Validation of e-Celsius gastrointestinal telemetry system as measure of core temperature

The main objective of this study was to validate gastrointestinal measurement with the e-Celsius® system composed of an ingestible electronic capsule and a monitor. Twenty-three healthy volunteers aged 18-59 years stayed at the hospital for 24 h under fasting conditions. They were only allowed for quiet activity and were asked to keep their sleeping habits. Subjects ingested a Jonah capsule and an e-Celsius® capsule, and a rectal probe and an esophageal probe were inserted. Mean temperature measured by the e-Celsius® device was lower than that measured by Vitalsense® (-0.12 ± 0.22°C; p < 0.001) and the rectal probe (-0.11 ± 0.03°C; p = 0.003) and higher than that measured by the esophageal probe (0.17 ± 0.05; p = 0.006). Mean difference (bias) and 95% confidence intervals between temperature of e-Celsius capsule, Vitalsense Jonah capsule, esophageal probe, and rectal probe were computed using Bland and Altman procedure. The magnitude of the measurement bias is significantly greater when comparing the e-Celsius® and the Vitalsense® device pair with any other device pairs containing the esophageal probe. Amplitude of confidence interval between the e-Celsius® system and the Vitalsense® system was 0.67°C. This amplitude was significantly lower than those of the esophageal probe-e-Celsius® pairing (0.83°C; p = 0.027), of the esophageal probe-Vitalsense (0.78°C; p = 0.046) and of the esophageal probe-rectal probe (0.83°C; p = 0.002). The statistical analysis did not reveal any effect of time on the amplitude of bias, whatever the device concerned. When comparing missing data rate of the e-Celsius® system (0.23 ± 0.15%) and the Vitalsense® devices (0.70 ± 0.11%) during the whole experiment, no differences was observed (p = 0.09). The e-Celsius® system could be used when a continuous following of internal temperature is needed.

High-frequency stimulation of the hippocampus blocks fear learning sensitization and return of extinguished fear

Patients with post-traumatic stress disorder (PTSD) present hippocampal (HPC) dysfunction, which may facilitate fear-related phenomena such as fear learning sensitization (i.e. potentiation of fear acquisition by initial fear conditioning (FC1)) and fear return (i.e. reactivation of extinguished fear). Fear return is sensitive to HPC high-frequency stimulation (HFS) in rats. The goal of the present study was to examine whether fear learning sensitization is also sensitive to HPC HFS in rats. We found in control conditions that, after FC1 (with 15 shock administrations) and extinction, conditioning in a different context with one shock administration was potentiated (proactive effect) and associated with fear return in the initial context (retroactive effect). Both phenomena were prevented by HPC HFS applied before the second conditioning. We also found that the effect of HPC HFS on fear learning sensitization required initial extinction. These findings suggest a pivotal role of the HPC in preventing proactive and retroactive effects of successive fear conditionings. These data also support the concept that HPC deactivation may be involved in fear learning sensitization and fear return in PTSD patients.