Ceramide inhibits axonal growth and nerve growth factor uptake without compromising the viability of sympathetic neurons

Ceramide inhibits axonal growth of cultured rat sympathetic neurons when the ceramide content of distal axons, but not cell bodies, is increased (Posse de Chaves, E. I., Bussiere, M. Vance, D. E., Campenot, R. B., and Vance, J.E. (1997) J. Biol. Chem. 272, 3028-3035). We now report that inhibition of growth does not result from cell death since although ceramide is a known apoptotic agent, C(6)-ceramide given to the neurons for 24 h did not cause cell death but instead protected the neurons from death induced by deprivation of nerve growth factor (NGF). We also find that a pool of ceramide generated from sphingomyelin in distal axons, but not cell bodies, inhibits axonal growth. Analysis of endogenous sphingomyelinase activities demonstrated that distal axons are rich in neutral sphingomyelinase activity but contain almost no acidic sphingomyelinase, which is concentrated in cell bodies/proximal axons. Together, these observations are consistent with the idea that generation of ceramide from sphingomyelin by a neutral sphingomyelinase in axons inhibits axonal growth. Furthermore, we demonstrate that treatment of distal axons with ceramide inhibits the uptake of NGF and low density lipoproteins by distal axons by approximately 70 and 40%, respectively, suggesting that the inhibition of axonal growth by ceramide might be due, at least in part, to impaired endocytosis of NGF. However, inhibition of endocytosis of NGF by ceramide could not be ascribed to decreased phosphorylation of TrkA.

Nd:YAG laser corneal disruption as adjuvant treatment for infectious crystalline keratopathy

PURPOSE

To report on the use of the Nd:YAG laser corneal disruption in the treatment of infectious crystalline keratopathy.

METHOD

Case report. A 52-year-old woman with infectious crystalline keratopathy unresponsive to topical antibiotics was treated with an Nd:YAG laser to the intrastromal crystals.

RESULTS

After Nd:YAG laser treatment, the infiltrate completely cleared within 4 weeks.

CONCLUSIONS

Nd:YAG laser treatment may be effective in disrupting the protective glycocalyx matrix within the intrastromal crystals, rendering the bacteria susceptible to topical antibiotics. This treatment should be considered for patients with infectious crystalline keratopathy clinically resistant to topical antibiotics.

High replicability of newly discovered social-behavioural findings is achievable

Failures to replicate evidence of new discoveries have forced scientists to ask whether this unreliability is due to suboptimal implementation of methods or whether presumptively optimal methods are not, in fact, optimal. This paper reports an investigation by four coordinated laboratories of the prospective replicability of 16 novel experimental findings using rigour-enhancing practices: confirmatory tests, large sample sizes, preregistration and methodological transparency. In contrast to past systematic replication efforts that reported replication rates averaging 50%, replication attempts here produced the expected effects with significance testing (P < 0.05) in 86% of attempts, slightly exceeding the maximum expected replicability based on observed effect sizes and sample sizes. When one lab attempted to replicate an effect discovered by another lab, the effect size in the replications was 97% that in the original study. This high replication rate justifies confidence in rigour-enhancing methods to increase the replicability of new discoveries.

Candidate name order effects in New Hampshire: Evidence from primaries and from general elections with party column ballots

Research in a few U.S. states has shown that candidates listed first on ballots gain extra votes as a result. This study explored name order effects for the first time in New Hampshire, where such effects might be weak or entirely absent because of high political engagement and the use of party column ballots. In general elections (in 2012 and 2016) for federal offices and the governorship and in primaries (in 2000, 2002, and 2004), evidence of primacy effects appeared in 86% of the 84 tests, including the 2016 presidential race, when Donald Trump gained 1.7 percentage points from first listing, and Hillary Clinton gained 1.5 percentage points. Consistent with theoretical predictions, primacy effects were larger in primaries and for major-party candidates in general elections than for non-major-party candidates in general elections, more pronounced in less publicized contests, and stronger in contests without an incumbent running. All of this constitutes evidence of the reliability and generalizability of evidence on candidate name order effects and their moderators.