Jun-Sub Choi

A Comparison of Vitamin A and Cyclosporine A 0.05% Eye Drops for Treatment of Dry Eye Syndrome

PURPOSE To compare the efficacy of vitamin A (retinyl palmitate) and cyclosporine A 0.05% eye drops in treating patients with dry eye disease. DESIGN Prospective, randomized, controlled, parallel group study. METHODS A total of 150 patients with defined dry eye disease participated (50 in each treatment group). In 3 identical clinical trials, patients were treated twice daily with cyclosporine A 0.05%, or four times daily with retinyl palmitate 0.05%, or with neither cyclosporine or retinyl palmitate. Adjunctive treatment with preservative-free artificial tears was undertaken four times daily in all 3 groups. Corneal fluorescein staining results, Schirmer tear test (without anesthesia) results, tear film break-up time (BUT), dry eye symptom score, and impression cytologic analysis results were obtained before treatment and at the first, second, and third months after initiation of treatment. RESULTS Both vitamin A eye drops and topical cyclosporine A 0.05% treatments led to significant improvement in blurred vision, tear film BUT, Schirmer I score results, and impression cytologic findings in patients with dry eye syndrome (P < .05) compared to the control group treated with preservative-free artificial tears alone. CONCLUSIONS Both vitamin A eye drops and topical cyclosporine A 0.05% treatments are effective for the treatment of dry eye disorder.

The resistance patterns of normal ocular bacterial flora to 4 fluoroquinolone antibiotics.

Purposes: The purposes of this study were to determine the normal ocular bacterial flora isolated from patients undergoing anterior segment surgery and to evaluate their in vitro susceptibility to ciprofloxacin, levofloxacin, gatifloxacin, and moxifloxacin. Methods: During January 2006 to December 2006, conjunctival swabs taken from 385 eyes were inoculated onto 5% blood agar plates. The isolated bacteria were classified by analysis of 16s ribosomal DNA sequencing. Disk diffusion testing was performed in accordance with Clinical and Laboratory Standards Institute Performance Standards. Results: Three hundred sixty-three microorganisms were isolated in 291 samples from 385 eyes. Gram-positive species predominated (89.8%, 326 of the 363 isolates), and Staphylococcus epidermidis was the most frequently isolated organism, accounting for 60.6% (220 of the 363 isolates). For 293 gram-positive isolates, the prevalence rates of in vitro resistance to ciprofloxacin, levofloxacin, gatifloxacin, and moxifloxacin were 22.2% (65 isolates), 11.6% (34), 2.7% (8), and 5.1% (15), respectively. Two of the gram-negative isolates were resistant to only ciprofloxacin (5.4%, 2 of 37 isolates) and not to other fluoroquinolones. Of 62 ciprofloxacin-resistant, coagulase-negative staphylococci, 32 (51.6%) showed coresistance to levofloxacin. Seven organisms were resistant to all the fluoroquinolones. Conclusions: Fluoroquinolones have activity against normal aerobic flora of the ocular surface. Normal ocular flora, especially gram-positive species, has low resistance to the fourth-generation fluoroquinolones-gatifloxacin and moxifloxacin.

Failure to activate NF-κB promotes apoptosis of retinal ganglion cells following optic nerve transection

NF-kappaB is a transcription factor, which is activated by various stimuli. One of the well-known activators of NF-kappaB is oxidative stress, which is a cause of cell death in some tissue, or cell types. Optic nerve transection, axotomy, results in retinal cell death, because of oxidative stress, deprivation of neurotrophic factors, etc. Since it has been hypothesized that the retinal ganglion cell death after axotomy is due to the generation of reactive oxygen species, we investigated whether NF-kappaB is involved in the retinal cell death after axotomy. This study was performed to investigate the role of NF-kappaB in retinal ganglion cell death after optic nerve transection. We used double staining experiment by using anti-NF-kappaB antibody and ethidium bromide to observe the correlation of NF-kappaB activation and the cell death. NF-kappaB was observed only in the surviving cells. NF-kappaB translocation was observed 3 days after the optic nerve transection. The NF-kappaB inhibitor, sulfasalazine, was used to block the activation of NF-kappaB in the axotomized retina, and the number of ganglion cells was quantified using retrograde in the presence or absence of sulfasalazine after axotomy. Inhibition of NF-kappaB by sulfasalazine accelerated the degeneration of ganglion cells in the retina. The results suggest that the activated NF-kappaB plays a protective role from the cell death in the injured ganglion cells.

