The extent of stretched lamellar cleavage and visual acuity in macular pseudoholes.

BACKGROUND/AIMS: To evaluate the extent of lamellar cleavage and its association with preoperative and postoperative visual acuity (VA) in macular pseudoholes. METHODS: One eye each of 50 patients with macular pseudohole who underwent vitrectomy was retrospectively investigated. Preoperative macular pseudoholes were evaluated using spectral-domain optical coherence tomography (SD-OCT) images taken radially around the central fovea at 30° intervals. The macular pseudoholes were categorised into stage 1 (no cleavage), stage 2 (localised cleavage with (2b) and without (2a) crossing central fovea) and stage 3 (diffuse cleavage). RESULTS: Among the 50 macular pseudoholes, 14, 13, 9 and 14 were categorised into stages 1, 2a, 2b and 3, respectively. The extent of stretched cleavages was associated with worse baseline VA (p=0.0049 by multiple regression model). After surgery, the stretched lamellar cleavage disappeared in 32 patients out of 36 who were postoperatively examined by SD-OCT. In addition, the extensive cleavage (stage 2b/3) independently predicted larger postoperative VA recovery at 3 months by 0.105 logMAR compared with no/mild cleavage (stage 1/2a, p=0.030 by multiple regression model). CONCLUSIONS: Although advanced cleavage in macular pseudohole is associated with worse VA before surgery, even an advanced pseudohole could show favourable visual recovery after surgery.

EFFECT OF INTERNAL LIMITING MEMBRANE PEELING DURING VITRECTOMY FOR DIABETIC MACULAR EDEMA: Systematic Review and Meta-analysis.

PURPOSE: To evaluate the effect of internal limiting membrane (ILM) peeling during vitrectomy for diabetic macular edema. METHODS: MEDLINE, EMBASE, and CENTRAL were systematically reviewed. Eligible studies included randomized or nonrandomized studies that compared surgical outcomes of vitrectomy with or without ILM peeling for diabetic macular edema. The primary and secondary outcome measures were postoperative best-corrected visual acuity and central macular thickness. Meta-analysis on mean differences between vitrectomy with and without ILM peeling was performed using inverse variance method in random effects. RESULTS: Five studies (7 articles) with 741 patients were eligible for analysis. Superiority (95% confidence interval) in postoperative best-corrected visual acuity in ILM peeling group compared with nonpeeling group was 0.04 (-0.05 to 0.13) logMAR (equivalent to 2.0 ETDRS letters, P = 0.37), and superiority in best-corrected visual acuity change in ILM peeling group was 0.04 (-0.02 to 0.09) logMAR (equivalent to 2.0 ETDRS letters, P = 0.16). There was no significant difference in postoperative central macular thickness and central macular thickness reduction between the two groups. CONCLUSION: The visual acuity outcomes using pars plana vitrectomy with ILM peeling versus no ILM peeling were not significantly different. A larger randomized prospective study would be necessary to adequately address the effectiveness of ILM peeling on visual acuity outcomes.

Quantitative assessment of manual and robotic microcannulation for eye surgery using new eye model.

BACKGROUND: Microcannulation, a surgical procedure for the eye that requires drug injection into a 60-90 µm retinal vein, is difficult to perform manually. Robotic assistance has been proposed; however, its effectiveness in comparison to manual operation has not been quantified. METHODS: An eye model has been developed to quantify the performance of manual and robotic microcannulation. The eye model, which is implemented with a force sensor and microchannels, also simulates the mechanical constraints of the instrument's movement. Ten subjects performed microcannulation using the model, with and without robotic assistance. RESULTS: The results showed that the robotic assistance was useful for motion stability when the drug was injected, whereas its positioning accuracy offered no advantage. CONCLUSIONS: An eye model was used to quantitatively assess the robotic microcannulation performance in comparison to manual operation. This approach could be valid for a better evaluation of surgical robotic assistance.

Systemic vascular safety of ranibizumab for age-related macular degeneration: systematic review and meta-analysis of randomized trials.

