2,851 research outputs found
Application of (lamellar) keratoplasty and limbal stem cell transplantation for corneal clouding in the mucopolysaccharidoses - a review
No full textCorneal clouding or opacification is a prominent feature of mucopolysaccharidosis (MPS), particularly in MPS I and VI. In patients with marked corneal clouding and visual impairment, penetrating keratoplasty may be considered to improve the patient's vision, functional capacity and quality of life. In MPS, glycosaminoglycans mainly accumulate in the corneal stroma and not in Descemet's membrane or the endothelium, therefore deep anterior lamellar keratoplasty (DALK) may be preferred in these patients over penetrating keratoplasty. Although there are only limited data on the use of DALK in MPS (I and VI) patients, the results are generally favourable. Nonetheless, when deciding on whether to perform keratoplasty in patients with MPS, the risk of general anaesthesia due to potential concomitant cardio-pulmonary problems and cervical spine instability, the potential presence of other ocular manifestations that also impair vision (e.g. glaucoma, retinal degeneration and optic atrophy) and/or complications such as allograft rejection and the risk of re-opacification of the graft, all need to be taken into consideration. Limbal stem cell transplantation, which can be combined with keratoplasty, also holds potential promise in the treatment of these complex cases. A review of the indications, local and systemic risks, techniques of lamellar and penetrating keratoplasty, and the potential of limbal stem cell transplantation is provided in the context of corneal opacity in MPS
Application of (lamellar) keratoplasty and limbal stem cell transplantation for corneal clouding in the mucopolysaccharidoses - a review
No full textCorneal clouding or opacification is a prominent feature of mucopolysaccharidosis (MPS), particularly in MPS I and VI. In patients with marked corneal clouding and visual impairment, penetrating keratoplasty may be considered to improve the patient's vision, functional capacity and quality of life. In MPS, glycosaminoglycans mainly accumulate in the corneal stroma and not in Descemet's membrane or the endothelium, therefore deep anterior lamellar keratoplasty (DALK) may be preferred in these patients over penetrating keratoplasty. Although there are only limited data on the use of DALK in MPS (I and VI) patients, the results are generally favourable. Nonetheless, when deciding on whether to perform keratoplasty in patients with MPS, the risk of general anaesthesia due to potential concomitant cardio-pulmonary problems and cervical spine instability, the potential presence of other ocular manifestations that also impair vision (e.g. glaucoma, retinal degeneration and optic atrophy) and/or complications such as allograft rejection and the risk of re-opacification of the graft, all need to be taken into consideration. Limbal stem cell transplantation, which can be combined with keratoplasty, also holds potential promise in the treatment of these complex cases. A review of the indications, local and systemic risks, techniques of lamellar andpenetrating keratoplasty, and the potential of limbal stem cell transplantation is provided in the context of corneal opacity in MPS
Correlation of central and peripheral keratometric parameters after corneal collagen cross-linking in keratoconus patients
No full textPurpose: To evaluate the difference in the central and peripheral keratometric parameters in patients with keratoconus after corneal collagen cross-linking (CXL). Methods: Forty-eight eyes of 32 patients (18 males, 16–28 years) affected by progressive keratoconus in different stages of evolution underwent CXL using the standard epithelium-off protocol. Corneal thickness and corneal curvature before CXL and after 6 and 12 months using the Sirius tomographer were analyzed. The values of the mean corneal thickness at the corneal apex (CAT), center of the pupil (PCT), thinnest point (CTTL) and along concentric circles of 2, 4, 6, 8, 8.5, 9, 9.5 and 10 mm diameter were evaluated; the values of the mean curvature at the corneal apex and at the points in which the inferior, superior, nasal and temporal meridians crossed the above-mentioned concentric circles were also evaluated. Results: The mean preoperative values for CAT, PCT and CTTL were 461.4 ± 30.3, 475.3 ± 30.5 and 441 ± 32.0, respectively. The values after 12 months of CXL were 444.6 ± 36.2, 451.6 ± 36.7 and 418.2 ± 41.4. The peripheral corneal thickness at the eight points ranged from 479 to 733 preoperatively. At 12-month post-CXL, the values ranged from 444.6 to 734.1. The mean posterior curvature from apex to periphery ranged from − 4.5 to − 9.1 days preoperatively and from − 4.5 to − 9.2 days at 12 months. These were not statistically significant (ANOVA and unpaired T test). Conclusions: Our data suggest that CXL over an 8-mm zone can stabilize the peripheral cornea. Longer-term follow-up studies on the peripheral cornea after CXL will provide useful information
Human Keratocytes from the Limbus and Cornea Both Express Epithelial Cytokeratin 3: Possible Mesenchymal-Epithelial Transition.
