Maternal psychologic problems increased the risk of childhood atopic dermatitis.

BACKGROUND: Little is known about the effect of postnatal maternal psychologic problems on the development of childhood atopic disorders. OBJECTIVES: To assess the association between early life maternal psychologic problems and atopic dermatitis (AD) in children in a national birth cohort. METHODS: We used multistage, stratified systematic sampling to recruit 24,200 mother-newborn pairs from the Taiwan national birth registration. Maternal psychologic problems and potential confounders were gathered by the standard questionnaire at 6 months old. At 3 years of age, information about the development of AD was assessed by International Study of Asthma and Allergies in Childhood via home interviews. Multiple logistic regression analysis was performed to estimate the association of postnatal maternal psychologic problems (postpartum depression (PPD) and maternal mental health index) and AD. RESULTS: The prevalence of physician-diagnosed AD was 10.5%. PPD increased the risk of subsequent physician-diagnosed AD in children after adjusting for potential confounders and other maternal mental health index (aOR = 1.42, 95% CI = 1.21-1.66). We observed that the risk of AD associated with PPD was not confounded by other social demographic factors such as maternal AD, maternal education, family income, breastfeeding, day care, and number of siblings. CONCLUSIONS: Postpartum depression increased the risk of childhood AD even when other maternal mental health index and social demographic factors are considered. Early intervention of PPD might be helpful for AD prevention.

Children with atopic dermatitis show clinical improvement after Lactobacillus exposure.

BACKGROUND: The role of probiotics in the treatment of atopic dermatitis (AD) is not clearly established. Further clinical trials with new probiotic formulations are warranted. OBJECTIVES: To assess the effects of Lactobacillus paracasei (LP) and Lactobacillus fermentum (LF), and their mixture on the disease severity, quality of life, and immune biomarkers of children with AD. METHOD: A double-blind, prospective, randomized placebo-controlled study was conducted on 220 children aged 1-18 years with moderate-to-severe AD (Trial number: NCT01635738). The children were randomized to receive LP, LF, LP + LF mixture, and placebo for 3 months. Changes in severity scoring of atopic dermatitis (SCORAD), Family Dermatology Life Quality Index (FDLQI), and Children's Dermatology Life Quality Index (CDLQI) scores in the different groups and at different visits were evaluated. Skin prick tests, levels of IgE, IFN-γ, IL-4, TGF-ß, and TNF-α, and urine biomarkers were also evaluated. RESULTS: Children who received LP, LF, and LP + LF mixture showed lower SCORAD scores than the placebo group (P < 0.001), and this difference remained even at 4 months after discontinuing the probiotics. The FDLQI and CDLQI scores were lower in the LP, LF, and LP + LF mixture group than in the placebo group (P = 0.02 and 0.03). IgE, TNF-α, urine eosinophilic protein X, and 8-OHdG levels decreased, whereas IFN-γ and TGF-ß increased in the probiotic groups, but these did not reach statistical significance except for IL-4 (P = 0.04). In subgroup analyses, SCORAD scores significantly decreased after probiotic treatment especially in children younger than age 12, with breastfeeding > 6 months, and with mite sensitization (P < 0.001). CONCLUSION: Supplementation of a probiotic mixture of LP and LF is associated with clinical improvement in children with AD.

Prenatal smoke exposure, DNA methylation, and childhood atopic dermatitis.