BACKGROUND: We conducted a meta-analysis of randomized trials of ranibizumab for age-related macular degeneration (AMD) to elucidate systemic vascular risk. CLINICAL RELEVANCE: Although intravitreal vascular endothelial growth factor inhibitors are widely used to treat AMD, whether they produce systemic adverse effects remains uncertain. METHODS: We searched MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials through March 2014 to identify the randomized trials that compared systemic safety among different intensities of ranibizumab treatment for AMD. The outcome measures were the incidence of cerebrovascular accidents (CVAs), myocardial infarctions, nonocular hemorrhages, overall arterial thromboembolic events (ATEs), and all-cause mortality. We calculated the Peto odds ratio (OR) with 95% confidence interval for the comparisons between different intensities of regimens in terms of dose and retreatment frequency. RESULTS: Eleven trials comprising 6596 patients with AMD were included in the meta-analysis. A significant increase was observed in the following comparisons: 0.5 versus 0.3/0.0 mg for CVA (OR, 1.86; 95% CI, 1.05-3.29; P = 0.03), monthly versus pro re nata (PRN)/0.0 mg for CVA (OR, 1.89; 95% CI, 1.06-3.38; P = 0.03), and 0.3/0.5 versus 0.0 mg for nonocular hemorrhage (OR, 1.57; 95% CI, 1.01-2.44; P = 0.04). A nonsignificant increase was observed in the following comparisons: 0.5 versus 0.0 mg for CVA (OR, 2.27; 95% CI, 0.90-5.69; P = 0.08), monthly versus PRN for CVA (OR, 2.04; 95% CI, 0.94-4.45; P = 0.07), 0.5 versus 0.0 mg for nonocular hemorrhage (OR, 1.68; 95% CI, 0.98-2.88; P = 0.06), 0.3 versus 0.0 mg for nonocular hemorrhage (OR, 1.68; 95% CI, 0.95-2.98; P = 0.07), monthly versus PRN/0.0 mg for nonocular hemorrhage (OR, 1.54; 95% CI, 0.98-2.42; P = 0.06), monthly versus PRN for ATE (OR, 1.58; 95% CI, 0.96-2.61; P = 0.07), and monthly versus PRN/0.0 mg for ATE (OR, 1.42; 95% CI, 0.99-2.05; P = 0.06). Among the other analyses, no protective or harmful effects of ranibizumab were observed. CONCLUSIONS: In ranibizumab treatment for patients with AMD, a possible relationship of more intensive treatment to more systemic vascular adverse events was identified, but no relationship with mortality was identified.

Protective role of glutathione peroxidase 4 in laser-induced choroidal neovascularization in mice.

PURPOSE: To evaluate the influence of glutathione peroxidase 4 (GPx4) expression in retinal pigment epithelium (RPE)/choroid tissue using a mouse model of laser-induced choroidal neovascularization (CNV). METHODS: In this study, GPx4+/-, GPx4+/+, and GPx4-overexpressing transgenic mice were created for comparison. The mRNA and protein expression of vascular endothelial growth factor (VEGF)-A in RPE/choroid tissue were evaluated before and after CNV induction by laser. Moreover, we investigated the changes in the VEGF-A mRNA level in RPE/choroid tissue in the CNV model that have not been clearly shown previously. Lipid peroxidation in RPE/choroid tissue was evaluated by immunohistochemistry using antibody against 4-hydroxy-2-nonenal. To investigate the protective role of GPx4, the size of laser-induced CNV was compared on day 7 among the mice expressing different levels of GPx4. RESULTS: In the laser-induced CNV mouse model, laser treatment reduced the VEGF-A mRNA level in RPE/choroid tissue, while it increased the VEGF-A protein level. Evaluation of VEGF-A expression in RPE/choroid tissue of the GPx4+/-, GPx4+/+, and GPx4 transgenic mice revealed that GPx4 increased the VEGF-A protein level under physiological conditions (i.e., without laser treatment), while GPx4 suppressed the increase in the VEGF-A protein level under pathological conditions (i.e., after CNV induction by laser). In addition, GPx4 reduced the CNV size in a dose-dependent manner in vivo. CONCLUSIONS: GPx4 suppresses the increase in the VEGF-A protein level, which occurs during the development of pathological CNV, thus partly explaining the protective effect of GPx4 against CNV.

Occult macular dystrophy with bilateral chronic subfoveal serous retinal detachment associated with a novel RP1L1 mutation (p.S1199P).

