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Biomedical subjects

Y S Yu

Publications and source records attributed to Y S Yu.

At least 19 recordsLinked to original sources
PubMed2004

The number of CD8+ T cells and NKT cells increases in the aqueous humor of patients with Behçet's uveitis.

To determine whether there are differences in the immunopathogenesis of different endogenous uveitis syndromes, the phenotypic characteristics of immune cells were analysed among patients with endogenous uveitis. The aetiology of the uveitis included idiopathic recurrent acute anterior uveitis (18 patients), idiopathic intermediate uveitis (13 patients), Behçet's uveitis (17 patients), Vogt-Koyanagi-Harada syndrome (7 patients), and so on. Flow cytometric analysis was performed using immune cells of the aqueous humor and the peripheral blood during the active phase of intraocular inflammation, and monoclonal antibodies to CD3, CD4, CD8, CD14, CD19, CD56, TCR gammadelta, pan TCR alphabeta and Valpha24. CD8+ T cells were predominant in the aqueous humor of the patients with Behçet's uveitis, whereas CD4+ T cells were mainly found in the aqueous humor of patients other than those with Behçet's uveitis. The number of NKT (CD3+CD56+) cells was significantly higher both in the aqueous humor and the peripheral blood of the patients with Behçet's uveitis compared with the other groups (P < 0.05). CD8+CD56+ cells were the predominant subtype of the increased NKT cells in patients with Behçet's uveitis. In addition, intraocular infiltration of CD14+ cells significantly differed among the uveitis patients (P < 0.05). These results suggest that the immunopathogenesis of endogenous uveitis can vary between syndromes, and that CD8+CD56+ NKT cells may play an important role in the immunopathogenesis of Behçet's uveitis.

Adolescent↗
PubMed2004

The Seoul Metropolitan Preschool Vision Screening Programme: results from South Korea.

AIM: To report on a new model of preschool vision screening that was performed in metropolitan Seoul and to investigate the distribution of various ocular disorders in this metropolitan preschool population. METHODS: Vision screening was conducted on 36 973 kindergarten children aged 3-5 years in a stepwise manner. The first step was home screening using a set of five picture cards and a questionnaire. The children who did not pass the first step (VA <0.5 in at least one eye or any abnormal responses on the questionnaire) were retested with regular vision charts at the regional public healthcare centres. After this retest, some children were referred to ophthalmologists. The referral criteria for visual acuity were <0.5 at 3 years and <0.63 at 4 or 5 years in at least one eye. RESULTS: Of those screened, 7116 (19.2%) children did not pass the home screening tests and 2058 (28.9%) out of the 7116 were referred. The results of the ophthalmological examination in eye clinics were only available for 894 children (43.4%) of those who were referred. The rest of the children did not visit ophthalmologists because they had been checked at an eye clinic, were currently under treatment, or for personal reasons. Refractive errors were found in 608 (1.6%) children. Astigmatism was associated in 78.2% of ametropes. Amblyopia was discovered in 149 (0.4%) children and refractive error was the major aetiology with a predominant rate (82.5%). Manifest strabismus was detected in 52 children. The positive predictive value of vision screening for any ophthalmological disorder was 0.77, and 0.49 for significant disorders requiring treatment. CONCLUSIONS: This preschool vision screening model was highly accessible to the children and their parents, easy to administer, and effective to detect a variety of ocular disorders. However, the participation rate of the referred children in the examinations by ophthalmologists was quite low. The performance and efficiency of this screening programme need to be optimised with further revision.

Amblyopia↗
PubMed2003

Studies of the cell cycle of in vitro cultured skin fibroblasts in goats: work in progress.

