Effects of unoprostone and endothelin 1 on L-type channel currents in human trabecular meshwork cells

BACKGROUND: The trabecular meshwork (TM) is a smooth muscle-like tissue with contractile properties and by this mechanisms involved in the regulation of aqueous humor outflow. Isopropyl unoprostone (Rescula, Novartis Ophthalmics), a synthetic docosanoid, reduces intraocular pressure in glaucoma patients and normal subjects. In isolated TM strips, unoprostone reduces TM contractility in the presence of endothelin 1 (ET-1). However, the signal transduction pathway of unoprostone still remains unclear. Since L-type channel currents are known to influence the contractility of TM, we examined the effects of unoprostone and ET-1 on L-type channel currents of TM cells. METHODS: The effects of unoprostone, ET-1 and the tyrosine kinase inhibitor herbimycin A on L-type channel currents of cultured human TM cells were investigated using the perforated patch configuration of the patch-clamp technique. RESULTS: Application of ET-1 had no effect on L-type channel currents. Unoprostone led to a dose-dependent reduction of control currents. The effect of unoprostone is independent of ET-1. After preincubation of cells with herbimycin A, unoprostone had no effect on the L-type channel current amplitude. Human TM cells preincubated with herbimycin A showed a reduced current density compared with control cells. Both substances, unoprostone and herbimycin A, increased the inactivation time constant of L-type channel currents. CONCLUSION: We conclude that unoprostone reduces the activity of L-type Ca2+ channels. This effect seems to be independent of ET-1. The signal transduction pathway seems to be mediated by tyrosine kinases.     

An evaluation of novel vital dyes for intraocular surgery

PURPOSE: To evaluate systematically the staining characteristics and safety of potential new dyes for intraocular surgery. METHODS: Six dyes were included in the investigation: light green SF (LGSF) yellowish, E68, bromophenol blue (BPB), Chicago blue (CB), rhodamine 6G, rhodulinblau-basic 3 (RDB-B3). All dyes were dissolved and diluted in a balanced saline saline solution. The light-absorbing properties of each dye were measured at a concentration of 0.05% between 200 and 1000 nm. Staining characteristics were examined by staining lens capsule tissue and epiretinal membranes (ERMs), removed intraoperatively, with dye concentrations of 1.0%, 0.5%, 0.2%, and 0.05%. Enucleated porcine eyes (postmortem time, 9 hours) were also stained. Dye-related toxicity was evaluated by a colorimetric test (MTT) measuring the inhibition of retinal pigment epithelium (RPE) cell proliferation (ARPE-19 and primary human RPE cells, passages 3-6). Cell viability was also quantified based on a two-color fluorescence cell-viability assay. Dyes were investigated in concentrations of 0.2% and 0.02%. RESULTS: All dyes investigated in this study stained human lens capsules, removed intraoperatively; ERMs, peeled during macular pucker surgery; and enucleated porcine eyes, depending on the concentration applied. The long-wavelength absorption maximum of the dyes was within the range of 527 to 655 nm at concentrations of 0.05%. Rhodamine G6 and RDB-B3 showed adverse effects on ARPE-19 cell proliferation at a concentration of 0.2% and were excluded from further investigation in primary RPE cells. The remaining four dyes showed no toxic effect on ARPE-19 and primary RPE cell proliferation at concentrations of 0.2% and 0.02%. Cell viability was affected by LGSF yellowish (0.2%) and CB (0.2% and 0.02%). Two dyes (E68 and BPB) showed no relevant toxicity in vitro. CONCLUSIONS: The systematic evaluation of dyes for intraocular use seems mandatory. In this study four dyes were identified with effective staining characteristics, with two of these dyes having no detectable toxic effect on RPE cells in vitro.     

Implicit and explicit attitudes toward smoking in a smoking and a nonsmoking setting

To test whether global smoking attitudes may be a driving factor in smoking behavior, Experiment 1 assessed smoking associations with the Implicit Association Test (IAT). Although smokers' attitudes (N=24) were less negative than those of nonsmokers (N=24), both displayed negative associations with smoking. To test whether these findings may be an artifact of measurement setting and/or the indirect measure that was used, Experiment 2 assessed attitudes in a smoking (N=20) or a nonsmoking setting (N=20) using the IAT and an Affective Simon Task. In both settings, negative attitudes emerged, suggesting that global (implicit) attitudes may be a moderating rather than a driving factor in smoking behavior.     

The prediction and cost of futility in the NICU

Aim: To quantify the cost and prediction of futile care in the Neonatal Intensive Care Unit (NICU). Methods: We observed 1813 infants on 100 000 NICU bed days between 1999 and 2008 at the University of Chicago. We determined costs and assessed predictions of futility for each day the infant required mechanical ventilation. Results: Only 6% of NICU expenses were spent on nonsurvivors, and in this sense, they were futile. If only money spent after predictions of death is considered, futile expenses fell to 4.5%. NICU care was preferentially directed to survivors for even the smallest infants, at the highest risk to die. Over 75% of ventilated NICU infants were correctly predicted to survive on every day of ventilation by every caretaker. However, predictions of ‘die before discharge’ were wrong more than one time in three. Attendings and neonatology fellows tended to be optimistic, while nurses and neonatal nurse practitioners tended to be pessimistic. Conclusions: Criticisms of the expense of NICU care find little support in these data. Rather, NICU care is remarkably well targeted to patients who will survive, particularly when contrasted with care in adult ICUs. We continue to search for better prognostic tools for individual infants.