Insights into pathophysiology and therapeutic strategies for heat stroke: Lessons from a baboon model

Heat stroke is a perilous condition marked by severe hyperthermia and extensive multiorgan dysfunction, posing a considerable risk of mortality if not promptly identified and treated. Furthermore, the complex biological mechanisms underlying heat stroke-induced tissue and cell damage across organ systems remain incompletely understood. This knowledge gap has hindered the advancement of effective preventive and therapeutic strategies against this condition. In this narrative review, we synthesize key insights gained over a decade using a translational baboon model of heat stroke. By replicating heat stroke pathology in a non-human primate species that closely resembles humans, we have unveiled novel insights into the pathways of organ injury and cell death elicited by this condition. Here, we contextualize and integrate the lessons learned concerning heat stroke pathophysiology and recovery, areas that are inherently challenging to investigate directly in human subjects. We suggest novel research directions to advance the understanding of the complex mechanisms underlying cell death and organ injury. This may lead to precise therapeutic strategies that benefit individuals suffering from this debilitating condition.

Escalating climate-related health risks for Hajj pilgrims to Mecca

BACKGROUND

Global temperatures are on the rise, leading to more frequent and severe heatwaves with associated health risks. Heat-related illnesses are an increasing threat for travellers to hot climate destinations. This study was designed to elucidate the interplay between increasing ambient temperatures, incidence of heat-related illnesses, and the effectiveness of mitigation strategies during the annual Hajj mass gathering over a 40-year period.

METHODS

An observational study was conducted utilizing historical records spanning four decades of meteorological data, and the rates of heat stroke and heat exhaustion during the Hajj pilgrimage in Mecca, Saudi Arabia. With an annual population exceeding two million participants from over 180 countries, the study analyzed temporal variations in weather conditions over two distinct Hajj hot cycles and correlated it with the occurrence of heat stroke and heat exhaustion. The effectiveness of deployed mitigation measures in alleviating health vulnerabilities between the two cycles was also assessed.

RESULTS

Throughout the study period, average dry and wet bulb temperatures in Mecca escalated by 0.4°C (Mann-Kendall p<0.0001) and 0.2°C (Mann-Kendall p=0.25) per decade respectively. Both temperatures were strongly correlated with the incidence of heat stroke and heat exhaustion (p<0.001). Despite the intensifying heat, the mitigation strategies including individual, structural and community measures were associated with a substantial 74.6% reduction in heat stroke cases and a 47.6% decrease in case fatality rate.

CONCLUSION

The study underscores the escalating climate-related health risks in Mecca over the study period. The mitigation measures' efficacy in such a globally representative setting emphasizes the findings' generalizability and the importance of refining public health interventions in the face of rising temperatures.

Transcriptome Changes and Metabolic Outcomes After Bariatric Surgery in Adults With Obesity and Type 2 Diabetes

Context

Bariatric surgery has been shown to be effective in inducing complete remission of type 2 diabetes in adults with obesity. However, its efficacy in achieving complete diabetes remission remains variable and difficult to predict before surgery.

Objective

We aimed to characterize bariatric surgery-induced transcriptome changes associated with diabetes remission and the predictive role of the baseline transcriptome.

Methods

We performed a whole-genome microarray in peripheral mononuclear cells at baseline (before surgery) and 2 and 12 months after bariatric surgery in a prospective cohort of 26 adults with obesity and type 2 diabetes. We applied machine learning to the baseline transcriptome to identify genes that predict metabolic outcomes. We validated the microarray expression profile using a real-time polymerase chain reaction.

Results

Sixteen patients entered diabetes remission at 12 months and 10 did not. The gene-expression analysis showed similarities and differences between responders and nonresponders. The difference included the expression of critical genes (SKT4, SIRT1, and TNF superfamily), metabolic and signaling pathways (Hippo, Sirtuin, ARE-mediated messenger RNA degradation, MSP-RON, and Huntington), and predicted biological functions (β-cell growth and proliferation, insulin and glucose metabolism, energy balance, inflammation, and neurodegeneration). Modeling the baseline transcriptome identified 10 genes that could hypothetically predict the metabolic outcome before bariatric surgery.

Conclusion

The changes in the transcriptome after bariatric surgery distinguish patients in whom diabetes enters complete remission from those who do not. The baseline transcriptome can contribute to the prediction of bariatric surgery-induced diabetes remission preoperatively.

