chromatography of the total soluble proteins showed the binding of HMW protein to the gel and the chromatogram of the second turbidity peak in the gel chromatography showed the binding of 43-kDa protein. These results indicated that 43-kDa protein, which is present as a subunit in HMW and also in free form, binds spermine and induces turbidity of lens soluble proteins and produces cataract in a cultured lens.

Animals↗

Effects of the beta1-selective adrenergic antagonist betaxolol on electroretinography in the perfused cat eye.

The effects of the beta1-selective adrenergic antagonist betaxolol on electroretinography (ERG) were studied in the isolated and arterially perfused cat eye. Betaxolol increased the perfusion flow rate, significantly at the administrations of more than 50 microM concentrations and induced a dose-related, reversible increase in the amplitudes of both the a-wave and b-wave of ERG. These results suggest that the calcium-channel blocking mechanism of betaxolol has a beneficial influence on ocular blood flow and retinal electrical activity in response to light. As it is known that ERG is a good indicator of the functional integrity of the retina, this indicates that betaxolol could be an ideal drug for treating glaucoma in which ischemia is involved to some extent.

Adrenergic beta-Antagonists↗

Quantitative analysis of eyelash lengthening following topical latanoprost therapy.

BACKGROUND: There have been several reports, mostly qualitative, of ocular side effects of latanoprost, including lengthening of eyelashes. We investigated changes in eyelash length in patients receiving topically administered latanoprost. METHODS: Seventeen patients (11 men and 6 women aged 63 to 80 years) with glaucoma or ocular hypertension were treated with latanoprost (one drop to one eye daily at bedtime). All had dark brown irises. At the start of treatment and after 2, 6 and 10 weeks of treatment, a single eyelash was removed from the centre of the upper eyelid of the treated and fellow (control) eyes and measured. Adverse events (defined as any undesirable event occurring in a subject, regardless of whether it was considered related to the latanoprost treatment) were monitored carefully. At each examination patients were asked whether they had any ocular or systemic symptoms. RESULTS: For the eyes treated with latanoprost, the mean eyelash length (and standard deviation) was 5.8 mm (0.7 mm) at baseline, 6.5 mm (0.6 mm) at 2 weeks, 6.5 mm (0.9 mm) at 6 weeks and 6.6 mm (0.7 mm) at 10 weeks (p < 0.001 for all differences from baseline). The corresponding values for the untreated eyes were 5.7 mm (0.7 mm), 5.8 mm (0.7 mm), 5.9 mm (0.7 mm) and 5.6 mm (0.7 mm); all differences were nonsignificant. INTERPRETATION: Latanoprost significantly increases eyelash length.

Administration, Topical↗

A case of Coats' disease with a peeling of premacular fibrosis after photocoagulation.

We report a 26-year-old man with Coats' disease associated with premacular fibrosis. As an initial treatment, the peripheral exduative area was treated with argon laser photocoagulation. Six weeks later, the premacular fibrosis was peeled off and the posterior vitreous membrane was also detached. The patient's visual acuity improved to 20/20. We also observed a change of the vitreous component before and after the treatment that was similar to posterior vitreous detachment (PVD). This is the first reported case in which a distinct vitreous change was observed after premacular fibrosis peeling in Coat's disease.

Adult↗

Supraciliochoroidal fluid in the eyes indicates good intraocular pressure control despite absence of obvious filtering bleb after trabeculectomy.

PURPOSE: To examine the presence of supraciliochoroidal fluid (SCF) by ultrasound biomicroscopy in posttrabeculectomy eyes that show good intraocular pressure (IOP) control despite the absence of an obvious filtering bleb. PATIENTS AND METHODS: Eyes were selected retrospectively according to the following criteria: IOP < 15 mm Hg, no antiglaucoma medication, no filtering bleb or a flattened bleb without microcystic spaces, and no ophthalmoscopic choroidal detachment after trabeculectomy with mitomycin C. The SCF was examined using 50-MHz ultrasound biomicroscopy (Zeiss-Humphrey). RESULTS: Ultrasound biomicroscopy detected SCF in five (63%) of eight eyes that met the study criteria. The extent of SCF in two of the eyes was four quadrants and one or two quadrants in three eyes. CONCLUSION: The presence of the SCF may explain increased uveoscleral outflow and may represent an IOP-lowering mechanism after trabeculectomy with mitomycin C, especially when IOP control is good and a filtering bleb is not obvious.

