Biomedical subjects

Shu-Wen Chang

Publications and source records attributed to Shu-Wen Chang.

13 recordsLinked to original sources

PubMed2006

Change of potassium current density in rabbit corneal epithelial cells during maturation and cellular senescence.

BACKGROUND: Voltage-gated potassium (K+) channels may participate in cellular developmental regulation, including cell differentiation, proliferation and apoptosis. This study investigated the change of K + current densities in corneal epithelial cells during maturation and cellular senescence. METHODS: New Zealand white rabbits were divided into three age groups: newborn ( 10.0 pF. Using a whole-cell clamp technique, K+ current was recorded and current densities were calculated. Differences in K+ current densities among newborn, young and adult rabbits, as well as differences among small, medium and large cells, were analyzed. RESULTS: We delineated two types of cells manifesting different amplitudes of depolarization-activated K+ outward currents. The averaged current density of type 1 response cells was significantly larger than that of type 2 cells in newborn, young, and adult groups. For newborn epithelial cells, the depolarization-gated outward K+ current density decreased from small to medium to large cells (p = 0.049, at a membrane potential of 140 mV). A similar pattern of change in current density was also delineated for these cell sizes in young and adult rabbit corneal cells (p < 0.001 for both young and adult rabbits). An increase in depolarization-gated outward K+ current density was also delineated from newborn to young to adult rabbits (p < 0.001, p < 0.001 and p < 0.006 for small, medium and large cells, respectively, at a membrane potential of 140 mV). CONCLUSIONS: Corneal epithelial cells expressed K+ channel densities that were distinct from basal to superficial cells and from newborn to adult rabbits.

Animals↗

PubMed2006

The effects of epithelial viability on stromal keratocyte apoptosis in porcine corneas stored in Optisol-GS.

PURPOSE: To investigate the effect of corneal epithelium on the viability of corneal stromal keratocytes in Optisol-GS. METHODS: After sterilization, corneoscleral buttons were excised and stored in Optisol-GS for various time periods. Group 1 corneas (n = 40) underwent mechanical corneal epithelial debridement before storage while group 2 corneas (n = 40) were stored with intact epithelium. Changes in corneal thickness, keratocyte density, and keratocyte apoptosis were investigated immediately, at 4 hours, and on days 1, 2, 3, 5, 7, and 14 in the preservation medium. The differences between group 1 and 2 corneas were analyzed. RESULTS: Corneal thickness increased significantly in the second week of preservation in both groups, though more substantially in group 1. Significant corneal epithelial apoptosis was noticed in the first week in group 2 corneas. Corneal stromal keratocyte density decreased with prolonged preservation time. DNA laddering was detected by ligation-mediated polymerase chain reaction throughout the experiment periods in both groups, but the increase of keratocyte apoptosis was more significant after 5 days of preservation, especially in group 1. CONCLUSIONS: Stromal keratocytes underwent apoptosis in Optisol-GS. The absence of corneal epithelium during preservation further increased the stromal keratocyte apoptosis.

Animals↗

PubMed2006

Oral cimetidine adjuvant therapy for recalcitrant, diffuse conjunctival papillomatosis.

PURPOSE: To describe a case of recurrent, advanced conjunctival papillomatosis, treated by oral cimetidine (CIM) combined with secondary surgical intervention and an application of intraoperative mitomycin C. METHODS: Case report and literature review. RESULTS: A 9-year-old boy suffered from recurrent, progressive, diffuse multifocal conjunctival papillomatosis over the left upper and lower palpebral and the fornical conjunctiva. He underwent 3 separate surgeries; however, they did not prevent tumor recurrence. The recurrent lesions were more severe and extensive than before the surgeries. To avoid postoperative symblepharon, ankyloblepharon, dry eye, and possible corneal neovascularization after extensive lesion excision, oral CIM at a dosage of 200 mg 4 times daily was administered for 4 months before surgery. A debulking excision of the residual tumor with an intraoperative application of mitomycin C was performed as a secondary therapy after the main mass decreased in size. Postoperative oral CIM was continued for 6 months. The papillomatosis cleared without recurrence or symblepharon, ankyloblepharon, conjunctival scarring, or corneal neovascularization after 4 years of follow-up examinations. CONCLUSION: Oral CIM can be used as an initial, nonsurgical strategy for treating cases of massive, recalcitrant conjunctival papillomatosis. If there is tumor shrinkage, surgical debulking with applications of mitomycin C may be sufficient to eliminate any residual tumor tissue without inducing conjunctival scarring or corneal neovascularization.

Administration, Oral↗

PubMed2006

Ethanol treatment induces significant cell death in porcine corneal fibroblasts.

