Purpose: To devise a rapid method of isolating the plasma membrane enriched fraction (PMEF) of the bovine retinal pigment epithelial (RPE) cells with Percoll cen-trifugation medium.Methods : The bovine RPE was homogen...Purpose: To devise a rapid method of isolating the plasma membrane enriched fraction (PMEF) of the bovine retinal pigment epithelial (RPE) cells with Percoll cen-trifugation medium.Methods : The bovine RPE was homogenised with a tight fit Dounce homogeniser and centrifuged in a 16. 7% Percoll gradient for 20 minutes. The RPE particulate fractions were characterised in terms of their protein concentrations, Na/K-ATPase and bicarbonate stimulated ATPase activities.Results ; The total protein recovery was 88.7% of the RPE homogenate. The nucleus layer was identified at the first band. The mitochondrial fraction was at the second layer according to its bicarbonate stimulated ATPase activity. The 3rd and 4th bands were enriched with plasma membranes and their Na/K-ATPase activities were 31. 5 and 34.6 μmol/mg/h respectively. The Na/K-ATPase activities were about six times that of the RPE homogenate.Conclusions: A rapid method of isolating the bovine RPE PMEF has been devised which involved a single展开更多
Purpose:To study the saturation characteristics of the glucose transport across the bovine retinal pigment epithelium(RPE).Methods:The bovine RPE preparations were munted with a modified Ussing chamber.The L-[^(3)H]-g...Purpose:To study the saturation characteristics of the glucose transport across the bovine retinal pigment epithelium(RPE).Methods:The bovine RPE preparations were munted with a modified Ussing chamber.The L-[^(3)H]-glucose and 3-0-methyl-D-[^(14)C]-glucose fluxes across the RPE from the choroid to retina were studied at different glucose concentrations.Results:The glucose transport was found to be stereospecific,with 3-0-methyl-D-glucose(MDG)being transported about three times faster than L-glucose.The glucose transport showed typical saturation characteristics in Michaelis-Menten fashion.The V_(max)and the K_(m)of corrected MDG were 2452 nmol cm^(-2)h^(-1)and 30.8 mM respectively.It was shown that the glucose transport system was saturated at 61.6 mM.Conclusions:The saturation characteristics of the corrected MDG flux suggested that the capacity of glucose transport through the bovine RPE is immense.展开更多
Background Myopia control interventions,such as defocus incorporated multiple segments(DIMS)spectacle lenses,have been adopted in school-aged children to reduce the prevalence of myopia and its complications.This stud...Background Myopia control interventions,such as defocus incorporated multiple segments(DIMS)spectacle lenses,have been adopted in school-aged children to reduce the prevalence of myopia and its complications.This study aimed to investigate the effect of DIMS spectacle lenses on subfoveal choroidal thickness(SfChT)over a period of two years,as the choroidal response to myopic control is a crucial factor in exploring its potential effect on predict-ingmyopiaprogression.Methods This study involved a secondary analysis of our previous randomized clinical trial.Myopic school-aged children aged 8-13 years were recruited in a two-year study investigating the effect of DIMS spectacle lenses on myo-pia progression.The treated group received DIMS spectacle lenses(n=78),while the control group was treated with a pair of single vision(SV)spectacle lenses(n=80).SfChT was monitored at 1 week,1,3,6,12,18 and 24 months post lens wear using spectral-domain optical coherence tomography and a custom made auto-segmentation algo-rithm utilizing convolutional neural networks.Results SfChT increased significantly after 1 week of DIMS spectacle lens wear compared to those wearing SV spectacle lenses(adjusted mean change relative to baseline±SEM at 1 week;DIMS vs.SV,6.75±1.52μum vs.-3.17±1.48μm;P<0.0001,general linear model).The thickness of choroid increased to 13.64±2.62μm after 12 months of DiMS lens wear while the choroid thinned in SV group(-9.46±2.55μm).Choroidal changes demonstrated a significant negative association with axial elongation over two years in both the DIMS and SV groups.Choroidal change at 3 months significantly predicted the changes in AL at 12 months after controlling the effect of age and gender.Conclusions Our study demonstrated a significant choroidal thickening in response to myopic defocus incorpo-rated in a spectacle lens after 1 week of lens wear,sustained over the two-year study period.The results suggested that choroidal changes at 3 months may help predict changes in axial length after one year.展开更多
