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Yi-Yu Tsai

Publications and source records attributed to Yi-Yu Tsai.

At least 19 recordsLinked to original sources
PubMed2006

An association between BPDE-like DNA adduct levels and P53 gene mutation in pterygium.

PURPOSE: A previous report of ours noted that not only p53 protein overexpression, but also p53 gene mutation. were indeed detected in pterygium. BaP 7,8-diol 9,10-epoxide (BPDE), an ultimate metabolite of BaP, attacks deoxyguanosine to form a BPDE-N2-dG adduct resulting in p53 mutations. The relationship between BPDE-like DNA adduct levels and abnormal p53 has not been clear in pterygium. Therefore, BPDE-like DNA adduct, p53 protein expression and p53 gene mutation were examined in this study to provide more molecular evidence to understand the cause of p53 gene mutation in pterygium. METHODS: In this study, immunohistochemical staining, using a monoclonal antibody (DO7) against p53 and a polyclonal antibody against BPDE-like DNA adducts, was performed on 73 pterygial specimens. DNA samples for p53 mutation analysis were extracted from epithelial cells and then subjected to DNA sequencing for the determination of mutations in exons 4, 5, 6, 7, and 8 of the p53 gene. RESULTS: BPDE-like DNA adducts were detected in 36.1% (26/73) pterygium samples. No correlation between adduct levels and p53 protein expression was found in these samples. Additionally, the p53 gene mutation and p53 mutation pattern also did not correlate with BPDE-like DNA adduct levels. CONCLUSIONS: Our data provides evidence that BPDE-like DNA adducts are indeed detected in pterygium samples, and they are only minor contributors to the abnormal p53 gene.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2006

Hypermethylation of the p16 gene promoter in pterygia and its association with the expression of DNA methyltransferase 3b.

PURPOSE: A pterygium has long been considered as a degenerative condition. After p53 protein was found to be abnormally expressed in the epithelium, researchers suggested that a pterygium may be a tumor, but additional evidence is required to support this hypothesis. Aberrant methylation of the p16 gene (CDKN2A) promoter and resultant gene silencing play important roles in the pathogenesis of many types of human cancers. The purpose of this study was to investigate hypermethylation of the p16 promoter in pterygia and the relationship between this hypermethylation and the expression of p16 and DNA methyltransferase 3b (DNMT3b) proteins. METHODS: We studied the methylation status of p16 and the expression of p16 and DNMT3b proteins by performing methylation-specific polymerase chain reaction and immunohistochemistry, respectively, in specimens of 129 pterygia and 16 normal conjunctiva. The results were statistically analyzed. RESULTS: Hypermethylation of the p16 gene promoter was detected in 21 (16.3%) of 129 pterygial specimens. Among them, 46 (35.7%) were positive for p16 protein expression, and 83 (64.3%) were negative. Staining for p16 was limited to the nuclei of the epithelial layer. We observed a significant reverse correlation between hypermethylation of the p16 promoter and the expression of p16 protein (p=0.006). Thirty-eight (29.5%) pterygial specimens were positive for DNMT3b protein expression, and 91 (70.5%) were negative. DNMT3b staining was limited to the nuclei of the epithelial layer. A significant correlation was found between hypermethylation of the p16 promoter and the expression of DNMT3b protein (p<0.001). CONCLUSIONS: The p16 gene promoter was hypermethylated in pterygia, and this hypermethylation was strongly linked to expression of the positive expression of DNMT3b protein and to the suppression of p16 protein. These data provided molecular evidence that methylation occurs in pterygia and that it may play a role in the their development.

Aged↗
PubMed2006

The TGFbeta1 gene codon 10 polymorphism contributes to the genetic predisposition to high myopia.

