This study demonstrates that both strength and endurance training improve peripheral insulin sensitivity, whereas only strength training reduces total body fat in HIV-infected patients with lipodystrophy.
We consider multi-class systems of interacting nonlinear Hawkes processes modeling several large families of neurons and study their mean field limits. As the total number of neurons goes to infinity we prove that the evolution within each class can be described by a nonlinear limit differential equation driven by a Poisson random measure, and state associated central limit theorems. We study situations in which the limit system exhibits oscillatory behavior, and relate the results to certain piecewise deterministic Markov processes and their diffusion approximations.
Circulating interleukin (IL)-18 is elevated in obesity, but paradoxically causes hypophagia. We hypothesized that IL-18 may attenuate high-fat diet (HFD)-induced insulin resistance by activating AMP-activated protein kinase (AMPK). We studied mice with a global deletion of the α-isoform of the IL-18 receptor (IL-18R−/−) fed a standard chow or HFD. We next performed gain-of-function experiments in skeletal muscle, in vitro, ex vivo, and in vivo. We show that IL-18 is implicated in metabolic homeostasis, inflammation, and insulin resistance via mechanisms involving the activation of AMPK in skeletal muscle. IL-18R−/− mice display increased weight gain, ectopic lipid deposition, inflammation, and reduced AMPK signaling in skeletal muscle. Treating myotubes or skeletal muscle strips with IL-18 activated AMPK and increased fat oxidation. Moreover, in vivo electroporation of IL-18 into skeletal muscle activated AMPK and concomitantly inhibited HFD-induced weight gain. In summary, IL-18 enhances AMPK signaling and lipid oxidation in skeletal muscle implicating IL-18 in metabolic homeostasis.
Changes in climate are rapidly modifying the Arctic environment. As a result, human activities—and the sounds they produce—are predicted to increase in remote areas of Greenland, such as those inhabited by the narwhals (Monodon monoceros) of East Greenland. Meanwhile, nothing is known about these whales’ acoustic behavior or their reactions to anthropogenic sounds. This lack of knowledge was addressed by instrumenting six narwhals in Scoresby Sound (Aug 2013–2016) with Acousonde™ acoustic tags and satellite tags. Continuous recordings over up to seven days were used to describe the acoustic behavior of the whales, in particular their use of three types of sounds serving two different purposes: echolocation clicks and buzzes, which serve feeding, and calls, presumably used for social communication. Logistic regression models were used to assess the effects of location in time and space on buzzing and calling rates. Buzzes were mostly produced at depths of 350–650 m and buzzing rates were higher in one particular fjord, likely a preferred feeding area. Calls generally occurred at shallower depths (<100 m), with more than half of these calls occurring near the surface (<7 m), where the whales also spent more than half of their time. A period of silence following release, present in all subjects, was attributed to the capture and tagging operations, emphasizing the importance of longer (multi-day) records. This study provides basic life-history information on a poorly known species—and therefore control data in ongoing or future sound-effect studies.
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