PURPOSE: The purpose of this study was to present an atypical case of occult macular dystrophy (OMD) with bilateral chronic subfoveal serous retinal detachment (SRD). METHODS: A 53-year-old man was ophthalmologically evaluated because of decreased visual acuity in both eyes. Genomic DNA was extracted from venous blood samples. Mutational analysis of the retinitis pigmentosa 1-like 1 (RP1L1) gene was performed by Sanger sequencing. RESULTS: Best-corrected visual acuity (BCVA) was 0.1 logMAR in both eyes until the age of 53, after which it gradually declined. Full-field electroretinography (ERG) was unremarkable, while multifocal ERG revealed a reduced central response in both eyes. Optical coherence tomography showed subfoveal SRD in both eyes, and fundus fluorescein angiography yielded unremarkable results. His brother and cousin had similar subjective symptoms. At age 58, his logMAR BCVA was 0.532 (OD) and 0.347 (OS). He was given 23 administrations of intravitreal bevacizumab (IVB; 1.25 mg) in both eyes alternately over a 2-year period and also underwent reduced-fluence photodynamic therapy in both eyes. Two years after the first administration of IVB, a reduction in SRD was obtained, and IVB was therefore discontinued. Three years after the first administration, logMAR BCVA was 0.155 (OD) and 0.523 (OS). Mutational analysis revealed a novel heterozygous missense mutation (p.S1199P). CONCLUSIONS: We describe in detail a case of bilateral chronic subfoveal SRD in an atypical OMD patient carrying a novel heterozygous RP1L1 mutation (p.S1199P). Our results further extend the phenotypic spectrum of RP1L1-associated OMD.

Long-term increase in subfoveal choroidal thickness after surgery for senile cataracts.

PURPOSE: To evaluate the impact of cataract surgery on subfoveal choroidal thickness and central retinal thickness in the elderly. DESIGN: Prospective observational case series. METHODS: This cohort study included 29 eyes of 29 patients with senile cataract, but no previous ocular surgery or other ocular abnormality. All 29 eyes received standard surgery by phacoemulsification and intraocular lens implantation. Subfoveal choroidal thickness and central retinal thickness were measured at baseline and 1, 3, and 6 months postoperatively by spectral-domain optical coherence tomography. Multiple regression analysis was conducted to identify predictors of larger changes in subfoveal choroidal thickness, including sex, age, baseline choroidal thickness, axial length, refractive status before surgery, and duration of surgery. RESULTS: The 29 patients with senile cataract received cataract surgery without complication. Mean subfoveal choroidal thickness was 193.8, 208.9, 210.2, and 209.3 µm at baseline and at postoperative 1, 3, and 6 months, respectively, with a statistically significant increase after surgery (repeated-measures ANOVA; P < .0001). In 20 eyes (69.0%), subfoveal choroidal thickness remained high even 6 months after surgery. Multiple regression analysis revealed that male sex (P = .014) and thicker baseline choroid (P = .0048) predicted larger increases in subfoveal choroidal thickness. In contrast, the tendency of transient increase in central retinal thickness was not statistically significant. CONCLUSION: Most elderly patients with senile cataracts are expected to maintain increased subfoveal choroidal thickness for at least 6 months after cataract surgery.

Design and development of miniature parallel robot for eye surgery.

A five degree-of-freedom (DOF) miniature parallel robot has been developed to precisely and safely remove the thin internal limiting membrane in the eye ground during vitreoretinal surgery. A simulator has been developed to determine the design parameters of this robot. The developed robot's size is 85 mm × 100 mm × 240 mm, and its weight is 770 g. This robot incorporates an emergency instrument retraction function to quickly remove the instrument from the eye in case of sudden intraoperative complications such as bleeding. Experiments were conducted to evaluate the robot's performance in the master-slave configuration, and the results demonstrated that it had a tracing accuracy of 40.0 µm.

Impact of robotic assistance on precision of vitreoretinal surgical procedures.

PURPOSE: To elucidate the merits of robotic application for vitreoretinal maneuver in comparison to conventional manual performance using an in-vitro eye model constructed for the present study. METHODS: Capability to accurately approach the target on the fundus, to stabilize the manipulator tip just above the fundus, and to perceive the contact of the manipulator tip with the fundus were tested. The accuracies were compared between the robotic and manual control, as well as between ophthalmologists and engineering students. RESULTS: In case of manual control, ophthalmologists were superior to engineering students in all the 3 test procedures. Robotic assistance significantly improved accuracy of all the test procedures performed by engineering students. For the ophthalmologists including a specialist of vitreoretinal surgery, robotic assistance enhanced the accuracy in the stabilization of manipulator tip (from 90.9 µm to 14.9 µm, P = 0.0006) and the perception of contact with the fundus (from 20.0 mN to 7.84 mN, P = 0.046), while robotic assistance did not improve pointing accuracy. CONCLUSIONS: It was confirmed that telerobotic assistance has a potential to significantly improve precision in vitreoretinal procedures in both experienced and inexperienced hands.