BACKGROUND: The biological mechanisms of how prenatal smoke exposure leading to atopic disorders remain to be addressed. Whether prenatal smoke exposure affects DNA methylation leading to atopic disorders is not clear. OBJECTIVE: As most children suffering from atopic dermatitis (AD) continue to develop asthma later in life, we explored whether prenatal smoke exposure induces cord blood DNA methylation. METHODS: Methylation differences associated with smoke exposure were screened by Illumina Infinium 27K methylation arrays for 14 children from the Taiwan birth panel study cohort initially. Information about development of atopic dermatitis (AD) and risk factors was collected. Cord blood cotinine levels were measured to represent prenatal smoke exposure. CpG loci that demonstrated a statistically significant difference in methylation were validated by methylation-dependent fragment separation (MDFS). Differential methylation in three genes (TSLP, GSTT1, and CYB5R3) was identified through the screen. RESULTS: Among these, only thymic stromal lymphopoietin (TSLP) gene displayed significant difference in promoter methylation percentage after being validated by MDFS (p = 0.018). TSLP gene was further investigated in a larger sample of 150 children from the cohort who completed the follow-up study. Methylation status of the TSLP 5'-CpG island (CGI) was found to be significantly associated with prenatal smoke exposure (OR = 3.17, 95% CI = 1.63-6.19) and with AD (OR = 2.32, 95% CI = 1.06-5.11). The degree of TSLP 5'CGI methylation inversely correlated with TSLP protein expression levels (r = -0.45, P = 0.001). CONCLUSIONS & CLINICAL RELEVANCE: The effect of prenatal tobacco smoke exposure on the risk for AD may be mediated through DNA methylation.

Maternal employment and atopic dermatitis in children: a prospective cohort study.

BACKGROUND: Considering the early onset of atopic dermatitis (AD), which most often arises in the first year of life, risk factors occurring very early in life must be considered. Little is known about the effects of maternal occupational exposure on the development of atopic disorders in children. OBJECTIVES: The aim of this study was to evaluate associations between maternal employment and childhood AD. METHODS: We used multistage stratified systematic sampling to recruit 24,200 mother-newborn pairs from the Taiwan national birth register. Information on maternal occupation categories, work stress, working time, shift work and potential confounders during pregnancy was gathered by questionnaires after birth. At 3 years of age, information on the development of AD was assessed by home interviews. Multiple logistic regression analysis was performed to estimate the association of maternal employment and AD. RESULTS: Overall, 11,962 out of 19,381 mothers (61·7%) worked during pregnancy. The children of mothers who worked during pregnancy had an increased risk of AD compared with those whose mothers did not work [odds ratio (OR) 1·38, 95% confidence interval (CI) 1·25-1·53]. The children of mothers with a professional or technical occupation had a higher risk of AD (OR 1·64, 95% CI 1·44-1·87). The risk of AD was found to increase with maternal work stress during pregnancy in a dose-response manner (P(trend)<0·01). The mothers of children with AD had a longer working time than those without AD (P<0·0001). However, no significant association between AD and maternal shift work was found. CONCLUSIONS: Working in professional or technical occupations increased the risk of childhood AD in addition to work stress during pregnancy.

Glutathione S-transferase, incense burning and asthma in children.

Incense burning is a popular practice in many family homes and temples. However, little is known about the effects of indoor incense burning and genetic polymorphisms on asthma. This study evaluated the effects of indoor incense burning and glutathione S-transferase (GST) genetic polymorphisms on asthma and wheeze. In 2007, 3,764 seventh-grade schoolchildren (mean±sd age 12.42±0.65 yrs) were evaluated using a standard questionnaire for information about respiratory symptoms and environmental exposures. Multiple logistic regressions were performed to assess the association between GST polymorphisms and incense burning frequency on asthma and wheeze, after adjusting for potential confounders. The frequency of incense burning at home was associated with increased risk of current asthma (p=0.05), medication use (p=0.03) and exercise wheeze (p=0.001). GST1 (GSTT1) null genotypes were associated with current asthma (OR 1.43, 95% CI 1.00-2.04) and medication use (OR 1.46, 95% CI 1.01-2.22). GSTT1 showed a significant interactive effect with incense burning on current asthma, current wheeze and nocturnal wheeze. The frequency of incense burning was associated with increased risk of current asthma, medication use, lifetime wheeze, nocturnal wheeze and exercise wheeze in an exposure-response manner among children with GSTT1 null genotype (p<0.05). Incense burning is a risk factor for asthma and wheezing, especially in GSTT1 genetically susceptible children.

Filaggrin polymorphism P478S, IgE level, and atopic phenotypes.