PURPOSE: Transforming growth factor-beta (TGFbeta), a multifunctional growth factor that plays a key role in the remodeling of scleral tissue, may be involved in the predisposition and pathophysiology of high myopia. Our aim was to examine the association between myopia and the polymorphisms within codon 10 of the TGFbeta1 gene. METHODS: This was a case control study. The study group contained participants who had high myopia and a spherical equivalent greater than -6.00 D. The control group was composed of medical students whose spherical equivalent was less then -0.5 D. All volunteers in this study were over 16 years old and had never undergone ocular surgery. Genotyping was conducted by restriction fragment length polymorphism, and the results were compared between myopia patients and control subjects. RESULTS: The frequency of the CC genotype in TGFbeta1 codon 10 differed significantly between patients in the high myopia group (n=201) and individuals in the control group (n=86; p<0.001). People with either the CT or TT genotype had a lower probability of having high myopia with a spherical equivalent greater than -6.00 D than those with the CC genotype. Furthermore, there was a higher frequency of the C allele in the high myopia group than with the control group (p<0.001, OR=1.83, CI=1.27-2.63). CONCLUSIONS: The frequency of the CC homozygote in the high myopia group was much higher than in the control group, indicating people with the CC homozygote may be at a higher risk of developing high myopia. Varied expression of this gene may contribute to the genetic predisposition to high myopia in Chinese Taiwanese.

Adolescent↗
PubMed2006

Stratus optical coherence tomography for evaluating optic disc pits associated with maculopathy before and after vitrectomy: two case reports.

Optic disc pit (ODP) can be either congenital or acquired. Congenital ODP is typically unilateral, and the visual acuity and visual field are normal unless associated with macular serous detachment, which occurs in about 25-75% of cases. Acquired ODP is known as an important risk factor for progressive visual field loss in glaucoma. The fundus finding of congenital ODP includes oval depression involving the optic disc, with or without macular serous detachment. We used third-generation Stratus optical coherence tomography (Straus OCT) to investigate the possible pathogenesis of ODP associated with maculopathy and to monitor the anatomic changes before and after treatment.

Adolescent↗
PubMed2005

Oxidative DNA damage in pterygium.

PURPOSE: Epidemiological evidence suggests that UV irradiation plays the most important role in pterygial formation. The noxious effects of UV irradiation are either directly by a UV phototoxic effect or indirectly by formation of radical oxygen species (ROS). ROS are very harmful to cells, because they injure cellular DNA, proteins, and lipids (called oxidative stress). Among numerous types of oxidative DNA damage, the formation of 8-hydroxydeoxyguanosine (8-OHdG) presents only a minor fraction of UV induced DNA damage, but it is a ubiquitous marker of oxidative stress. If pterygium is related to UV, we surmised oxidative stress exists in pterygium. To provide the molecular evidence of UV radiation, 8-OHdG was detected in pterygium. Moreover, human 8-oxoguanine glycosylase (hOGG1) is the key component responsible for the removal of 8-OHdG. To determine whether the hOGG1 was expressed in pterygium, this enzyme was also evaluated. METHODS: Immunohistochemical staining using a monoclonal antibody to 8-OHdG and hOGG1 were performed on 52 pterygial specimens and 6 normal conjunctiva. RESULTS: There were 12 (23.1%) pterygial specimens positive for 8-OHdG staining, limited to the nuclei of the epithelial layer. No substantial staining was visible in the subepithelial fibrovascular layers. In pterygium with 8-OHdG staining, there were 4 (4/11, 36.4%) specimens with hOGG1 expression. However, in pterygium without 8-OHdG staining, there were only 3 (3/41, 7.3%) specimens with hOGG1 expression. hOGG1 expression was significantly associated with 8-OHdG positive staining. All normal controls were negative for 8-OHdG and hOGG1 staining. CONCLUSIONS: Our study demonstrated for the first time 8-OHdG in pterygium, which represented oxidative stress in pterygium. The increased level of 8-OHdG in pterygium is not due to decreased expression of hOGG1, while increased levels of 8-OHdG induced the expression of hOGG1.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2005

P53 gene mutation spectrum and the relationship between gene mutation and protein levels in pterygium.

