Transcriptome Profiling Reveals Enhanced Mitochondrial Activity as a Cold Adaptive Strategy to Hypothermia in Zebrafish Muscle

Reduced ATP turnover during hibernation in relaxed skeletal muscle

Hibernating brown bears, due to a drastic reduction in metabolic rate, show only moderate muscle wasting. Here, we evaluate if ATPase activity of resting skeletal muscle myosin can contribute to this energy sparing. By analyzing single muscle fibers taken from the same bears, either during hibernation or in summer, we find that fibers from hibernating bears have a mild decline in force production and a significant reduction in ATPase activity. Single fiber proteomics, western blotting, and immunohistochemical analyses reveal major remodeling of the mitochondrial proteome during hibernation. Furthermore, using bioinformatical approaches and western blotting we find that phosphorylated myosin light chain, a known stimulator of basal myosin ATPase activity, is decreased in hibernating and disused muscles. These results suggest that skeletal muscle limits energy loss by reducing myosin ATPase activity, indicating a possible role for myosin ATPase activity modulation in multiple muscle wasting conditions.

Amphiregulin is overexpressed in human cardiac tissue in hypothermia deaths; associations between the transcript and stress hormone levels in cardiac deaths

BACKGROUND

Amphiregulin (AREG) is a growth factor linked to cardioprotection and heart pathology during myocardial stress. Our aim was to investigate cardiac AREG expression, its potential as a postmortem hypothermia marker and its possible stress hormone dependency in different types of deaths.

MATERIALS AND METHODS

Heart RNA was isolated from hypothermic, cardiac and non-cardiac deaths. Relative AREG mRNA levels and urine stress hormone concentrations were measured by qPCR and enzyme-linked immunosorbent assays from eight different death cause groups. Receiver operating characteristic curve was used to evaluate a cut-off point for AREG expression as a hypothermia marker. Regulatory elements were predicted by PROMO.

RESULTS

The AREG mRNA levels were significantly higher in hypothermic deaths than in most cardiac and non-cardiac deaths. AREG expression indicated hypothermic deaths with nearly 70% sensitivity and specificity. However, high expression levels were also detected in non-ischaemic deaths. The highest concentrations of adrenaline and cortisol were detected in hypothermic deaths, while the highest noradrenaline concentrations associated with atherosclerotic heart disease (AHD) deaths with acute myocardial infarction and trauma deaths. There were no significant correlations between stress hormones and AREG mRNA in hypothermic and non-cardiac deaths, whereas moderate-to-high associations were detected in cardiac deaths. Putative response elements for cortisol and catecholamines were found in AREG.

CONCLUSIONS

Severe hypothermia activates cardiac AREG expression practicable as a postmortem hypothermia marker. Cortisol and catecholamines may act as transcriptional modifiers of this gene, especially in long-term ischaemic heart disease. However, the exact role of these hormones in upregulation of AREG during hypothermia remains unclear.

Survival and neurological function in patients treated with extracorporeal membrane oxygenation and therapeutic hypothermia: a protocol for updating a systematic review

INTRODUCTION

The widespread application of extracorporeal membrane oxygenation (ECMO) has enhanced clinical outcomes for patients experiencing cardiac arrest. However, its effectiveness is still limited and falls short of the desired level. Therapeutic hypothermia, which maintains body temperatures between 32°C and 36°C in cardiac arrest patients treated with ECMO, has been proposed as a potential means of neuroprotection and increased survival rates. Nevertheless, it remains controversial, and its impact on patient complications has yet to be fully understood. Thus, this paper aims to update the protocol for a systematic review of patients treated with ECMO and therapeutic hypothermia, in order to explore its effects on survival and neurological function.

METHOD AND ANALYSIS

This protocol has been developed in compliance with the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols 2015. The following databases will be systematically searched: PubMed, Web of Science, Cochrane Library, Embase, Ovid, CNKI, Wanfang and China Biology Medicine Disc. The database search strategy will use a combination of subject terms and free-text keywords. The search will encompass articles from the inception of each database up to 15 June 2023. Inclusion criteria encompass randomised controlled trials, cohort studies, case-control studies and quasi-experimental studies. Two researchers will independently review articles and extract relevant data based on these criteria. Any disagreements will be resolved through discussion. Data analysis will be performed using Review Manager software.

ETHICS AND DISSEMINATION

Since no patient data were collected in this study, ethical approval was not required. Research findings will be released in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42023435353.