Changes in T cell metabolism in post-cardiac arrest patients

Objective: The survival rates for cardiac arrest patients to hospital discharge are very low. Post-arrest patients have an immune response and usually a period of immunosuppression. When CD3+ T cells activate, they switch from primarily relying on aerobic metabolism to primarily relying on anaerobic metabolism. The goal of this study is to characterize the immune system of post-cardiac arrest patients. The specific objectives are (1) to determine the time period after the occurrence of a cardiac arrest that a patient acquires an infection, (2) to identify the most common types of infections in post-arrest patients, (3) to compare in vitro the cellular oxygen consumption of immune cells post-cardiac arrest with healthy controls, and (4) to compare cell proliferation and ATP production of immune cells post-cardiac arrest with healthy controls. Methods: We conducted a retrospective chart review of 170 cardiac arrest patients (Beth Israel Deaconess Medical Center) who had return of spontaneous circulation. We measured oxygen consumption rates of peripheral blood mononuclear cells (PBMCs) in cardiac arrest patients and healthy controls. We also measured cell proliferation and ATP production of CD3+ T cells in cardiac arrest patients and healthy controls. Results: Of the 170 cardiac arrest patients we reviewed, 42% had at least one incidence of infection. The length of time from cardiac arrest to first positive culture was 4 days, with pneumonia and urinary tract infections the most common diagnoses. The PBMCs of cardiac arrest patients showed a significant decrease in oxygen consumption post arrest compared with healthy controls. When thiamine was added to the PBMC samples of cardiac arrest patients, there was a significant increase in oxygen consumption from baseline. There was no significant difference in cell proliferation or ATP production of CD3+ T cells between the two groups of post-cardiac arrest patients and healthy controls. Conclusion: Many patients suffer from infections post-cardiac arrest, and future research is needed on this subject. Our data support the hypothesis that post-arrest patients have a period of hyperimmune response followed by a period of immunosuppression

Visualizing climate change adaptation: An effective tool for agricultural outreach?

Landscape photovisualizations (PVZs) are digitally altered photographs that show existing landscapes altered to include a simulated future scenario. They are commonly used to support dialogue and decision-making in multistakeholder contexts. In agricultural sectors, stakeholders increasingly must contend with pressures to adapt to climatic changes and shifts in weather patterns. This study examines the potential of PVZs to engage agricultural stakeholders about climate change adaptation, specifically around best management practices (BMPs). In 2015, survey data were collected (n 5 133) at six agricultural confer-ences Vermont. Participants were asked about their climate change knowledge, perceptions of adaptation, and their intentions to adopt or recommend one or more of the following BMPs: riparian buffers, drainage tiles with constructed wetlands, retention ponds, and silvopasture. In addition, respondents were asked about how well PVZs did or did not clarify their understanding of each BMP and its associated limiting factors. Results from five multivariate ordered logit models show an increase in interest among some ag-ricultural stakeholders in adopting a BMP (among farmers) or recommending a BMP (among agricultural advisors) after seeing a PVZ depicting that practice. Interest in adoption or recommendation of BMPs was also more likely among respondents who believe that it is important for farms to adapt to climate change. Although PVZs are not common in agricultural outreach programs, these results suggest that PVZs are relevant to agricultural education and land-use decision-making, specifically in the domain of climate change adaptation

An allosteric gating model recapitulates the biophysical properties of IK,L expressed in mouse vestibular Type I hair cells

Type I and Type II hair cells are the sensory receptors of the mammalian vestibular epithelia. Type I hair cells are characterized by their basolateral membrane being enveloped in a single large afferent nerve terminal, named calyx, and by the expression of a low-voltage-activated outward rectifying K(+) current, IK,L . The biophysical properties and molecular profile of IK,L are still largely unknown. By using the patch-clamp whole-cell technique, we examined the voltage- and time-dependent properties of IK,L in Type I hair cells of the mouse semicircular canal. We found that the biophysical properties of IK,L were affected by an unstable K(+) equilibrium potential (Veq K(+) ). Both the outward and inward K(+) currents shifted Veq K(+) consistent with K(+) accumulation or depletion, respectively, in the extracellular space, which we attributed to a residual calyx attached to the basolateral membrane of the hair cells. We therefore optimized the hair cell dissociation protocol in order to isolate mature Type I hair cells without their calyx. In these cells, the uncontaminated IK,L showed a half-activation at -79.6 mV and a steep voltage dependence (2.8 mV). IK,L also showed complex activation and deactivation kinetics, which we faithfully reproduced by an allosteric channel gating scheme where the channel is able to open from all (five) closed states. The "early" open states substantially contribute to IK,L activation at negative voltages. This study provides the first complete description of the "native" biophysical properties of IK,L in adult mouse vestibular Type I hair cells. This article is protected by copyright. All rights reserved

Etoposide Induces ATM-Dependent Mitochondrial Biogenesis through AMPK Activation

DNA damage such as double-stranded DNA breaks (DSBs) has been reported to stimulate mitochondrial biogenesis. However, the underlying mechanism is poorly understood. The major player in response to DSBs is ATM (ataxia telangiectasia mutated). Upon sensing DSBs, ATM is activated through autophosphorylation and phosphorylates a number of substrates for DNA repair, cell cycle regulation and apoptosis. ATM has been reported to phosphorylate the alpha subunit of AMP-activated protein kinase (AMPK), which senses AMP/ATP ratio in cells, and can be activated by upstream kinases. Here we provide evidence for a novel role of ATM in mitochondrial biogenesis through AMPK activation in response to etoposide-induced DNA damage.Three pairs of human ATM+ and ATM- cells were employed. Cells treated with etoposide exhibited an ATM-dependent increase in mitochondrial mass as measured by 10-N-Nonyl-Acridine Orange and MitoTracker Green FM staining, as well as an increase in mitochondrial DNA content. In addition, the expression of several known mitochondrial biogenesis regulators such as the major mitochondrial transcription factor NRF-1, PGC-1alpha and TFAM was also elevated in response to etoposide treatment as monitored by RT-PCR. Three pieces of evidence suggest that etoposide-induced mitochondrial biogenesis is due to ATM-dependent activation of AMPK. First, etoposide induced ATM-dependent phosphorylation of AMPK alpha subunit at Thr172, indicative of AMPK activation. Second, inhibition of AMPK blocked etoposide-induced mitochondrial biogenesis. Third, activation of AMPK by AICAR (an AMP analogue) stimulated mitochondrial biogenesis in an ATM-dependent manner, suggesting that ATM may be an upstream kinase of AMPK in the mitochondrial biogenesis pathway.These results suggest that activation of ATM by etoposide can lead to mitochondrial biogenesis through AMPK activation. We propose that ATM-dependent mitochondrial biogenesis may play a role in DNA damage response and ROS regulation, and that defect in ATM-dependent mitochondrial biogenesis could contribute to the manifestations of A-T disease