Heat stress-induced platelet dysfunction is associated with loss of fibrinogen and is improved by fibrinogen supplementation.

INTRODUCTION: Heatstroke is a critical heat-related condition characterized by coagulopathy and multiple organ dysfunction. One of the most severe complications of heatstroke is disseminated intravascular coagulation. This condition manifests as excessive clot formation and bleeding that are primarily due to platelet depletion and dysfunction. Fibrinogen plays a crucial role in hemostasis because it links integrin αIIbß3 on adjacent platelets, thereby promoting the platelet activation and aggregation necessary for clot formation. However, reduced fibrinogen levels may impair the formation of the initial platelet plug and increase the risk of bleeding. The current study explored the effect of fibrinogen on platelet dysfunction in a heatstroke model. MATERIALS AND METHODS: Male Wistar rats were subjected to heat stress, and subsequent changes in hemodynamic, biochemical, and coagulation parameters were analyzed. Platelet viability, aggregation, adhesion, spreading and fibrin clot retraction were assessed. RESULTS: The rats with heatstroke exhibited a variety of clinical symptoms, including hypotension, tachycardia, multiple organ dysfunction, and coagulopathy. Platelet viability in the heatstroke group was comparable to that in the healthy control group. However, the heatstroke group exhibited significant reductions in plasma fibrinogen levels and platelet aggregation, adhesion, spreading, and fibrin clot retraction. Notably, fibrinogen supplementation markedly augmented the aggregation responses of platelets in the heatstroke group. The impairment of platelet adhesion, spreading, and fibrin clot retraction in the rats with heatstroke was partially ameliorated by fibrinogen supplementation. CONCLUSIONS: An early use of fibrinogen replacement may serve as a therapeutic intervention to alleviate platelet hyporeactivity and prevent the complications in patients with heatstroke.

Heat stroke with significantly elevated troponin and dynamic ECG changes: Myocardial infarction or myocardial injury?

We described an 82-year-old man who was taken to our emergency department after being found unconscious. His electrocardiogram (ECG) showed ST-segment elevation in leads V4-V6 and cardiac troponin I (cTnI) was abnormally elevated. In addition to ECG and cTnI changes, this patient was combined with unconsciousness, high fever, abnormal liver function, acute renal failure, and rhabdomyolysis. The initial diagnosis was heat stroke, so cooling measures were initiated immediately, but a concurrent myocardial infarction was suspected. Meanwhile, emergency coronary angiography was performed, but no severe coronary stenosis or thrombosis was found. We first evaluated quantitative flow ratio (QFR) and coronary angiography-derived index of microvascular resistance (ca-IMR) in patients with heat stroke. Ca-IMR was 260 mmHg*s/m in the left circumflex artery, indicating the presence of coronary microvascular dysfunction (CMD). After several days of treatment, the patient recovered from multiple organ damage. Therefore, ECG and troponin results should be interpreted carefully in patients with high fever and coma during high temperature seasons.

Prognostic significance of nadir platelet count in patients with heatstroke: A multi-center retrospective study.

BACKGROUND: Heatstroke (HS), associated with the early activation of the coagulation system and frequently presenting with thrombocytopenia, poses a significant healthcare challenge. Understanding the relationship of nadir platelet count (PLT) within 24 h for adverse outcomes in HS patients is crucial for optimizing management strategies. METHODS: This retrospective cohort study, conducted in six tertiary care hospitals, involved patients diagnosed with HS and admitted to the emergency departments. The primary and secondary outcomes included in-hospital mortality and various acute complications, respectively, with logistic regression models utilized for assessing associations between nadir PLT and outcomes. The PLT count change curve was described using a generalized additive mixed model (GAMM), with additional analyses involving body temperature (BT) at 2 h also conducted. RESULTS: Of the 152 patients included, 19 (12.5%) died in-hospital. The median nadir PLT within 24 h was 99.5 (58.8-145.0)*10^9/L. Notably, as a continuous variable (10*10^9/L), nadir PLT was significantly associated with in-hospital mortality (OR 0.76; 95% CI 0.64-0.91; P = 0.003) and other adverse outcomes like acute kidney and liver injury, even after adjustment for confounders. GAMM revealed a more rapid and significant PLT decline in the non-survival group over 24 h, with differential PLT dynamics also observed based on BT at 2 h. CONCLUSIONS: Nadir PLT within 24 h were tied to in-hospital mortality and various adverse outcomes in HS patients. Early effective cooling measures demonstrated a positive impact on these associations, underscoring their importance in patient management.