PURPOSE: To explore the effect of ethanol treatment on corneal stromal cells. METHODS: Primary porcine corneal fibroblasts from passages 3 to 5 were treated with ethanol at concentrations of 10%, 15%, 20%, and 50% for 30 seconds. A control group was treated with phosphate-buffered saline (PBS) for 30 seconds. Morphologic changes were documented with phase-contrast microscopy, and the growth curves were examined with a PicoGreen assay. Cellular viability was examined with an ethidium homodimer and calcein-AM stain, whereas cellular apoptosis and/or necrosis were analyzed by a YO-PRO-1 dye/propidium iodide apoptosis assay coupled with flow cytometry and further confirmed with a genomic DNA pattern assay. Cellular toxicity was examined with a lactate dehydrogenase (LDH) assay. RESULTS: Significant cell rounding and detachment from the culture dish were noticed after 20% ethanol treatment of 30 seconds, despite that the cell morphology remained unchanged in the PBS and 10% and 15% ethanol groups. Twenty percent ethanol induced significant cellular toxicity, causing cell death as shown by ethidium homodimer and calcein-AM stain, YO-PRO-1 dye/propidium iodide apoptosis assay, and LDH assay, although 10% and 15% ethanol caused minimal changes to corneal fibroblasts. Cellular death was most significant 6 hours after the 20% ethanol treatment. The genomic DNA pattern revealed intact DNA in the control, 10% ethanol, and 15% ethanol groups at all times, whereas DNA smearing was noticed at 48 hours after the 20% ethanol treatment. However, none of the DNA examined revealed significant DNA laddering patterns of apoptosis. Fifty percent ethanol treatment of 30 seconds resulted in cell fixation and cell death. CONCLUSION: Treatment with 20% ethanol for 30 seconds induced significant porcine corneal fibroblast cell death, whereas 10% and 15% ethanol treatment of 30 seconds caused minimal changes. We propose that, when applied for 30 seconds, 20% ethanol is the threshold level that causes cell death in cultured porcine corneal fibroblasts.

Animals↗

PubMed2005

Circumscribed choroidal hemangioma in a Chinese patient treated using transpupillary thermotherapy: a case report.

We describe the first case of a Chinese patient with circumscribed choroidal hemangioma (CCH) effectively managed using transpupillary thermotherapy (TTT). A 57-year-old man had an elevated orange-red subretinal mass with a base of 5 x 5 mm superior to the optic disc, along with serous macular detachment in the left eye. Ultrasonography depicted a mass 3 mm thick with acoustic solidity and high internal reflectivity. Fluorescein angiography showed an area of hyperfluorescence in the prearterial phase and tumor staining in the late phase, consistent with a diagnosis of CCH. Therefore, TTT (spot size, 3 mm; exposure, 1 min) was performed with a diode laser, delivered through a slit-lamp biomicroscope. The laser power was first set at 300 mW and then increased in 50-mW increments, until test shots in the mid-peripheral retina outside the lesion produced a slightly grayish appearance in the irradiated area. The tumor was covered with four overlapping laser spots and subjected to an average beam power of 400 mW. Best-corrected visual acuity increased from 20/50 before treatment, to 20/20 3 months following one session of TTT. The lesion became atrophic and the subretinal fluid disappeared. Our experience shows that TTT can be an even more effective treatment strategy for CCH in Asians than in Caucasians. In Chinese patients, the power level of the diode laser should be lower than that used in Caucasians.

Choroid Neoplasms↗

PubMed2005

Recurrent Alcaligenes xylosoxidans keratitis.

PURPOSE: To describe a case of postkeratoplasty recurrent Alcaligenes xylosoxidans keratitis. METHODS: A 33-year-old man with a history of penetrating keratoplasty developed corneal infiltrate with intact epithelium and then was treated with broad-spectrum antibiotics. Corneal scraping was taken for microbiologic study. RESULTS: The culture result identified A. xylosoxidans, sensitive to piperacillin and ceftazidime. There were 3 recurrent episodes within 2 months after each apparent resolution achieved after the instillation of topical piperacillin (10 mg/mL). During the fourth attack, the lesion responded poorly to piperacillin and ceftazidime (25 mg/mL), so therapeutic penetrating keratoplasty was performed to eradicate the recalcitrant infection. CONCLUSIONS: A. xylosoxidans has probably been underreported as a cause of ocular infection. It does not respond to conventional antibiotic therapy and may be difficult to eradicate. Therapeutic penetrating keratoplasty might be necessary if medical treatment fails.

Abscess↗

PubMed2004

From D-glucose to biologically potent L-hexose derivatives: synthesis of alpha-L-iduronidase fluorogenic detector and the disaccharide moieties of bleomycin A2 and heparan sulfate.