The effect of serum starvation and olomoucine treatment on the cell cycle and apoptosis of goat skin fibroblasts cultured in vitro is reported in this paper. The cells were obtained from the ear of a female goat 1.5 years of age. Analysis of cell cycle distribution by fluorescence-activated cell sorting (FACS) showed that 3.4, 60.8 and 15.1% of normally cycling cells were at G1, G0 and S phase, respectively. Serum starvation for 1, 3 and 5 days arrested 70.1, 70.2 and 83.4% cells, respectively, at G0/G1 phase. Seventy-eight percent of confluent cells were at G0/G1 stage, but in contrast to the serum starved group, this high percentage of G0/G1 cells was mainly associated with G1 cells. Of cells not deprived of serum, 73.6% were arrested at G1/G0 when treated with 100 microM olomoucine for 9 h compared to 85.5% of cells that had been starved of serum for 2 days (co-inhibition) (P<0.01). After co-inhibition, 45% of cells entered S phase when re-cultured in normal medium for 5 h, indicating that the inhibition was reversible. Under normal culture conditions, 1.2% of cells underwent apoptosis. Serum starvation for 1, 2, 3, 5 and 10 days caused apoptosis in 1.7, 3.9, 4.5, 11.7 and 90.3% of cells, respectively. Treatment with 100 microM olomoucine for 9h did not increase the number of apoptotic cells significantly (1.9%, P>0.05). When cells were co-inhibited, 4.1% of cells underwent apoptosis. In conclusion, although serum withdrawal for 5 days or more effectively arrested cells at G0/G1 stages, it increased apoptosis of cells significantly. However, co-inhibition by serum withdrawal and olomoucine treatment was found to be an appropriate treatment to obtain more healthy G0/G1 cells based on the low percentage of apoptotic cells after treatment.

Animals↗
PubMed2003

Denitrification and phosphorus release under anoxic conditions in an anoxic-anaerobic-aerobic BNR process.

An anoxic-anaerobic-aerobic biologial nutrient removal process was used in this study. The kinetic aspects of denitrification and phosphorus release under anoxic conditions were investigated by conducting a pilot-scale plant operation under various SRTs (solids retention times), HRTs (hydraulic retention times) and internal recycle ratios. The process was capable of completely denitrifying the NOx- -N (the sum of NO2- -N and NO3- -N) in the nitrified recycle, resulting in an NOx- -N concentration of less than 1.0 mg l(-1) N in the anoxic zones. Denitrification and phosphorus release were accomplished due to abundant organic substrates in the anoxic zone at the head end of the process and achieved approximately equivalent rates with respect to influent SCOD loading in the zone. Phosphorus release continued without any nitrate inhibition due to low NOx- -N concentrations of less than 2.0 mg l(-1) N in the anaerobic zone.

Bacteria, Aerobic↗
PubMed2002

Characteristic ocular findings in Asian children with Down syndrome.

AIMS/PURPOSE: To identify the characteristic ocular findings in Asian children with Down syndrome. METHODS: A total of 123 Korean children with Down's syndrome between 6 months and 14 years of age were examined for ocular findings from March 1999 to April 2000. Ocular examinations including visual acuity assessment, slit-lamp biomicroscopy, ocular motility, cycloplegic refraction, and ophthalmoscopy were performed. RESULTS: The ocular findings in decreasing prevalence were the following: upward slanting of the palpebral fissure (78 patients, 63%), epicanthus (75 patients, 61%), epiblepharon (66 patients, 54%), astigmatism (38 patients, 31%), hyperopia (35 patients, 28%), myopia (31 patients, 25%), strabismus (31 patients, 25%, 18 esotropia and 13 exotropia), nystagmus (27 patients, 22%), nasolacrimal duct obstruction (21 patients, 17%), blepharoconjunctivitis (20 patients, 16%), retinal abnormalities (18 patients, 15%), cataract (four patients, 13%), and glaucoma (one patient, 0.8%). Brushfield spots and keratoconus were not found. CONCLUSIONS: Asian children with Down syndrome demonstrate unreported, high incidence of epiblepharon, the high rate of exotropia, and essentially no notable Brushfield spots, which are in contrast to the ocular findings in Caucasian patients with Down syndrome.

Adolescent↗
PubMed2001

Identification of four novel RB1 germline mutations in Korean retinoblastoma patients.