Thromboelastometry for assessment of hemostasis and disease severity in 42 dogs with naturally-occurring heatstroke.

BACKGROUND: Thromboelastometry (TEM) provides a comprehensive overview of the entire coagulation process and has not been evaluated in heatstroke-induced coagulopathies in dogs. OBJECTIVES: To determine the diagnostic and prognostic utility of TEM in dogs with heatstroke. ANIMALS: Forty-two client-owned dogs with heatstroke. METHODS: Prospective observational study. Blood samples for intrinsic and extrinsic TEM (INTEM and EXTEM, respectively) were collected at presentation and every 12 to 24 hours for 48 hours. Coagulation phenotype (hypo-, normo-, or hypercoagulable) was defined based on TEM area under the 1st derivative curve (AUC). RESULTS: Case fatality rate was 31%. Median TEM variables associated with death (P < .05 for all) included longer INTEM clotting time, lower AUC at presentation and at 12 to 24 hours postpresentation (PP), lower INTEM alpha angle, maximum clot firmness, and maximum lysis (ML) at 12 to 24 hours PP, and lower EXTEM ML at 12 to 24 hours PP. Most dogs were normo-coagulable on presentation (66% and 63% on EXTEM and INTEM, respectively), but hypo-coagulable 12 to 24 PP (63% for both EXTEM and INTEM). A hypo-coagulable INTEM phenotype was more frequent at presentation and 12 to 24 PP among nonsurvivors compared to survivors (55% vs 15% and 100% vs 50%, P = .045 and .026, respectively). AKI was more frequent (P = .015) in dogs with hypo-coagulable INTEM tracings at 12 to 24 hours. Disseminated intravascular coagulation was more frequent (P < .05) in dogs with a hypo-coagulable INTEM phenotype and in nonsurvivors at all timepoints. CONCLUSIONS AND CLINICAL RELEVANCE: Hypocoagulability, based on INTEM AUC, is predictive of worse prognosis and occurrence of secondary complications.

Exosomes Derived From Heat Stroke Cases Carry miRNAs Associated With Inflammation and Coagulation Cascade.

The pathological mechanism underlying heat stroke (HS) is associated with the dysbalanced inflammation and coagulation cascade. Cell-derived circulating extracellular vesicles (EVs), as a novel pathway mediating intercellular communication, are associated with the immune response and inflammation in critical inflammatory syndromes, such as sepsis. Although these vesicles contain genetic material correlated with their biological function, their molecular cargo during HS remains unknown. In this study, we evaluate the presence of microRNAs (miRNAs) and messenger RNAs (mRNAs) associated with inflammatory responses and coagulation cascade in exosomes of patients with HS. Blood samples were collected from three patients with HS at the time of admission to the intensive care unit; three healthy volunteers were selected as control. Exosomes were isolated using ultracentrifugation, and their miRNA content was profiled using next-generation sequencing; mRNA content was evaluated using qPCR array. Compared with those from healthy volunteers, exosomes from patients with HS showed substantial changes in the expression of 202 exosomal miRNAs (154 upregulated and 48 downregulated miRNAs). The most upregulated miRNAs included miR-511-3p, miR-122-5p, miR-155-3p, miR-1290, and let7-5p, whereas the most downregulated ones included miR-150-3p, 146a-5p, and 151a-3p. Gene ontology enrichment of the miRNAs of patients with HS compared with control subjects were associated mostly with inflammatory response, including T cell activation, B cell receptor signaling, dendritic cell chemotaxis and leukocyte migration, and platelet activation and blood coagulation. The identified miRNAs were primarily enriched to the signal transduction pathways namely, T cell receptor signaling, Ras signaling, chemokine signaling, platelet activation, and leukocyte transendothelial migration, all of which are associated with inflammation and hemostasis. Multiple targeted mRNAs associated with the inflammatory response, blood coagulation, and platelet activation were further verified in serum exosomes. Exosomes from patients with HS convey miRNAs and mRNAs associated with pathogenic pathways, including inflammatory response and coagulation cascade. Exosomes may represent a novel mechanism for intercellular communication during HS.

The Role of Skeletal Muscles in Exertional Heat Stroke Pathophysiology.