PURPOSE: To investigate the spectrum of p53 gene mutations and the relationship between gene mutation and p53 protein levels in pterygium. METHODS: Pterygial samples were harvested from 51 patients undergoing pterygium surgery. DNA samples for p53 mutation analyses were extracted from epithelial cells and subjected to DNA sequencing for examination of mutations in exons 4, 5, 6, 7, and 8 of the p53 gene. In situ levels of p53 protein were studied by immunohistochemistry (IHC) and the percentage of positively stained cells quantified. Ten normal conjunctiva samples were included in this study as controls. RESULTS: Mutations within the p53 gene were detected in 8 pterygial samples (15.7%) with only one mutation found in each sample. All the mutations observed were point mutations, with 6 being substitutions and 2 deletions. Three mutations were identified in exon 6, two in exon 7, and a single mutation found in each of exons 4, 5, and 8. P53 protein levels were scored as 0 (negative) in 31 pterygial specimens (60.8%), +1 in 9 samples (17.6%), +2 in 5 samples (9.8%), and +3 in 6 samples (11.8%) by IHC. The 8 samples found to have p53 gene mutations were equally distributed among the different levels of p53 protein observed using IHC, with 2 samples in each group. The two deletion mutations, which caused a frame shift to occur, were found in samples negative for p53 immunostaining (score 0), while substitution mutations were found in samples positively stained (score +1, +2, and +3). CONCLUSIONS: Mutations within p53 gene exons 4-8 were detected in pterygial epithelium and the mutations showed no correlation with p53 protein levels as seen by IHC.

Aged↗
PubMed2005

Noninfectious hypopion after intravitreal triamcinolone acetonide injection for central retinal vein occlusion: a case report.

Although it is rare, infectious endophthalmitis is a severe ocular complication resulting from intravitreal injection of triamcinolone acetonide (TA). Therefore, care must be taken by ophthalmologists to differentiate between what is infectious and noninfectious endophthalmitis. We report on a 62-year-old woman who received an intravitreal injection of TA for treatment of central retinal vein occlusion. One day after the injection, a hypopion (a white-yellowish deposit) was noted in the inferior anterior chamber. The patient complained that her vision had deteriorated, but there was no pain, eyelid edema, increased conjunctival injection or corneal edema. The hypopion gradually diminished and by the fifth postoperative day, resolved completely without the administration of intravitreal or systemic antibiotic therapy.

Anti-Bacterial Agents↗
PubMed2005

Effects of laser in situ keratomileusis on the corneal endothelium.

The purpose of this study was to assess the effects of laser in situ keratomileusis (LASIK) on the corneal endothelium. In a prospective study, the corneal endothelium of 87 eyes (45 patients) was examined before and 1 month after LASIK. Patients were divided into two groups: people who wear contact lenses (48 eyes) and people who had never worn contact lenses (39 eyes). The corneal endothelium was analyzed for cell density, percentage of hexagonal cells, and coefficient of variation (CV) of cell size. The mean cell density and percentage of hexagonal cells was significantly higher 1 month after LASIK for all 87 eyes. However, the mean CV of cell size was not significantly different. In contact lens wearers, there was a significant increase in mean cell density and percentage of hexagonal cells, but there was no significant change in mean CV of cell size after LASIK. Among patients who had never worn contact lenses, no significant changes were noted in mean cell density, percentage of hexagonal cells, or mean CV of cell size. In this study, LASIK caused no damage to the corneal endothelium. Postoperative improvements in the mean cell density and percentage of hexagonal cells in patients who were contact lens wearers may be related to the discontinuance of contact lens use after LASIK.

Adolescent↗
PubMed2005

The fixed combination of fortified vancomycin and amikacin ophthalmic solution--VA solution: in vitro study of the potency and stability.

PURPOSE: We compared the in vitro potency and stability of a fixed combination of vancomycin and amikacin solution (VA solution) with amikacin or vancomycin solution. METHODS: Solutions of 2% amikacin (20 mg/mL) and of 5% vancomycin (50 mg/mL) and VA solution (each 1 mL contained 20 mg of amikacin and 50 mg of vancomycin) were prepared from parenteral antibiotics by reconstituting them with sterile injection water and refrigerated (4 degrees C) in the dark. Triplicate 5-mL portions of each solution were tested before storage and 7 and 14 days after preparation for potency of antimicrobial activity by the disk diffusion method and for stability. RESULTS: There were no significant differences in the diameter of zones of inhibition of VA solution compared with amikacin or vancomycin solution within a 2-week period. Visual inspection revealed that all solutions remained clear, colorless, and particle-free at 4 degrees C throughout the study period. For osmolarity, the VA solution was much higher than that of either amikacin or vancomycin solution at all tested times and more near the well-tolerated range of human eyes. There were no significant differences at days 0, 7, or 14 for either vancomycin, amikacin, or VA solution. For pH, the VA solution was higher than that of vancomycin solution (nearly equal to that of amikacin solution) at each time and more near the level of normal tear film. The pH did not differ significantly for either vancomycin, amikacin, or VA solution at all tested times. CONCLUSIONS: The vancomycin and amikacin ophthalmic solutions can be mixed together with the same potency and stable physical properties. It may be useful in the treatment of bacterial keratitis pending clinical trials to determine its effectiveness and safety.

