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Dispersion impairments are a well-known limitation in data center communications, limiting both the usable data rates and reaches. Several companies today adopt silicon photonics as a core technology in their transceiver products. This presents an opportunity for silicon photonics-based dispersion management technologies to be integrated with the transceiver transmitter or receiver. In this manuscript, we present a ring-resonator based, tunable dispersion compensation device, providing dispersion ranging as wide from + 12.9 × 103ps/nm to -12.3 × 103ps/nm. Thermo-optic tuning from 20°C to 70°C is demonstrated to allow continuous wavelength tuning across 200â GHz. High-speed experiments using 25 Gb/s non-return-to-zero data propagating through 20â km of single mode fiber show that a significant improvement in the eye diagram is achieved after compensation with the ring-resonator device. We demonstrate a significant improvement in the BER from 10-3 to 10-11 for data rates of 25 and 25.78125 Gb/s.
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We report on the design and experimental demonstration of a broadband silicon polarization beam splitter (PBS) with a high extinction ratio (ER)≥30 dB. This was achieved using triple-bent-waveguide directional coupling in a single PBS, and cascaded PBS topology. For the single PBS, the bandwidths for an ER≥30 dB are 20 nm for the quasi-TE mode, and 70 nm for the quasi-TM mode when a broadband light source (1520-1610 nm) was employed. The insertion loss (IL) varies from 0.2 to 1 dB for the quasi-TE mode and 0.2-2 dB for the quasi-TM mode. The cascaded PBS improved the bandwidth of the quasi-TE mode for an ER≥30 dB to 90 nm, with a low IL of 0.2-2 dB. To the best of our knowledge, our PBS system is one of the best broadband PBSs with an ER as high as â¼42 dB and a low IL below 1 dB around the central wavelength, and experimentally demonstrated using edge-coupling.
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Multiplexing of optical modes in waveguides is demonstrated using coupled vertical gratings. The device utilizes sinusoidally corrugated waveguides of different widths with a period designed to multiplex information at 1.55 µm. The design, fabrication and characterization of devices is performed. Multiplexing of modes is demonstrated in optical structures which support 3 and 5 quasi-TE modes. The design utilizes counter-propagating modes in periodic structures, thus enabling the device to combine its mode division multiplexing capabilities with wavelength division multiplexing functionalities to further augment the multiplexing capacity of the device.
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A 1 by 4 wavelength division multiplexer with 0.5nm bandwidth and no free spectral range limitation is demonstrated on silicon. The device utilizes wide bandwidth filters cascaded with ring resonators in order to select specific ring resonator modes and route each resonant mode to a separate port. This technology will enable dense wavelength division multiplexing covering the C - and L - bands with up to 100 10GB/s channels separated by 100GHz to be implemented for optical interconnects applications. A 1 by 4 wavelength division multiplexer with 3dB channel bandwidths as small as 0.5nm and 1dB insertion loss are demonstrated with 16dB inter-channel crosstalk suppression. A second wavelength division multiplexer scheme with four channels, each spaced 0.5nm apart without any free spectral range limitations is also demonstrated using wide bandwidth filters centered at the same wavelength to select resonances from four different ring resonators with slightly different widths.
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The simultaneous generation of second and third order dispersion is demonstrated using nonlinearly chirped silicon waveguide gratings. The nonlinearly chirped gratings are designed to generate varying signs and magnitudes of group velocity dispersion and dispersion slope. The design, fabrication, and experimental characterization of the silicon waveguide gratings are performed. Second order dispersion as high as -2.3 X 106 ps/nm²/km and third order dispersion as high as 1.2 X 105 ps/nm²/km and as low as 1.2 X 104 ps/nm²/km is demonstrated at 1.55 µm.
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This paper reviews recent work in the area of silicon photonic devices and circuits for monolithic and heterogeneous integration of circuits and systems on a chip. In this context, it presents fabrication results for producing low-loss silicon waveguides without etching. Resonators and add-drop distributed filters utilizing sidewall modulation fabricated in a single lithography and etching step are demonstrated. It also presents an optical pulse compressor that monolithically integrates self-phase modulation and anomalous dispersion compensation devices on a silicon chip. As an example of heterogeneous integration, we demonstrate vertical emitting metallo-dielectric nanolasers integrated onto a silicon platform. Future research directions toward large-scale photonic circuits and systems on a chip also are discussed.