The active participation of skeletal muscles is a unique characteristic of exertional heat stroke. Nevertheless, the only well-documented link between skeletal muscle activities and exertional heat stroke pathophysiology is the extensive muscle damage (e. g., rhabdomyolysis) and subsequent leakage of intramuscular content into the circulation of exertional heat stroke victims. Here, we will present and discuss rarely explored roles of skeletal muscles in the context of exertional heat stroke pathophysiology and recovery. This includes an overview of heat production that contributes to severe hyperthermia and the synthesis and secretion of bioactive molecules, such as cytokines, chemokines and acute phase proteins. These molecules can alter the overall inflammatory status from pro- to anti-inflammatory, affecting other organ systems and influencing recovery. The activation of innate immunity can determine whether a victim is ready to return to physical activity or experiences a prolonged convalescence. We also provide a brief discussion on whether heat acclimation can shift skeletal muscle secretory phenotype to prevent or aid recovery from exertional heat stroke. We conclude that skeletal muscles should be considered as a key organ system in exertional heat stroke pathophysiology.

Metabolomic profiling identifies a novel mechanism for heat stroke­related acute kidney injury.

Heat stroke can induce a systemic inflammatory response, which may lead to multi­organ dysfunction including acute kidney injury (AKI) and electrolyte disturbances. To investigate the pathogenesis of heat stroke (HS)­related AKI, a mouse model of HS was induced by increasing the animal's core temperature to 41˚C. Blood samples obtained from the tail vein were used to measure plasma glucose and creatinine levels. Micro­positron emission tomography­computed tomography (micro­PET/CT), H&E staining and transmission electron microscopy were conducted to examine metabolic and morphological changes in the mouse kidneys. Immunohistochemistry (IHC) and western blot analyses were performed to investigate the expression of apoptosis­inducing factor mitochondria­associated 2 (Aifm2), high­mobility group box 1 (HMGB1) and receptor for advanced glycosylation end products (RAGE). Liquid chromatography­mass spectrometry analysis was conducted to find differential metabolites and signaling pathways. The HS mouse model was built successfully, with significantly increased creatinine levels detected in the serum of HS mice compared with controls, whereas micro­PET/CT revealed active metabolism in the whole body of HS mice. H&E and TUNEL staining revealed that the kidneys of HS mice exhibited signs of hemorrhage and apoptosis. IHC and western blotting demonstrated significant upregulation of Aifm2, HMGB1 and RAGE in response to HS. Finally, 136 differential metabolites were screened out, and enrichment of the 'biosynthesis of unsaturated fatty acids' pathway was detected. HS­associated AKI is the renal manifestation of systemic inflammatory response syndrome, and may be triggered by the HMGB1/RAGE pathway. Metabolomics indicated increased adrenic acid, docosahexaenoic acid and eicosapentaenoic acid may serve as metabolic biomarkers for AKI in HS. The findings suggested that a correlation between the HMGB1/RAGE pathway and biosynthesis of unsaturated fatty acids may contribute to the progression of HS­related AKI.

Indicators of Acute Kidney Injury as Biomarkers to Differentiate Heatstroke from Coronavirus Disease 2019: A Retrospective Multicenter Analysis.

BACKGROUND: Coronavirus disease 2019 (COVID-19) and heat-related illness are systemic febrile diseases. These illnesses must be differentiated during a COVID-19 pandemic in summer. However, no studies have compared and distinguished heat-related illness and COVID-19. We compared data from patients with early heat-related illness and those with COVID-19. METHODS: This retrospective observational study included 90 patients with early heat-related illness selected from the Heatstroke STUDY 2017-2019 (nationwide registries of heat-related illness in Japan) and 86 patients with laboratory-confirmed COVID-19 who had fever or fatigue and were admitted to one of two hospitals in Tokyo, Japan. RESULTS: Among vital signs, systolic blood pressure (119 vs. 125 mm Hg, p = 0.02), oxygen saturation (98% vs. 97%, p < 0.001), and body temperature (36.6°C vs. 37.6°C, p<0.001) showed significant between-group differences in the heatstroke and COVID-19 groups, respectively. The numerous intergroup differences in laboratory findings included disparities in white blood cell count (10.8 × 103/µL vs. 5.2 × 103/µL, p<0.001), creatinine (2.2 vs. 0.85 mg/dL, p<0.001), and C-reactive protein (0.2 vs. 2.8 mg/dL, p<0.001), although a logistic regression model achieved an area under the curve (AUC) of 0.966 using these three factors. A Random Forest machine learning model achieved an accuracy, precision, recall, and AUC of 0.908, 0.976, 0.842, and 0.978, respectively. Creatinine was the most important feature of this model. CONCLUSIONS: Acute kidney injury was associated with heat-related illness, which could be essential in distinguishing or evaluating patients with fever in the summer during a COVID-19 pandemic.