Anterior Eye Segment↗

Effects of haloperidol on K(+) currents in acutely isolated rat retinal ganglion cells.

PURPOSE: Effects of haloperidol on K(+) currents (IKs) of rat retinal ganglion cells (RGCs) were examined, with the hypothesis that its alteration of IKs explains alterations in the pattern electroretinogram (PERG). METHODS: Fast blue was injected into superior colliculi of rats (3-8 days old) to identify RGCs under epifluorescence illumination after retrograde transport to retinas. Retinas were dissected, treated enzymatically, and dissociated with trituration. Effects of haloperidol on membrane currents at -70 mV, voltage-dependent IK, and Ca(2+)-dependent K(+) currents (K(Ca)) were examined by whole-cell patch voltage clamp. Na(+) currents were abolished by tetrodotoxin (1 microM; TTX). Voltage-gated IKs were isolated by Ca(2+)-free perfusate. Persistent and transient components of the voltage-sensitive IKs were isolated by prepulses, and sensitivity of each component to tetraethylammonium (TEA, 20 mM) and 4-aminopyridine (5 mM) was tested. K(Ca) was identified by its response to TEA, charybdotoxin (CTX), and apamin. Haloperidol (0.01-100 microM) was instilled into the perfusate dissolved in dimethyl sulfoxide (DMSO). RESULTS: Currents recorded at -70 mV were not affected by haloperidol, whereas the persistent component of the voltage-dependent IK was reversibly reduced by haloperidol, with a dose dependence fitted with the Hill equation (median inhibitory concentration [IC(50)] = 4.2 microM). The transient component of the voltage-gated IK was less sensitive to haloperidol. Haloperidol (10 nM) blocked the apamin-sensitive K(Ca) but not the CTX-sensitive K(Ca). CONCLUSIONS: Haloperidol reduced voltage-dependent IKs in RGCs, but at a higher concentration than that needed to antagonize dopamine receptors. Haloperidol (10 nM) blocked the apamin-sensitive K(Ca) which modulates the firing rate of RGCs and may contribute to the alteration of PERG.

Animals↗

Switch to latanoprost monotherapy from combined treatment with beta-antagonist and other antiglaucoma agents in patients with glaucoma or ocular hypertension.

PURPOSE: To investigate the effects on intraocular pressure (IOP) and the occurrence of adverse events upon switching directly to latanoprost monotherapy from multiple drug therapy, including a beta-antagonist, for glaucomatous eyes. METHODS: Patients with primary open-angle glaucoma or ocular hypertension and receiving long-term therapy with two or three topical ocular hypotensive drugs (including one topical beta-antagonist) were switched to latanoprost monotherapy for 12 weeks without any intervening washout period. Observations were performed before switching (baseline) and at weeks 4, 8, and 12 after switching to latanoprost monotherapy. RESULTS: Of the 29 enrolled patients, 26 (90%) completed this protocol. Three patients had excessive IOP elevation, and these patients were withdrawn. The switch to latanoprost monotherapy was followed by a significant ( P < 0.0001) mean reduction of 3.9 mmHg at week 12 in per-protocol cases ( n = 26) and a significant ( P = 0.0016) mean reduction of 2.8 mmHg at last postswitch visit in patients in the intent-to-treat analysis group ( n = 29). Adverse ocular events other than IOP elevation were mild. CONCLUSIONS: The switch to latanoprost monotherapy in glaucoma patients receiving multiple drug therapy resulted in an additional, significant IOP reduction.

Administration, Topical↗

Symmetry analysis for detecting early glaucomatous changes in ocular hypertension using optical coherence tomography.

