Understanding the Reaction Mechanism of Ni-Catalyzed Regio- and Enantioselective Hydroalkylation of Enamines: Chemoselectivity of (Bi-oxazoline)NiH.

This density functional theory study explores the detailed mechanism of nickel-catalyzed hydroalkylation of the C═C bond of N-Cbz-protected enamines (Cbz = benzyloxycarbonyl) with alkyl iodides to give chiral α-alkyl amines. The active catalyst (biOx)NiH, a chiral bioxazoline (biOx)-chelated Ni(I) hydride, exhibits chemoselectivity that favors single electron transfer to the alkyl iodide over C═C hydrometalation with the enamine. This generates an alkyl radical and a Ni(II) intermediate, which takes up the enamine substrate CbzNHCH═CH2CH3 via a regio- and enantioselective C═C insertion into the NiII-H bond. The resulting Ni(II) alkyl complex combines with the alkyl radical, forming a Ni(III) intermediate, from which the alkyl-alkyl reductive elimination delivers the chiral amine product. The regioselectivity arises from a combination of orbital and noncovalent interactions, both of which are induced by the Cbz group. Thus, Cbz plays an additional role in controlling regioselectivity. The enantioselectivity stems from the differing distortion energies of CbzNHCH═CH2CH3. The reductive elimination is the rate-determining step (ΔG⧧ = 18.7 kcal/mol). In addition, the calculations show a noninnocent behavior of the biOx ligand induced by the insertion of CbzNHCH═CH2CH3 into the Ni-H bond of (biOx)NiH. These computationally gained insights can have implications for developing new Ni(I)-catalyzed reactions.

Alteration of UCP2 and ZO-1 expression in trabecular meshwork of neovascular glaucoma patients.

PURPOSE: The aim of this study was to investigate the expression of uncoupling protein 2 (UCP2) and zonula occludens-1 (ZO-1) in the trabecular meshwork (TM) of neovascular glaucoma (NVG) patients treated with trabeculectomy. MATERIALS AND METHODS: Six eyes with NVG underwent trabeculectomy for therapeutic purposes. The data consisted of patient demographics, presurgical and postsurgical visual acuity, intraocular pressure, gonioscopy, and neovascularization of iris and/or the anterior chamber angle. TM samples were obtained from the NVG eyes that had undergone surgery. Immunofluorescence and confocal laser scanning microscopy were carried out to determine the expression of UCP2 and ZO-1 in the TM cells. RESULTS: The baseline median visual acuity was light perception, and the mean intraocular pressure (standard error) was 52.5 (8.3) mm Hg. All eyes displayed neovascularization of the iris and the anterior chamber angle. The expression of UCP2 was significantly decreased in TM cells of NVG compared with the control (P=0.000), whereas increase in ZO-1 expression was detected in staining cells with NVG in comparison with the control (P=0.000). The necrotic cells in the TM were increased (P=0.000), whereas the viable cells were reduced (P=0.000) in comparison with the control. CONCLUSIONS: The decreased UCP2 expression and increased ZO-1 expression suggest that the oxidative stress-induced mitochondrial dysfunction and tight junction formation may play pivotal roles in the progress of NVG.

Overexpression of CDKN1B inhibits fibroblast proliferation in a rabbit model of experimental glaucoma filtration surgery.

PURPOSE: To investigate the potential antiproliferative effect of cyclin-dependent kinase inhibitor 1B (CDKN1B) overexpression in a rabbit model of glaucoma filtration surgery (GFS). METHODS: The recombinant adenovector expressing exogenous CDKN1B was delivered to Tenon's capsule by subconjunctival injection during unilateral filtration surgery. The time course of CDKN1B expression was monitored by immunohistochemistry and Western blot analysis. Evaluation of proliferating activity was performed by proliferating cell nuclear antigen (PCNA), argyrophilic nucleolar organizing region (AgNOR) staining, and fibroblast-specific protein 1 (FSP-1). Cyclin-dependent kinase 2 (Cdk2) and Cdk4 expression were detected with immunohistochemical analysis. RESULTS: The overexpression of CDKN1B in Tenon's capsule was monitored throughout the experimental period. Immunoreactivity to CDKN1B was mainly observed in the nucleus of fibroblasts. The increased expression of CDKN1B in sclera was detected up to 21 days after viral infection, whereas the level of CDKN1B protein in corneal stroma was not significantly increased. The overexpression of CDKN1B induced a significant decrease in AgNOR number/nucleus and area/nucleus, PCNA staining, FSP-1 positive cells, and the decreased expressions of Cdk2 and Cdk4, as evidenced by nuclear and cytoplasmic immunoreactivity to Cdk2 and Cdk4 antibodies in positive fibroblasts. CONCLUSIONS: The persistent overexpression of CDKN1B mediated by the recombinant adenovector expressing exogenous CDKN1B in Tenon's fibroblasts after GFS may lead to the inhibition of fibroblast proliferation and the downregulation of Cdk2 and Cdk4 activity, thereby reducing the severity of scar formation and the surgical outcome.