BACKGROUND: Whether environmental exposures may modulate the effect of the skin barrier gene on atopic dermatitis (AD) remains to be elucidated. OBJECTIVES: To determine whether filaggrin (FLG) variants can serve as a predictor for atopic disorders in Chinese individuals and if allergen exposures may modify the effect of FLG variants on AD by total IgE levels. METHODS: In total, 116 children aged 2-5years with AD and 212 control subjects were analysed for the FLG variants using DNA sequencing. Multiple logistic regression models were performed to estimate the association among FLG polymorphisms and atopic phenotypes. Serum total IgE level, standing for the degree of allergen exposures, was later stratified to determine the effects of FLG polymorphisms on AD. RESULTS: A significant difference in genotype frequency was found among AD cases and controls in FLG P478S polymorphism. FLG P478S GG genotype significantly increased the risk of AD [odds ratio (OR) 4·60, 95% confidence interval (CI) 1·88-11·24]. In addition, among subjects with AD, GG genotypes also significantly increased the risk of developing asthma (OR 4·68, 95% CI 1·37-16·03). Further, a similar result was obtained for allergic rhinitis (OR 3·23, 95% CI 1·01-10·30). Interestingly, the P478S GG genotype was significantly related to AD (OR 5·67, 95% CI 1·93-16·60) in children with IgE level ≥100 kU L(-1) . However, the association was not evident when IgE level was < 100 kU L(-1) . CONCLUSIONS: Our results suggest that the FLG P478S polymorphism may confer susceptibility to the development of AD among Chinese individuals and may be modified by IgE levels.

Neuro-mediators as predictors of paediatric atopic dermatitis.

BACKGROUND: Attempts to identify predictors of atopic dermatitis (AD) have focused on genetic and immunologic factors. However, the role of neuro-mediators remains to be elucidated. OBJECTIVE: To evaluate nerve growth factor (NGF) and vaso-active intestinal peptide (VIP) in predicting paediatric AD and assess their correlation with intrinsic and extrinsic types of AD. METHODS: We performed a nested case-control study in the prospective Taiwan birth panel cohort study. Cord and maternal plasma and questionnaires were gathered at birth. During follow-up, we identified 40 available AD cases, which were matched to 80 unaffected controls chosen from this cohort. The concentrations of IgE, NGF, and VIP in cord and maternal plasma of these subjects were performed by ELISA. Receiver-operating characteristic (ROC) curves were generated to see how well each biomarker could predict AD. RESULTS: The NGF levels were significantly higher in AD patients than controls (mean+/-SD: 65.47+/-44.45 vs. 49.21+/-12.18 pg/mL for cord plasma and 89.68+/-41.04 vs. 66.96+/-23.05 pg/mL for maternal plasma) (P<0.05). VIP levels were also higher but not statistically significant. Plasma NGF may be a better biomarker than IgE in detecting paediatric AD (area under the ROC curve=0.65 vs. 0.61 for cord plasma and 0.69 vs. 0.61 for maternal plasma). Maternal NGF levels were significantly higher in patients with both intrinsic (96.18+/-48.15 pg/mL) and extrinsic (86.18+/-37.23 pg/mL) types of AD compared with controls (66.96+/-23.05 pg/mL) (P<0.05). We assessed a significant correlation between self-reported stress during pregnancy and maternal NGF levels (r=0.22, P=0.02). CONCLUSION: Our results suggest that NGF is a good alternative biomarker in predicting children with a risk of AD.

Trends in blind and low vision registrations in Taipei City.

PURPOSE: To determine the overall reported incidence and causes of registrable blindness and low vision in Taipei, Taiwan, that have occurred in the previous 10 years. METHODS: Study data were obtained from disability identification registration forms completed between January 1995 and December 2004. Definitions of low vision and blindness were defined by WHO criteria: low vision included visual acuity worse than 6/18 (20/60) to a lower limit of 3/60 (20/400). Blindness was defined as visual acuity worse than 3/60 (20/400) in the better eye with best possible correction. RESULTS: There were 3151 registrations for visual impairment during the study period. A total of 239 registrations were excluded due to insufficient data. Of the remaining 2912 (1518 males and 1394 females), 640 males and 647 females were legally blind (44.20%). A total of 878 males and 747 females were partially sighted. The six leading causes of low vision and blindness, in decreasing frequency, were glaucoma, optic neuropathy, diabetic retinopathy, retinitis pigmentosa, age-related macular degeneration, and myopic macular degeneration. CONCLUSIONS: The proportions of new registrations owing to glaucoma, diabetic retinopathy, age-related macular degeneration, and myopic macular degeneration have changed significantly since 2000; the proportion due to diabetic retinopathy has increased.

