The photocycle intermediates of photoactive yellow protein (PYP) were characterized by low-temperature Fourier transform infrared spectroscopy. The difference FTIR spectra of PYP(B), PYP(H), PYP(L), and PYP(M) minus PYP were measured under the irradiation condition determined by UV-visible spectroscopy. Although the chromophore bands of PYP(B) were weak, intense sharp bands complementary to the 1163-cm(-1) band of PYP, which show the chromophore is deprotonated, were observed at 1168-1169 cm(-1) for PYP(H) and PYP(L), indicating that the proton at Glu46 is not transferred before formation of PYP(M). Free trans-p-coumaric acid had a 1294-cm(-1) band, which was shifted to 1288 cm(-1) in the cis form. All the difference FTIR spectra obtained had the pair of bands corresponding to them, indicating that all the intermediates have the chromophore in the cis configuration. The characteristic vibrational modes at 1020-960 cm(-1) distinguished the intermediates. Because these modes were shifted by deuterium-labeling at the ethylene bond of the chromophore while labeling at the phenol part had no effect, they were attributed to the ethylene bond region. Hence, structural differences among the intermediates are present in this region. Bands at about 1730 cm(-1), which show that Glu46 is protonated, were observed for all intermediates except for PYP(M). Because the frequency of this mode was constant in PYP(B), PYP(H), and PYP(L), the environment of Glu46 is conserved in these intermediates. The photocycle of PYP would therefore proceed by changing the structure of the twisted ethylene bond of the chromophore.
PURPOSE.To follow the changes in the metamorphopsia, visual acuity, and OCT parameters after epiretinal membrane (ERM) removal.METHODS. The study included 49 eyes of 49 patients with an ERM who underwent vitrectomy and membrane peeling. The changes in the best-corrected visual acuity (BCVA), metamorphopsia, and central foveal thickness (CFT) were evaluated at baseline and 1, 3, 6, 9, and 12 months postoperatively. M-CHARTS were used to quantify metamorphopsia. RESULTS.The mean BCVA, metamorphopsia scores for horizontal lines (MH) and vertical lines (MV), and CFT improved significantly at 12 months after surgery (P < 0.001). The baseline BCVA, MH score, and MV score were significantly correlated with the corresponding BCVA, MH score, and MV score at 12 months after surgery (P < 0.01). The MH and MV scores at 12 months was significantly correlated with the BCVA at 12 months (P < 0.01), and the baseline MV score was significantly correlated with the BCVA at 12 months (P < 0.05). The MH score but not the MV score was significantly correlated with the CFT at baseline and 12 months (P < 0.05).CONCLUSIONS. The preoperative BCVA, MH score, and MV score were prognostic factors for the corresponding postoperative BCVA, MH score, and MV score. These results suggest that surgery for ERM should be considered before severe reduction in the BCVA or the degree of metamorphopsia. In addition, the preoperative MV score was a prognostic factor for postoperative BCVA. The MH score but not the MV score was correlated with the CFT preoperatively and postoperatively. (Invest Ophthalmol Vis Sci. 2012;53:3592-3597) DOI:10.1167/ iovs.12-9493 P atients with an idiopathic epiretinal membrane (ERM) often suffer from metamorphopsia, which impairs the quality of vision even when the conventional visual acuity is relatively good. To resolve these visual difficulties, these eyes commonly undergo vitrectomy with the removal of the ERM. Despite a successful removal of an ERM and an improvement of the visual acuity, the patient's quality of vision may not be completely normal mainly because of residual metamorphopsia. Thus, it is essential to evaluate the visual outcome in terms of the quality of vision as well as by the visual acuity. Okamoto et al.1,2 demonstrated that the changes in metamorphopsia but not the visual acuity were significantly associated with changes in the 25-item National Eye Institute Visual Function Questionnaire composite score on the quality of vision after ERM surgery. Therefore, assessing not only the visual acuity but also the severity of metamorphopsia is important when deciding the timing of the ERM surgery and for evaluating the postoperative quality of vision.Amsler charts have been widely used for detecting metamorphopsia, 3 but it is difficult to quantify the severity of the metamorphopsia. Some investigators have evaluated metamorphopsia by the numbers of distorted squares on the Amsler charts 4 or a laser grid generated by a scanning laser ophthalmoscope, 5 but these findings represent the range rather than the ...
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