Thiourea Derivative of 2-[(1 R)-1-Aminoethyl]phenol: A Flexible Pocket-like Chiral Solvating Agent (CSA) for the Enantiodifferentiation of Amino Acid Derivatives by NMR Spectroscopy

Thiourea derivatives of 2-[(1R)-1-aminoethyl]phenol, (1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, (1R,2R)-(1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, and (R)-1-phenylethanamine have been compared as chiral solvating agents (CSAs) for the enantiodiscrimination of derivatized amino acids using nuclear magnetic resonance (NMR) spectroscopy. Thiourea derivative, prepared by reacting 2-[(1R)-1-aminoethyl]phenol with benzoyl isothiocyanate, constitutes an effective CSA for the enantiodiscrimination of N-3,5-dinitrobenzoyl (DNB) derivatives of amino acids with free or derivatized carboxyl functions. A base additive 1,4-diazabicyclo[2.2.2]octane(DABCO)/N,N-dimethylpyridin-4-amine (DMAP)/NBu4OH) is required both to solubilize amino acid derivatives with free carboxyl groups in CDCl3 and to mediate their interaction with the chiral auxiliary to attain efficient differentiation of the NMR signals of enantiomeric substrates. For ternary systems CSA/substrate/DABCO, the chiral discrimination mechanism has been ascertained through the NMR determination of complexation stoichiometry, association constants, and stereochemical features of the diastereomeric solvates

Intraocular pressure in silicon-oil tamponated eyes using a non-contact pulse synchronous tonometer: IOP measurement in vitrectomized and silicon-oil tamponated eyes by NT-4000

Objective To assess the reliability of intraocular pressure (IOP)measurement by means of NidekNT - 4000 tonometer in vitrectomized and siliconoil tamponaded (VSOT)eyes. Methods IOP was measured by means of NidekNT - 4000 and compared with standard Goldmann applanation tonometer (GAT)in 36 consecutive VSOT eyes and 36 normal eyes. Results In VSOT and nor mal eyes NidekNT - 4000 showed agreement with GAT (VSOT eyes mean difference:1. 83 ± 2. 64,P = 0 55;correlation:P < 0 0001,r = 0 95;Normal eyes mean difference:1 ± 2 8,P = 0 42;correlation:P = 0 0045,r = 0 69 ). Differences were similar be tween groups (P = 0 81). Conclusions NidekNT - 4000 tonometer offers a new affordable method to measure IOP in vitrectomized and siliconoil tamponaded eyes

Diathermy of leaking sclerotomies after 23-gauge transconjunctival pars plana vitrectomy: a prospective study.

PURPOSE: To evaluate the efficacy of bipolar diathermy in ensuring closure of leaking sclerotomies after complete 23-gauge transconjunctival sutureless vitrectomy. METHODS: In this prospective, interventional case series, in 136 eyes of 136 patients with at least one leaking sclerotomy at the end of a complete 23-gauge transconjunctival sutureless vitrectomy, external bipolar wet-field diathermy was applied to leaking sclerotomies, including the conjunctiva and sclera. Intraoperative wound closure, and postoperatively, at 6 hours, 1 day and 3 days, sclerotomies leakage, intraocular pressure, hypotony, and hypotony-related complications were evaluated. RESULTS: Intraoperative closure was achieved in 231 of 238 leaking sclerotomies (97%) that received diathermy. One of these with postoperative leakage needed suture. Compared with baseline (14.4 ± 2.8 mmHg), mean intraocular pressure was lower at 6 hours (13.2 ± 3.8 mmHg, Tukey-Kramer P &lt; 0.001) and not different at 24 hours or 72 hours. Hypotony (intraocular pressure &lt;5 mmHg) was observed in 6 eyes (4.5%) at 6 hours, in 2 (1.5%) at 24 hours, and in none at 3 days. Logistic regression analysis showed that, 6 hours postoperatively, hypotony was related to younger age (≤50 years) at surgery (P = 0.031). No hypotony-related complications were recorded. CONCLUSION: Bipolar wet-field diathermy of sutureless sclerotomies is an effective method for ensuring a leaking sclerotomies closure

Hydrolysis and enantiodiscrimination of (R)-and (s)-oxazepam hemisuccinate by methylated β-cyclodextrins: An nmr investigation

Partially and exhaustively methylated β-cyclodextrins [(2-methyl)-β-CD (MCD), heptakis-(2,6-di-O-methyl)-β-CD (DIMEB), and heptakis-(2,3,6-tri-O-methyl)-β-CD (TRIMEB)] have been compared in the hydrolysis and enantiodiscrimination of benzodiazepine derivative (R)-or (S)-oxazepam hemisuccinate (OXEMIS), using nuclear magnetic resonance (NMR) spectroscopy as an investigation tool. After 6 h, MCD induced an 11% hydrolysis of OXEMIS, remarkably lower in comparison with underivatized β-CD (48%), whereas no hydrolysis was detected in the presence of DIMEB or TRIMEB after 24 h. DIMEB showed greater ability to differentiate OXEMIS enantiomers in comparison to TRIMEB, by contrast MCD did not produce any splitting of racemic OXEMIS resonances. Both enantiomers of OXEMIS underwent deep inclusion of their phenyl pendant into cyclodextrins cavities from their wider rims, but tighter complexes were formed by DIMEB with respect to TRIMEB