The prognostic value of routine coagulation tests for patients with heat stroke.

OBJECTIVE: To evaluate the prognostic value of routine coagulation tests for patients with heat stroke. METHODS: This was a multi-center retrospective study. Patients who arrived at the hospital <24 h after the onset of Heat Stroke (HS) were included. The routine coagulation variables were detected within 24 h after the onset, including the lowest platelet count (PLC). RESULTS: 60-day mortality rate was 20.9%. The median Prothrombin Time-International Normalized Ratio (PT-INR) of the non-surviving patients was significantly higher than that of the survivors (P < 0.01). The median Activated Partial Thromboplastin Time (APTT) in non-surviving patients was significantly higher than in the surviving patients (P < 0.01). A Cox regression analysis revealed that 60-day mortality was associated with PT-INR (P = 0.032) and APTT (P = 0.004). The optimal PT-INR point for predicting 60-day mortality rate was 1.7. The optimal APTT point for predicting 60-day mortality was 51.45. Patients with increased PT-INR (≥1.7) levels had, overall, a significantly reduced survival time (P < 0.01). Patients with elevated APTT (≥51.45) also had a decrease in survival time (P < 0.01). The prognostic scoring, with increased PT-INR (≥1.7) and prolonged APTT (≥51.45) at one point each, was also demonstrated to be useful in predicting 60-day mortality. Patients whose temperature fell to 38.9 °C within 30 min had significantly lower levels of PT-INR and APTT within 24 h than those who took longer to cool down. CONCLUSIONS: A prolonged APTT and elevated PT-INR within 24 h are independent prognostic factors of 60-day mortality in HS.

Prior viral illness increases heat stroke severity in mice.

NEW FINDINGS: What is the central question of this study? We hypothesized that prior illness would increase the susceptibility to and severity of heat stroke (HS). What is the main finding and its importance? We provide the first experimental evidence, using a mouse model of HS, that recent viral illness increases the severity of HS. Our data indicate that this effect is not attributable to the exacerbation of hyperthermia but is a consequence of ongoing coagulation and systemic inflammatory reactions. Our data suggest that measurement of platelets, cytokines and chemokines before heat exposure might be indicative of susceptibility to HS, with coagulation and inflammation being potential targets for intervention that could improve recovery. ABSTRACT: It is hypothesized that prior illness exacerbates heat stroke (HS) in otherwise healthy organisms by augmenting hyperthermia during heat exposure or deactivating cellular pathways that protect against organ injury. To test these hypotheses, we injected telemetered male C57BL/6J mice with lipopolysaccharide (LPS; 50 µg kg-1 i.p.) or polyinosinic:polycytidylic acid (PIC; 100 µg i.p.) as a bacterial or a viral mimic, respectively, with saline (SAL; equivalent volume) as a control. Mice recovered for 48 or 72 h before HS (maximal core temperature = 42.4°C). Platelet counts, cytokines, chemokines and organ injury were determined 48 or 72 h after injection (without heating) or at maximal core temperature and at 1 day of recovery from HS. In the absence of heat, PIC induced more robust signs of sickness and increased cytokines and chemokines (TNF-α, RANTES, IP-10 and MIP-1ß) at 48 h, which was not observed with LPS (P < 0.05). Responses of both groups recovered by 72 h, although low platelet counts persisted after PIC (P < 0.05). Heat-induced hyperthermia was similar among mice injected with SAL, LPS and PIC; however, PIC-injected mice displayed more severe responses during recovery from HS, with reduced survival (48 h, 70 versus 100%; P < 0.05), deeper and longer post-HS hypothermia, greater reductions in platelets, elevated RANTES, IP-10, IL-6 and TNF-α and greater duodenal injury (P < 0.05). By 72 h, survival from HS was no longer reduced in PIC-injected mice, although hypothermia, the reduction in platelets and elevated cytokines persisted. Our data indicate that prior illness exacerbates the severity of HS in the absence of signs of illness at the time of heat exposure and suggest that this is attributable to persistent coagulation and inflammatory reactions that might be targets for intervention to improve recovery.

Biochemical recovery from exertional heat stroke follows a 16-day time course.