Synthesis, characterization, and preliminary assessment of anti-Flt1 peptide-hyaluronate conjugate for the treatment of corneal neovascularization

Anti-Flt1 peptide of GNQWFI has been reported to inhibit vascular endothelial growth factor receptor 1 (VEGFR1) - mediated endothelial cell migration and tube formation. In this work, a protocol to synthesize anti-Flt1 peptide-hyaluronate (HA) conjugate was successfully developed for the treatment of corneal neovascularization. Using tetrabutyl ammonium salt of HA (HA-TBA), water-insoluble anti-Flt1 peptide could be conjugated with HA in dimethyl sulfoxide (DMSO) by the amide bond formation between carboxyl groups of HA and N-terminal amine groups of GGNQWFI. The formation of anti-Flt1 peptide-HA conjugate was confirmed by (1)H NMR and fluorometric analyses. The average number of grafted peptide molecules in anti-Flt1 peptide-HA conjugates could be controlled from 3 to 30 per single HA chain by changing the feeding amount of peptide for the conjugation reaction. According to in vitro biological activity tests, anti-Flt1 peptide-HA conjugate exhibited a significant inhibition effect on the binding of Flt1-Fc to VEGF(165) coated on the well. Furthermore, in vivo biological activity of anti-Flt1 peptide-HA conjugate was confirmed from the inhibitory effect on corneal neovascularization in silver nitrate cauterized corneas of SD rats. The VEGF receptor 2 expression was also reduced after treatment with anti-Flt1 peptide-HA conjugate. The water-soluble anti-Flt1 peptide-HA conjugate was thought to have a potential to be developed as anti-angiogenic therapeutics for the treatment of corneal neovascularization.

Anti-Flt1 peptide – Hyaluronate conjugate for the treatment of retinal neovascularization and diabetic retinopathy

Anti-angiogenic therapeutics has been investigated extensively for the treatment of retinal and choroidal vascular diseases, and diabetic retinopathy. Anti-Flt1 peptide of GNQWFI is an antagonistic peptide for vascular endothelial growth factor receptor 1 (VEGFR1 or Flt1) inhibiting VEGFR1-mediated endothelial cell migration and tube formation. In this work, anti-Flt1 peptide (GGNQWFI) was chemically conjugated to tetra-n-butyl ammonium modified hyaluronate (HA-TBA) via amide bond formation in dimethyl sulfoxide (DMSO) using benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP). The resulting HA - GGNQWFI conjugate self-assembled to form micelle-like nanoparticles in aqueous solution, as confirmed and characterized by transmission electron microscopy (TEM). According to in vitro biological activity tests, HA - GGNQWFI conjugate exhibited a dose-dependent inhibition effect on the binding of Flt1-Fc to VEGF(165) coated on the well. Furthermore, anti-Flt1 peptide - HA conjugate effectively inhibited retinal choroidal neovascularization (CNV) in laser induced CNV model rats. The retinal vascular permeability and the deformation of retinal vascular structure were also significantly reduced in diabetic retinopathy model rats after treatment with anti-Flt1 peptide - HA conjugate. Pharmacokinetic analysis confirmed the increased mean residence time of anti-Flt1 peptide after conjugation to HA longer than 2 weeks.

Effect of resection velocity and suction ring on corneal flap formation in laser in situ keratomileusis.

PURPOSE To determine the effects of microkeratome-cutting velocities and the suction ring on corneal flap creation. SETTING Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea. METHODS Procedures were performed under clinical settings in 65 pig eyes. Keratometric diopters (D) were measured before and after application of the suction ring. Corneal thickness was measured before and after resection cutting, and the difference was taken as flap thickness. The microkeratome was initially set at a resection thickness of 160 microns. The blade oscillation (turbine velocity) was set at 30, 35, and 42 psi. The translational velocity was arbitrarily divided into high (1 to 2 seconds), moderate (3 to 5 seconds), and low (6 seconds or more). Data were analyzed by varying the velocities consecutively. Photographs of the cut surface were acquired by scanning electron microscopy to evaluate resection morphology by comparison. RESULTS Mean refractive powers were 39.94 D +/- 0.66 (SD) and 39.69 +/- 0.98 D before and after application of the suction ring, respectively; however, no significant difference was observed (P = .216). Lower surgeon translational velocity resulted in a significantly thicker corneal flap in 8 of the 9 paired comparisons (P < .05). Higher turbine velocity resulted in a significantly thicker corneal flap in 7 of the 9 paired comparisons (P < .05). The cut surface was smoother at higher turbine and lower translational velocity. The initial cut margin was steeper at higher translational velocity. CONCLUSIONS The increase in intraocular pressure induced by the suction ring had no significant effect on keratometric power. At higher turbine and lower translational velocities, the corneal flap was thicker and the cut surface smoother. Higher translational velocities made the initial cut margin steeper.