A comparison of the effect of carbomer-, cellulose- and mineral oil-based artificial tear formulations.

PURPOSE: To compare the efficacy, safety, and local tolerance between carbomer-based artificial tears, cellulose-, and mineral oil-based artificial tears. METHODS: A randomized, open-label, parallel-group comparative 28-day study was designed for 67 patients who were randomized into three treatment groups. Measurements included the scoring of total subjective symptoms and objective signs, Schirmer-Jones test values, and tear break-up time (BUT) at baseline, and after 2 and 4 weeks of treatment. Safety of study treatment was also assessed. Outcomes measured at baseline and 2 and 4 weeks follow-up included the scoring of total subjective symptoms and objective signs, Schirmer-Jones test values, and tear BUT, subjective assessments, and safety. RESULTS: There were no differences regarding total scores, Schirmer-Jones test, or tear BUT at baseline among these three groups at 2 and 4 weeks. Patients in all three treatment groups experienced a significant improvement from baseline in total scores and Schirmer-Jones test values after treatment. Subjective assessment was better with carbomer-based treatment. CONCLUSIONS: Each artificial tear formulation successfully relieved symptoms and signs of keratoconjunctivitis sicca. The tolerance of carbomer-based artificial tears was comparable to that of cellulose- and mineral oil-based artificial tears.

Effect of tear film stability on fluctuation of vision after photorefractive keratectomy.

PURPOSE: To evaluate the difference in tear film break-up between normal eyes and eyes after photorefractive keratectomy (PRK) and its impact on quality of vision in PRK eyes. METHODS: Seventy-seven normal eyes and 76 eyes with no ocular pathology except refractive error that had PRK were enrolled. Tear film break-up time was determined under slit-lamp microscopy with fluorescent staining. Two videokeratographs (TMS-1) were taken before and immediately after tear film break-up. Surface asymmetry index, surface regularity index, and subtractive maps were analyzed to evaluate corneal topographic changes before and after tear film break-up. RESULTS: The distribution of tear film break-up in the central cornea was different in PRK eyes than in normal eyes (P < .0001). Distributions of tear film break-up after PRK were localized more in the upper and lower temporal regions than in normal eyes; incidence of tear film break-up in the central cornea was decreased. There were no significant differences in tear film break-up between normal eyes and eyes after PRK (P = .69). Twelve PRK patients (24 eyes, 32%) experienced fluctuation of vision and fatigue during normal activities after PRK. We divided eyes after PRK into two groups (with and without fluctuation of vision) and found a statistically significant difference in surface asymmetry index before tear film break-up between the two groups (P = .0092). CONCLUSION: The distribution of tear film break-up is changed after PRK. Eyes after PRK experienced more fluctuation of vision than normal eyes.

Immunohistochemical study of subepithelial haze after phototherapeutic keratectomy.

PURPOSE: Subepithelial haze is a frequent complication and is often the cause of regression after photorefractive keratectomy (PRK). The lack of understanding of this undesirable complication following PRK is in part due to the limited availability of suitable tissues for pathological studies. METHODS: We examined the expression of various extracellular components in the cornea of a 46-year-old man who underwent phototherapeutic keratectomy (PTK) to remove a central corneal scar secondary to trauma. The patient subsequently underwent penetrating keratoplasty. A scar-free region containing an area of slight subepithelial haze adjacent to normal cornea was used for immunohistochemical staining with antibodies directed against cytoskeletal proteins, ie, vimentin, desmin and smooth muscle actin, and the extracellular components, laminin, heparan sulfate, keratan sulfate, and collagen types III, IV, V, and VII. RESULTS: Immunohistochemistry revealed that basal epithelial cells expressed components of basement membrane. The stromal fibroblasts within the haze tissue were labeled by anti-smooth muscle actin antibodies, a characteristic of myofibroblasts, which synthesized and secreted extracellular matrix components that contributed to the formation of the disorganized collagenous matrix and may account for subepithelial haze. CONCLUSIONS: The expression patterns for the cytoskeletal proteins and extracellular components indicated that the formation of subepithelial haze is a process of tissue remodeling, involving both corneal basal epithelial cells and keratocytes during wound repair.

