Reverberation of Excitation in Living “Hippocampal Formation–Entorhinal Cortex” Slices from Rats. Optical Recording

A vital potential-dependent dye was used to conduct optical recording of the electrical activity of the hippocampal formation in living slices of the rat brain including the hippocampal formation and the entorhinal cortex. These studies showed that single electrical stimuli applied to the entorhinal cortex, subiculum, and dentate gyrus produced responses in which waves of excitation passed across the hippocampal formation sequentially from the dentate gyrus, through CA3, to the CA1 field of the hippocampus. When GABAergic inhibition was partially blocked with picrotoxin, the first wave of excitation was immediately followed by several further waves in all zones of the hippocampal formation, with a constant shift in latency, which increased from the dentate gyrus to CA3 and CA1. Reverberation of excitation in the hippocampal formation-entorhinal cortex structure is regarded as the most probable cause for the appearance of these sequences of waves.     

Frequency-Dependent Properties of a Fluid Jet Stimulus: Calibration,Modeling, and Application to Cochlear Hair Cell Bundles

The investigation of small physiological mechano-sensory systems, such as hair cells or their accessory structures in the inner ear or lateral line organ, requires mechanical stimulus equipment that allows spatial manipulation with micrometer precision and stimulation with amplitudes down to the nanometer scale. Here, we describe the calibration of a microfluid jet produced by a device that was designed to excite individual cochlear hair cell bundles or cupulae of the fish superficial lateral line system. The calibration involves a precise definition of the linearity and time- and frequency-dependent characteristics of the fluid jet as produced by a pressurized fluid-filled container combined with a glass pipette having a microscopically sized tip acting as an orifice. A procedure is described that can be applied during experiments to obtain a fluid jet’s frequency response, which may vary with each individual glass pipette. At small orifice diameters (<15 μm), the fluid velocity of the jet is proportional to the displacement of the piezoelectric actuator pressurizing the container’s volume and is suitable to stimulate the hair bundles of sensory hair cells. With increasing diameter, the fluid jet velocity becomes proportional to the actuator’s velocity. The experimentally observed characteristics can be described adequately by a dynamical model of damped fluid masses coupled by elastic components.     

Transcultural validation of a French version of the Iowa Satisfaction with Anesthesia Scale (ISAS-F)

Canadian Journal of Anesthesia/Journal canadien d'anesthésie - We sought to validate a French translation of the Iowa Satisfaction with Anesthesia Scale (ISAS), a tool to assess the...     

Harder,better, faster … Yet stronger? Working conditions and self‐declaration of chronic diseases

The role played by working conditions in worker health status has been widely acknowledged in the literature in general but has received less attention in economics, due to the inherent statistical biases and lack of data available to determine the role of simultaneous and chronic exposures. This study aims to estimate the causal impact of detrimental working conditions on the self‐declaration of chronic diseases in France. Using a rebuilt retrospective lifelong panel and defining indicators for physical and psychosocial strains, I implement a mixed econometric strategy that relies on difference‐in‐differences and matching methods to take into account for selection biases as well as unobserved heterogeneity. For men and women, I find deleterious effects of both types of working conditions on the declaration of chronic diseases after exposure, with varying patterns of impacts according to the nature and magnitude of the strains. These results provide insights into the debate on legal retirement age postponement and justify not only policies being enacted early in individuals' careers in order to prevent subsequent midcareer health repercussions, but also schemes that are more focused on psychosocial risk factors.     

Gerontologists and the media in a time of gerontologyexpansion

Gerontology research is now of high concern,particularly to the media, and a risk could exist thatgerontologists may give people false hopes or prematureconclusions. This article describes two examples: thehypothesis that median longevity will be 150 yearsin 2100, and the recent results on telomerase. Itis concluded that it is prudent forgerontologists to maintain a cautious attitude withthe media.     

A mild stress due to hypergravity exposure at youngage increases longevity in Drosophila melanogaster males

Drosophila melanogaster flies were exposed to hypergravity starting at two days of age, the range of gravity levels used being 2.58–7.38 g. No longevity change was observed for exposures of less than 14 days. The longevity of males increased if they were submitted to hypergravity for durations ranging from 14 to 24 days. This increase in longevity was never observed in females. The positive effect of exposure to hypergravity has been replicated in two laboratories using two wild-type strains and different rearing conditions. A short hypergravity exposure seems to be a mild stress, yielding positive effects on longevity. This is in accordance with two previous studies showing a slight longevity increase after heat shock in the nematode Caenorhabditis elegans and in Drosophila melanogaster.