A novel and convenient route for the synthesis of biologically potent and rare L-hexose derivatives from D-glucose is described. Conversion of diacetone-alpha-D-glucose (14) into 1,2:3,5-di-O-isopropylidene-beta-L-idofuranose (19) was efficiently carried out in two steps. Orthogonal isopropylidene rearrangement of compound 19 led to 1,2:5,6-di-O-isopropylidene-beta-L-idofuranose (27), which underwent regioselective epimerization at the C3 position to give the L-talo- and 3-functionalized L-idofuranosyl derivatives. Hydrolysis of compound 19 under acidic conditions furnished 1,6-anhydro-beta-L-idopyranose (35) in excellent yield, which was successfully transformed into the corresponding L-allo, L-altro, L-gulo, and L-ido derivatives via regioselective benzylation, benzoylation, triflation and nucleophilic substitution as the key steps. Applications of these 1,6-anhydro-beta-L-hexopyranoses as valuable building blocks to the syntheses of 4-methylcoumarin-7-yl-alpha-L-iduronic acid and the disaccharide moieties of bleomycin A(2) as well as heparan sulfate are highlighted.

Bleomycin↗

PubMed2004

Early corneal edema following topical application of mitomycin-C.

PURPOSE: To determine the effect of mitomycin-C (MMC) on the cornea after a single intraoperative application. SETTING: Department of Ophthalmology, Far Eastern Memorial Hospital, Ban-Chiao, Taipei, Taiwan. METHODS: Mechanical epithelium debridement of the central 10.0 mm of the cornea was performed in 63 pigmented rabbits. One group of corneas (MMC1, n = 42) was soaked with MMC 0.01% solution for 2 minutes; the second group (MMC2, n = 42) was soaked with MMC 0.02% solution for 2 minutes. Control corneas (n = 42) were soaked with balanced salt solution for 2 minutes. Changes in the central corneal thickness, clarity, epithelial defect size, endothelial cell density, and endothelial apoptosis in the 3 groups were examined on days 0, 1, 2, 3, 5, 7, and 14. RESULTS: There was a dose-dependent increase in corneal thickness, decrease in corneal clarity, and increase in endothelial apoptosis after a single intraoperative application of MMC. The endothelium was significantly swollen and became pleomorphic and polymegethic with a concomitant decrease in endothelial cell density, also in a dose-dependent manner. CONCLUSIONS: A single application of MMC on the corneal surface caused dose-dependent corneal edema and endothelial apoptosis in the rabbit model. Further clinical study of human eyes is warranted.

Administration, Topical↗

PubMed2004

Adjunctive treatment with interferon alpha-2b may decrease the risk of papilloma-associated conjunctival intraepithelial neoplasm recurrence.

PURPOSE: To report a case of bilateral papilloma virus-positive conjunctival intraepithelial neoplasm and the treatment results of using adjunctive interferon alpha-2b. METHODS: Case report and literature review. RESULTS: A 73-year-old man underwent subtotal excisional biopsy of the 270-degree gelatinous limbal lesion of the right eye to avoid creating a limbal deficiency and cicatricial change. Total excisional biopsy of the temporal elevated leukoplakic limbal lesion was performed on his left eye. Histology examination showed bilateral intraepithelial neoplasia, and human papilloma virus-16 and -18 were detected by polymerase chain reaction in both lesions. Two supplemental perilesional injections of interferon alpha-2b in the right eye were given, and the residual mass decreased in size gradually and completed clinical resolution 7 weeks following initial surgery. Although no recurrence was noticed in the right eye, recurrence of the conjunctival intraepithelial neoplasm lesion was noticed in the left eye. CONCLUSION: Adjunctive therapy might lower CIN recurrence rate, especially in extensive lesions, when surgical excision cannot ensure a tumor-free margin. Our bilateral case provided a good control example for the recurrence with or without adjunctive therapy.

Aged↗

PubMedDate not supplied

Health-related behavior and adolescent mothers.

OBJECTIVE: To explore health-related behaviors among adolescent mothers living in the rural area of Taoyuan, Taiwan. DESIGN: A cross-sectional descriptive design and nonrandom survey method were used. SAMPLE: The sample consisted of 37 adolescent mothers, identified by public health nurses. MEASUREMENTS: Standardized interview and Adolescent Health Promotion (AHP) questionnaire. RESULTS: Findings revealed a pattern of economic disadvantage. Nearly half of the participants still lived with their biological parents. Two-thirds needed economic support from their parents (generally coming from their biological mother). Thirty-five percent of participants reported never using contraceptives, two-thirds had never had a Pap smear, and 44% did not breast-feed their infants. Nearly 60% of the children were cared for by the biological mothers of the participants. Adolescent mothers with high school education, and who were employed, married, and received parental economic support had better health-related behaviors than adolescent mothers without these characteristics. CONCLUSIONS: Although the study sample has geographic limitations, future international studies with similar populations of adolescent mothers in rural settings will help public health nurses understand adolescent mothers' stressors and needs which in turn affect their health-related behaviors. Intervention strategies are needed to encourage behaviors to keep this population healthy.