Robot-assisted vitreoretinal surgery: development of a prototype and feasibility studies in an animal model.

PURPOSE: To develop a prototype robotic system designed to assist vitreoretinal surgery and to evaluate its accuracy and maneuverability. DESIGN: Experimental study. PARTICIPANTS: This study used harvested porcine eyes. METHODS: After development of a prototype robotic system, pointing accuracy tests of the system were performed on graph paper and in harvested porcine eyes. The average maximal deviation from the aiming point to the actual position of the tip of the instrument was compared between manually conducted procedures and those conducted with robotic assistance. The feasibility of creating posterior vitreous detachment (PVD), retinal vessel sheathotomy (RVS), and retinal vessel microcannulation also were evaluated in porcine eye models, and the success rates of 4 consecutive attempts for each kind of procedure were evaluated. MAIN OUTCOME MEASURES: The average maximum deviation in pointing accuracy tests both on graph paper and in animal eye models was a main outcome measure. The success rate of making PVD, RVS, and retinal vessel microcannulation was the other primary outcome measure. RESULTS: The pointing accuracy was superior with robotic assistance both on graph paper (327.0 microm vs. 32.3 microm) and in animal eye models (140.8 microm vs. 33.5 microm). Creating PVD, RVS, and retinal vessel microcannulation was feasible in 4 of 4 attempts, 4 of 4 attempts, and 2 of 4 attempts, respectively. The 2 failures in microcannulation were considered to be the result of difficulty in visual differentiation between the retinal vessel and retina in harvested porcine eyes. CONCLUSIONS: Improved accuracy and desirable feasibility of a prototype robotic system to assist vitreoretinal surgery were shown in this study. Research for wider implementation of robot-assisted surgery should be continued; there are some hurdles to overcome.

Glycerol-induced folding of unstructured disulfide-deficient lysozyme into a native-like conformation.

2SS[6-127,64-80] variant of lysozyme which has two disulfide bridges, Cys6-Cys127 and Cys64-Cys80, and lacks the other two disulfide bridges, Cys30-Cys115 and Cys76-Cys94, was quite unstructured in water, but a part of the polypeptide chain was gradually frozen into a native-like conformation with increasing glycerol concentration. It was monitored from the protection factors of amide hydrogens against H/D exchange. In solution containing various concentrations of glycerol, H/D exchange reactions were carried out at pH* 3.0 and 4 degrees C. Then, (1)H-(15)N-HSQC spectra of partially deuterated protein were measured in a quenching buffer for H/D exchange (95% DMSO/5% D(2)O mixture at pH* 5.5 adjusted with dichloroacetate). In a solution of 10% glycerol, the protection factors were nearly equal to 10 at most of residues. With increasing glycerol concentration, some selected regions were further protected, and their protection factors reached about a 1000 in 30% glycerol solution. The highly protected residues were included in A-, B-, and C-helices and beta3-strand, and especially centered on Ile 55 and Leu 56. In 2SS[6-127,64-80], long-range interactions were recovered due to the preferential hydration by glycerol in the hydrophobic box of the alpha-domain. Glycerol-induced recovering of the native-like structure is discussed from the viewpoint of molten globules growing with the protein folding. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 665-675, 2009.This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com.

The confirmation of the denatured structure of pyrrolidone carboxyl peptidase under nondenaturing conditions: difference in helix propensity of two synthetic peptides with single amino acid substitution.

