Non-Exertional Heatstroke: A Case Report and Review of the Literature

TRPV1/cPLA2/AA pathway contributes to ferroptosis-mediated acute liver injury in heatstroke

With the increasing frequency of global heatwaves, the incidence of heatstroke (HS) is significantly rising. The liver plays a crucial role in metabolism and is an organ highly sensitive to temperature. Acute liver injury (ALI) frequently occurs in patients with HS, yet the exact mechanisms driving ALI in HS are still unknown. In this basic study, we investigated the specific molecular mechanisms by which cytosolic phospholipase A2 (cPLA2) mediates ferroptosis, contributing to the development of ALI following HS. We utilized a mouse model of HS and divided the mice into healthy control and HS groups for a series of experiments. Firstly, we assessed oxidative damage markers in tissues and cells, as well as ferroptosis biomarkers. Additionally, we conducted a non-targeted metabolomics analysis to validate the role of key enzymes in metabolism and the ferroptosis pathway. Our results indicated that ferroptosis contributed to the progression of ALI after HS. Administering the ferroptosis inhibitor liproxstatin-1 (10 mg/kg) post-HS onset significantly inhibits HS-induced ALI progression. Mechanistically, heatstroke triggered cPLA2 activation and increased the levels of its metabolic product, arachidonic acid, thereby further promoted the occurrence of ferroptosis. Furthermore, heatstroke mediated cPLA2 activation might involve enhancing transient receptor potential vanilloid subtype 1 (TRPV1) receptor function. Overall, these results highlighted the critical role that cPLA2-mediated ferroptosis plays in the development of ALI following HS, indicating that inhibiting cPLA2 may present a novel therapeutic approach to prevent ALI after HS by limiting liver cell death.

Skin-inspired, sensory robots for electronic implants

Drawing inspiration from cohesive integration of skeletal muscles and sensory skins in vertebrate animals, we present a design strategy of soft robots, primarily consisting of an electronic skin (e-skin) and an artificial muscle. These robots integrate multifunctional sensing and on-demand actuation into a biocompatible platform using an in-situ solution-based method. They feature biomimetic designs that enable adaptive motions and stress-free contact with tissues, supported by a battery-free wireless module for untethered operation. Demonstrations range from a robotic cuff for detecting blood pressure, to a robotic gripper for tracking bladder volume, an ingestible robot for pH sensing and on-site drug delivery, and a robotic patch for quantifying cardiac function and delivering electrotherapy, highlighting the application versatilities and potentials of the bio-inspired soft robots. Our designs establish a universal strategy with a broad range of sensing and responsive materials, to form integrated soft robots for medical technology and beyond.

Skin-inspired, sensory robots for electronic implants

Living organisms with motor and sensor units integrated seamlessly demonstrate effective adaptation to dynamically changing environments. Drawing inspiration from cohesive integration of skeletal muscles and sensory skins in these organisms, we present a design strategy of soft robots, primarily consisting of an electronic skin (e-skin) and an artificial muscle, that naturally couples multifunctional sensing and on-demand actuation in a biocompatible platform. We introduce an in situ solution-based method to create an e-skin layer with diverse sensing materials (e.g., silver nanowires, reduced graphene oxide, MXene, and conductive polymers) incorporated within a polymer matrix (e.g., polyimide), imitating complex skin receptors to perceive various stimuli. Biomimicry designs (e.g., starfish and chiral seedpods) of the robots enable various motions (e.g., bending, expanding, and twisting) on demand and realize good fixation and stress-free contact with tissues. Furthermore, integration of a battery-free wireless module into these robots enables operation and communication without tethering, thus enhancing the safety and biocompatibility as minimally invasive implants. Demonstrations range from a robotic cuff encircling a blood vessel for detecting blood pressure, to a robotic gripper holding onto a bladder for tracking bladder volume, an ingestible robot residing inside stomach for pH sensing and on-site drug delivery, and a robotic patch wrapping onto a beating heart for quantifying cardiac contractility, temperature and applying cardiac pacing, highlighting the application versatilities and potentials of the nature-inspired soft robots. Our designs establish a universal strategy with a broad range of sensing and responsive materials, to form integrated soft robots for medical technology and beyond.