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PURPOSE: The availability of knockout mouse species provide a highly versatile platform for critically examining the corneal wound healing response. We aimed to develop and characterize the wound healing response in a mouse model of intrastromal femtosecond laser (FSL) keratotomy. METHODS: An intrastromal lamellar dissection using a Visumax FSL was performed on 16 wild type mice (C57BL6) . The energy level was optimized at 150nJ. The FSL was programmed to perform a lamellar dissection at 50 µM depth without sidecut. The flap was not lifted. Fellow eyes were used as controls. Slit lamp photography and confocal microscopy were performed immediately before the mice were sacrificed 4 h, 1, 3, and 7 days post surgery. Corneas were harvested for immunocytochemistry, transmission electron microscopy (TEM) and light microscopy (LM). RESULTS: Confocal microscopy showed an absence of keratocytes in the area immediately surrounding the dissection plane. The dissection plane and individual FSL plasma cavitation bubbles were clearly evident on TEM. There was evidence of Keratocyte cell death along the laser resection plane on TEM. LM revealed the dissection plane at a 20 µM depth, although not all epithelial cell layers were intact. Staining for monocytes using antibodies for CD11b (cluster of differentiation 11b) showed early migration at the peripheries at 4 h that increased at 24 h and became more central in treated corneas (p<0.001). Apoptotic cells were evident on TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay in the immediate ablation zone and were significantly raised at 4 and 24 h (p<0.001). Ki67 (Kiel 67 protein) positive proliferating keratocytes are evident at 3 days and increased significantly by 7 days (p<0.001). Minimal fibroblast (cluster of differentiation 90, CD90) transformation was seen at 1 week. No myofibroblasts were detected. DISCUSSION: We have demonstrated that FSL lamellar cuts can be effectively performed on mice and that this model exhibits typical signs of the corneal wound healing response. This model could provide a ubiquitous platform in which to study corneal wound healing responses in both wild type and knockout mice species. The ability to create such a lamellar pocket may be utilizzd for intrastromal drug delivery.
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Sustancia Propia/cirugía , Sustancia Propia/ultraestructura , Cirugía Laser de Córnea/métodos , Inflamación/patología , Cicatrización de Heridas , Animales , Antígeno CD11b/metabolismo , Proliferación Celular , Sustancia Propia/patología , Modelos Animales de Enfermedad , Inmunohistoquímica , Antígeno Ki-67/metabolismo , Ratones , Ratones Endogámicos C57BL , Microscopía Confocal , Miofibroblastos/patología , Factores de TiempoRESUMEN
We demonstrate an add/drop filter based on coupled vertical gratings on silicon. Tailoring of the channel bandwidth and wavelength is experimentally demonstrated. The concept is extended to implement a 1 by 4 wavelength division multiplexer with 6 nm channel separation, 3 nm bandwidth, a flat top response with < 0.8 dB ripple within the 3 dB passband, 1 dB insertion loss and 16 dB crosstalk suppression. The device is ultracompact, having a footprint < 2 X 10(-9)/2.
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Dispositivos Ópticos , Refractometría/instrumentación , Silicio/química , Telecomunicaciones/instrumentación , Diseño Asistido por Computadora , Diseño de Equipo , Análisis de Falla de Equipo , MiniaturizaciónRESUMEN
OBJECTIVE: To evaluate the degree of agreement in first-trimester nasal bone assessment in a group of sonographers before and after training, using a semi-quantitative scoring system. METHODS: Four sonographers who routinely perform first-trimester screening were first shown 46 images from both normal and trisomy 21 pregnancies. For each image, they were asked to score from 0 (disagree) to 3 (agree) on five different criteria that were deemed important in nasal-bone assessment, including image size, plane and visibility of nasal bone. A training program was then conducted, and a repeat exercise was carried out using the same 46 images. Finally, in a third exercise, images from 42 patients were presented, some having more than one image. The sonographers were required to give one overall nasal-bone score for each patient. In each exercise interobserver agreement was evaluated by intraclass correlation coefficient (ICC). RESULTS: Before training, the sonographers agreed reasonably well on the five proposed criteria (ICC, 0.752), with some disagreement on their perceived image quality. The training program further improved the agreement (ICC, 0.790), particularly on whether the nasal bone was the biggest and brightest echogenic component. Agreement was excellent when they were asked to give one overall score on the nasal bone based on multiple images from one patient (ICC, 0.929). CONCLUSION: The proposed scoring system can be used to improve consistency and reliability in first-trimester nasal-bone assessment.