Clinical evaluation of traumatic ciliochoroidal detachment with surgical treatment.

PURPOSE: To determine the clinical features of traumatic ciliochoroidal detachment (CCD), and to evaluate the surgical outcomes. METHODS: We retrospectively reviewed the records of 37 consecutive patients with traumatic CCD who underwent surgical procedures, including ciliary body suturing, transscleral cyclophotocoagulation, and cyclocryopexy. A complete ocular examination was performed at pre-surgery and at periodical post-surgery follow-ups. We compared visual acuity (VA), intraocular pressure (IOP), and morphologic changes with UBM among the different surgical procedures at the pre-surgery and periodical follow-ups. RESULTS: The mean IOP was 6.62 mmHg, and the median VA was 20/200 at baseline. The mean final IOP was 11.03 mmHg, and the final median VA improved to 20/50. IOPs were significantly different in post-surgery compared with those at baseline (P = 0.000) among the ciliary body suturing, cyclophotocoagulation, and cyclocryopexy groups. However, no significant differences were noted at each follow-up among the 3 groups (P > 0.05). The post-surgical morphological figures consisted of complete reattachment, partial reattachment, and the complete detachment. Cyclocryopexy (71.4%), suturing (68.4%), and cyclophotocoagulation (63.6%) produced similar surgical outcomes of the complete reattachment based on UBM images. CONCLUSION: Prompt treatment and periodic follow-ups are necessary after traumatic CCD, based on accurate dimensions and configuration by UBM. The appropriate choice of surgical procedures is pivotal for an optimal outcome.

Histological and ultrastructural features for proliferation inhibition by delivery of exogenous p27Kip1 to rabbit models after glaucoma filtration surgery.

PURPOSE: To investigate postoperative inhibition of cell proliferation in animals treated with exogenous p27Kip1 during an experimental glaucoma filtration surgery (GFS) by histological and ultrastructural examinations. METHODS: The primer was designed according to p27Kip1 gene sequence of GenBank. The p27Kip1-expressing adenovirus-mediated Ad-p27 was constructed according to standard techniques. Gene therapy was performed by subconjunctival delivery of Ad-p27, mitomycin C (MMC) and PBS served as controls. Histological and ultastructural changes at surgical sites were observed for 28 days postoperatively. RESULTS: Histologically, evident cellular proliferation induced by Ad-p27 was observed on day 7, with appreciable filtering cavity. However, thin conjunctival layers were noted, and the number of fibroblasts decreased in the Tenon's capsule on day 14. On day 28, the filtering cavity partially disappeared. The histological features of the animals with MMC delivery were similar to those treated by Ad-p27. In contrast, in the PBS treatment group, thick conjunctival layers were observed, and the number of goblet cells and fibroblasts, increased markedly. The filtering cavity disappeared at postoperative day 21. Twenty eight day postoperatively, ultrastructural findings showed that most conjunctival epithelial cells in the Ad-p27 treatment group were under static state, and that organelles were inactive. The number of goblet cells, and the secretion of mucin, were decreased. The amount of fibroblasts also decreased with partial apoptotic cells. The ultrastructural features presented by rabbits with the MMC delivery resembled those treated with Ad-p27. In the PBS treatment group, the number of conjunctival epithelial cells increased; the amount of goblet cells increased as the secretion of mucin was strengthened, and a substantial amount of fibroblasts were observed with active and productive organelles. CONCLUSION: Ad-p27 inhibits the proliferation of Tenon's capsule fibroblasts at surgical sites, and suppresses the formation of scars, thereby promoting surgical efficacy.