PURPOSE: To compare symmetry analysis of the retinal nerve fiber layer (RNFL) in ocular-hypertensive, normal, and glaucomatous eyes using optical coherence tomography (OCT). METHODS: Thirty-three consecutive ocular-hypertensive patients (33 eyes), 25 normal volunteers (25 eyes), and 35 open-angle glaucoma patients (35 eyes) were enrolled in this study. Circular OCT scans were obtained using a diameter of 3.4 mm around the optic disc. RNFL thickness was measured, and a symmetry analysis was performed using symmetry ratios. To calculate the symmetry ratios, the circle was divided into the superior and inferior hemiretina. The superior hemiretina was further subdivided into three (area I, temporal 45 degrees; area II, superior 90 degrees; and area III, nasal 45 degrees ) or five (with areas 1-5, each spanning 36 degrees ) zones. The symmetry ratios were defined as the ratios comparing the RNFL thickness within each of the zones with that in the analogous zone in the inferior hemiretina. RESULTS: RNFL thickness measurements could distinguish glaucomatous eyes from other groups, but could not distinguish ocular-hypertensive from normal eyes. However, the symmetry analysis revealed differences between ocular-hypertensive and normal eyes in area II (mean +/- SD, 0.77 +/- 0.16 vs. 0.85 +/- 0.12, P = 0.0379). CONCLUSIONS: Early glaucomatous RNFL changes might exist in some areas of ocular-hypertensive eyes, and a symmetry analysis may be a useful method for detecting these changes.

Adult↗

Contribution of nitric oxide-producing cells in normal and diabetic rat retina.

PURPOSE: To examine the immunohistochemical localization of L-arginine and L-citrulline and determine where and how nitric oxide (NO) is produced in the normal and streptozotocin (STZ)-induced diabetic rat retinas. METHODS: NO is produced when L-arginine is changed to L-citrulline by NO synthase (NOS). In normal and STZ-induced diabetic rats, using an immunohistochemical method, we examined the retinal distribution of L-arginine and L-citrulline after intracardiac perfusion. We studied the distribution of NOS after immersed fixation and analyzed the number of neuronal NOS (nNOS)-positive neurons. RESULTS: We observed L-arginine localization in the internal limiting membrane (ILM), the ganglion cell layer (GCL), and the inner nuclear layer (INL). L-Arginine immunoreactivity in the diabetic rat retinas was found in the inner plexiform layer (IPL), as well as in the normal retina. L-Citrulline immunoreactivity in the normal and diabetic retinas was observed in the ILM, the GCL, the IPL, and the INL. nNOS staining in the normal and diabetic rat retinas was observed in the GCL, the IPL and the INL. The number of nNOS-positive amacrine cells was less in the diabetic rat retinas. CONCLUSION: NO might be produced in the GCL and amacrine cells, which show immunoreactivity to L-arginine, L-citrulline, and nNOS. In the early stage of diabetic retinopathy in STZ rat retinas, diabetes disturbed the function of the nNOS-positive amacrine cells and reduced NO production via nNOS.

Amacrine Cells↗

Changes in electroretinogram oscillatory potentials during dark adaptation.

PURPOSE: To investigate changes in the oscillatory potentials (OPs) of electroretinograms (ERGs) during dark adaptation (DA). METHODS: ERGs were recorded from ten normal subjects. Following 15 min of light adaptation, ERGs were recorded every 30 s for 20 min to follow the changes in the OPs during the course of DA. A 20-ms, 560-nm rectangular pulse of light was presented at 3.3 Hz to elicit the ERGs. RESULTS: The latencies of OP1 and OP2 did not change significantly, but the amplitudes decreased slightly during DA. OP3 was not observed at 30 s, but appeared after 1 min of DA between OP2 and OP4. Similar results were obtained with stimulus durations of 10 to 100 ms in 10-ms steps. The amplitude of OP3 increased to 10 min of DA and then plateaued. CONCLUSION: The characteristics of OP3, which increases during DA, indicate that it is probably related to rod activity.

Adolescent↗