Assessing the role of Piscine orthoreovirus in disease and the associated risk for wild Pacific salmon.

This paper is a response to Polinski, M. P. et al. Innate antiviral defense demonstrates high energetic efficiency in a bony fish. BMC Biology 19, 138 (2021). https://doi.org/10.1186/s12915-021-01069-2.

Innate antiviral defense demonstrates high energetic efficiency in a bony fish.

BACKGROUND: Viruses can impose energetic demands on organisms they infect, in part by hosts mounting resistance. Recognizing that oxygen uptake reliably indicates steady-state energy consumption in all vertebrates, we comprehensively evaluated oxygen uptake and select transcriptomic messaging in sockeye salmon challenged with either a virulent rhabdovirus (IHNV) or a low-virulent reovirus (PRV). We tested three hypotheses relating to the energetic costs of viral resistance and tolerance in this vertebrate system: (1) mounting resistance incurs a metabolic cost or limitation, (2) induction of the innate antiviral interferon system compromises homeostasis, and (3) antiviral defenses are weakened by acute stress. RESULTS: IHNV infections either produced mortality within 1-4 weeks or the survivors cleared infections within 1-9 weeks. Transcription of three interferon-stimulated genes (ISGs) was strongly correlated with IHNV load but not respiratory performance. Instead, early IHNV resistance was associated with a mean 19% (95% CI = 7-31%; p = 0.003) reduction in standard metabolic rate. The stress of exhaustive exercise did not increase IHNV transcript loads, but elevated host inflammatory transcriptional signaling up to sevenfold. For PRV, sockeye tolerated high-load systemic PRV blood infections. ISG transcription was transiently induced at peak PRV loads without associated morbidity, microscopic lesions, or major changes in aerobic or anaerobic respiratory performance, but some individuals with high-load blood infections experienced a transient, minor reduction in hemoglobin concentration and increased duration of excess post-exercise oxygen consumption. CONCLUSIONS: Contrary to our first hypothesis, effective resistance against life-threatening rhabdovirus infections or tolerance to high-load reovirus infections incurred minimal metabolic costs to salmon. Even robust systemic activation of the interferon system did not levy an allostatic load sufficient to compromise host homeostasis or respiratory performance, rejecting our second hypothesis that this ancient innate vertebrate antiviral defense is itself energetically expensive. Lastly, an acute stress experienced during testing did not weaken host antiviral defenses sufficiently to promote viral replication; however, a possibility for disease intensification contingent upon underlying inflammation was indicated. These data cumulatively demonstrate that fundamental innate vertebrate defense strategies against potentially life-threatening viral exposure impose limited putative costs on concurrent aerobic or energetic demands of the organism.

Acclimation potential of Arctic cod (Boreogadus saida) from the rapidly warming Arctic Ocean.

As a consequence of the growing concern about warming of the Arctic Ocean, this study quantified the thermal acclimation responses of Boreogadus saida, a key Arctic food web fish. Physiological rates for cardio-respiratory functions as well as critical maximum temperature (Tc,max) for loss of equilibrium (LOE) were measured. The transition temperatures for these events (LOE, the rate of oxygen uptake and maximum heart rate) during acute warming were used to gauge phenotypic plasticity after thermal acclimation from 0.5°C up to 6.5°C for 1 month (respiratory and Tc,max measurements) and 6 months (cardiac measurements). Tc,max increased significantly by 2.3°C from 14.9°C to 17.1°C with thermal acclimation, while the optimum temperature for absolute aerobic scope increased by 4.5°C over the same range of thermal acclimation. Warm acclimation reset the maximum heart rate to a statistically lower rate, but the first Arrhenius breakpoint temperature during acute warming was unchanged. The hierarchy of transition temperatures was quantified at three acclimation temperatures and was fitted inside a Fry temperature tolerance polygon to better define ecologically relevant thermal limits to performance of B. saida We conclude that B. saida can acclimate to 6.5°C water temperatures in the laboratory. However, at this acclimation temperature 50% of the fish were unable to recover from maximum swimming at the 8.5°C test temperature and their cardio-respiratory performance started to decline at water temperatures greater than 5.4°C. Such costs in performance may limit the ecological significance of B. saida acclimation potential.

A novel protocol for assessing exercise performance and dystropathophysiology in the mdx mouse.

INTRODUCTION: Dystrophinopathy in the young mdx mouse model of Duchenne muscular dystrophy is comparatively mild, requires induction, and is rarely assessed with tests of systemic muscle function in whole animals. METHODS: A modified TREAT-NMD induction protocol was used to evaluate respiratory and exercise performance, starting and ending with maximum oxygen consumption (VO2max ) tests. RESULTS: The initial and/or final VO2max , time to exhaustion, speed at exhaustion, and total expended calories were significantly lower in mdx mice. Episodic VO2 and VCO2 fluctuations occurred during training and resulted in dissociated patterns of VO2 and respiratory exchange ratio (RER). These fluctuations further resulted in significantly greater VO2 coefficient of variation and RER values and lower minimal VO2 values. CONCLUSIONS: Quantifying respiratory performance during exercise is a potentially useful means for studying pathophysiology in mdx mice, as it assesses intact animals over time, is more sensitive than some histological markers, and assesses systemic muscle function.

Enhancing Cardiovascular Health and Functional Recovery in Stroke Survivors: A Randomized Controlled Trial of Stroke-Specific and Cardiac Rehabilitation Protocols for Optimized Rehabilitation.

BACKGROUND: Stroke is a major contributor to disability and mortality globally. It leads to physical impairments, including weakness and cardiovascular deconditioning, posing significant challenges to stroke survivors' quality of life. Exercise-based cardiac rehabilitation has shown promise as a rehabilitation strategy. This study aims to assess and compare the impacts of stroke-specific rehabilitation and individualized cardiac rehabilitation exercises on various health parameters in stroke patients. METHODS: A randomized controlled trial was conducted, involving 38 stroke patients aged 40-75 years. Group A received stroke-specific rehabilitation, which consisted of a combination of range of motion exercises, strength training for the paralyzed side, balance and coordination training, gait training, functional mobility exercises, neuromuscular reeducation, and breathing exercises. This program was conducted five days per week for 12 weeks. Group B received individually designed cardiac rehabilitation exercises, in addition to stroke-specific rehabilitation. They engaged in this exercise for at least 30-45 min per day, four days per week, and incorporated two days of resistive training over a 12-week period. Baseline and post-intervention assessments included measures of cardiac autonomic function, balance (Berg Balance Scale), mobility (Timed Up and Go Test), cardiovascular fitness indicators, respiratory parameters, exercise efficiency, and perceived exertion. RESULTS: Group B receiving individualized cardio rehab showed significant improvements in balance and mobility compared to Group A receiving conventional stroke-specific rehab. Moreover, Group B exhibited enhanced cardiovascular fitness, respiratory performance, exercise efficiency, and autonomic function post-intervention. Notably, Group A displayed no significant improvements in these parameters. CONCLUSIONS: Individualized cardiac rehabilitation exercises demonstrated favorable outcomes in improving certain health parameters, highlighting the potential benefits of individualized rehabilitation strategies for stroke patients.