Comparison of posterior capsule opacification in rabbits receiving either mitomycin-C or distilled water for sealed-capsule irrigation during cataract surgery

Purpose:  To compare posterior capsule opacification (PCO) in rabbits who undergo cataract surgery and receive either mitomycin‐C (MMC) or distilled water (DW) during sealed‐capsule irrigation (SCI). In addition, we examined the toxicity of DW and MMC.

Activation of Caspase-3 during Degeneration of the Outer Nuclear Layer in the rd Mouse Retina

Caspase activation has been implicated in apoptosis, and the nature of the apoptotic stimulus determines the specific caspase activation during apoptosis. In this study, we examined the activation of caspase-3 during photoreceptor degeneration in the rd mouse, which has a mutation on a gene encoding cyclic GMP phosphodiesterase. The outer nuclear layer of the rd mouse retina was observed using light and electron microscopy. The progress of degeneration was determined chronologically and correlated with the activation of caspase-3 and the fragmentation of poly-ADP-ribose polymerase. Additionally, the active form of caspase-3 was detected during photoreceptor degeneration in the outer nuclear layer of the rd mouse. The chronological observation of the caspase-3 activation pattern correlates with the pattern of photoreceptor degeneration. As a result of this study, we present here our findings that caspase-3 was activated in photoreceptor cells of the rd mouse.

Corneal ectasia after PRK : Clinicopathologic case report

Purpose: To describe the clinical and ultrastructural features of a prominent ectasia of the cornea that occurred 9 years after excimer laser photorefractive keratectomy (PRK). Methods: Analysis of corneal topography and ultrastructural examination by transmission electron microscopy (TEM) were used to assess the ectatic cornea. Results: The intended laser ablation in the left eye was 74 μm, and the preoperative ultrasonic pachymetry was 536 μm. Orbscan II (V 3.00; Orbtek, Salt Lake City, UT) observations revealed inferior topographic steepening and protrusion of the anterior and posterior corneal surfaces 13 years after the patient underwent PRK. The least thickness of the cornea was 456 μm. TEM showed that the epithelial basement membrane had degenerated into subepithelial stroma, and apoptotic keratocytes with cell debris on the extracellular matrix were observed in the stroma. However, the endothelial cells were normal. Conclusion: Clinical examination of an eye that had developed corneal ectasia 9 years after PRK showed forward protrusion of both anterior and posterior corneal surfaces. Ultrastructural examination also revealed a degenerated stroma. However, there was no abnormality of the corneal endothelium.

Flt1 peptide–hyaluronate conjugate micelle-like nanoparticles encapsulating genistein for the treatment of ocular neovascularization

Flt1 peptide of GNQWFI is an antagonistic peptide for vascular endothelial growth factor receptor 1 (VEGFR1 or Flt1). In this work, Flt1 peptide-hyaluronate (HA) conjugates were successfully synthesized and the resulting micelle-like nanoparticles were exploited to encapsulate genistein, an inhibitor of tyrosine-specific protein kinases, for the treatment of ocular neovascularization. The mean diameter of genistein-loaded Flt1 peptide-HA conjugate micelles was measured to be 172.0±18.7 nm, with a drug-loading efficiency of 40-50%. In vitro release tests of genistein from the genistein-loaded Flt1 peptide-HA conjugate micelles exhibited the controlled release for longer than 24h. In vitro biological activity of genistein/Flt1 peptide-HA micelles was corroborated from the synergistic anti-proliferation of human umbilical vein endothelial cells (HUVECs). Furthermore, we could confirm the anti-angiogenic effect of genistein/Flt1 peptide-HA micelles from the statistically significant suppression of corneal neovascularization in silver nitrate cauterized corneas of SD rats. The retinal vascular hyperpermeability was also drastically reduced by the treatment in diabetic retinopathy model rats.