To elucidate RB1 germline mutations in Korean retinoblastoma patients, DNA samples from 14 children with bilateral (including three familial cases) and 19 children with unilateral retinoblastoma were analyzed. We found germline mutations in three out of 14 bilateral cases and one out of 19 unilateral cases. There were no germline mutations in the three familial cases. PCR-SSCP from each exon showed bandshifts in four patients which, upon sequencing, were shown to be K616E in exon 19 (c.1846A>G), an AA insertion in exon 7 (c.684-685insAA), R500G in exon 16 (c.1498A>G), and an A insertion in exon 23 (c.2391-2392insA), respectively. Hum Mutat 18:252, 2001.

Chromosomes, Human, Pair 13↗
PubMed2001

Prevalence and analysis of risk factors for infections caused by resistant Escherichia coli strains in Anhui, China.

BACKGROUND: This study analyzes the prevalence of hospital and community-acquired infections caused by Escherichia coli. PATIENTS AND METHODS: The antibiotic resistance pattern was used to characterize the isolates, and a retrospective observational study was performed to assess the relationship between antimicrobial use and bacterial resistance. The study was conducted during a 1-year and 7-month period in a 1,500-bed tertiary care hospital in Anhui, China. RESULTS: An E. coli infection was diagnosed in 1.4% of patients (519/36,179) admitted to the hospital between March 1, 1999 and August 31, 2000. Of the 519 isolates, 489 (94.2%) were resistant to at least one antimicrobial; 86% were resistant to ampicillin, 85% to cephalothin, 83% to piperacillin, 77% to ampicillin/sulbactam, 72% to trimethoprim/sulfamethoxazole (TMP-SMZ), 70% to ciprofloxacin, 61% to cefoperazone, 58% to tobramycin, 56% to gentamicin, 48% to ticarcillin-clavulanate, 44% to cefazolin, 43% to cefuroxime, 36% to cefoxitin, 32% to cefepime, 29% to aztreonam, cefetaxime and ceftriaxone, 28% to ceftazidime, 19% to piperacillin/tazobactam, 10% to amikacin, while all strains tested were susceptible to imipenem. CONCLUSION: Prior receipt of amtimicrobial therapy was significantly associated with infection caused by a resistant organism.

Adolescent↗
PubMed2001

Mechanism of growth inhibitory effect of Mitomycin-C on cultured human retinal pigment epithelial cells: apoptosis and cell cycle arrest.

PURPOSE: To investigate the therapeutic potential of Mitomycin-C (MMC) in the management of proliferative vitreoretinopathy, the antiproliferative effect of MMC on cultured human retinal pigment epithelial (RPE) cells were investigated in vitro. METHODS: Drug sensitivities of cultured human RPE cells to MMC were determined using the tetrazolium dye assay. In order to detect the presence of apoptosis, DNA fragmentation was assessed by DAPI staining, and TdT-dUTP nick-end labeling (TUNEL) assay. The relative amount of DNA fragmentation was quantified by flow cytometric analysis. To analyze the cell cycle response of RPE cells to MMC, flow cytometric analysis of propidium iodide stained nuclei was performed. The levels of proteins related to DNA damage in the RPE cells were then determined by Western blot analysis. RESULTS: MMC inhibited cell proliferation in a dose-dependent manner. The majority of RPE cells following treatment with 10 microg/ml of MMC exhibited fragmented nuclei as observed by DAPI staining and TUNEL assay. Cell cycle analysis demonstrated an accumulation of cells arrested in S and G2/M phase following treatment with 1 microg/ml of MMC. At 10 microg/ml of MMC, a dramatic increase of the cell population in the sub G1 peak, which can be considered a marker of cell death by apoptosis, was observed by flow cytometry. Western blot analysis of p53 and p21 revealed a gradual increase in the level of these proteins when RPE cells were exposed to increasing concentrations of MMC. CONCLUSIONS: This study demonstrated that the response of RPE cells to MMC was bi-directional: 1) partial arrest of the cell cycle at S, G2/M phase, and 2) induction of apoptotic cell death.

Adolescent↗
PubMed2001

Comparison between anisometropic and strabismic amblyopia using functional magnetic resonance imaging.

