Alien Registration- Letourneau, Joseph C. (Lewiston, Androscoggin County)

https://digitalmaine.com/alien_docs/27236/thumbnail.jp

Actin turnover is required to prevent axon retraction driven by endogenous actomyosin contractility

Growth cone motility and guidance depend on the dynamic reorganization of filamentous actin (F-actin). In the growth cone, F-actin undergoes turnover, which is the exchange of actin subunits from existing filaments. However, the function of F-actin turnover is not clear. We used jasplakinolide (jasp), a cell-permeable macrocyclic peptide that inhibits F-actin turnover, to study the role of F-actin turnover in axon extension. Treatment with jasp caused axon retraction, demonstrating that axon extension requires F-actin turnover. The retraction of axons in response to the inhibition of F-actin turnover was dependent on myosin activity and regulated by RhoA and myosin light chain kinase. Significantly, the endogenous myosin-based contractility was sufficient to cause axon retraction, because jasp did not alter myosin activity. Based on these observations, we asked whether guidance cues that cause axon retraction (ephrin-A2) inhibit F-actin turnover. Axon retraction in response to ephrin-A2 correlated with decreased F-actin turnover and required RhoA activity. These observations demonstrate that axon extension depends on an interaction between endogenous myosin-driven contractility and F-actin turnover, and that guidance cues that cause axon retraction inhibit F-actin turnover

Influence of gender and age on cognitive inhibition in late-onset depression: a case-control study

ObjectiveTo compare cognitive inhibition performance between people with early-onset (EOD) or late-onset depression (LOD) and controls, and between women and men with LOD.MethodsOn the basis of a case-control design, global executive performance (Frontal Assessment Battery); verbal (Hayling), attention (Stroop), and motor (Go/No-Go) components of cognitive inhibition; mental shifting (Trail Making Test parts A and B); and updating in working memory (Wechsler Adult Intelligence Scale) were assessed in 40 participants (10 depressed women with LOD (i.e., 60years old), 10 depressed women with EOD (i.e., <60years old), 10 healthy women and 10 depressed men with LOD (i.e., 60years old)). ResultsOlder depressed women, irrespective of age of depression onset, had greater cognitive inhibition impairments (attention and verbal component) compared with healthy women. LOD was significantly associated with the attention component of cognitive inhibition impairment, unlike EOD (p=0.026). No executive differences were found regarding age of first-onset depression in older depressed women, and between women and men with LOD. ConclusionCognitive inhibition impairment, and more specifically its attention component, was the main characteristic of depression in the studied sample of older adults, independently of gender and age of depression onset. It is essential to perform similar studies in both genders in view of future tailor-made therapeutic modalities. Copyright (c) 2013 John Wiley & Sons, Ltd

Estimate of the impact of background particles on the X-Ray Microcalorimeter Spectrometer on IXO

We present the results of a study on the impact of particles of galactic (GCR) and solar origin for the X-ray Microcalorimeter Spectrometer (XMS) aboard an astronomical satellite flying in an orbit at the second Lagrangian point (L2). The detailed configuration presented in this paper is the one adopted for the International X-Ray Observatory (IXO) study, however the derived estimates can be considered a conservative limit for ATHENA, that is the IXO redefined mission proposed to ESA. This work is aimed at the estimate of the residual background level expected on the focal plane detector during the mission lifetime, a crucial information in the development of any instrumental configuration that optimizes the XMS scientific performances. We used the Geant4 toolkit, a Monte Carlo based simulator, to investigate the rejection efficiency of the anticoincidence system and assess the residual background on the detector.Comment: 18 pages, 9 figure