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Síndrome de Down/diagnóstico por imagen , Hueso Nasal/diagnóstico por imagen , Primer Trimestre del Embarazo , Ultrasonografía Prenatal/métodos , Síndrome de Down/embriología , Femenino , Humanos , Hueso Nasal/embriología , Variaciones Dependientes del Observador , Embarazo , Garantía de la Calidad de Atención de Salud , Reproducibilidad de los Resultados , Encuestas y CuestionariosRESUMEN
Infrared (IR)-emitting RE doped materials have been extensively used to fabricate active components of integrated optical devices in various fields, such as fiber amplifiers, telecommunications, optoelectronics, and waveguides. Among various RE elements, trivalent erbium ions (Er 3+) are of great interest since their emissive behavior span the low loss telecommunication window of 1300-1650 nm. In this paper, we report two types of polymeric waveguide amplifiers. 8 cm long, lithographically patterned spiral waveguides provide 8 dB of gain using a 980 nm pump power of 95 mW. Gain is observed from 1530 to 1590 nm. We further report the first demonstration of polymeric waveguide amplifiers fabricated using 3D printing methods based on two-photon lithography, paving the way for rapid prototyping of active 3D printed devices and active photonic devices which may transcend planar limitations.
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PURPOSE: To describe the cellular components, biochemical composition, and membrane surface characteristics of denuded human amniotic membrane (DHAM) treated with Dispase II. METHODS: DHAM was incubated with Dispase II (1.2 U/ml) for 30 min, 60 min, or 120 min. This was followed by gentle scraping to remove any remaining epithelial cells using a cell scraper. Histology, immunohistochemistry for extracellular matrix molecules and growth factors, and transmission (TEM) and scanning electron microscopy (SEM) were performed to assess the effects of increasing durations of incubation on DHAM structure. RESULTS: Dispase II treatment was associated with the digestion of several ECM molecules, particularly those in the basement membrane including collagen VI, fibronectin, and laminin. FGF-2 and PDGF-B expression were unaffected by Dispase II, but TGF-alpha, TGF-beta1, TGF-beta 2R, PDGF-A, VEGF, and EGFR expression were all reduced by Dispase II incubation. TEM confirmed the disruption of DHAM ultrastructure with increasing duration of Dispase II incubation, beginning with disruption of the basal lamina and progressing to loosening of the stromal collagen network as well. CONCLUSIONS: The use of Dispase II in the preparation of DHAM causes significant changes to the ultrastructure of the membrane, particularly the BM. Prolonged incubation with dispase may cause significant disruption in DHAM structure which may affect cell growth in cultured explants.
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Amnios/metabolismo , Amnios/ultraestructura , Endopeptidasas/metabolismo , Amnios/citología , Amnios/efectos de los fármacos , Endopeptidasas/farmacología , Matriz Extracelular/efectos de los fármacos , Matriz Extracelular/metabolismo , Humanos , Inmunohistoquímica , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Receptores de Factores de Crecimiento/metabolismoRESUMEN
The aim of this retrospective study was to describe the oral procedures used in osteo-odonto-keratoprosthesis (OOKP) surgery, and the demographics and oral findings of candidate patients in Singapore. The OOKP procedure utilizes an autologous tooth-bone complex to mount a poly-methylmethacrylate optical cylinder, as an artificial cornea, stabilized by an overlying autologous buccal mucosal graft. Consecutive patients referred over 3 years for dental evaluation prior to OOKP surgery were included. A total of 21 patients underwent oral clinical and radiographic evaluation. The aetiology of blindness included Stevens-Johnson's syndrome (11 cases), chemical burns (9 cases) and multiple failed corneal grafts (1 case). Evaluation revealed that 12 patients were suitable for OOKP surgery, 8 were at risk of complication or failure and 1 had no usable teeth. Fourteen patients have undergone unilateral OOKP Stage 1 surgery successfully. Complications included fracture of a tooth from its lingual bone necessitating the harvesting of a second tooth (1 case), oronasal perforation (1 case), exposure of adjacent roots (5 teeth), lower lip paresthesia (2 cases) and submucosal scar band formation in the buccal mucosal graft donor site (10 cases). Thirteen patients have completed Stage 2 surgery, with attainment of their best possible visual potential following OOKP surgery.