BACKGROUND: The aim of this study was to characterize the time-resolved progression of clinical laboratory disturbances days-following an exertional heat stroke (EHS). Currently, normalization of organ injury clinical biomarker values is the primary indicator of EHS recovery. However, an archetypical biochemical recovery profile following EHS has not been established. METHODS: We performed a retrospective analysis of EHS patient records in US military personnel from 2008-2014 using the Military Health System Data Repository (MDR). We focused on commonly reported clinical laboratory analytes measured on the day of injury and all proceeding follow-up visits. RESULTS: Over the prescribed period, there were 2,529 EHS episodes treated at 250 unique treatment locations. Laboratory results, including a standardized set of blood, serum and urine assays, were analyzed from 0-340 days following the initial injury. Indicators of acute kidney injury, including serum electrolyte disturbances and abnormal urinalysis findings, were most prevalent on the day of the injury but normalized within 24-48hours (creatinine, blood urea nitrogen, and blood and protein in urine). Muscle damage and liver function-associated markers peaked 0-4 days after injury and persisted outside their respective reference ranges for 2-16 days (alanine aminotransferase, aspartate aminotransferase, creatine phosphokinase, myoglobin, prothrombin time). CONCLUSION: Biochemical recovery from EHS spans a 16-day time course, and markers of end-organ damage exhibit distinct patterns over this period. This analysis underscores the prognostic value of each clinical laboratory analyte and will assist in evaluating EHS patient presentation, injury severity and physiological recovery.

[Predictive value of myoglobin and D-dimer on severe heat stroke: a clinical analysis of 38 patients with severe heat stroke].

OBJECTIVE: To explore the clinical characteristics and early sensitive indicators of severe heat stroke patients in order to predict the development of severe heat stroke in the early stage. METHODS: Thirty-eight patients with severe heat stroke admitted to emergency department of Beijing Daxing District People's Hospital from July 30th to August 5th in 2018 were enrolled. There were 18 patients suffered from exertional heat stroke (EHS), and 12 patients suffered from classical heat stroke (CHS), and 8 patients with heat spasm and heat exhaustion were selected as control group. The gender, age, onset time, body temperature, heart rate (HR), lactic acid (Lac), platelet (PLT), alanine aminotransferase (ALT), alanine aminotransferase (AST), blood urea nitrogen (BUN), serum creatinine (SCr), serum sodium at admission of hospital, as well as positive rate of myoglobin (MYO) and D-dimer (the positive threshold of MYO and D-dimer was 107 µg/L and 600 µg/L respectively) were recorded and compared among the groups. Receiver operating characteristic (ROC) curve was plotted to analyze the prognostic value of MYO and D-dimer on heat stroke. The outcome of all patients was followed up, and the 28-day mortality between EHS and CHS patients was compared. The patient's body temperature was measured again after 4 hours of active cooling treatment (T4 h), and the relationship between T4 h and 28-day mortality was discussed. RESULTS: The majority of severe heat stroke patients were male, especially in EHS patients. EHS patients were younger than CHS ones, and had shorter onset time, with significant differences among the groups. The body temperature and HR at admission in the EHS group and the CHS group were significantly higher than those in the control group [body temperature (centigrade): 41.34±0.67, 40.39±0.58 vs. 37.80±1.39; HR (bpm): 139.78±15.63, 113.08±17.70 vs. 92.00±15.89, all P < 0.05], PLT was significantly lowered (×109/L: 164.94±73.80, 165.78±53.49 vs. 249.50±84.22, both P < 0.05), and the positive rates of MYO and D-dimer were also significantly increased [MYO positive rate: 100.0% (18/18), 100.0% (12/12) vs. 50.0% (4/8); D-dimer positive rate: 77.8% (14/18), 100.0% (12/12) vs. 12.5% (1/8), all P < 0.05]. ROC curve analysis showed that positive MYO and D-dimer at admission had certain diagnostic value for heat stroke, the area under ROC curve (AUC) was 0.750 and 0.871, the sensitivity was 50.0% and 87.5%, and the specificity was 100% and 86.7%, respectively. The 28-day mortality of the EHS group was significantly higher than that of the CHS group [44.4% (8/18) vs. 8.3% (1/12), P < 0.05]. Furthermore, the 28-day mortality of the patients with T4 h ≥ 38 centigrade in the EHS group was significantly higher than those with T4 h < 38 centigrade [70.0% (7/10) vs. 12.5% (1/8), P < 0.05]. CONCLUSIONS: The decreased PLT and the increased D-dimer in the early stage of heat stroke indicate that the damage of coagulation mechanism is prominent in patients with heat stroke. EHS patients have the characteristics of acute onset, severe condition, rapid progression and poor prognosis, and the 28-day mortality is significantly higher than that of CHS patients. MYO and D-dimer are sensitive indicators in early stage of heat stroke patients, which can be used as reference for early diagnosis of heat stroke.