Amikacin↗
PubMed2005

p53 Expression in pterygium by immunohistochemical analysis: a series report of 127 cases and review of the literature.

PURPOSE: To assess the p53 protein expression in pterygial tissue and to review all immunohistochemical studies on pterygium from Medline to evaluate the roles of age, gender, race, p53 antibody, cutoff levels of immunohistochemical analysis, parts of pterygium, p53 gene mutation spectrum, and primary or recurrent pterygium on the p53 staining results. METHODS: Immunohistochemical staining was performed on 127 pterygial specimens and 18 normal conjunctival samples. All 8 immunohistochemical studies on p53 expression in pterygium from Medline were reviewed. RESULTS: Among the 127 pterygial samples, there were 29 specimens (22.8%) positive for p53 expression. There was no significant difference between the p53-positive and p53-negative groups with respect to age or gender. CONCLUSION: The positive rate of p53 staining in 8 immunohistochemical studies was 7.9%, 36.8%, 37.5%, 38.1%, 50%, 53.8%, 60%, and 100%, respectively. p53 protein antibody, cutoff level, race, and p53 gene mutational spectra all affect the results on the p53 staining. Different parts of pterygium and gender merit further evaluation in their role on p53 staining result.

Aged↗
PubMed2005

Effect of p53 codon 72 polymorphism on p53 protein expression in pterygium.

BACKGROUND: The p53 protein is expressed in pterygial epithelium, but the reported prevalence of its expression varies widely. Although the cause of this variation is unknown, several factors that may play a role have been investigated, but without conclusive findings. In the present study, the role of p53 codon 72 polymorphism, and that of both age and gender, on p53 expression in pterygium was investigated. METHODS: Pterygium and blood samples were harvested from 55 patients undergoing pterygium surgery. The pterygial specimens were studied immunohistochemically using antibodies against p53 protein. Polymerase chain reaction based analysis was used to resolve the p53 codon 72 polymorphism. RESULTS: Thirty-one (56.4%) of the 55 pterygial specimens were positive for p53 staining. The distributions of the three genotypes of the p53 codon 72 polymorphism in the p53-positive and -negative staining groups were not statistically different. The allelic frequency in the two groups was also not statistically different, nor was there any significant difference between both groups with respect to age or gender. CONCLUSIONS: A correlation between p53 codon 72 polymorphism, sex and gender and p53 protein expression was not found.

Age Factors↗
PubMed2005

Laser in situ keratomileusis for different degrees of myopia.