AIMS: To assess calcarine activation with functional magnetic resonance imaging (fMRI) in patients with anisometropic and strabismic amblyopia. METHODS: 14 amblyopes (eight anisometropic and six strabismic) were studied with fMRI using stimuli of checkerboards of various checker sizes and temporal frequencies. While T2* weighted MRI were obtained every 3 seconds for 6 minutes, patients viewed the stimuli monocularly with either the amblyopic or sound eye. RESULTS: Amblyopic eyes showed reduced calcarine activation compared with contralateral sound eyes in fMRI in all subjects. The calcarine activation from amblyopic eyes in anisometropic amblyopes was more suppressed at higher spatial frequencies, while that from amblyopic eyes in strabismic amblyopes was more suppressed at lower spatial frequencies. CONCLUSION: These results suggest that fMRI is a useful tool for the study of amblyopia in humans. The calcarine activation via amblyopic eyes because of anisometropia or strabismus has different temporospatial characteristics, which suggests differences in the neurophysiological mechanisms between two types of amblyopia.

Adolescent↗
PubMed2001

The effect of oxygen on retinal degeneration in wild-type and hsp70.1 knockout neonatal retinal degeneration mice.

The present study examined the effect of oxygen on photoreceptor degeneration in the retina of heat shock protein 70.1 (hsp70.1) knockout type and wild-type retinal degeneration (rd) mice. All the neonatal rd mice were exposed to hyperoixa for 5 days after birth, and then were returned to room air before being sacrificed. At the postnatal 10, 14, 18, and 21 days, the ratio of outer nuclear layer (ONL) thickness to total retinal thickness was compared between hsp70.1 knockout type and wild type. The retina was also examined for DNA fragmentation by TdT-mediated biotin-dUTP nick-end labeling (TUNEL). In hsp70.1 knockout type, the ratio of ONL to total retinal thickness was higher than that in the wild type at each time. There was the remarkable difference in the number and distribution of TUNEL-positive cells between hsp70.1 knockout type and wild type rd mice. In conclusion, an oxygen-induced modulation of the rate of photoreceptor degeneration was more marked in the hsp70.1 knockout type than wild type rd mice.

Animals↗
PubMed2001

Effect of the absence of heat shock protein 70.1 (hsp70.1) on retinal photoreceptors in normal and rd mice.

The purposes of this study are to elucidate the retinal changes of heat shock protein 70.1 (hsp70.1) knockout mice and to compare them between in normal and in retinal degeneration (rd) mice. Eyes of hsp70.1 wild type (+/+) and knockout (-/-) mice in the C57BL/6 or FVB genetic backgrounds respectively, which were reared in the normal environment, were examined by fundus photography, electroretinography, light microscopy, terminal dUTP nick-end labeling (TUNEL) stain, and immunohistochemistry. In C57BL/6 mice, fundus photography showed no changes between hsp70.1+/+ and -/- mice at 1 and 6 months of age. Electroretinographic examination showed a tendency of decreased amplitude of a- and b-wave with aging in both genotype, but there were not different statistically. The ratios of the thickness of inner nuclear and outer nuclear layer to the retinal thickness were respectively decreased with aging in both genotype, but there were not different statstically. TUNEL assay showed a few positively labeled cells in the ganglion cell, inner nuclear and outer nuclear layers and the immunohistochemistry showed no immunopositivity of hsp70 in the inner segments of photoreceptor cell layer in both genotype. In rd mice, fundus photography showed a narrowing of the retinal vessels at the age of 4 weeks, however, there were no differences of retinal changes including pigment epithelial layer in both genotype. Electroretinographic examination at the postnatal 2, 3 and 4 weeks showed no differences between them. Loss of photoreceptor cell and outer nuclear layers showed no differences in both genotype. In conclusion, there were no differences of the retinal changes at least under the normal environmental condition in hsp70.1+/+ and -/- mice. These results show that hsp70.1-/- mice can be used to study the role of hsp70.1 to the external stress to the retina.

Animals↗
PubMed2001

Extraocular muscle changes after cryotherapy for retinopathy of prematurity and the development of strabismus in premature infants.