No full textBackground: The corneal limbus is the repository of epithelial stem cells (SC) that sustain the turnover of corneal epithelial cells. The limbus stroma contains mesenchymal SC that generates stromal keratocytes. Mesenchymal-epithelial transition is a phenomenon wherein cells of mesenchymal phenotype can transdifferentiate to epithelial phenotype. Our aim was to study whether limbal keratocytes, cytokeratin 3 (CK3) negative, could be induced to transdifferentiate into CK3 positive cells.
Methods: Human keratocytes were isolated from the limbus and cornea of cadaver donors, cultured and evaluated for CD34, CK3 and vimentin expression by immunofluorescence and RT-PCR and for keratocan by RT-PCR.
Results: All cells regardless of site expressed vimentin and some also expressed CD34 and CK3. Double immunofluorescence revealed three subpopulations: CK3−/CD34+, CK3+/CD34+ and CK3+/CD34−. Total CD34 cell yield was higher in the limbus with a peak time to confluence (TTC) of more than 30 days. Total CK3 cell yield was greater in the cornea with a peak TTC of less than 30 days. Increasing donor age corresponded to a decreased CD34 yield and an increased CK3 yield. CK3−/CD34+ and CK3+/CD34− cells behaved similarly to total CD34 and CK3 cells in relation to age, site and TTC while CK3+/CD34+ cells showed intermediate features. Keratocan was present in corneal samples.
Conclusions: Suspension cultured human keratocytes of the limbus behave as progenitor cells of corneal keratocytes being slower cycling and with a greater proportion expressing CD34. Cultured keratocytes both from the limbus and cornea are able to express CK3. This phenomenon may reflect mesenchymal-epithelial transition or, given the loss in vitro of the micro-anatomical features of the limbal-corneal area, may indicate the acquisition by keratocytes of a differentiation and migration pathway similar to that of the overlying epithelium. This suggests that the limbus/ corneal stromal niche may exhibit site-specific modulating abilities that direct the development of site-dependent intermediate filament repertoire of epithelial cells
Topical chemotherapy for ocular surface squamous neoplasia: current status.
No full textBr J Ophthalmol. 2010 May;94(5):532-5. Epub 2009 Sep 23.
Topical chemotherapy for ocular surface squamous neoplasia: current status.
Sepulveda R, Pe'er J, Midena E, Seregard S, Dua HS, Singh AD.
SourceDepartment of Ophthalmic Oncology, Cole Eye Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Abstract
Although there are no randomised trials directly comparing topical chemotherapeutic agents mitomycin-C, 5-fluorouracil, and interferon-alpha2b, published studies indicate equal efficacy of these agents for treatment of non-invasive ocular surface squamous neoplasia (80%-88%). 5-Fluorouracil may be preferred, given low incidence of serious side effects and low cost to the patient.
PMID: 19776089 [PubMed - indexed for MEDLINE
Epithelial dendritic cell distribution in normal and inflamed human cornea: in vivo confocal microscopy study
No full textPURPOSE: To evaluate dendritic cell (DCs) density,
distribution, and morphology in central corneal and limbal
epithelium in normal subjects and patients with immunemediated
corneal inflammation using in vivo confocal
microscopy (IVCM).
DESIGN: Comparative case-controlled, observational
confocal microscopy study.
METHODS: A total of 135 eyes of 135 patients were
investigated. Group 1 (normal eyes) included 45 eyes
of 45 healthy volunteers, group 2 photorefractive keratectomy
(PRK-treated eyes) included 45 myopic eyes of
45 patients treated with PRK, and group 3 (inflamed
eyes) comprised 45 eyes of 45 patients affected by
immune-mediated corneal inflammation. The central cornea
and limbus were examined for epithelial dendriticshaped
cells using laser scanning IVCM. DCs density
was calculated using image analysis software.