In the denatured state (D(1) state) of cystein-free pyrrolidone carboxyl peptidase (PCP-0SH) from Pyrococcus furiosus, a hyperthermophile under nondenaturing conditions, a fairly stable alpha-helix (alpha6-helix) has been determined from H/D exchange-NMR experiments. On the other hand, the alpha6-helix region of the proline-mutant at position 199 (A199P) was unstructured in the D(1) state unlike that of the wild-type PCP-0SH, although the folded conformations of both proteins were almost identical to each other. This finding has been deduced from the information regarding the remaining amide hydrogens in the HSQC spectra after H/D exchanges in the D(1) state. To confirm this inference, we examined the helical propensities of two synthetic peptides from their NMR structural analysis in the presence of trifluoroethanol (TFE). One is an 18-residue peptide called the wild-type H6-peptide corresponding to the alpha6-helix (from Ser188 to Glu205) of the wild-type PCP-0SH, and the other is the mutant H6-peptide corresponding to the alpha6-helix region of A199P. The NOE-contact information obtained from the 2D-(1)H-NOESY spectra measured for both peptides in the presence of 30% TFE clearly demonstrated that the wild-type H6-peptide had a high helical propensity, but the mutant H6-peptide was almost totally unstructured. The TFE-induced helical propensities for these peptide fragments confirmed the conclusions deduced from the H/D exchange data measured in the D(1) states of two proteins.

Closed funnel-shaped proliferative vitreoretinopathy in patients with cognitive disabilities.

BACKGROUND AND OBJECTIVE: To report severe proliferative vitreoretinopathy (PVR) cases in patients with cognitive disabilities treated with vitrectomy. PATIENTS AND METHODS: This retrospective study included 10 eyes of 9 consecutively enrolled patients with cognitive disabilities. The severity of PVR was grade C type 2345 with widespread preretinal and subretinal proliferation in all cases. The surgical management was vitrectomy with scleral buckling, retinotomy, removal of preretinal and subretinal proliferation, and silicone oil tamponade. Mandatory prone positioning and limb restraint were not indicated. Postoperative anatomic and functional success were studied. The follow-up ranged from 3 to 62 months (mean: 25.8 months). RESULTS: The retina was attached in 10 eyes (100%) at the final examination. Functional success, based on an improvement in patient daily activity, was achieved in 4 patients (44%). No severe complications were noted. CONCLUSIONS: Treatment with vitrectomy was effective to manage severe PVR in patients with cognitive disabilities and contributed to improve daily life.

Characterization of the denatured structure of pyrrolidone carboxyl peptidase from a hyperthermophile under nondenaturing conditions: role of the C-terminal alpha-helix of the protein in folding and stability.

The cysteine-free pyrrolidone carboxyl peptidase (PCP-0SH) from a hyperthermophile, Pyrococcus furiosus, can be trapped in the denatured state under nondenaturing conditions, corresponding to the denatured structure that exists in equilibrium with the native state under physiological conditions. The denatured state is the initial state (D1 state) in the refolding process but differs from the completely denatured state (D2 state) in the concentrated denaturant. Also, it has been found that the D1 state corresponds to the heat-denatured state. To elucidate the structural basis of the D1 state, H/D exchange experiments with PCP-0SH were performed at pD 3.4 and 4 degrees C. The results indicated that amide protons in the C-terminal alpha6-helix region hardly exchanged in the D1 state with deuterium even after 7 days, suggesting that the alpha6-helix (from Ser188 to Glu205) of PCP-0SH was stably formed in the D1 state. In order to examine the role of the alpha6-helix in folding and stability, H/D exchange experiments with a mutant, A199P, at position 199 in the alpha6-helix region were performed. The alpha6-helix region of A199P in the D1 state was partially unprotected, while some hydrophobic residues were protected against the H/D exchange, although these hydrophobic residues were unprotected in the wild-type protein. These results suggest that the structure of A199P in the D1 state formed a temporary stable denatured structure with a non-native hydrophobic cluster and the unstructured alpha6-helix. Both the stability and the refolding rate decreased by the substitution of Pro for Ala199. We can conclude that the native-like helix (alpha6-helix) of PCP-0SH is already constructed in the D1 state and is necessary for efficient refolding into the native structure and stabilization of PCP-0SH.

Unusually slow denaturation and refolding processes of pyrrolidone carboxyl peptidase from a hyperthermophile are highly cooperative: real-time NMR studies.

