Effects of Lidocaine on Mitomycin C Cytotoxicity.

PURPOSE: Intra-Tenon or subconjunctival injection of a solution of mitomycin C (MMC) and 1% preservative-free lidocaine (as an anesthetic) has gained popularity for its use in trabeculectomy, a filtering surgery for glaucoma. To our knowledge, no studies have analyzed the impact of lidocaine on the cytotoxic effects of MMC in this setting. This study was conducted to evaluate in vitro fibroblast cytotoxicity to a solution of MMC (0.2 mg/ml) and 1% preservative-free lidocaine. DESIGN: Experimental study. PARTICIPANTS: Nonhuman subject research. METHODS: Cultured human conjunctival fibroblasts were incubated in phosphate-buffered saline (PBS) (control), MMC (0.2 mg/ml), a mixture of 0.2 mg/ml MMC + 1% preservative-free lidocaine, or 1% preservative-free lidocaine. Samples were taken at 2, 5, 10, 30, and 60 minutes, and a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay with photoabsorbance testing was used to assess conjunctival cell viability. MAIN OUTCOME MEASURE: Mean photoabsorbance. RESULTS: Mean photoabsorbance across all time intervals was 0.680 for solutions incubated in PBS, 0.642 for MMC, 0.612 for MMC + 1% preservative-free lidocaine, and 0.605 for 1% preservative-free lidocaine. A 2-way analysis of variance analyzing solution, time, and solution-time interaction on photoabsorbance showed that PBS was least cytotoxic and an optimal control for this study. Tukey post hoc comparisons showed that MMC was more cytotoxic than PBS (P < 0.001). However, both MMC + 1% preservative-free lidocaine and 1% preservative-free lidocaine were more cytotoxic than MMC and PBS (P < 0.01 for all). No significant differences in cytotoxicity comparing lidocaine-containing solutions were observed. CONCLUSIONS: In this in vitro study, we found an increase in cytotoxicity when MMC (0.2 mg/ml) was combined with 1% preservative-free lidocaine. We note that lidocaine did not inhibit MMC cytotoxicity and exhibited a significant cytotoxic effect on its own.

Kinetic Modeling of West Nile Virus Fusion Indicates an Off-Pathway State.

West Nile virus (WNV) is a prominent mosquito-borne flavivirus that causes febrile illness in humans. To infect host cells, WNV virions first bind to plasma membrane receptors, then initiate membrane fusion following endocytosis. The viral transmembrane E protein, triggered by endosomal pH, catalyzes fusion while undergoing a dimer-to-trimer transition. Previously, single-particle WNV fusion data was interrogated with a stochastic cellular automaton simulation, which modeled the E proteins during the fusion process. The results supported a linear fusion mechanism, with E protein trimerization being rate-limiting. Here, we present corrections to the previous simulation, and apply them to the WNV fusion data. We observe that a linear mechanism is no longer sufficient to fit the data. Instead, an off-pathway state is necessary; these results are corroborated by per virus chemical kinetics modeling. When compared with a similar Zika virus fusion model, this suggests that off-pathway fusion mechanisms may characterize flaviviruses more broadly.

Ptosis after glaucoma surgery.

PURPOSE: Evaluate factors contributing to ptosis after glaucoma surgery. METHODS: Three-year retrospective chart review from January 1, 2012, to January 1, 2015, 157 eyes, 3 surgeons, at Boston Medical Center, to determine the incidence of ptosis and the effects of each variable contributing to ptosis at 3 months after surgery. Each variable was analyzed using the chi-square or independent samples t-test analysis to determine statistical significance of ptosis compared with above variables. RESULTS: The t-test or chi-square analysis showed that gender, steroid duration, use of mitomycin C, duration of surgery, and prior surgeries were not statistically significant factors for ptosis. There was a statistically significant association between those <70 years of age and ptosis (P<0.05), non-combined surgery and ptosis (P<0.05), shunting surgery and ptosis (P<0.05). CONCLUSION: Ptotic changes occurred more often in those who have shunting (Ahmed and Baerveldt) surgeries compared with filtering (trabeculectomy and Express) surgeries.

Choroidal Ganglioneuroma and Orbital Plexiform Neurofibroma Presenting as Buphthalmos in an Infant With Neurofibromatosis Type 1.

Neurofibromatosis type 1 (NF-1) is an autosomal dominant familial tumor predisposition syndrome characterized by the growth of benign and malignant tumors involving the peripheral and central nervous system. In the following report, the authors describe a case of a 1-year-old child with NF-1, who underwent enucleation for a blind, proptotic, painful eye with subsequent histopathological examination revealing choroidal ganglioneuroma, a very rare entity.