RESULTS: Cells with a branching dendritic morphology
were visualized in the basal epithelial layer, basal
lamina, and subbasal nerve plexus, in the central cornea,
and in the basal layer and basal membrane of the limbal
epithelium. The limbal epithelium demonstrated DCs
in 93.3%, 89%, and 97.7% of eyes in group 1, 2, and
3, respectively (P ns). Central epithelial DCs were
observed in 20.0% and 13.3% of eyes in group 1 and 2
(P ns), while in 93.3% of eyes in group 3 (P < .001).
DCs were found to be significantly higher at the limbus
compared with central cornea in each group (P < .001).
Cell densities observed in group 3 were significantly
greater than groups 1 and 2, at both locations (P < .05).
CONCLUSIONS: Laser scanning IVCM is a useful
method for evaluating epithelial DCs distribution at the
limbus and central cornea in both healthy and diseased
eyes
Epithelial dendritic cell distribution in normal and inflamed human cornea: in vivo confocal microscopy study
No full textThe use of machine learning to identify the correctness of HS Code for the customs import declarations
No full textAs an increasing volume of international trade activities around the world, the amount of cross-boarder import declarations grows rapidly, resulting in an unprecedented scale of potentially fraudulent transactions, in particular false commodity code (e.g., HS Code). The incorrect HS Code will cause duty risk and adversely impact the revenue collection. Physical investigation by the customs administrations is impractical due to the substantial quantity of declarations. This paper provides an automatic approach by harnessing the power of machine learning techniques to relief the burden of customs targeting officers. We introduced a novel model based on the off-the-shelf embedding encoder to identify the correctness of HS Code without any human effort. Determining whether the HS Code is correctly matched with commodity description is a classification task, so the labelled data is typically required. However, the lack of gold standard labelled data sets in customs domain limits the development of supervised-based approach. Our model is developed by the unsupervised mechanism and trained on the unlabelled historical declaration records, which is robust and able to be smoothly adapted by the different customs administrations. Rather than typically classifying whether the HS Code is correct or not, our model predicts the score to indicate the degree of the HS Code being correct. We have evaluated our proposed model on the ground-truth data set provided by Dutch customs officers. Results show promising performance of 71% overall accuracy.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Information and Communication Technolog
HS-stability and complex products in involution semigroups
No full textWhen does the complex product of a given number of subsets of a group generate the same subgroup as their union? We answer this question in a more general form by introducing HS-stability and characterising the HS-stable involution subsemigroup generated by a subset of a given involution semigroup. We study HS-stability for the special cases of regular ∗-semigroups and commutative involution semigroups.</p
Corneal confocal scanning laser microscopy in patients with dry eye disease treated with topical cyclosporine
No full textPurpose To investigate the effect of cyclosporine on corneal ultrastructure and on major signs and symptoms of patients with dry eye disease.Patients and methods In this prospective cohort study, patients with dry eye disease were treated with a drop of cyclosporine 0.05% twice daily. Clinical evaluation was carried out at baseline and at months 1, 3, and 6. All patients completed the Ocular Surface Disease Index (OSDI) questionnaire, and tear film break-up time (BUT), fluorescein and lissamine green staining, and Schirmer test were carried out. In vivo confocal microscopy was also performed and epithelial cellular density, keratocyte activation, and subbasal plexus morphology were assessed.Results A total of 40 patients completed the study. After 6 months, OSDI, BUT, and fluorescein and lissamine green staining showed a clinically significant improvement. During the 6-month follow-up, density of intermediate epithelial cells increased from 1969.5 +/- 85.4 cell/mm(2) to 4881.2 +/- 75.7 cell/mm(2) (P<0.01); average grade of keratocyte activation decreased from 3.6 +/- 0.1 to 1.8 +/- 0.1 (P<0.001); average grade of number of subbasal nerves decreased from 5.3 +/- 0.2 to 2.6 +/- 0.2 (P<0.001); average grade of nerve reflectivity decreased from 3.8 +/- 0.1 to 2.1 +/- 0.2 (P<0.001); and average grade of nerve tortuosity decreased from 3.8 +/- 0.1 to 2.2 +/- 0.2 (P<0.001).Conclusion Cyclosporine was effective in controlling symptoms and signs of dry eye disease. In vivo confocal microscopy showed an increase in cell density of intermediate epithelium cells, a decrease in hyper-reflective keratocytes, and a decrease in density, tortuosity, and reflectivity of nerve fibers
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