Surgical results of photorefractive keratectomy with different operative modes.

PURPOSE: To compare the predictability, efficacy, and safety of photorefractive keratectomy (PRK) using different operative modes. SETTING: National Taiwan University Hospital, Taipei, Taiwan. METHODS: One hundred fifty-three eyes of 80 patients who had PRK for myopia with a follow-up of at least 6 months were studied. All patients were sequentially assigned to 1 of the following surgical modes: mode 1: PRK with the Summit OmniMed excimer laser; mode 2: PRK with the Summit Apex Plus laser; mode 3: PRK with the Summit Apex Plus laser with anti-central-island pretreatment. RESULTS: Six months after treatment, a homogeneous topographic pattern was seen in 76% of mode 1 eyes, 70% of mode 2 eyes, and 88% of mode 3 eyes. In the low myopia group (< or =-6.0 diopters [D]), the mean residual refractive error was -0.79 D +/- 0.59 (SD) in mode 1, -0.94 +/- 1.02 D in mode 2, and -0.31 +/- 0.42 D in mode 3. In the high myopia group (>-6.0 D), it was -1.93 +/- 1.51 D, -1.54 +/- 0.88 D, and -0.70 +/- 0.81 D, respectively. Uncorrected visual acuity of 20/25 or better was achieved in 81% of mode 1 eyes, 56% of mode 2 eyes, and 89% of mode 3 eyes in the low myopia group, and in 48%, 28%, and 72%, respectively, in the high myopia group. CONCLUSIONS: Photorefractive keratectomy appears to be a predictable and effective procedure. The best results were achieved with the Summit Apex Plus laser with anti-central-island pretreatment, followed by the Summit OmniMed laser. The Summit Apex Plus laser without anti-central-island pretreatment produced less satisfactory results.

Changing indications for penetrating keratoplasty in Taiwan from 1987 to 1999.

PURPOSE: To determine the leading indications for penetrating keratoplasty and to identify changing trends in these indications during the past 12 years. METHODS: We retrospectively performed a chart review of the hospital records of all patients undergoing penetrating keratoplasty at the National Taiwan University Hospital during a 12-year period (1987-1999). When possible, the clinical indication was corroborated by the pathologic report. RESULTS: A total of 770 corneal transplants were performed. The leading indications for penetrating keratoplasty. in order of decreasing frequency, were corneal scars (27.9%), regraft (21.0%), acute necrotizing and ulcerative keratitis (17.9%), pseudophakic or aphakic bullous keratopathy (17.6%), Fuchs' dystrophy (4.5%), and keratoconus (2.5%). A trend of increasing frequency of regraft and acute necrotizing and ulcerative keratitis, a decreasing frequency of corneal scar, and an initially decreasing then increasing frequency of pseudophakic and aphakic bullous keratopathy were found during the 12-year study period. Acute necrotizing and ulcerative keratitis was found to be the most frequent indication for regraft. CONCLUSION: In this series, corneal scars, regraft, and acute necrotizing and ulcerative keratitis were the leading indications for penetrating keratoplasty. A changing incidence of pseudophakic and aphakic bullous keratopathy noted during the study period was related to the type of intraocular lens implanted and the method of cataract surgery performed. This study found a comparatively high frequency of acute necrotizing and ulcerative keratitis and an extremely low frequency of keratoconus compared with previous reports.

Outcomes of penetrating keratoplasty with imported donor corneas.