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Proceso Alveolar/trasplante , Bioprótesis , Ceguera/cirugía , Procedimientos Quirúrgicos Orales/métodos , Implantes Orbitales , Raíz del Diente/trasplante , Adolescente , Adulto , Ceguera/rehabilitación , Trasplante Óseo/métodos , Córnea/patología , Córnea/cirugía , Opacidad de la Córnea/cirugía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Procedimientos Quirúrgicos Oftalmológicos/métodos , Osteotomía/métodos , Diseño de Prótesis , Implantación de Prótesis/métodos , Procedimientos de Cirugía Plástica/métodos , Refracción Ocular , Estudios RetrospectivosRESUMEN
Ring resonators on silicon rich nitride for potential use as rare-earth doped amplifiers pumped at 1310 nm with amplification at telecommunications-band are designed and characterized. The ring resonators are fabricated on 300 nm and 400 nm silicon rich nitride films and characterized at both 1310 nm and 1550 nm. We demonstrate ring resonators exhibiting similar quality factors exceeding 10,000 simultaneously at 1310 nm and 1550 nm. A Dysprosium-Erbium material system exhibiting photoluminescence at 1510 nm when pumped at 1310 nm is experimentally demonstrated. When used together with Dy-Er co-doped particles, these resonators with similar quality factors at 1310 nm and 1550 nm may be used for O-band pumped amplifiers for the telecommunications-band.
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CMOS platforms operating at the telecommunications wavelength either reside within the highly dissipative two-photon regime in silicon-based optical devices, or possess small nonlinearities. Bandgap engineering of non-stoichiometric silicon nitride using state-of-the-art fabrication techniques has led to our development of USRN (ultra-silicon-rich nitride) in the form of Si7N3, that possesses a high Kerr nonlinearity (2.8 × 10-13 cm2 W-1), an order of magnitude larger than that in stoichiometric silicon nitride. Here we experimentally demonstrate high-gain optical parametric amplification using USRN, which is compositionally tailored such that the 1,550 nm wavelength resides above the two-photon absorption edge, while still possessing large nonlinearities. Optical parametric gain of 42.5 dB, as well as cascaded four-wave mixing with gain down to the third idler is observed and attributed to the high photon efficiency achieved through operating above the two-photon absorption edge, representing one of the largest optical parametric gains to date on a CMOS platform.
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BACKGROUND: Pterygium is a fibrovascular overgrowth from the conjunctiva onto the cornea. The pathogenesis of this common ocular surface disorder is not well understood and the only treatment is surgical removal. METHODS: DNA microarray analysis of primary pterygium tissue was carried out using uninvolved conjunctiva tissue as a comparison for gene expression levels. Real time polymerase chain reaction (PCR) was used to verify the mRNA level of expression for genes changed in pterygium. Western blot analysis and immunohistochemistry showed protein expression levels and the tissue distribution. RESULTS: Microarray analysis revealed that mRNA levels of a number of genes were changed in primary pterygium. In particular the gene for insulin-like growth factor binding protein-3, (IGFBP3), which modulates the effects of insulin-like growth factor on cells was significantly decreased. Both the message and protein expression of IGFBP3 in pterygium were decreased compared to normal, uninvolved conjunctiva. CONCLUSION: Decreased levels of IGFBP3 protein have been strongly correlated with the presence of cancer. Identification of the low level of expression of IGFBP3 in pterygium suggests that the pathway controlling cell proliferation has lost an important control mechanism, which may explain the continued growth of pterygium.
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Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/biosíntesis , Pterigion/metabolismo , Adulto , Western Blotting , Regulación hacia Abajo , Femenino , Humanos , Proteína 2 de Unión a Factor de Crecimiento Similar a la Insulina/biosíntesis , Proteína 2 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Masculino , Persona de Mediana Edad , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Reacción en Cadena de la Polimerasa/métodos , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodosRESUMEN
AIM: To determine the association of spherical equivalent (SE) with low uncorrected visual acuity (VA) along with a proposed definition for myopia using logMAR VA >0.3 as the criteria. METHODS: 1334 Chinese schoolchildren (mean age 7.8; range 7-9 years) were enrolled in the study after those who had hyperopia > or =+2.00 dioptres (D) and astigmatism > = -2.00 D were excluded. Uncorrected logMAR VA was measured for both eyes. Cycloplegia autorefraction was achieved by the instillation of three drops of 1% cyclopentolate 5 minutes apart. The average of five successful consecutive refraction and keratometry readings were obtained with calibrated Canon RK5 autokeratorefractometers by well trained optometry students, at least 30 minutes after the instillation of the third drop of cyclopentolate. SE cut-off points (-0.25 D, -0.5D, -0.75 D, -1.0 D) were evaluated. RESULTS: Using different SE cut-off points, the myopia prevalence rates of this sample of schoolchildren varied from 45.8% (SE at least -0.25 D) to 30.7% (SE at least -1.0 D). The cut-off point of > or =-0.75 D had a sensitivity and specificity of 91.8% (95% CI, 89.2 to 94.4) and 93.7% (95% CI, 92.1 to 95.3), respectively, to predict low vision defined as uncorrected logMAR VA > 0.3 (either eye). The next best cut-off point of -0.5D had a higher sensitivity (93.3%), but lower specificity (87.9%). CONCLUSIONS: The cut-off points of -0.75D and -0.5D in SE refraction are appropriate for the prediction of uncorrected logMAR VA worse than 0.3, which is the criterion for the US common state adult driver licensing standard.