Inflammation, coagulation, and cellular injury in heat-induced shock

BACKGROUND

The number of heatstroke victims hit record numbers in 2022 as global warming continues. In heat-induced injuries, circulatory shock is the most severe and deadly complication. This review aims to examine the mechanisms and potential approaches to heat-induced shock and the life-threatening complications of heatstroke.

METHODS

A computer-based online search was performed using the PubMed database and Web of Science database for published articles concerning heatstroke, shock, inflammation, coagulopathy, endothelial cell, cell death, and heat shock proteins.

RESULTS

Dehydration and heat-induced cardiomyopathy were reported as the major causes of heat-induced shock, although other heat-induced injuries are also involved in the pathogenesis of circulatory shock. In addition to dehydration, the blood volume decreases considerably due to the increased vascular permeability as a consequence of endothelial damage. Systemic inflammation is induced by factors that include elevated cytokine and chemokine levels, dysregulated coagulation/fibrinolytic responses, and the release of damage-associated molecular patterns (DAMPs) from necrotic cell death that cause distributive shock. The cytoprotective heat shock proteins can also facilitate circulatory disturbance under excess heat stress.

CONCLUSIONS

Multiple mechanisms are involved in the pathogenesis of heat-induced shock. In addition to dehydration, heat stress-induced cardiomyopathy due to the thermal damage of mitochondria, upregulated inflammation via damage-associated molecular patterns released from oncotic cells, unbalanced coagulation/fibrinolysis, and endothelial damage are the major factors that are related to circulatory shock.

Diagnostic Significance of Combined Calcitoninogen, Platelet, and D-Dimer Assay in Severe Heatstroke: with Clinical Data Analysis of 70 Patients with Severe Heatstroke

The significance of calcitoninogen detection among inpatients was discussed by analyzing the clinical characteristics of severe heatstroke (HS). HS patients who were admitted to the Second Hospital of Nantong University, Jiangsu Province, China, between July 1, 2015, and October 30, 2020, were reviewed. Patients' clinical characteristics and laboratory data were recorded, and they were divided into three groups, that is, a control group (heat cramps and heat exhaustion), an exertional HS (EHS) group, and a classical HS (CHS) group to compare the differences among them. Receiver operating characteristic (ROC) curves were plotted to evaluate patients' clinical utility. (1) The body temperatures in the EHS and CHS groups were significantly higher than in the control group (all p < 0.05). (2) The D-dimer (DD), procalcitonin (PCT), and Acute Physiology and Chronic Health Evaluation (APACHE) II score of the EHS group were significantly higher compared with the control and CHS groups (all p < 0.05); the platelets (PLT), C-reactive protein (CRP), blood sodium (Na), and intravenous glucose (GLU) of the EHS group were lower than in the control and CHS groups (all p < 0.05). (3) The ROC curve analysis showed the performance results for DD (area under the curve [AUC] 0.670, 95% confidence interval [CI] 0.547-0.777), PCT (AUC 0.705, 95% CI 0.584-0.808), and PLT (AUC 0.791, 95% CI 0.677-0.879). The sensitivity was 40.48%, 100%, and 73.81%, and the specificity was 96.43%, 32.14%, and 78.57%, respectively. Using three combined analyses, an elevated AUC of 0.838, 95% CI 0.731-0.916, with a sensitivity of 71.43% and a specificity of 85.71%, respectively, was revealed. Patients in the EHS group had higher DD, PCT, and APACHE II values, whereas PLT, CRP, Na, and GLU were reduced. The apparent decrease in the PLT, as well as the increase in PCT and DD values, could be considered as early sensitivity indicators of severe HS. A combined test of these three indicators presented significant diagnostic value for detecting severe cases of HS.

Severe heat stress modulated nuclear factor erythroid 2-related factor 2 and macrophage migration inhibitory factor pathway in rat liver

Heat stress impairs physiology and overall functionality of the body at tissue and organ level in animals. Liver being a vital organ performs more than hundreds regulatory functions of the body. Present study investigates the modulation of molecular pathways that are responsible for liver damage triggered by heat stress. Male Sprague dawley rats were exposed to heat stress (45 °C) in heat simulation chamber till core temperature reaches 40 °C and 42 °C in 25 and 42 min respectively. For in-depth evaluation of liver functions during severe heat stress, hepatic transcriptome and proteome were analysed by microarray and two dimensional gel electrophoresis respectively. Results revealed major alterations in redox status, inflammation, mitochondrial dysfunction and proteostasis related pathways. Data of molecular pathway analysis demonstrate that nuclear factor erythroid 2-related factor 2 (NRF-2) mediated oxidative stress response and macrophage migration inhibitory factor (MIF) regulated inflammatory pathways were upregulated in severe heat stressed liver. Expression levels of downstream molecules of above pathways such as heat shock protein 90AB 1, peroxiredoxin 5, Jun N-terminal kinases 1/2, heme-oxygenase 1, apolipoprotein 1 and interleukin 10 were examined and result suggested the upregulation of these genes modulates the NRF-2 and MIF regulated pathways in heat stressed liver. Irregularity in molecular signalling networks lead to mitochondrial dysfunction indicated by upregulation of ATP synthase β and peroxiredoxin 1 along with decreased levels of glucose-6-phosphate dehydrogenase and enhanced activity of cytochrome c in liver mitochondria. Thus, current study demonstrated heat induced alterations in key liver functions were regulated by NRF-2 and MIF pathways.

Tolerability of long-term temperature controlled whole-body thermal treatment in advanced cancer-bearing dogs

Aim: In oncology, thermal therapy is the application of external heat to fight cancer cells. The goal of whole-body thermal treatment (WBTT) is to raise the patient's core temperature to 39-42 °C, and represents the only thermal treatment modality that can act on both the primary tumor and distant metastases. However, WBTT carries potential risks for toxicity when applied without accurate thermometry and monitoring.Methods: ElmediX has developed a medical device, HyperTherm, to deliver long-term controlled and accurate WBTT (41.5 °C, up to 8 h). The safety of the device and thermal treatment protocol was initially evaluated in minipigs, and we present the confirmation of tolerability of WBTT in dogs with advanced cancer, in combination with a reduced dose of radiotherapy or chemotherapy.Results: Thermometry in liver, rectum, and tumor confirmed a homogeneous heating of these body parts. Monitoring of clinical parameters showed acceptable and reversible changes in liver, cardiac, muscle and coagulation parameters, as was expected. Combination of WBTT with both radiotherapy and chemotherapy only caused some low-grade adverse events.Conclusion: We conclude that our findings support the safe use of HyperTherm-mediated WBTT for canine patients with advanced malignancies. They also tend to support a genuine therapeutic potential for long-term WBTT which needs to be confirmed on a larger dog patient population. Combined with previously reported safety results in minipigs, these contribute to support the ongoing clinical evaluation of WBTT in advanced human cancer patients.

N-Methyl-3,4-methylendioxymethamphetamine (MDMA)-related coagulopathy and rhabdomyolysis: A case series and literature review

Coagulation changes, thrombosis, and hemorrhage have been described in patients following N-methyl-3,4-methylenedioxymethylamphetamine (MDMA) intoxication who subsequently developed serotonin syndrome and rhabdomyolysis. The clinical features and mechanism of this remain poorly described. We describe 5 sequential cases admitted to critical care due to severe recreational MDMA toxicity where coagulopathy occurred, and discuss key clinical issues. All patients presented with hyperpyrexia then developed subsequent rhabdomyolysis accompanied by a coagulopathy within 24 hours of presentation. This included a severe thrombocytopenia, prolonged coagulation times, grossly elevated D-dimer levels, and hypofibrogenemia. Multiorgan dysfunction was seen in all patients, including stroke in one patient and major hemorrhage in another. In 2 cases, low-dose low-molecular-weight heparin was used early after presentation, with no significant bleeding complications. Blood products usage was high but variable between the patients with lower use in those who received low-molecular-weight heparin early. Other treatments included intravascular therapeutic cooling, renal replacement therapy with large filter pores and cyprohepatidine. Current evidence suggests that in this group, rhabdomyolysis with subsequent myosin release may be a profound activator of coagulation leading to disseminated intravascular coagulation. Myosin-activated coagulation seems a potential cause of MDMA-related coagulopathy in the setting of rhabdomyolysis and serotonin syndrome. Further studies are needed to validate this and explore the use of low-molecular-weight heparin to reduce the clinical effects of this coagulopathy.