Chi-Ting Horng

Visual fields during acute exposure to a simulated altitude of 7620 m.

BACKGROUND The hypoxia associated with sudden exposure to high altitude is known to impair vision and may thereby affect flight safety. However, no data were available regarding hypoxic effects on visual fields. The aim of this study was to evaluate black-and-white visual field sensitivity with acute hypoxia during acute exposure to a simulated altitude of 7620 m. METHODS Subjects were 15 male pilots 26-39 yr of age. We measured arterial oxygen saturation (S(aO2)%) using transdermal pulse oximetry while the visual field was measured within a 30 degrees eccentricity in the right eye by computerized perimetry. The subject breathed 100% O2 for 30 min before and during chamber ascent, then removed his mask while measurements were performed. RESULTS The S(aO2)% and visual field sensitivities (mean +/- SD) at ground level were 99.1 +/- 0.4% and 43.9 +/- 2.1 dB, respectively. During hypoxia, the S(aO2)% dropped to 64.0 +/- 5.4% within 3 min. Mean visual sensitivity was significantly reduced by 7.2 +/- 1.6 dB. Furthermore, peripheral sensitivity was slightly but significantly more diminished than central sensitivity. CONCLUSIONS Severe acute hypoxia reduces central and moderate peripheral black-and-white vision by a factor of two with the strongest effect in the periphery.

Regression of choroidal metastasis secondary to breast carcinoma with adjuvant intravitreal injection of bevacizumab.

Editor, T he choroid, which is supplied by rich vessels, is the most common site of intraocular metastasis. Choroidal metastases originate most commonly from a primary cancer of the breast or lung. Systemic chemotherapy is in widespread use and is efficient in the control of choroidal metastatic tumours. However, vision may be endangered or intolerable ocular pain may occur and progress despite systemic chemotherapy. Therefore, additional approaches are necessary. The treatment modalities for choroidal metastasis vary and include external beam radiotherapy, brachytherapy, laser photocoagulation and enucleation (Kanthan et al. 2007). However, current treatments have several drawbacks, such as limited facilities, the possibility of radiation-related ocular damage, loss of vision, etc. Bevacizumab, an anti-vascular endothelial growth factor therapy, has been proven to be effective in the treatment of metastatic carcinoma of the colon or rectum by the Food and Drug Administration (Giantonio et al. 2007). Moreover, previous research has shown that the choroidal metastastic lesion may manifest angiogenesis and its pathogenesis depends on the haematogenous dissemination of the primary malignancy. Thus, bevacizumab was considered to represent a promising approach to the treatment of choroidal metastasis. In December 2006, a 50-year-old woman with breast carcinoma was referred to our uveitis service with painful visual loss in the left eye. Previously, the patient had been diagnosed with breast carcinoma, grade 3, T2N0M0, stage IIA. Immunohistochemical stains expressed negative

Optic disc hemorrhages in a patient with hemophilia A

To report a hemophilia patient complicated with optic disc hemorrhages. A 13-year-old boy presented to our emergency room with a black shadow in the left eye for 1 day. The best-corrected visual acuity was 6/6 in both eyes. Peripapillary retinal and subretinal hemorrhages were found in the left eye. Result of the laboratory examination showed an extremely low level of coagulation factor VIII (1.9%). Factor VIII concentrate was given for 8 weeks. A follow-up 3 months later showed absorption of the hemorrhages, black shadow diminished, and the vision was 6/6.

Ocular Responses and Visual Performance after High-Acceleration Force Exposure

PURPOSE To evaluate ocular responses and visual performance after high-acceleration force exposure. METHODS Fourteen men were enrolled in the study. A human centrifuge was used to induce nine times the acceleration force in the head-to-toe (z-axis) direction (+9 Gz force). Visual performance was evaluated using the ETDRS (Early Treatment of Diabetic Retinopathy Study) visual chart, and contrast sensitivity (CS) was examined before and after centrifugation. Ocular responses were assessed with biomicroscopy and topographic mapping after gravitational stress. RESULTS Transient visual acuity reduction (0.02 +/- 0.04 logMar vs. 0.19 +/- 0.07 logMar VA; P < 0.05) and temporary ocular anterior segment reactions were observed immediately after centrifugation. These reactions included changes in corneal thickening (553.7 +/- 21.7 mum vs. 591.2 +/- 20.6 mum; P < 0.05), increasing anterior chamber depth (ACD; 3.19 +/- 0.26 mm vs. 4.53 +/- 0.34 mm; P < 0.05), and pupillary enlargement (3.54 +/- 0.73 mm vs. 5.76 +/- 0.61 mm; P < 0.05). The increase in ACD continued for 15 minutes after exposure to acceleration (3.19 +/- 0.26 mm vs. 4.39 +/- 0.27 mm; P < 0.05). Pupillary dilation was noted both 15 (3.54 +/- 0.73 mm vs. 5.56 +/- 0.67 mm; P < 0.05) and 30 (5.47 +/- 0.59 mm, P < 0.05) minutes after the gravitational stress. CS decreased significantly at low and medium spatial frequencies (1.5, 3, and 6 cyc/deg) and did not return to the baseline level by 30 minutes. CONCLUSIONS High-acceleration force may induce transient visual acuity reduction and temporary corneal thickening. Prolonged increase in ACD and pupillary dilation were also observed. The decrease in CS persisted for 30 minutes after centrifugation. The mechanisms underlying these observations are not clear, because there are no previous reports on this topic. Further studies are needed.

