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Background Retinal development continues during the early postnatal period in mammals.Correct arrangement of layers and precise location of various cells in the retina are vital for forming normal visual function during critical period plasticity.Spectral-domain optical coherence tomography(SD-OCT)provides highquality in vivo retinal imaging and the possibility to measure retinal thickness longitudinally. Objective The present study was to investigate the changes of retinal thickness during critical period plasticity in rats. Methods In vivo consecutive scanning of retinal image was performed in 10 SPF Sprague-Dawley rats at postnatal day 14(P14),P18,P21,P24 and P42 with SD-OCT,and retinal histopathological examination was used to detect retinal morphologic changes at the same postnatal ages in 20 matched rats.The whole retinal thickness,the thickness from inner limiting membrane(ILM)to inner plexiform layer(IPL),the thickness of inner nuclear layer(INL)and the thickness from outer nuclear layer(ONL)to retinal pigment epithelium(RPE)were measured using Cirrus HD-OCT system and HMIAS-2000 Imaging System in retinal sections.The measurement parameters by Cirrus HD-OCT and those by hematoxylin-eosin staining were compared.The use of animals followed the Statement of National Institute of Health (USA). Results In vivo high-resolution images of rat retinas with SD-OCT compared well with histology,which enabled quantitative comparison of the SD-OCT and histological data during critical period plasticity in rats.From P14 to P42,the retinal thickness gradually decreased with the increase of rat ages(F=15.425,P=0.000),and so were the thickness from ILM to IPL,the thickness of INL and the thickness from ONL to RPE(F=3.973,P=0.007;F=17.529,P=0.000;F=7.038,P=0.000).The retinal thickness,thickness of INL.thickness from ONL to RPE measured by Cirrus HD-OCT were significantly correlated with those measured by retinal sections among P14,P18,P21,P24 and P42 rats(r=0.794,P=0.000;r=0.784,P=0.000;r=0.681,P=0.000). Conclusion SD-OCT is a demonstratably valuable technology to study the structure of retinas in rats.The retinal thickness is shown to reduce in thickness throughout the development of the retina during critical period plasticity due to the decrease in thickness of INL and the distance from the ONL to RPE,as illustrated by OCT scanning.
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AIM: To express the DT389-hbFGF (389 amino acid residues of the N-terminus of diphtheria toxin (human basic fibroblast growth factor) fusion protein for potential targeting therapy towards posterior capsule opacification (PCO) after cataract surgery.METHODS: The DNA of inactivated diphtheria bacillus and RNA of 12-week fetal brain cortex were extracted, respectively. The fragments of truncated diphtheria toxin (containing 389 amino acids of N-terminus, DT389) )and full-length human basic fibroblast growth factor(hbFGF) sequence (encoding 18kDa protein) were amplified by PCR. The two fragments were inserted into pGEX-4T-1 prokaryotic expression vector to obtain pGEX-DT389-hbFGF prokaryotic expression plasmid. After sequence analysis, the expressing plasmid was transformed into Escherichia Coli BL21 strain and expression was induced under IPTG. The expressed fusion protein was purified and identified.RESULTS: The gene fragments encoding DT389 and hbFGF were amplified and their gene sequences were confirmed. Hybrid gene expression plasmid pGEX-DT389 (hbFGF was constructed. The fusion protein DT389-hbFGF was expressed and purified.CONCLUSIONS: The successful cloning and expression of DT389-hbFGF immunotoxin provides a foundation for targeting therapy towards posterior capsule opacification.