Metal Ion Dependence of the Asymmetric Transamination of Phenylpyruvic Acid by Pyridoxamine in the Presence of β-Cyclodextrin

Transamination reactions of phenylpyruvic acid and pyridoxamine in the presence of metal ions and B-cyclodextrin as a chiral auxiliary have been investigated in neutral aqueous solution. The rate and extent of the transamination, and the asymmetric induction observed in the reaction depend upon the nature of the metal ion. In particular, while Zn2+and C02+yield preferentially the aldimine complex of L-phenylalanine, Cu2\u27 yields preferentially the complex of D-phenylalanine and Ni2+only the racemic product. It is proposed that the ketimine complexes are bound to B-cyclodextrin through the phenyl group of the keto acid residue and that the stereoselectivity of the reaction is originated by some direct interaction of the hydroxyl groups of the cyclodextrin moiety and the metal ions. Although the extent of asymmetric induction is modest in these simple systems (10-20°/0 optical purities), the present results show that transition metal complexes can play a prominent role in determining the steric course of the asymmetric reaction

Comparison of Newly Diagnosed Ocular Hypertension and Open-Angle Glaucoma: Ocular Variables, Risk Factors, and Disease Severity

Purpose. To describe the distribution of ocular variables, risk factors, and disease severity in newly diagnosed ocular hypertension (OH) or open-angle glaucoma (OAG). Methods. Eligible subjects underwent a complete history and examination. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) obtained from multiple logistic regression models were used to compare OAG to OH and advanced to early/moderate OAG. Results. 405 subjects were enrolled: 292 (72.1%) with OAG and 113 (27.9%) with OH. 51.7% had early, 27.1% moderate, and 20.9% advanced OAG. The OR for OAG versus OH was 8.19 (P < 0.0001) for disc notch, 5.36 (P < 0.0001) for abnormal visual field, 1.45 (P = 0.001) for worsening mean deviation, 1.91 (P < 0.0001) for increased cupping, 1.03 for increased age (P = 0.030), and 0.36 (P = 0.010) for smoking. Conclusions. Increased age was a risk for OAG, and smoking decreased the risk of OAG compared to OH. Almost half of the OAG subjects had moderate/advanced disease at diagnosis