PURPOSE: To analyze factors influencing the surgical success of penetrating keratoplasty and long-term graft survival when using imported donor corneas. METHODS: Sixty-three donor corneas imported to Taipei from the Cincinnati Eye Bank from July 1992-June 1993 were used for penetrating keratoplasty. The corneal endothelium was examined using specular microscopy on arrival in Taiwan. The endothelial morphology and endothelial cell density (ECD) were compared with the photograph of the same cornea taken in the United States. The relationships of the surgical success rate with donor age, death to enucleation time, death to surgery time, and ECD were analyzed. The long-term graft survival and ECD of clear grafts were analyzed 4 years after surgery. RESULTS: On specular microscopic examination. the imported corneas showed diminished endothelial reflection, blurred cellular borders, and increased dark areas, which were markedly different from the pictures of the corneal endothelium taken in the United States. The average ECD before transportation was 2,525+/-267/mm2 and decreased to 1,934+/-250/mm2 after transportation (p < 0.001), with an average endothelial cell loss of 590+/-247/mm2. The overall surgical success rate was 89% and did not correlate with any of the donor factors tested except death to surgery time. The surgical success rate decreased when the time from death to surgery was >7 days (p = 0.05), mainly because of poor reepithelialization. Four years after surgery, 24 grafts remained clear. The ECD had decreased by 72+/-5% in the clear grafts. CONCLUSIONS: Our findings show that endothelial changes in imported donor corneas do occur after transportation, but the surgical success rate may not be influenced significantly if the penetrating keratoplasty is performed within 7 days after donor death. However, the ECD in the clear grafts 4 years after surgery is low.

Effect of shaking of corneal endothelial preservation.

PURPOSE: To investigate the effect of shaking on corneal endothelial preservation. METHODS: Thirty-six dog corneal buttons were obtained under standard eye bank procedure, after the animals had been sacrificed for cardiovascular experiments in the surgical department. They were equally divided into two groups. In Group I, buttons were put in Dexsol preservative medium and preserved at 4 degrees C. In Group II, buttons were put in Dexsol preservative medium and shaken in a shaking incubator at a speed of 5 rpm. at 4 degrees C for 10 h. After shaking, they were returned to a 4 degrees C refrigerator until examination. Three buttons from each group underwent specular microscopy, scanning electron microscopy (SEM), and alizarin red with trypan blue stain examinations on days 0, 1, 3, 5, 7 and 9, respectively. RESULTS: In Group I, intercellular borders became blurred under specular microscopy, beginning on day 5. However, endothelial cell count did not change significantly until day 9. Intercellular digitations and wrinkling of intercellular borders were seen under alizarin red with trypan blue stain and SEM examination, beginning on day 3. Pleomorphism and ill-defined intercellular junctions were seen under SEM on day 7. There was no obvious denudement of the endothelial sheet, but a few scattered exfoliations were seen in Group I. In Group II, endothelial cell count did not decrease on day 1, but an endothelial image could not be obtained by specular microscopy 3 days after treatment. Alizarin red with trypan blue stain and SEM examination revealed that the endothelial cells were denuded from the Descemet's membrane three days after shaking. Severe stromal edema was seen under SEM five days after shaking. CONCLUSIONS: The results showed that shaking had a detrimental effect on endothelial cell preservation. Vigorous shaking should be avoided during transportation of corneal buttons. It is advisable to perform penetrating keratoplasty as soon as possible upon receiving transported donor corneas.

Comparison of topical antibiotics for treating Mycobacterium chelonae keratitis in a rabbit model.

PURPOSE: To investigate the effect of topical amikacin (25 mg/ml), imipenem (25 mg/ml), ciprofloxacin (3 mg/ml), clarithromycin (20 mg/ml), amikacin combined with ciprofloxacin, amikacin combined with imipenem, and amikacin combined with clarithromycin on Mycobacterium chelonae keratitis. METHODS: Ninety New Zealand albino rabbits were infected with a strain of M. chelonae for which minimum inhibitory concentration indicated in vitro sensitivity to the above antibiotics. The rabbits were treated for one or two weeks. The treatment efficacy was judged by the size of stromal infiltrate and quantitative culture of the infected corneas. RESULTS: The size of the stromal infiltrate showed no significant difference in treated eyes compared to the untreated, control eyes. However, all treatments significantly reduced the number of organisms in treated eyes compared to untreated, control eyes (all p-values < 0.05). No significant difference in treatment efficacy was found between individual treatment groups. In none of the cases were organisms eliminated from the infected eyes, even after 2 weeks of treatment. CONCLUSIONS: The results suggest that topical amikacin, imipenem, ciprofloxacin and clarithromycin had some therapeutic effect on M. chelonae keratitis; however, amikacin combined with imipenem, ciprofloxacin, and clarithromycin showed no increased efficacy over single agent therapy during 2 weeks of treatment. Long term treatment may be required to eradicate M. chelonae.

Impression cytology of pterygium.

The purpose of this study was to study the morphology and cytokeratin expression in the epithelia of pterygia. Impression cytology and immunohistochemical staining with antikeratin antibodies were performed in 32 eyes of 16 patients with pterygia. TUNEL stain and electron microscopy were also performed in surgical specimens ofpterygium. Squamous metaplasia-like epithelial cells were found in all specimens of impression cytology, especially in the head part. These specimens had positive immunostaining by antipancytokeratin antibodies, but not by anti-K12 AK2 mAb. Goblet cells were found around the area of these abnormal epithelial cells. TUNEL-positive cells were found in the epithelia of the pterygial head, but not in the body of pterygia and normal conjunctiva. The expressional patterns of keratin by these epithelial cells ofpterygia are consistent with the notion that they are derived from conjunctival epithelium and mimic the process of squamous metaplasia.

The regulation of the scleral growth associated with deprivation myopia in chicks.

The mechanism of axial elongation caused by experimental or clinical myopia is still unknown. We sought to explore the changes of scleral chondrocytes during myopia formation through the cell biology model. White Leghorn chicks were used for this study. The right eye was covered with a translucent goggle after hatching, and the left eye was left uncovered for control. The chicks were maintained on 12 hours light-dark cycle for two weeks, then sacrificed every other day and the eyeballs removed for study. Our results in the primary culture of scleral chondrocytes showed that the densities of chondrocytes on myopic eyes were significantly higher than those of the controlled non-myopic eyes, and 3H-thymidine incorporation rate also increased with the increasing of the concentration of fetal bovine serum. The PCNA index of chondrocytes in myopic eyes was also higher than that of the controlled non-myopic eyes. Thus, axial elongation of experimental myopia in the chick is the result of active tissue remodeling rather than passive scleral stretching alone.

Influence of destruction of retina-RPE complex on the proliferation of scleral chondrocytes in chicks.

We studied the role of the retina-retinal pigment epithelium (RPE) complex in the proliferation of scleral chondrocytes in chicks. Seventy-two chicks were allocated to one of four groups: intravitreal gentamicin (400 microg) injection (destruction of retina-RPE complex); intravitreal gentamicin injection with goggling; goggling only (form-deprivation myopia); and intravitreal saline injection (control). The chicks were killed and retina-RPE complexes were harvested under a microscope. Retina-RPE complexes were then co-cultured with primary culture of first day scleral chondrocytes in Transwell-COL co-culture systems (Costar), with two different pore sizes (0.4 and 3.0 microm) and serum-deprivation medium. An MTT assay was performed at A550 after 4 days. In the 0.4 microm pore size system, the absorbency at A550 showed no differences between groups. However, in the 3.0 microm pore size system, the absorbency at A550s in the intravitreal gentamicin groups was significantly lower than in the control and the goggle groups (p<0.05), indicating that destruction of the retina-RPE complex inhibited chondrocyte proliferation. The absorbency in the goggle group was higher than in the control group (p<0.05). These results indicate that the retina-RPE complex exerts a positive effect on the proliferation of scleral chondrocytes via a molecule sized between 0.4.and 3.0 microm in diameter.