Fatal Consequences: Obstructive Sleep Apnea in a Train Engineer

This special report describes the findings of the National Transportation Safety Board’s investigation into the probable cause of the derailment of a Metro-North passenger train in the Bronx, New York on December 1, 2013, that resulted in 4 deaths and injuries to 59 additional persons. A key finding in the medical investigation was the engineer’s post-accident diagnosis of severe, obstructive sleep apnea, and the probable cause of the accident was determined to be the result of the engineer having fallen asleep while operating the train. This accident highlights the importance of screening, evaluating, and ensuring adequate treatment of obstructive sleep apnea, particularly among patients working in positions where impairment of physical or cognitive function or sudden incapacitation may result in serious harm to the public.     

Microbial life at ?13 °C in the brine of an ice-sealed Antarctic lake

The permanent ice cover of Lake Vida (Antarctica) encapsulates an extreme cryogenic brine ecosystem (−13 °C; salinity, 200). This aphotic ecosystem is anoxic and consists of a slightly acidic (pH 6.2) sodium chloride-dominated brine. Expeditions in 2005 and 2010 were conducted to investigate the biogeochemistry of Lake Vida’s brine system. A phylogenetically diverse and metabolically active Bacteria dominated microbial assemblage was observed in the brine. These bacteria live under very high levels of reduced metals, ammonia, molecular hydrogen (H₂), and dissolved organic carbon, as well as high concentrations of oxidized species of nitrogen (i.e., supersaturated nitrous oxide and ∼1 mmol⋅L⁻¹ nitrate) and sulfur (as sulfate). The existence of this system, with active biota, and a suite of reduced as well as oxidized compounds, is unusual given the millennial scale of its isolation from external sources of energy. The geochemistry of the brine suggests that abiotic brine-rock reactions may occur in this system and that the rich sources of dissolved electron acceptors prevent sulfate reduction and methanogenesis from being energetically favorable. The discovery of this ecosystem and the in situ biotic and abiotic processes occurring at low temperature provides a tractable system to study habitability of isolated terrestrial cryoenvironments (e.g., permafrost cryopegs and subglacial ecosystems), and is a potential analog for habitats on other icy worlds where water-rock reactions may cooccur with saline deposits and subsurface oceans.     

Mesenchymal progenitor cells derived from traumatized muscle enhance neurite growth

The success of peripheral nerve regeneration is governed by the rate and quality of axon bridging and myelination that occurs across the damaged region. Neurite growth and the migration of Schwann cells is regulated by neurotrophic factors produced as the nerve regenerates, and these processes can be enhanced by mesenchymal stem cells (MSCs), which also produce neurotrophic factors and other factors that improve functional tissue regeneration. Our laboratory has recently identified a population of mesenchymal progenitor cells (MPCs) that can be harvested from traumatized muscle tissue debrided and collected during orthopaedic reconstructive surgery. The objective of this study was to determine whether the traumatized muscle‐derived MPCs exhibit neurotrophic function equivalent to that of bone marrow‐derived MSCs. Similar gene‐ and protein‐level expression of specific neurotrophic factors was observed for both cell types, and we localized neurogenic intracellular cell markers (brain‐derived neurotrophic factor and nestin) to a subpopulation of both MPCs and MSCs. Furthermore, we demonstrated that the MPC‐secreted factors were sufficient to enhance in vitro axon growth and cell migration in a chick embryonic dorsal root ganglia (DRG) model. Finally, DRGs in co‐culture with the MPCs appeared to increase their neurotrophic function via soluble factor communication. Our findings suggest that the neurotrophic function of traumatized muscle‐derived MPCs is substantially equivalent to that of the well‐characterized population of bone marrow‐derived MPCs, and suggest that the MPCs may be further developed as a cellular therapy to promote peripheral nerve regeneration. Copyright © 2012 John Wiley & Sons, Ltd.     

Who benefits from extended continuing care for cocaine dependence?

The goal of this study was to determine which cocaine dependent patients engaged in an intensive outpatient program (IOP) were most likely to benefit from extended continuing care (24 months). Participants (N = 321) were randomized to: IOP treatment as usual (TAU), TAU plus Telephone Monitoring and Counseling (TMC), or TAU plus TMC plus incentives for session attendance (TMC +). Potential moderators examined were gender, stay in a controlled environment prior to IOP, number of prior drug treatments, and seven measures of progress toward IOP goals. Outcomes were: (1) abstinence from all drugs and heavy alcohol use, and (2) cocaine urine toxicology. Follow-ups were conducted at 3, 6, 9, 12, 18, and 24 months post-baseline. Results indicated that there were significant effects favoring TMC + over TAU on the cocaine urine toxicology outcome for participants in a controlled environment prior to IOP and for those with no days of depression early in IOP. Trends were obtained favoring TMC over TAU for those in a controlled environment (cocaine urine toxicology outcome) or with high family/social problem severity (abstinence composite outcome), and TMC + over TAU for those with high family/social problem severity or high self-efficacy (cocaine urine toxicology outcome). None of the other potential moderator effects examined reached the level of a trend. These results generally do not suggest that patients with greater problem severity or poorer performance early in treatment on the measures considered in this report will benefit to a greater degree from extended continuing care.     

How Individuals Feel About the Past,Present, and Future Bears Little Relation to Alcohol-Related Problems,Anxiety, and Depression: A Person-Centered Analysis in a University Sample

Previous studies using bivariate or correlational analyses have established a relationship between alcohol use, symptoms of anxiety and depression, and scores on a range of temporal psychology measures. Temporal psychology measures variously assess the cognitive or affective (or in some cases, both) engagement with the past, present, and future. Although developed and validated in adolescents, recent research has suggested that the Time Attitudes Scale is internally consistent and reliable in adults also. The present study is the first to apply a person-centered approach to assessing the relationship between scores on the Time Attitudes Scale and symptoms of anxiety, depression, and alcohol-related problems in adults. Participants were recruited from a University in England. Results support the validity and internal consistency of the Time Attitudes Scale. Meaningful time attitudes profiles emerged, however, taking the sample size into account, the only substantive finding showed that those with a negative time attitudes profile scored higher on depressive symptomatology than those with a positive profile. While elsewhere, Zimbardo Time Perspective Inventory scores have been shown to be meaningfully related to anxiety, depression and alcohol use, the present study questions the degree to which the affective dimension of temporal psychology is driving that relationship.