Adolescent↗

PubMedDate not supplied

Corneal keratocyte apoptosis following topical intraoperative mitomycin C in rabbits.

PURPOSE: To determine the soaking duration and concentration effect of mitomycin C (MMC) on the corneal keratocyte following single intraoperative application. METHODS: Two hundred ten pigmented rabbit eyes underwent mechanical epithelium debridement of the central 10-mm comea followed by soaking of six different solutions: MMC1A: 0.01% MMC x 1 minute; MMC1B: 0.01% MMC x 2 minutes; MMC2A: 0.02% MMC x 1 minute; MMC2B: 0.02% MMC x 2 minutes; BSS1: balanced salt solution (BSS) x 1 minute; and BSS2: BSS x 2 minutes. Thirty-five eyes were allocated into each group. Changes of the central comeal thickness, corneal clarity score, and keratocyte apoptosis were examined on days 0, 1, 2, 3, 5, 7, and 14. RESULTS: A significant increase of central corneal thickness and corneal clarity score was noted in all MMC treated groups. The central corneal thickness recovered to its baseline level whereas the corneal clarity score remained increased at 2 weeks. The changes were more significant in MMC2 than in MMC1 corneas. However, changes of central corneal thickness and corneal clarity score were more significant in MMC1B than in MMC1A, whereas no difference was noted between MMC2A and MMC2B. Significantly higher stromal keratocyte loss and keratocyte apoptosis, from superficial to deep corneal stroma, was noted in MMC1 and MMC2 groups up to 14 days postoperatively, in a soaking duration and dose-dependent manner. CONCLUSIONS: Single application of MMC on the corneal surface caused soaking concentration and duration dependent corneal edema and keratocyte apoptosis in this rabbit model.

Administration, Topical↗

PubMedDate not supplied

Bilateral retinal hemorrhages following automated lamellar keratoplasty.

We describe a case of bilateral multifocal retinal hemorrhages after receiving automated lamellar keratoplasty (ALK) surgery in a 32-year-old male with extremly myopic eyes. Before surgery, there was no retinal hemorrhage in routine fundus examination. This patient visited our clinic and complained of decreased vision in both eyes 2 weeks after the ALK surgery. Upon examination, his best-corrected visual acuity (BCVA) was 0.6 with -8.5-1.5 x 100(0) in the right eye and 0.9 with -4.0-2.50 x 90(0) in the left eye. Fundus examination revealed scattered multiple round focal retinal hemorrhages in both eyes. No evidence of choroidal neovascularization was noted. The retinal hemorrhages resolved 10 weeks later. The BCVA recovered to 1.0 in the right eye and 0.9 in the left eye. This case highlights the relationship between the postoperative bilateral posterior pole hemorrhages and the automated lamellar keratoplasty surgery, in which a microkeratome was used to create a corneal flap and keratectomy. Patients should be informed of this rare complication before surgery.

Adult↗

PubMedDate not supplied

Amniotic membrane transplantation for corneal perforation related to vitamin A deficiency.

Corneal perforation is one of the most vision-threatening consequences of vitamin A deficiency. Amniotic membrane transplantation was performed in a 36-year-old man who presented with bilateral corneal ulcers. There was a small, sharply demarcated superficial ulcer with crevices of surrounding keratinized epithelium converging on the ulcer and minimal infiltration at the inferior periphery of the right cornea. A 3-mm perforation on a 9 x 7-mm area of stromal melting was noticed in the left cornea. The serum vitamin A level was 14.0 microg/dL (normal, 24.57 to 105.71 microg/dL) at presentation. A biopsy of the right corneal epithelium was performed to confirm the diagnosis. Multilayered amniotic membrane transplantation with debridement of the necrotic corneal stroma was performed on the left cornea. In addition to systemic vitamin A replacement, topical antibiotics and lubricants were also administered. The cornea ulcers healed in 10 days along with the restoration of the serum vitamin A level. The visual acuity improved from 20/250 to 20/20 in the right eye and from light perception to hand movement in the left eye at 3 months. Amniotic membrane transplantation could save eyes with corneal perforation related to vitamin A deficiency before reconstructive surgeries, such as penetrating keratoplasty, are necessary.

Adult↗