Renoprotective effect of oral rehydration solution III in exertional heatstroke rats.

AIM: Exertional heastroke (EHS) can lead to acute kidney injury. Oral rehydration solution III (ORS III), recommended by WHO in 2004, is used to rehydrate children with gastroenteritis. This study aimed to characterize the renoprotective effect of ORS III in EHS rats. METHODS: Rats were randomly divided into Group Control, Group EHS, Group EHS + Water, and Group EHS + ORS. Thirty minutes before the experiment, ORS III was orally administrated to Group EHS + ORS, Water was given to Group EHS + Water. Rats from Group EHS, Group EHS + Water and Group EHS + ORS were then forced to run until they fatigued. Core temperature (Tc) was monitored and 40.5 °C was considered as the onset of heatstroke. Serum creatinine (SCr), blood urea nitrogen (BUN) were measured using an automated biochemical analyzer. Serum neutrophil gelatinase-associated lipocalin (NGAL) was measured using an NGAL ELISA Kit. Light microscopy was used for kidney structural analysis. RESULTS: SCr level in Group EHS was no different from Group Control (p > .05), while BUN and NGAL levels in Group EHS were higher than Group Control (p <.001, p < .001). SCr, BUN and NGAL concentrations in group EHS + Water were no different from Group EHS (p > .05). SCr, BUN levels in Group EHS + ORS were no different from Group EHS (p > .05). But NGAL levels were significant in these two groups (p = .012). Renal histopathologies of rats in Group EHS and Group EHS + Water showed flattened lumens filled with eosinophilic materials. The damage was milder in Group EHS + ORS, in which injured tubules showed degeneration of the tubular epithelium and sloughing of the brush border membrane. CONCLUSION: ORS III could alleviate the kidney injury in EHS rats.

[Effect of curcumin on expressions of CD11b and CD19 in peripheral blood of heat stroke rats in a simulation dry-heat environment].

OBJECTIVE: To investigate the effects of different doses of curcumin on the levels of immune factors CD11b and CD19 in peripheral blood of heat stroke rats in a simulation dry-heat environment. METHODS: 160 SPF healthy male Sprague-Dawley (SD) rats were selected and divided into different groups according to random number table method: normal saline (NS) control group (given NS), solvent control group [given sodium carboxymethylcellulose (CMCNa)], and curcumin low, medium and high dose pretreatment group (given 0.05, 0.10, 0.20 mg/g of curcumin+0.5% CMCNa solution). There were 32 rats in each group, and were challenged only by 10 mL×kg-1×d-1 lavage, and continuous dosing for 7 days. On the 8th day, rats were challenged at ambient temperature (41.0±0.5) centigrade, relative humidity (10±1)% of the northwest in the special environment of artificial lab, placed in 0 (normal temperature), 50, 100 and 150 minutes respectively. The levels of CD19 and CD11b in peripheral blood of each rat were detected by flow cytometry instrument. RESULTS: With the extension of time in the simulated dry and heat environment, the level of CD11b in peripheral blood was gradually increased in each group, and the peak value was reached at 150 minutes, the NS control group, solvent control group and curcumin low, medium and high dose pretreatment groups were 0.346±0.013, 0.342±0.013, 0.342±0.012, 0.325±0.012, and 0.281±0.012, respectively. In each group, the level of CD19 was first increased and then decreased, reaching its peak value at 100 minutes, and the level of the NS control group, solvent control group and curcumin low, medium and high dose pretreatment groups were 0.586±0.010, 0.601±0.014, 0.684±0.009, 0.613±0.012 and 0.604±0.006, respectively. The level of CD11b in the curcumin medium and high dose pretreatment groups were significantly lower than those in the NS control group and solvent control group (50 minutes: 0.237±0.011, 0.188±0.006 vs. 0.283±0.009, 0.289±0.012; 100 minutes: 0.260±0.010, 0.248±0.008 vs. 0.293±0.008, 0.290±0.007, all P < 0.05), and after placement for 150 minutes, the level of CD11b in the curcumin high dose pretreatment group was significantly lower than that in the NS control group, solvent control group and curcumin low dose pretreatment group (0.281±0.012 vs. 0.346±0.013, 0.342±0.013, 0.342±0.012, all P < 0.05). The level of CD19 in the curcumin low, medium and high dose pretreatment groups were significantly higher than those in the NS control group and solvent control group at 50 minutes in the dry and hot environment (0.394±0.001, 0.436±0.009, 0.553±0.011 vs. 0.205±0.005, 0.197±0.003, all P < 0.05), at 100 minutes, the level of CD19 in the curcumin low dose pretreatment group was significantly higher than that in the NS control group and solvent control group (0.684±0.009 vs. 0.586±0.010, 0.601±0.014, both P < 0.05), there was no significant difference in CD19 level between the other dose pretreatment groups and NS control group; at 150 minutes, there was no significant difference in CD19 level between the curcumin pretreatment groups, the NS control group, and the solvent control group. The peripheral blood immune factors CD11b and CD19 levels in the NS control group and solvent control group were not significantly changed, and there was no significant difference between two groups. CONCLUSIONS: Curcumin pretreatment can reduce the level of CD11b and increase the level of CD19 in peripheral blood of rats with dry heat stroke in the early and middle stages, which may enhance the heat resistance and prevent the occurrence of multiple organ dysfunction by increasing the body immunity, and this effect has nothing to do with the dose of curcumin.