Effect of clotrimazole on cytosolic Ca2+ rise and viability in HA59T human hepatoma cells

Abstract Clotrimazole is an antimycotic imidazole derivative that interferes with cellular Ca2+ homeostasis. This study examined the effect of clotrimazole on cytosolic Ca2+ concentrations ([Ca2+]i) and viability in HA59T human hepatoma cells. The Ca2+-sensitive fluorescent dye fura-2 was applied to measure [Ca2+]i. Clotrimazole induced [Ca2+]i rises in a concentration-dependent manner. The response was reduced by removing extracellular Ca2+. Clotrimazole-evoked Ca2+ entry was suppressed by store-operated channel inhibitors (nifedipine, econazole and SK&F96365) and protein kinase C modulators (GF109203X and phorbol, 12-myristate, 13-acetate). In Ca2+-free medium, incubation with the endoplasmic reticulum Ca2+ pump inhibitor 2,5-di-tert-butylhydroquinone abolished clotrimazole-induced [Ca2+]i rise. Inhibition of phospholipase C with U73122 abolished clotrimazole-induced [Ca2+]i rise. At 10–40 µM, clotrimazole inhibited cell viability, which was not reversed by chelating cytosolic Ca2+. Clotrimazole at 10 and 30 µM also induced apoptosis. Collectively, in HA59T cells, clotrimazole-induced [Ca2+]i rises by evoking phospholipase C-dependent Ca2+ release from the endoplasmic reticulum and Ca2+ entry via store-operated Ca2+ channels. Clotrimazole also caused apoptosis.

Koelreuteria Formosana Extract Induces Growth Inhibition and Cell Death in Human Colon Carcinoma Cells via G2/M Arrest and LC3-II Activation-Dependent Autophagy

ABSTRACT Autophagy is a self-destructive process that degrades cytoplasmic constituents. In our previous study, Koelreuteria formosana ethanolic extract (KFEE), which is obtained from natural plants endemic to Taiwan, has inhibited cell metastasis in renal carcinoma cells. However, the anticancer effects of KFEE on colon cancer remain unclear. In this study, KFEE exerted a strong cytotoxic effect on DLD-1 and COLO 205 human colorectal cancer cell lines. KFEE effectively inhibited cancer cell proliferation, induced G2/M-phase arrest associated with downregulaton of cyclin E, cyclin B and cdc25C and upregulation of p21, and induced cell death by activating autophagy but did not cause apoptotic cell death. Exposed KFEE cells showed increased levels of acridine orange, autophagic vacuoles, and LC3-II proteins, which are specific autophagic markers. Bcl-2, p-Akt, and p-mTOR levels, which have been implicated in autophagic downregulation, were decreased after KFEE treatment. Autophagy inhibitor 3-methyladenosine and bafilomycin-A1 and genetic silencing of LC3 attenuated KFEE-induced growth inhibition. These findings suggested that KFEE causes cytostatic effect through autophagy. In xenograft studies, oral administration of KFEE had significantly inhibited the tumor growth in nude mice that had received subcutaneous injection of DLD-1 cells. KFEE is a promising candidate in phytochemical-based, mechanistic, and pathway-targeted cancer prevention strategies.

Predicting the Incidence of Human Cataract through Retinal Imaging Technology

With the progress of science, technology and medicine, the proportion of elderly people in society has gradually increased over the years. Thus, the medical care and health issues of this population have drawn increasing attention. In particular, among the common medical problems of the elderly, the occurrence of cataracts has been widely observed. In this study, we developed retinal imaging technology by establishing a human eye module with ray tracing. Periodic hole arrays with different degrees were constructed on the anterior surface of the lens to emulate the eyesight decline caused by cataracts. Then, we successfully predicted the incidence of cataracts among people with myopia ranging from −3.0 D to −9.0 D. Results show that periodic hole arrays cause severe eyesight decline when they are centralized in the visual center. However, the wide distribution of these arrays on the anterior surface of the lens would not significantly affect one’s eyesight.