Diagnosing and managing heat exhaustion: insights from a systematic review of cases in the desert climate of Mecca

Heat exhaustion (HE) is a common, yet obscure, heat-related illness that affects millions of people yearly and its burden is projected to rise due to climate change. A comprehensive literature synthesis is lacking despite previous studies on various HE aspects. This systematic review aims to fill this gap by identifying and synthesizing available evidence on the risk factors, symptoms, biomarkers, treatment options, and outcomes for HE. The review focused on HE during the Muslim (Hajj) pilgrimage where the condition is endemic. We conducted a structured search of MEDLINE/PubMed, Embase, Web of Science Core Collection, SCOPUS, and CINAHL databases. We summarized the data from eligible studies and synthesized them in narrative form using pooled descriptive statistics. Ten studies were included between 1980 and 2019, reporting over 1,194 HE cases. HE cases presented with elevated core temperature (up to 40°C) and mainly affected older males from the Middle East and North Africa region, with overweight individuals at a higher risk. Clinical symptoms included hyperventilation, fatigue, dizziness, headaches, nausea, and vomiting, but not central nervous system disturbances. HE was associated with cardiac stress, and with water, electrolyte, and acid-base alterations. Cooling and hydration therapy were the primary management strategies, leading to a low mortality rate (pooled case fatality rate=0.11 % [95 % CI: 0.01, 0.3]). Most cases recovered within a few hours without complications. HE is associated with cardiac stress and changes in homeostasis, leading to distinct clinical symptoms. Early diagnosis and treatment of HE are crucial in reducing the risk of complications and mortality. The review provides insights into the pathophysiology and outcomes of HE, adding to the scarce literature on the subject. Prospero registration number: CRD42022325759.

Whole genome transcriptomic reveals heat stroke molecular signatures in humans

An evolutionary heat shock response (HSR) protects most living species, including humans, from heat-induced macromolecular damage. However, its role in the pathogenesis of heat stroke is unknown. We examined the whole genome transcriptome in peripheral blood mononuclear cells of a cohort of subjects exposed to the same high environmental heat conditions, who developed heat stroke (n = 19) versus those who did not (n = 19). Patients with heat stroke had a mean rectal temperature at admission of 41.7 ± 0.8°C, and eight were in deep coma (Glasgow Coma Score = 3). The transcriptome showed that genes involved in more than half of the entire chaperome were differentially expressed relative to heat stress control. These include the heat shock protein, cochaperone, and chaperonin genes, indicating a robust HSR. Differentially expressed genes also encoded proteins related to unfolded protein response, DNA repair, energy metabolism, oxidative stress, and immunity. The analysis predicted perturbations of the proteome network and energy production. Cooling therapy attenuated these alterations without complete restoration of homeostasis. We validated the significantly expressed genes by a real-time polymerase chain reaction. The findings reveal the molecular signature of heat stroke. They also suggested that a powerful HSR may not be sufficient to protect against heat injury. The overwhelming proteotoxicity and energy failure could play a pathogenic role. KEY POINTS: Most living species, including humans, have inherent heat stress response (HSR) that shields them against heat-induced macromolecular damage. The role of the HSR in subjects exposed to environmental heat who progressed to heat stroke versus those that did not is unknown. Our findings suggest that heat stroke induces a broad and robust HSR of nearly half of the total heat shock proteins, cochaperones, and chaperonin genes. Heat stroke patients exhibited inhibition of genes involved in energy production, including oxidative phosphorylation and ATP production. Significant enrichment of neurodegenerative pathways, including amyloid processing signalling, the Huntington's and Parkinson's disease signalling suggestive of brain proteotoxicity was noted. The data suggests that more than a powerful HSR may be required to protect against heat stroke. Overwhelming proteotoxicity and energy failure might contribute to its pathogenesis.

Human tolerance to extreme heat: evidence from a desert climate population

BACKGROUND

Ambient temperatures exceeding 40 °C are projected to become common in many temperate climatic zones due to global warming. Therefore, understanding the health effects of continuous exposure to high ambient temperatures on populations living in hot climatic regions can help identify the limits of human tolerance.

OBJECTIVE

We studied the relationship between ambient temperature and non-accidental mortality in the hot desert city of Mecca, Saudi Arabia, between 2006 and 2015.

METHODS

We used a distributed lag nonlinear model to estimate the mortality-temperature association over 25 days of lag. We determined the minimum mortality temperature (MMT) and the deaths that are attributable to heat and cold.

RESULTS

We analyzed 37,178 non-accidental deaths reported in the ten-year study period among Mecca residents. The median average daily temperature was 32 °C (19-42 °C) during the same study period. We observed a U-shaped relationship between daily temperature and mortality with an MMT of 31.8 °C. The total temperature-attributable mortality of Mecca residents was 6.9% (-3.2; 14.8) without reaching statistical significance. However, extreme heat, higher than 38 °C, was significantly associated with increased risk of mortality. The lag structure effect of the temperature showed an immediate impact, followed by a decline in mortality over many days of heat. No effect of cold on mortality was observed.