文摘Purpose: To devise a rapid method of isolating the plasma membrane enriched fraction (PMEF) of the bovine retinal pigment epithelial (RPE) cells with Percoll cen-trifugation medium.Methods : The bovine RPE was homogenised with a tight fit Dounce homogeniser and centrifuged in a 16. 7% Percoll gradient for 20 minutes. The RPE particulate fractions were characterised in terms of their protein concentrations, Na/K-ATPase and bicarbonate stimulated ATPase activities.Results ; The total protein recovery was 88.7% of the RPE homogenate. The nucleus layer was identified at the first band. The mitochondrial fraction was at the second layer according to its bicarbonate stimulated ATPase activity. The 3rd and 4th bands were enriched with plasma membranes and their Na/K-ATPase activities were 31. 5 and 34.6 μmol/mg/h respectively. The Na/K-ATPase activities were about six times that of the RPE homogenate.Conclusions: A rapid method of isolating the bovine RPE PMEF has been devised which involved a single
基金Correspondence address:Chi Ho T0,PhD Assistant Professor,Departnent of Optometry and Radiography.The Hong Kong Poly-lechric University,Hung Hom,Kowloon,Hong Kong.Telephone:(0852)27666102,Fax mumber(0852)27646051,Email:ORCHTO@P0LYU.EDU.HK
文摘Purpose:To study the saturation characteristics of the glucose transport across the bovine retinal pigment epithelium(RPE).Methods:The bovine RPE preparations were munted with a modified Ussing chamber.The L-[^(3)H]-glucose and 3-0-methyl-D-[^(14)C]-glucose fluxes across the RPE from the choroid to retina were studied at different glucose concentrations.Results:The glucose transport was found to be stereospecific,with 3-0-methyl-D-glucose(MDG)being transported about three times faster than L-glucose.The glucose transport showed typical saturation characteristics in Michaelis-Menten fashion.The V_(max)and the K_(m)of corrected MDG were 2452 nmol cm^(-2)h^(-1)and 30.8 mM respectively.It was shown that the glucose transport system was saturated at 61.6 mM.Conclusions:The saturation characteristics of the corrected MDG flux suggested that the capacity of glucose transport through the bovine RPE is immense.
基金support as the collabora-tive research(PolyU Grant No.H-ZG3B and 1-87LK)the spectacles and lenses for the study+4 种基金supported by other PolyU Grants(Grant Nos.BD90,ZVS5,ZVN1)Research Impact Fund(Grant No.R5032-18)Research Center for SHARP Vision(Grant No.1-BBCO)Henry G.Leong Endowed Professorship in Elderly Vision Health(Grant No.8-847)The Hong Kong Special Administrative Region Government(InnoHK initiative).
文摘Background Myopia control interventions,such as defocus incorporated multiple segments(DIMS)spectacle lenses,have been adopted in school-aged children to reduce the prevalence of myopia and its complications.This study aimed to investigate the effect of DIMS spectacle lenses on subfoveal choroidal thickness(SfChT)over a period of two years,as the choroidal response to myopic control is a crucial factor in exploring its potential effect on predict-ingmyopiaprogression.Methods This study involved a secondary analysis of our previous randomized clinical trial.Myopic school-aged children aged 8-13 years were recruited in a two-year study investigating the effect of DIMS spectacle lenses on myo-pia progression.The treated group received DIMS spectacle lenses(n=78),while the control group was treated with a pair of single vision(SV)spectacle lenses(n=80).SfChT was monitored at 1 week,1,3,6,12,18 and 24 months post lens wear using spectral-domain optical coherence tomography and a custom made auto-segmentation algo-rithm utilizing convolutional neural networks.Results SfChT increased significantly after 1 week of DIMS spectacle lens wear compared to those wearing SV spectacle lenses(adjusted mean change relative to baseline±SEM at 1 week;DIMS vs.SV,6.75±1.52μum vs.-3.17±1.48μm;P<0.0001,general linear model).The thickness of choroid increased to 13.64±2.62μm after 12 months of DiMS lens wear while the choroid thinned in SV group(-9.46±2.55μm).Choroidal changes demonstrated a significant negative association with axial elongation over two years in both the DIMS and SV groups.Choroidal change at 3 months significantly predicted the changes in AL at 12 months after controlling the effect of age and gender.Conclusions Our study demonstrated a significant choroidal thickening in response to myopic defocus incorpo-rated in a spectacle lens after 1 week of lens wear,sustained over the two-year study period.The results suggested that choroidal changes at 3 months may help predict changes in axial length after one year.
