Restraint Induces Sickness Responses Independent of Injection with Epstein-Barr Virus (EBV)-Encoded dUTPase

Most adult humans have been infected by Epstein-Barr virus (EBV), a putative cause of chronic fatigue syndrome, and carry latent EBV. The EBV-encoded dUTPase can induce sickness responses in mice and chronic stress exacerbates this response. Because individuals often adapt to chronic stress, we tested the hypothesis that acute restraint stress would potentiate these sickness responses elicited by EBV-encoded dUTPase. Male CD-1 mice were injected daily for one or three days with either saline or EBV-encoded dUTPase. Additionally, mice from each condition were either restrained for three hours daily or left undisturbed during the light phase when mice are inactive. Restraint decreased weight gain during the one- and three-day experiments. Restraint in saline injected mice increased anxiety-like behavior in the open field during the three-day experiment. There were no behavioral differences during the one-day experiment. Restraint stress had no effect when experienced acutely on one day, but did produce a sickness response after three days of exposure regardless of saline or dUTPase injection. In contrast to the effects of chronic stress and EBV-encoded dUTPase on the sickness response, acute stress did not affect sickness responses in association with EBV-encoded dUTPase. Thus, dUTPase does not appear to provoke the same sickness responses after acute stress as compared to chronic stress.

Chronic Physical Stress Does Not Interact with Epstein-Barr Virus (EBV)-Encoded Dutpase to Alter the Sickness Response

Most adult humans have been infected with Epstein-Barr virus (EBV), which is thought to contribute to the development of chronic fatigue syndrome. Stress is known to influence the immune system and can exacerbate the sickness response. Although a role for psychological stress in the sickness response, particularly in combination with EBV-encoded deoxyuridine triphosphate nucleotidohydrolase (dUTPase) has been established, and the role of physical stressors in these interactions remains unspecified. In this study, we seek to determine the interaction of chronic physical (swim) stress and EBV-encoded dUTPase injection. We hypothesize that a chronic physical stressor will exacerbate the sickness response following EBV-encoded dUTPase injection. To test this hypothesis mice receive daily injections of EBV-encoded dUTPase or vehicle and are subjected to 15 min of swim stress each day for 14 days or left unmanipulated. On the final evening of injections mice undergo behavioral testing. EBV-encoded dUTPase injection alone produces some sickness behaviors. The physical swimming stress does not alter the sickness response.

An IDDES study of the near-wake flow topology of a simplified heavy vehicle

The complex wake flow of a GTS(ground transportation system)model contributes to large percentage of the aerodynamic drag force.Therefore,predicting accurate wake flow will help carry out the drag reduction strategies.In this paper,the near-wake flow topology of the GTS was studied at Re=2.7×104 to assess the capability of a hybrid RANS/LES(Reynolds-averaged Navier–Stokes/large eddy simulation)approach,known as IDDES(improved delayed detached eddy simulation).The current study also aims to understand the effects of different computational parameters,e.g.the spatial resolution,time step,residual level,discretization scheme and turbulence model,on this asymmetrical wake flow configuration.A comparison of IDDES with previous water channel tests,wellresolved LES,partially averaged Navier–Stokes and URANS(unsteady RANS)was included to better understand the benefits of this hybrid RANS/LES approach.The results show that on the medium and fine grids,the IDDES produces an asymmetrical flow topology(known as flow state I)in the near-wake of the vertical midplane,as reported in previous studies.The recommended parameters for the time step(1×10^(–4 )s)and residual level(1×10^(–4))provide sufficient accuracy of wake predictions to show good agreement with experiments.For the convective term of the momentum equation in IDDES,the bounded central difference discretization scheme is proposed to be adopted for discretization.Additionally,URANS cannot accurately capture this asymmetrical flow field.IDDES proves to be capable of predicting thewake flowfield of this simplified heavy vehicle with high accuracy.All obtained conclusions can provide references for the aerodynamic drag reduction of the GTS.