To find out whether the cryotherapy for the treatment of the retinopathy of prematurity (ROP) causes structural changes of the extraocular muscle (EOM), and also whether the changes are related with the occurrence of strabismus. To examine the acute stage change, we conducted a transconjunctival cryotherapy around the superior rectus muscle of a rabbit and resected it 0, 3, 7, 14, and 28 days after the cryotherapy. In observing chronic changes, we first categorized patients who had an esotropia surgery into groups, one of which combined prematurity and cryotherapy and one group affected by prematurity but without having had cryotherapy. Then we compared the change of EOM with that of a fullterm infant group. In a rabbit, edema, acute inflammatory cells and a large amount of degenerated muscle fibers were observed immediately after the cryotherapy and on the 3rd day. On the 7th day, regenerated muscle fibers were observed and on the 14th day, the inflammatory cells decreased and the amount of regenerated muscle fiber increased. On the 28th day, abnormal findings were not observed any more and the muscle was found to be normal. When chronic changes of EOM in human on 1 1/2 to 8 1/2 years after cryotherapy, there were no abnormal findings observed in three groups. From the study, we can infer that cryotherapy can cause acute inflammation and necrosis of muscle fiber but such an acute change will improve and does not result in structural change in the long term. Therefore, the occurrence of strabismus in patients with ROP is considered to be attributable to reasons other than injury of EOM.

Animals↗
PubMed2001

[Mitochondrial DNA sequence variations of Shui ethnic group].

The mtDNA hypervariable segment I sequences (HVS I) were sequenced in 64 Shuis from Guizhou Province. 73 sites were polymorphic in the 495 bp fragment that sequenced, identified 48 different haplotypes. Phylogenetic analysis of the haplotypes suggested that there were some ancestral haplotypes in current Shuis, and these haplotypes were also present in Eurasia populations as well as in other ethnic groups. Demographic analysis of the Shuis demonstrated a unimodal distribution that is typical for a population undergone expansion in the past and with a high Tau value, which suggested that the Shui group might be a ancestral population. Combined with the analysis of the reported data, the Shui ethnic group showed a generally similar genetic component with the Zhuang from Guangxi, but it is also different from these typical south populations as Zhuang, Cantonese.

Asian People↗
PubMed2000

Effects of scleral buckling of refraction and ocular growth in young rabbits.

BACKGROUND: There have been a series of reports indicating that scleral buckling (SB) surgery may induce high myopia in advanced retinopathy of prematurity. The mechanism of SB on refractive change in children, however, is not clearly known. We designed this study to investigate the effects of SB on refractive error and ocular growth in young rabbits and demonstrate their mechanisms. METHODS: For the study, SB surgery was performed on the right eyes of nine 5-week-old rabbits and 11 8-week old rabbits, with encircling buckle. The left eyes were monitored for control. Spherical equivalent, corneal power, and axial length were measured before SB and postoperatively at 2, 4, and 8 weeks. We compared the experimental group with the control group and analyzed the influence of age at the time of operation. RESULTS: In the control group of eyes, corneal power decreased, axial length increased, and spherical equivalent developed emmetropization with aging. In all eyes that underwent SB surgery, high myopia developed, with the increase in axial length as a major factor in inducing myopia. These changes were greater in the 5-week-old group than in the 8-week-old group. In the eyes that underwent SB surgery, axial length increased more than the eyes in the control group up to 2 weeks after surgery, but ocular growth was arrested after that time. CONCLUSIONS: SB in young rabbits effects ocular growth and results in high myopia, and an increase of axial length plays a major role in this mechanism. Also, the difference in the effects of SB according to age at the time of surgery may suggest that SB in premature infants could induce a significant axial myopia and secondary amblyopia.

Aging↗
PubMed2000

Surgical management of congenital cataract associated with severe microphthalmos.