Effects of Horizontal Acceleration on Human Visual Acuity and Stereopsis

The effect of horizontal acceleration on human visual acuity and stereopsis is demonstrated in this study. Twenty participants (mean age 22.6 years) were enrolled in the experiment. Acceleration from two different directions was performed at the Taiwan High-Speed Rail Laboratory. Gx and Gy (< and >0.1 g) were produced on an accelerating platform where the subjects stood. The visual acuity and stereopsis of the right eye were measured before and during the acceleration. Acceleration <0.1 g in the X- or Y-axis did not affect dynamic vision and stereopsis. Vision decreased (mean from 0.02 logMAR to 0.25 logMAR) and stereopsis declined significantly (mean from 40 s to 60.2 s of arc) when Gx > 0.1 g. Visual acuity worsened (mean from 0.02 logMAR to 0.19 logMAR) and poor stereopsis was noted (mean from 40 s to 50.2 s of arc) when Gy > 0.1 g. The effect of acceleration from the X-axis on the visual system was higher than that from the Y-axis. During acceleration, most subjects complained of ocular strain when reading. To our knowledge, this study is the first to report the exact levels of visual function loss during Gx and Gy.

The Activity of Lowering Intraocular Pressure of Cassiae Seed Extract in a DBA/2J Mouse Glaucoma Model

PURPOSE To evaluate the activity of lowering intraocular pressure (IOP) by Cassiae seed in the DBA/2J mouse glaucoma model. METHODS Young male (mean age: 3 months) inherited glaucoma mice (BDA/2J) were enrolled in this study. To evaluate the potential of Cassiae seed in the treatment of glaucoma, all subjects were divided into 6 groups. There were 1 sham group, positive control identified as group 2 topical brimonidine and group 3 oral acetazolamide, and groups 4-6 Cassiae seed extract (CSE) groups. The lactate dehydrogenase (LDH) level in the anterior aqueous humor and the changes of IOP were investigated. Contents of total polyphenol glycosides in the CSE were measured using a high-performance liquid chromatography (HPLC) method. Chromatographic separation was performed on a Cosmosil 5C(18)-MS reverse-phase HPLC column (4.6×250-mm i.d., 5 μm) with methanol/0.1% H(3)PO(4) as the mobile phases in a gradient elution mode at a flow rate of 1.0 mL/min and an injection volume of 10 μL. The wavelength of UV detector was set at 254 nm. RESULTS The LDH level in the anterior aqueous humor and IOP significantly decreased after treatment with CSE. The IOP-lowering effect of CSE was comparable to those of oral acetazolamide and brimonidine instillation. There were no abnormal findings in the external appearance, and body weight change after treatment with CSE for 5 weeks. Chrysophanol and physcion were measured by an HPLC method to obtain total polyphenol glycosides of the CSE, and were involved in the IOP-lowering function. CONCLUSION Cassiae seed may be safe and beneficial for treating glaucoma due to its significant IOP- and LDH-lowering activities.

Changes in Visual Function During the Coriolis Illusion

BACKGROUND The Coriolis illusion produces spatial disorientation and is, therefore, dangerous for pilots. It is not known whether it also affects visual function (visual acuity and stereopsis). METHODS There were 18 subjects (15 men and 3 women, mean age 24.7 yr) enrolled in the study. A spatial disorientation simulator was used to produce Coriolis stimulation. The visual acuity of the subjects was evaluated with the Rosenbaum Vision Card before and during Coriolis stimulation. Stereopsis was measured with the Titmus stereo test. Throughout the experiments, eyeball movements were observed on a television monitor. Electrooculography (EOG) and electroencephalography (EEG) were also documented. RESULTS Before Coriolis stimulation, the visual acuity and stereopsis of all subjects were 20/20 and 40 s of arc, respectively. During the Coriolis illusion, the visual acuity of nine subjects (50%) remained 20/20, whereas the visual acuity of the others (50%) dropped by two lines. The stereopsis of most subjects (77.8%) decreased to 800 arc-seconds or less. Rhythmic nystagmus was observed, while EOG amplitudes were significantly elevated compared with those at baseline (9.41 +/- 0.26 microv2 and 8.45 +/- 0.36 microv2, respectively). EEG activity (frequency) was also greater than at baseline (13.15 +/- 0.84 Hz and 11.94 +/- 1.20 Hz, respectively; P < 0.05). CONCLUSIONS During Coriolis stimulation, the visual acuity of the subjects remained stable, but their stereopsis was reduced. Further study is warranted.