PURPOSE: To determine the efficacy, predictability, stability and safety of laser in situ keratomileusis (LASIK) in treating patients with different degrees of myopia. METHODS: We enrolled 386 eyes of 200 consecutive patients who underwent LASIK and divided them into four groups according to their degree of preoperative spherical equivalent (SE). Group 1 eyes ranged between - 1.00 and - 3.99 dioptres (D) (low myopia). Group 2 eyes ranged between - 4.00 and - 5.99 D (moderate myopia). Group 3 eyes ranged between - 6.00 and - 9.99 D (high myopia). Group 4 eyes were over - 9.99 D (extreme myopia). Follow-up was at 1 day, 1 week and 1, 3, 6, 12 and 18 months postoperatively. RESULTS: Our study included 386 eyes of 200 patients with SE ranging from - 3.00 to - 16.00 D (mean - 7.14 +/- 2.87 D). All eyes were seen at 1 day postoperatively. A total of 360 eyes (93%) were examined at 1 week, 330 eyes (85%) at 1 month, 281 eyes (73%) at 3 months, 247 eyes (64%) at 6 months, 199 eyes (52%) at 12 months and 142 eyes (37%) at 18 months. The postoperative data from 1 day to 12 months were used because of the low follow-up rate at 18 months postoperatively. Group 1 consisted of 30 eyes. The mean SE was - 3.52 +/- 0.43 D preoperatively and - 0.40 +/- 0.58 D at 1 month, - 0.46 +/- 0.60 D at 6 months and - 0.42 +/- 0.50 D at 12 months postoperatively. Uncorrected visual acuity (UCVA) was 20/40 or better in 95% of eyes at 1 day and in 100% of eyes at 6 and 12 months postoperatively. Group 2 consisted of 151 eyes. The mean SE was - 5.36 +/- 0.67 D preoperatively and - 0.54 +/- 0.78 D at 1 month, - 0.56 +/- 0.90 D at 6 months and - 0.55 +/- 0.82 D at 12 months postoperatively. Uncorrected VA was 20/40 or better in 95% of eyes at 1 day and in 100% of eyes at 6 and 12 months postoperatively. Group 3 consisted of 167 eyes. The mean SE was - 8.15 +/- 0.94 D preoperatively and - 0.58 +/- 0.90 D at 1 month, - 0.67 +/- 1.00 D at 6 months and - 0.64 +/- 0.95 D at 12 months postoperatively. Uncorrected VA was 20/40 or better in 90% of eyes at 1 day and in 98% of eyes at 6 and 12 months postoperatively. Group 4 consisted of 38 eyes. The mean SE was - 11.09 +/- 1.10 D preoperatively and - 1.25 +/- 1.20 D at 1 month, - 1.13 +/- 1.30 D at 6 months and - 1.20 +/- 1.25 D at 12 months postoperatively. Uncorrected VA was 20/40 or better in 78% of eyes at 1 day, in 94% at 6 months and in 90% at 12 months postoperatively. Intraoperative complications (free cap) occurred in two eyes and postoperative complications were observed in three eyes, making the total complications rate 1.29% (5/386). Seven eyes lost one Snellen line of BCVA, five lost two lines and two lost more than two lines (total: 3.64%, 14/386). CONCLUSION: In conclusion, LASIK is effective, predictable and safe for correcting myopia but is more accurate for correcting myopia up to -10.00 D. With more improvement in algorithms and ablation profile, we believe that LASIK can offer better results for higher myopia.

Adult↗
PubMed2004

Null type of glutathione S-transferase M1 polymorphism is associated with early onset pterygium.

PURPOSE: To investigate the association of glutathione S-transferase M1 (GSTM1) null genotype with pterygium. METHODS: One hundred and twenty seven pterygium patients and 102 volunteers without pterygium were enrolled in this study. Polymerase chain reaction based analysis was used to resolve the GSTM1 null and positive genotypes. RESULTS: There was no significant difference between total pterygium and the control group. When stratified by the age, there was a significantly higher frequency of the GSTM1 null genotype in younger patients. The difference was not significant between patients and controls older than 60 years old. CONCLUSIONS: These results indicate GSTM1 null genotype is associated with early onset pterygium, but not associated with late onset pterygium.

Adult↗
PubMed2004

Comparison of ablation centration in initial and retreatment active eye-tracker-assisted laser in situ keratomileusis and the effect on visual outcome.

PURPOSE: To evaluate the relationship between initial and retreatment ablation centers in active eye-tracker-assisted myopic laser in situ keratomileusis (LASIK) and determine whether the relationship between the 2 ablation centers influences the visual outcome after retreatment. SETTING: Department of Ophthalmology, China Medical University Hospital, Taichung, Taiwan. METHODS: This retrospective study comprised 21 eyes of 15 patients who had retreatment at least 3 months after primary myopic LASIK by lifting the initial flap. Corneal topography and best corrected visual acuity (BCVA) were evaluated preoperatively and 3 months postoperatively. The ablation centration was analyzed by corneal topography preoperatively and at 3 months. RESULTS: The mean decentration of the primary treatment was 0.43 mm +/- 0.21 (SD) and of the retreatment, 0.34 +/- 0.15 mm. There was no significant difference between them (P =.07). The 2 ablation centers were close each other. The mean distance between the 2 ablation centers was 0.29 +/- 0.18 mm and the mean angle between them, 39.7 +/- 46.2 degrees. The BCVA was unchanged after retreatment regardless of the relationship between the 2 ablation centers. CONCLUSIONS: With an active eye-tracking system, the retreatment center was not only close to the pupil center but also close to the primary ablation center. Regardless of the relationship between the 2 ablation centers, the BCVA did not change if the retreatment ablation was well centered.

Adult↗