PURPOSE: To report the results of cataract surgery in children with severe microphthalmos and congenital cataract. SETTING: Seoul National University, Department of Ophthalmology, Seoul, Korea. METHODS: Retrospective studies were conducted by reviewing the charts of 20 eyes of 11 patients with severe microcornea and microphthalmos or severe microcornea with a corneal diameter smaller than 9.0 mm. The patient pool was divided according to surgical method, specifically by incision site: an anterior group that had corneal limbal incisions and a posterior group treated via pars plicata incisions. Preoperative examinations included bilaterality, corneal diameter, axial length, and eye and systemic abnormalities. Postoperative results and complications of the 2 operative methods were compared. RESULTS: All 11 patients had bilateral congenital cataract and microphthalmos. Except in 1 case, surgeries were done in patients ranging in age from 2 to 16 months. Mean follow-up was 2 years. Corneal diameter was smaller than 9.0 mm in all 20 eyes and smaller than 7.5 mm in 11 eyes. Ten eyes were categorized into the anterior group, and the other 10 eyes were placed in the posterior group. Postoperative complications included secondary membranes in 3 eyes in the posterior group and corneal opacity in 3 eyes in the anterior group. CONCLUSION: The surgical management of children with congenital cataract and severe microphthalmos is recommended as a way to improve vision but must be performed carefully to avoid complications.

Abnormalities, Multiple↗
PubMed2000

Efficacy of removal of buckle after scleral buckling surgery for retinopathy of prematurity.

UNLABELLED: BACKGROUND OR PURPOSE: A series of encouraging reports over the past decade indicate that scleral buckling (SB) surgery may lessen or eliminate vitreoretinal traction in advanced retinopathy of prematurity (ROP). The effects of SB surgery on refraction and ocular growth, however, have not been demonstrated. We investigated the effects of postoperative removal of buckle in infants whose retinas were reattached in stage 4 ROP. METHODS: Selected for study were 6 eyes of 3 patients whose retinas had been reattached by placing an encircling buckle, 2.5 mm in width, around the eye and whose buckles were subsequently removed. Axial lengths and refractive errors were compared before and after removal of the buckles. The patients were examined for at least 3 years after removal. RESULTS: There was high myopia in all eyes treated for stage 4 ROP with SB. All retinas remained attached after removal of the buckle. Although there was a variable degree of increase in axial length, myopic refractive error tended to decrease after removal of the buckle. CONCLUSIONS: There was some decrease in degree of myopia without resulting in retinal detachment or continued vitreous traction after buckle removal following SB surgery for ROP.

Device Removal↗
PubMed2000

Long term refractive outcome in eyes of preterm infants with and without retinopathy of prematurity: comparison of keratometric value, axial length, anterior chamber depth, and lens thickness.

BACKGROUND/AIMS: A longitudinal study of premature infants was conducted to examine changes in refractive status and their relation with age and factors influencing the occurrence and degree of myopia. Identification of which of the various refractive factors play important parts in relation to myopia in premature infants was attempted. METHODS: Under observation were 125 eyes in 65 patients who were found to demonstrate no signs of retinopathy of prematurity (ROP) or who had grade I or II ROP without or after cryotherapy. Cycloplegic refractions were conducted at 6 months, 3 years, and 6 years of age; at 6 years of age keratometric values, lens thicknesses, and axial lengths were recorded, and anterior chamber depths also were measured. RESULTS: Myopia begins to appear at 6 months of age and its severity increases between the ages of 6 months and 3 years. The condition showed no further progress in subjects older than 3 years. Of the 104 eyes with ROP, those eyes with cicatricial retinopathy tended towards myopia and high myopia while there was no difference in the degree of myopia related to whether or not cryotherapy was conducted. At 6 years of age, the premature infants exhibited shallower anterior chambers, thicker lenses, and higher axial lengths when the degree of the myopia was higher. The keratometric values, however, appeared to bear no relation to the degree of the myopia. CONCLUSION: These results suggest that the occurrence of myopia is related more strongly to whether or not there is cicatricial retinopathy than whether or not there is cryotherapy. Also, the degree of the myopia was found to be related to the depth of the anterior chamber, the thickness of the lens, and the change in axial length but not to keratometric value.

Age Factors↗