A Dimeric Thiourea CSA for the Enantiodiscrimination of Amino Acid Derivatives by NMR Spectroscopy

The reaction of benzoyl isothiocyanate with (1R,2R)-1,2-bis(2-hydroxyphenyl)ethylenediamine afforded a new thiourea chiral solvating agent (CSA) with a very high ability to differentiate 1H and 13C NMR signals of simple amino acid derivatives, even at low concentrations. The enantiodiscrimination efficiency was higher with respect to that of the parent monomer, a thiourea derivative of 2-((1R)-1-aminoethyl)phenol, thus putting into light the relevance of the cooperativity between the two molecular portions of the dimer in a cleft conformation stabilized by interchain hydrogen bond interactions. An achiral base additive (DABCO or DMAP) played an active role in the chiral discrimination processes, mediating the interaction between the CSA and the enantiomeric mixtures. The chiral discrimination mechanism was investigated by NMR spectroscopy through the determination of complexation stoichiometries, association constants, and the stereochemistry of the diastereomeric solvates

Perfluorocarbon liquid-assisted inverted inner limiting membrane-flap for large macular hole after recurrent rhegmatogenous retinal detachment

A 45-year-old Caucasian myopic woman with a severe vision impairment (20/320) in the left eye due to a macula-off rhegmatogenous retinal detachment (RRD) underwent vitrectomy with silicone oil tamponade followed by an inferior relaxing retinectomy with heavy silicone oil tamponade during the second procedure for recurrence of RRD due to proliferative vitreoretinopathy. Four weeks after the second surgery, visual acuity was 20/200 and the patient complained metamorphopsia in the same eye due to a large full-thickness macular hole. A perfluorocarbon liquid-assisted inverted inner limiting membrane-flap technique was performed. Visual acuity improved to 20/80 after closing of macular hole and partial recovery of outer retinal layers at 3 months from the last surgery

Analysis of morphologic and functional outcomes in macular edema due to central retinal vein occlusion treated with intravitreal dexamethasone implant

Purpose. To analyze anatomic and functional retinal changes and their correlation after intravitreal dexamethasone implant (DEX implant) in patients with central retinal vein occlusion- (CRVO-) related macular edema (ME) using optical coherence tomography and microperimetry. Methods. Fifteen treatment-naïve patients with functional impairment due to CRVO-related ME were enrolled in this prospective interventional case series. Main outcomes were best-corrected visual acuity (BCVA), retinal sensitivity (RS), and central retinal thickness (CRT). Secondary outcomes were ellipsoid zone (EZ) status and fixation behaviour. All patients underwent DEX implant and were retreated according to predefined criteria. Data were prospectively recorded at baseline and at month 1, 3, 6, 9, and 12. Correlation between main outcomes was analyzed. Results. Fifteen eyes of 15 patients (9 men, 6 women; mean age 61.8 ± 10.9 years) were included. BCVA and CRT significantly improved at all follow-up visits, while RS significantly improved at 3, 6, 9, and 12 months. EZ status and fixation behaviour did not change significantly. Baseline CRT had a significant negative correlation with BCVA and RS at different follow-up visits (r=-0.52 to -0.63, p≤0.04; r=-0.52, p=0.04; resp.). At all time points, there was not a significant correlation between CRT and BCVA and RS, while RS and BCVA showed a significant correlation, increasing over time (r=-0.72 to -0.89; p&lt;0.001). Conclusion. DEX implant led to a significant morphofunctional improvement. Baseline CRT is predictive of changes of functional outcomes whose correlation increases over time after treatment

INVERTED INTERNAL LIMITING MEMBRANE-FLAP TECHNIQUE FOR OPTIC DISK PIT MACULOPATHY: MORPHOLOGIC AND FUNCTIONAL ANALYSIS

To analyze morphologic and functional changes after inverted internal limiting membrane-flap technique for optic disk pit maculopathy using optical coherence tomography, multifocal electroretinography, and microperimetry

Anterior capsule staining using micronized triamcinolone in the absence of red reflex

We describe a technique to stain the anterior lens capsule with micronized triamcinolone to perform a continuous curvilinear capsulorhexis (CCC) during phacoemulsification in the absence of a red reflex due to vitreous hemorrhage. After a self-sealing clear corneal tunnel incision is performed using a 2.75 mm blade, a dispersive ophthalmic viscosurgical device (OVD) is injected to protect the iridocorneal angle. An air bubble as large as possible is injected into the center of the anterior chamber, and a small amount of micronized triamcinolone is then injected as needed to stain the anterior lens capsule. The OVD injection permits the removal of excessive triamcinolone and protects the corneal endothelium from damage during phacoemulsification. A capsulorhexis forceps is used to perform the CCC. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned