Bers-ERK Schwann Cells Coordinate Nerve Regeneration

In this issue of Neuron, Napoli et al. (2012) demonstrate that elevated ERK/MAPK signaling in Schwann cells is a crucial trigger for Schwann cell dedifferentiation in vivo. Moreover, the authors show that dedifferentiated Schwann cells have the potential to coordinate much of the peripheral nerve response to injury

Different Signaling Pathways Mediate Regenerative versus Developmental Sensory Axon Growth

Recent advances in defining neurotrophin signaling mediators have provided insights into the signal transduction mechanisms that underlie axon growth. Evidence is accumulating that major Trk effectors regulate the morphological development of embryonic peripheral neurons. Less is known about signaling related to the robust axon extension that follows peripheral axotomy of adult neurons. Regenerative axon growth can be mimicked in vitro by a "conditioning" lesion performed 2 weeks before culture (Smith and Skene, 1997). Previous work has implicated both neurotrophins and cytokines in this response. Because signal transduction mediators of both of these families of growth factors are well characterized, we have compared the role of neurotrophin and cytokine signaling in developmental versus regenerative sensory axon growth. Chemical inhibitors were administrated to embryonic and axotomized sensory neurons in vitro to block the activation of Erk kinase (MEK)-extracellular signal-regulated kinase (ERK), phosphatidylinositol-3 kinase (PI3-K), and janus kinase (JAK) signaling. As expected, both MEK and PI3-K inhibition blocked axon growth from both naive and NGF-stimulated embryonic day 13 sensory neurons, whereas inhibition of JAK phosphorylation had no effect. In contrast, neither MEK nor PI3-K inhibitors blocked elongation of adult sensory neurons after a conditioning lesion. However, the addition of a JAK2 inhibitor prevented the regenerative axon response. Consistent with these pharmacological results, the percentage of neurons showing intense nuclear signal transducers and activators of transcription 3 phosphorylation after a conditioning lesion was markedly increased compared with controls. These observations demonstrate that the signaling mediators that underlie regenerative axon growth are distinct from those used during development and suggest that cytokine signaling may be critical to peripheral nervous system regeneration

Functions of GSK-3 Signaling in Development of the Nervous System

Glycogen synthase kinase-3 (GSK-3) is central to multiple intracellular pathways including those activated by Wnt/β-catenin, Sonic Hedgehog, Notch, growth factor/RTK, and G protein-coupled receptor signals. All of these signals importantly contribute to neural development. Early attention on GSK-3 signaling in neural development centered on the regulation of neuronal polarity using in vitro paradigms. However, recent creation of appropriate genetic models has demonstrated the importance of GSK-3 to multiple aspects of neural development including neural progenitor self-renewal, neurogenesis, neuronal migration, neural differentiation, and synaptic development

“Runx”ing towards Sensory Differentiation

Somatosensory stimuli are encoded by molecularly and anatomically diverse classes of dorsal root ganglia (DRG) neurons. In this issue of Neuron, three papers demonstrate that the Runx transcription factors, Runx1 and Runx3, respectively regulate the molecular identities and spinal terminations of TrkA+ nociceptive neurons and TrkC+ proprioceptive neurons. These findings emphasize the importance of intrinsic genetic programs in generating the diversity of DRG neurons and specifying the circuits into which they incorporate

Pilot evaluation of the Text4Baby mobile health program

Background Mobile phone technologies for health promotion and disease prevention have evolved rapidly, but few studies have tested the efficacy of mobile health in full-fledged programs. Text4baby is an example of mobile health based on behavioral theory, and it delivers text messages to traditionally underserved pregnant women and new mothers to change their health, health care beliefs, practices, and behaviors in order to improve clinical outcomes. The purpose of this pilot evaluation study is to assess the efficacy of this text messaging campaign. Methods We conducted a randomized pilot evaluation study. All participants were pregnant women first presenting for care at the Fairfax County, Virginia Health Department. We randomized participants to enroll in text4baby and receive usual health care (intervention), or continue simply to receive usual care (control). We then conducted a 24-item survey by telephone of attitudes and behaviors related to text4baby. We surveyed participants at baseline, before text4baby was delivered to the intervention group, and at follow-up at approximately 28 weeks of baby’s gestational age. Results We completed 123 baseline interviews in English and in Spanish. Overall, the sample was predominantly of Hispanic origin (79.7%) with an average age of 27.6 years. We completed 90 follow-up interviews, and achieved a 73% retention rate. We used a logistic generalized estimating equation model to evaluate intervention effects on measured outcomes. We found a significant effect of text4baby intervention exposure on increased agreement with the attitude statement “I am prepared to be a new mother” (OR = 2.73, CI = 1.04, 7.18, p = 0.042) between baseline and follow-up. For those who had attained a high school education or greater, we observed a significantly higher overall agreement to attitudes against alcohol consumption during pregnancy (OR = 2.80, CI = 1.13, 6.90, p = 0.026). We also observed a significant improvement of attitudes toward alcohol consumption from baseline to follow-up (OR = 3.57, CI = 1.13 – 11.24, p = 0.029). Conclusions This pilot study is the first randomized evaluation of text4baby. It is a promising program in that exposure to the text messages was associated with changes in specific beliefs targeted by the messages

Electro-optically Tunable Microring Resonators for Non-Linear Frequency Modulated Waveform Generation

Microring resonators are a fundamental building block for integrated optical filters, and have both modulation and waveform generation applications. A hybrid chalcogenide (As2S3) on titanium diffused (Ti:LiNbO3) waveguide platform has been developed to realize tunable microring resonators on a lithium niobate (LiNbO3) substrate. The use of a LiNbO3 substrate allows for electro-optic tuning, which is demonstrated for the first time on an As2S3 guided optical mode. While optical modes confined in diffused waveguides are commonly electro-optically tuned, the use of a rib waveguide external to the substrate poses new design challenges. Simulation work to determine the optimum electrode design was carried out, while also taking into account the limitations of working with a low melting temperature chalcogenide material. The tuning of this hybrid As2S3 on Ti:LiNbO3 device structure is demonstrated with fabricated Mach-Zehnder interferometers and ring resonators. Electro-optic tuning of the TM polarization utilizing the r13 LiNbO3 tuning coefficient is shown, yielding results that show an improvement over previous tunable LiNbO3 microring resonators. Simulations are also carried out to show the waveform generating capabilities of this hybrid device platform

Real-time processing of a long perimeter fiber optic intrusion system

This thesis reports on recent advances made in real-time intruder detection for an intrusion system developed at Texas A&M University that utilizes a phase-sensitive optical time-domain reflectometer. The system uses light pulses from a highly coherent laser to interrogate a length of buried optical fiber. The Rayleigh backscattered light is detected, and a FPGA-based system is used to implement real-time signal processing algorithms. With the introduction of real-time signal processing, the system can run continuously, only triggering intrusions when they are detected. These recent advances allow for more effective processing of intruder signatures, while still giving results comparable to previous off-line signal processing results. With these advances, this technology is a prime candidate for low-cost perimeter monitoring of high-value and high-security targets, such as nuclear power plants, military bases, and national borders