Identification of whole blood mRNA and microRNA biomarkers of tissue damage and immune function resulting from amphetamine exposure or heat stroke in adult male rats.

This work extends the understanding of how toxic exposures to amphetamine (AMPH) adversely affect the immune system and lead to tissue damage. Importantly, it determines which effects of AMPH are and are not due to pronounced hyperthermia. Whole blood messenger RNA (mRNA) and whole blood and serum microRNA (miRNA) transcripts were identified in adult male Sprague-Dawley rats after exposure to toxic AMPH under normothermic conditions, AMPH when it produces pronounced hyperthermia, or environmentally-induced hyperthermia (EIH). mRNA transcripts with large increases in fold-change in treated relative to control rats and very low expression in the control group were a rich source of organ-specific transcripts in blood. When severe hyperthermia was produced by either EIH or AMPH, significant increases in circulating organ-specific transcripts for liver (Alb, Fbg, F2), pancreas (Spink1), bronchi/lungs (F3, Cyp4b1), bone marrow (Np4, RatNP-3b), and kidney (Cesl1, Slc22a8) were observed. Liver damage was suggested also by increased miR-122 levels in the serum. Increases in muscle/heart-enriched transcripts were produced by AMPH even in the absence of hyperthermia. Expression increases in immune-related transcripts, particularly Cd14 and Vcan, indicate that AMPH can activate the innate immune system in the absence of hyperthermia. Most transcripts specific for T-cells decreased 50-70% after AMPH exposure or EIH, with the noted exception of Ccr5 and Chst12. This is probably due to T-cells leaving the circulation and down-regulation of these genes. Transcript changes specific for B-cells or B-lymphoblasts in the AMPH and EIH groups ranged widely from decreasing ≈ 40% (Cd19, Cd180) to increasing 30 to 100% (Tk1, Ahsa1) to increasing ≥500% (Stip1, Ackr3). The marked increases in Ccr2, Ccr5, Pld1, and Ackr3 produced by either AMPH or EIH observed in vivo provide further insight into the initial immune system alterations that result from methamphetamine and AMPH abuse and could modify risk for HIV and other viral infections.

Cryptdin-2 predicts intestinal injury during heatstroke in mice.