IMPACT STATEMENT

High ambient temperatures are projected to become future norms in temperate climates. Studying populations familiar with desert climates for generations with access to air-conditioning would inform on the mitigation measures to protect other populations from heat and on the limits of human tolerance to extreme temperatures. We studied the relationship between ambient temperature and all-cause mortality in the hot desert city of Mecca. We found that Mecca population is adapted to high temperatures, although there was a limit to tolerance to extreme heat. This implies that mitigation measures should be directed to accelerate individual adaptation to heat and societal reorganization.

Association of Ambient Temperature with Mortality in Resident and Multiethnic Transient Populations in a Desert Climate, 2006-2014

BACKGROUND

Although the association between ambient temperature and mortality in local populations is evident, this relationship remains unclear in transient populations (e.g., due to immigration, mass gatherings, or displacement). The holy city of Mecca annually shelters two populations comprising its residents and the transitory Hajj pilgrims (>2 million people from >180 countries). Both live side by side in a hot desert climate, rendering the development of evidence-based heat-protective measures challenging.

OBJECTIVES

We aimed to characterize the ambient temperature-mortality relationship and burden for the Mecca resident and Hajj transient populations, which have distinct levels of adaptation to ambient temperature.

METHODS

We analyzed daily air temperature and mortality data for Mecca residents and pilgrims over nine Hajj seasons between 2006 and 2014, using a fitted standard time-series Poisson model. We characterized the temperature-mortality relationship with a distributed lag nonlinear model with 10 d of lag. We determined the minimum mortality temperature (MMT) and attributable deaths for heat and cold for the two populations.

RESULTS

The median average daily temperature during the Hajj seasons was 30°C (19°C-37°C). There were 8,543 and 10,457 nonaccidental deaths reported during the study period among Mecca residents and pilgrims, respectively. The MMT was 2.5°C lower for pilgrims in comparison with the MMT for Mecca residents (23.5°C vs. 26.0°C). The temperature-mortality relationship shape varied from inverted J to U shape for the Mecca and pilgrim populations, respectively. Neither hot nor cold temperatures had a statistically significant association with mortality in Mecca residents. In contrast, for pilgrims, elevated temperatures were associated with significantly high attributable mortality of 70.8% [95% confidence interval (CI): 62.8, 76.0]. The effect of heat on pilgrims was immediate and sustained.

DISCUSSION

Our findings indicate that pilgrims and Mecca residents exposed to the same hot environmental conditions exhibited distinct health outcomes. This conclusion suggests that a precision public health approach may be warranted to protect against high environmental temperature during mass gatherings of diverse populations. https://doi.org/10.1289/EHP9838.

Classic heat stroke in a desert climate: A systematic review of 2,632 cases

BACKGROUND

Although classic heat stroke (HS) is one of the most ancient conditions known to humans, the description of its early clinical manifestations, natural course, and complications remains uncertain.

OBJECTIVES

A systematic review of the demographics, clinical characteristics, biomarkers, therapy, and outcomes of HS during the Muslim (Hajj) pilgrimage in the desert climate of Makkah, Saudi Arabia.

METHODS

We searched the MEDLINE, Embase, Web of Science Core Collection, SCOPUS, and CINAHL databases from inception to April 2022. We summarized the data from eligible studies and synthesized them in narrative form using pooled descriptive statistics.

RESULTS

Forty-four studies, including 2,632 patients with HS, met the inclusion criteria. Overweight or obesity, diabetes, and cardiovascular disease were prevalent among cases of HS. Evidence suggests that extreme hyperthermia (pooled mean = 42.0°C [95%CI: 41.9, 42.1], range 40-44.8°C) with hot and dry skin (>99% of cases) and severe loss of consciousness (mean GCS<8 in 53.8% of cases) were the dominant clinical characteristics of classic HS. Hypotension, tachypnea, vomiting, diarrhea, and biochemical biomarkers indicating mild to moderate rhabdomyolysis, acute kidney, liver, and heart injury, and coagulopathy were frequent at the onset. Concomitantly, stress hormones (cortisol and catecholamines) and biomarkers of systemic inflammation and coagulation activation were increased. HS was fatal in 1 in 18 cases (pooled case fatality rate = 5.6% [95%CI: 4.6, 6.5]).

CONCLUSIONS

The findings of this review suggest that HS induces an early multiorgan injury that can progress rapidly to organ failure, culminating in death, if it is not recognized and treated promptly.

PROSPERO REGISTRATION

CRD42022325759. This article is protected by copyright. All rights reserved.