The refolding rate of heat-denatured cysteine-free pyrrolidone carboxyl peptidase (PCP-0SH) from Pyrococcus furiosus has been reported to be unusually slow under some conditions. To elucidate the structural basis of the unusually slow kinetics of the protein, the denaturation and refolding processes of the PCP-0SH were investigated using a real-time 2D (1)H-(15)N HSQC and CD experiments. At 2 M urea denaturation of the PCP-0SH in the acidic region, all of the native peaks in the 2D HSQC spectrum completely disappeared. The conformation of the PCP-0SH just after removal of 6 M GuHCl could be observed as a stable intermediate (D(1) state) in 2D HSQC and CD experiments, which is similar to a molten globule structure. The D(1) state of the PCP-0SH, which is the initial state of refolding, corresponded to the state at 2 M urea and seemed to be the denatured state in equilibrium with the native state under the physiological conditions. The refolding of PCP-0SH from the D(1) state to the native state could be observed to be highly cooperative without any intermediates between them, even if the refolding rate was quite slow. In the higher concentration of denaturants, PCP-0SH showed HSQC and CD spectra characteristic of completely unfolded proteins called the D(2) state. The unusually slow refolding rate was discussed as originating in the conformations in the transition state and/or the retardation of reorganization in an ensemble of nonrandom denatured structures in the D(1) state.

Magnetic attraction of iron-endocytosed corneal endothelial cells to Descemet's membrane.

PURPOSE: To evaluate the feasibility of a novel method of magnetic attraction of iron-endocytosed corneal endothelial cells to Descemet's membrane. METHODS: Cultured rabbit corneal endothelial cells (RCEC) were exposed to spherical iron powder at various concentration ranging 0-100 micro moll(-1). After 24hr, the cell density and morphology were evaluated. RCEC that had been exposed to spherical iron powder (RCEC-iron), were trypsinized and poured onto a culture dish where a neodium magnet was fixated paracentrally. After 24hr, the cell density was measured at the areas with and without a magnet. Rabbits' corneas were cryo-injuried to detach corneal endothelial cells and 1x10(5)/200 micro l RCEC-iron were injected into the anterior chamber. Neogium magnet was fixed on the lid for 24hr to attract RCEC to Descemet's membrane. Each operated eye was observed up to 2 months after the injury. RCEC group (rabbits with cryo-injury and injection of normal cultured RCEC) and cryo group (rabbits with cryo-injury but without injection of RCEC) served as controls. RESULTS: The RCEC-iron density on the dish decreased in the medium containing iron powder of 10 micro moll(-1) or more. When RCEC had been exposed to iron powder of between 5 and 10 micro moll(-1), the ratio of RCEC in the field with a magnet to RCEC in the field without a magnet increased. In the RCEC-iron group, the mean corneal thickness gradually decreased and was significantly less than in the other two groups at 2, 4, and 8 weeks after the cell injection. Fluorescein microscopic examination showed a monolayer of DiI-labelled cells on the Descemet's membrane. CONCLUSION: Magnetic attachment of iron-endocytosed corneal endothelial cells to Descemet's nembrane can be a method of choice for corneal endothelial decompensation.

NMR structural study of two-disulfide variant of hen lysozyme: 2SS[6-127, 30-115]--a disulfide intermediate with a partly unfolded structure.

The 15N-labeled recombinant hen lysozyme and two species of two-disulfide variants, denoted as 2SS[6-127, 30-115] and 2SS[64-80, 76-94], were studied by means of NMR spectroscopy. The former variant contains two disulfide bridges in the alpha-domain, while the latter has one disulfide bridge in the beta-domain and the other one at the interface between two domains. Resonance assignments were performed using 3D TOCSY-HSQC and NOESY-HSQC spectra. The 15N-1H-HSQC spectrum of 2SS[6-127, 30-115] was similar to that of recombinant lysozyme as a whole, although a number of cross-peaks disappeared. On the other hand, the HSQC spectrum of 2SS[64-80, 76-94] was characteristic of unfolded proteins. The structure of 2SS[6-127, 30-115] was thoroughly examined on the basis of NOE contacts determined by NMR spectroscopy. The structure of the alpha-domain was quite similar to that of authentic lysozyme, while the beta-domain was largely unstructured. However, NMR data clearly demonstrated that some residual structures exist in the beta-domain. The beta1 and beta2 strands were maintained stably as an antiparallel beta-sheet. In addition, the residues 55 and 56 were located in the vicinity of the end of the B-helix. Further, the C-helix was properly set with side-chains of I88, V92, K96, and V99 facing toward the hydrophobic core in the alpha-domain. These residual structures inherent in the amino acid sequence were evaluated concerning the folding process of lysozyme. Our experiments imply that the establishment of the backbone conformation ranging from residues 76-99 plays a key role in attaining the cooperativity between two domains required for the folding transition.