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Miopía/diagnóstico , Agudeza Visual , Niño , Métodos Epidemiológicos , Femenino , Humanos , Masculino , Miopía/epidemiología , Miopía/fisiopatología , Optometría/métodos , Singapur/epidemiologíaRESUMEN
AIM: To compare the prevalences of refractive errors in Malay, Chinese and Indian children in Malaysia and Singapore. METHODS: Children aged 7-9 years from three schools in the Singapore Cohort study of the Risk factors for Myopia (n = 1962) and similarly aged children from a random cluster sample in the metropolitan Kuala Lumpur area in the Malaysia Refractive Error Study in Children (n = 1752) were compared. Cycloplegic autorefraction was conducted in both countries. RESULTS: The prevalence of myopia (spherical equivalent of at least -0.5 diopters (D) in either eye) was higher in Singapore Malays (22.1%) than in Malays in Malaysia (9.2%; 95% confidence interval (CI) 11.2 to 14.7; p<0.001). Similarly, Singapore Chinese (40.1%) had higher prevalences than Malaysian Chinese (30.9%; 95% CI 1.5 to 16.9). Singapore Indians had a higher prevalence (34.1%) than Malaysian Indians (12.5%; 95% CI 17.4 to 25.9). The multivariate odds ratio of astigmatism (cylinder at least 0.75 D in either eye) in Singapore Malays compared with Malaysian Malays was 3.47 (95% CI 2.79 to 4.32). Ethnicity-specific hyperopia rates did not differ in Singapore and Malaysia. CONCLUSION: The ethnicity-specific prevalences of myopia in Singapore Malays, Chinese and Indians are higher than those in Malaysian Malays, Chinese and Indians. As Malays, Chinese and Indians in Malaysia have genetic make-up similar to that of Malays, Chinese and Indians in Singapore, environmental factors may contribute to the higher myopia rates.
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Errores de Refracción/etnología , Pueblo Asiatico/estadística & datos numéricos , Astigmatismo/etnología , Niño , Escolaridad , Femenino , Humanos , Hiperopía/etnología , Malasia/epidemiología , Masculino , Miopía/etnología , Prevalencia , Singapur/epidemiología , Población Blanca/estadística & datos numéricosRESUMEN
PURPOSE: To investigate independent risk factors for contact lens-related microbial keratitis in Singapore and estimate their impact on disease load. METHODS: Cases were contact lens wearers presenting to Singapore National Eye Centre with microbial keratitis between 2008 and 2010. Community contact lens wearers were recruited as controls. All wearers completed a previously validated questionnaire describing contact lens wear history, hygiene and compliance habits, and demographics. Risk factors significant in univariate analysis (P<0.2) were evaluated in a multivariate model. RESULTS: In all, 58 cases of microbial keratitis and 152 contemporaneous controls were identified. When controlling for other variables, Chinese had a 7 × lower risk compared with other races (95% CI: 2.3-21.3, P=0.001). Those aged between 25 and 44 years were at 3 × increased risk compared with younger wearers (95% CI: 1.1-9.6, P=0.04). Occasional overnight contact lens wear (less often than one night per week) was associated with a 4 × higher risk (95% CI: 1.2-15.4, P=0.03) compared with daily use. Not washing hands before handling was associated with a 13 × increased risk (95% CI: 1.9-84.8, P=0.008). Use of multipurpose solution A carried a 16 × higher risk compared with hydrogen peroxide (95% CI: 1.5-174.0, P=0.02). The combined PAR% for modifiable risk factors (occasional overnight wear, not washing of hands, and MPS A) was 82%. CONCLUSIONS: Consistent with previous findings, independent risk factors for contact lens-related microbial keratitis include poor hand hygiene, occasional overnight wear, and type of lens care solution. Prolonged overnight or extended contact lens use was infrequent in this population.