Intestinal injury-induced bacterial translocation and endotoxemia are important in the pathophysiological process of heatstroke. However, the underlying mechanism remains to be fully elucidated. Previous studies using 2D-gel electrophoresis found that defensin-related cryptdin-2 (Cry-2), an intestinal α-defensin, is upregulated in intestinal tissues during heatstroke in mice, and that treatment with ulinastatin, a multivalent enzyme inhibitor, reduced heat-induced acute lung injury. To investigate the association between Cry-2 and heat stress (HS)-induced intestinal injury and the probable protective role of ulinastatin, the present study examined the intestinal expression of Cry-2 via histopathologic analysis and reverse transcription-quantitative polymerase chain reaction analysis in mice with heatstroke. The heat-stressed mice were exposed to different core temperatures and cooling treatments, and intestinal pathological changes and Chiu scores were determined. Chemical markers of intestinal injury, serum and intestinal concentrations of diamine oxidase (DAO) and D-lactic acid (D-Lac), and serum and intestinal concentrations of Cry-2 were also determined. Correlations were analyzed using Spearman's correlation analysis. It was found that HS upregulated the expression of Cry-2, and the serum and intestinal concentrations of Cry-2 were correlated with the severity of HS-induced intestinal damage, indicated by pathology scores and concentrations of DAO and D-lac. Ulinastatin protected the intestines from HS-induced injury and downregulated the expression of Cry-2, which was also correlated with the extent of intestinal injury. Therefore, ulinastatin administration may be beneficial for patients with heatstroke, and Cry-2 may be a novel predictor of HS-induced intestinal injury.

Serum histones as biomarkers of the severity of heatstroke in dogs.

Heatstroke is associated with systemic inflammatory response syndrome, leading to multiple organ dysfunction and death. Currently, there is no specific treatment decreasing hyperthermia-induced inflammatory/hemostatic derangements. Emerging studies indicate that histones leaking from damaged cells into the extracellular space are toxic, pro-inflammatory, and pro-thrombotic. We therefore hypothesize that serum histones (sHs) are elevated during heatstroke and are associated with the severity of the disease. Sixteen dogs with heatstroke and seven healthy controls were included in the study. Median serum histones (sHs) upon admission in dogs with heatstroke were significantly higher (P = 0.043) compared to that in seven controls (13.2 vs. 7.3 ng/mL, respectively). sHs level was significantly higher among non-survivors and among dogs with severe hemostatic derangement (P = 0.049, median 21.4 ng/mL vs. median 8.16 ng/mL and P = 0.038, 19.0 vs. 7.0 ng/mL, respectively). There were significant positive correlation between sHs and urea (r = 0.8, P = 0.02); total CO2 (r = 0.661, P = 0.05); CK (r = 0.678, P = 0.04); and prothrombin time (PT) 12 h post presentation (r = 0.888, P = 0.04). The significant positive correlation between sHs and other heatstroke severity biomarkers, and significant increase among severely affected dogs, implies its role in inflammation/oxidation/coagulation during heatstroke. sHs, unlike other prognostic and severity biomarkers in heatstroke, can be pharmacologically manipulated, offering a potential therapeutic target.

Hemostatic abnormalities in dogs with naturally occurring heatstroke.

OBJECTIVE: To investigate hemostatic analyte abnormalities and their association with mortality in dogs with naturally occurring heatstroke. DESIGN: Prospective observational study. SETTING: University teaching hospital. ANIMALS: Thirty client-owned dogs with naturally occurring heatstroke. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Citrated and EDTA blood samples were collected at presentation and at 4, 12, 24, 36, and 48 hours postpresentation (PP). Hemostatic tests performed included platelet count, prothrombin and activated partial thromboplastin times (PT and aPTT, respectively), antithrombin activity (ATA), total protein C activity (tPCA), fibrinogen, and D-dimer concentrations. The overall survival rate was 60% (18/30 dogs). Older age, higher heart rate and rectal temperature at presentation, and time from onset of clinical signs to presentation were significantly associated with mortality. Hemostatic analytes at presentation were not associated with mortality. Prolonged PT and aPTT at 12-24 hours PP, lower tPCA at 12 hours PP, and hypofibrinogenemia at 24 hours PP were significantly (P < 0.05) associated with mortality. Increased D-dimer concentration and low ATA were common at all time points, but were not associated with mortality. The frequency of disseminated intravascular coagulation (DIC) increased in nonsurvivors throughout hospitalization, but the development of DIC was not associated with mortality. The number of abnormal coagulation disturbances during the first 24 hours was significantly higher in nonsurvivors (P = 0.04). CONCLUSIONS: Hemostatic derangements are common in dogs with naturally occurring heatstroke. Alterations in PT, aPTT, tPCA, and fibrinogen concentrations appear to be associated with the outcome at 12-24 hours PP, exemplifying the need for serial measurement of multiple laboratory hemostatic tests during hospitalization, even when within reference interval on presentation. The development of DIC, as defined in this cohort, was not associated with mortality; however, nonsurvivors had significantly more coagulation abnormalities during the first 24 hours PP.