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Lentes de Contacto/efectos adversos , Úlcera de la Córnea/epidemiología , Infecciones Bacterianas del Ojo/epidemiología , Adolescente , Adulto , Anciano , Úlcera de la Córnea/microbiología , Infecciones Bacterianas del Ojo/microbiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infecciones por Pseudomonas/epidemiología , Infecciones por Pseudomonas/microbiología , Factores de Riesgo , Infecciones por Serratia/epidemiología , Infecciones por Serratia/microbiología , Singapur/epidemiología , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Encuestas y Cuestionarios , Adulto JovenRESUMEN
AIM: To evaluate the use of human serum (HS) in supporting the in vitro and in vivo proliferation of human conjunctival epithelial cells, and compare it with fetal bovine serum (FBS) and bovine pituitary extract (BPE). METHODS: Conjunctival epithelial cells were cultivated in media supplemented with HS (5%, 10%), FBS (5%, 10%), and BPE (70 microg/ml, 140 microg/ml). The colony forming efficiency (CFE), bromodeoxyuridine (BrdU) ELISA proliferation assay, and cell generations were analysed. Cells were evaluated for keratin (K4, K19, and K3) and MUC5AC expression by immunostaining and RT-PCR. Conjunctival equivalents constructed on amniotic membranes were transplanted onto severe combined immune deficient (SCID) mice for 10 days and analysed histologically. RESULTS: The proliferation assays of HS supplemented cultures (CFE, 6.7% (SD 1.8%); BrdU absorbance, 0.86 (0.16)) were comparable to FBS supplemented (CFE, 9.3% (1.8%); BrdU absorbance, 1.11 (0.18)) and BPE supplemented cultures (CFE, 5.9 (1.5); BrdU absorbance, 0.65 (0.12)). Goblet cell densities for HS, FBS, and BPE supplemented media were 52 cells/cm(2), 60 cells/cm(2), and 50 cells/cm(2), respectively. HS supplemented cultures formed stratified epithelial sheets in vivo following transplantation. CONCLUSIONS: The proliferative capacity of conjunctival epithelial cells cultivated in HS supplemented cultures was comparable to FBS and BPE supplemented cultures. The elimination of animal material from the culture system is advantageous when cultivating cells for clinical transplantation.
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Conjuntiva/citología , Células Epiteliales/citología , Suero , Ingeniería de Tejidos/métodos , Animales , Bromodesoxiuridina , Bovinos , Técnicas de Cultivo de Célula/métodos , Diferenciación Celular , División Celular , Tamaño de la Célula , Conjuntiva/metabolismo , Conjuntiva/trasplante , Medios de Cultivo , Células Epiteliales/metabolismo , Células Epiteliales/trasplante , Células Caliciformes/citología , Humanos , Queratinas/metabolismo , Ratones , Ratones SCID , Microscopía de Contraste de Fase , Mucina 5AC , Mucinas/metabolismo , Células MadreRESUMEN
AIMS: To assess the longitudinal changes in biometric parameters and associated factors in young myopic children aged 7--9 years followed prospectively in Singapore. METHODS: Children aged 7--9 years from three Singapore schools were invited to participate in the SCORM (Singapore Cohort study Of the Risk factors for Myopia) study. Yearly eye examinations involving biometry measures were performed in the schools. Only myopic children (n=543) with 3 year follow up data were included in this analysis. RESULTS: The 3 year increases in axial length, anterior chamber depth, lens thickness, vitreous chamber depth, and corneal curvature were 0.89 mm, -0.02 mm, -0.01 mm, 0.92 mm, and 0.01 mm, respectively. Children who were younger, female, and who had a parental history of myopia were more likely to have greater increases in axial length. After adjustment for school, age, sex, race, parental myopia and reading in books per week, the age (p<0.001), sex (p=0.012), and parental myopia (p=0.027) remained significantly associated with the 3 year change in axial length. Reading in books per week, however, was not associated with axial length change. Children with faster rates of progression of myopia had greater increases in axial length (Pearson correlation coefficient (r)=-0.69) and vitreous chamber depth (r=-0.83). CONCLUSIONS: The 3 year change in axial length of Singapore children aged 7--9 years at baseline was high and greater in younger children, females, and children with a parental history of myopia. Myopia progression was driven largely by vitreous chamber depth increase.