Profiling the Hsp70 Chaperone Network in Heat-Induced Proteotoxic Stress Models of Human Neurons

Heat stroke is among the most hazardous hyperthermia-related illnesses and an emerging threat to humans from climate change. Acute brain injury and long-lasting brain damage are the hallmarks of this condition. Hyperthermic neurological manifestations are remarkable for their damage correlation with stress amplitude and long-term persistence. Hyperthermia-induced protein unfolding, and nonspecific aggregation accumulation have neurotoxic effects and contribute to the pathogenesis of brain damage in heat stroke. Therefore, we generated heat-induced, dose-responsive extreme and mild proteotoxic stress models in medulloblastoma [Daoy] and neuroblastoma [SH-SY5Y] and differentiated SH-SY5Y neuronal cells. We show that heat-induced protein aggregation is associated with reduced cell proliferation and viability. Higher protein aggregation in differentiated neurons than in neuroblastoma precursors suggests a differential neuronal vulnerability to heat. We characterized the neuronal heat shock response through RT-PCR array analysis of eighty-four genes involved in protein folding and protein quality control (PQC). We identify seventeen significantly expressed genes, five of which are Hsp70 chaperones, and four of their known complementing function proteins. Protein expression analysis determined the individual differential contribution of the five Hsp70 chaperones to the proteotoxic stress response and the significance of only two members under mild conditions. The co-expression analysis reveals significantly high co-expression between the Hsp70 chaperones and their interacting partners. The findings of this study lend support to the hypothesis that hyperthermia-induced proteotoxicity may underlie the brain injury of heat stroke. Additionally, this study presents a comprehensive map of the Hsp70 network in these models with potential clinical and translational implications.

Biomarkers of heatstroke-induced organ injury and repair

NEW FINDINGS

What is the topic of this review? The status and potential role of novel biological markers (biomarkers) that can help identify the patients at risk of organ injury or long-term complications following heatstroke. What advances does it highlight? Numerous biomarkers were identified related to many aspects of generalized heatstroke-induced cellular injury and tissue damage, and heatstroke-provoked cardiovascular, renal, cerebral, intestinal and skeletal muscle injury. No novel biomarkers were identified for liver or lung injury.

ABSTRACT

Classic and exertional heatstroke cause acute injury and damage across numerous organ systems. Moreover, heatstroke survivors may sustain long-term neurological, cardiovascular and renal complications with a persistent risk of death. In this context, biomarkers, defined as biological samples obtained from heatstroke patients, are needed to detect early organ injury, and predict outcomes to develop novel organ preservation therapeutic strategies. This narrative review provides preliminary insights that will guide the development and future utilization of these biomarkers. To this end, we have identified numerous biomarkers of widespread heatstroke-associated cellular injury, tissue damage and repair (extracellular heat shock proteins 72 and 60, high mobility group box protein 1, histone H3, and interleukin-1α), and other organ-specific biomarkers including those related to the cardiovascular system (cardiac troponin I, endothelium-derived factors, circulation endothelial cells, adhesion molecules, thrombomodulin and von Willebrand factor antigen), the kidneys (plasma and urinary neutrophil gelatinase-associated lipocalin), the intestines (intestinal fatty acid-binding protein 2), the brain (serum S100β and neuron-specific enolase) and skeletal muscle (creatine kinase, myoglobin). No specific biomarkers have been identified so far for liver or lung injury in heatstroke. Before translating the identified biomarkers into clinical practice, additional preclinical and clinical prospective studies are required to further understand their clinical utility, particularly for the biomarkers related to long-term post-heatstroke health outcomes.

Classic and exertional heatstroke

In the past two decades, record-breaking heatwaves have caused an increasing number of heat-related deaths, including heatstroke, globally. Heatstroke is a heat illness characterized by the rapid rise of core body temperature above 40 °C and central nervous system dysfunction. It is categorized as classic when it results from passive exposure to extreme environmental heat and as exertional when it develops during strenuous exercise. Classic heatstroke occurs in epidemic form and contributes to 9-37% of heat-related fatalities during heatwaves. Exertional heatstroke sporadically affects predominantly young and healthy individuals. Under intensive care, mortality reaches 26.5% and 63.2% in exertional and classic heatstroke, respectively. Pathological studies disclose endothelial cell injury, inflammation, widespread thrombosis and bleeding in most organs. Survivors of heatstroke may experience long-term neurological and cardiovascular complications with a persistent risk of death. No specific therapy other than rapid cooling is available. Physiological and morphological factors contribute to the susceptibility to heatstroke. Future research should identify genetic factors that further describe individual heat illness risk and form the basis of precision-based public health response. Prioritizing research towards fundamental mechanism and diagnostic biomarker discovery is crucial for the design of specific management approaches.

Interferon-induced transmembrane protein-3 genetic variant rs12252 is associated with COVID-19 mortality

Interferon-induced membrane proteins (IFITM) 3 gene variants are known risk factor for severe viral diseases. We examined whether IFITM3 variant may underlie the heterogeneous clinical outcomes of SARS-CoV-2 infection-induced COVID-19 in large Arab population. We genotyped 880 Saudi patients; 93.8% were PCR-confirmed SARS-CoV-2 infection, encompassing most COVID-19 phenotypes. Mortality at 90 days was 9.1%. IFITM3-SNP, rs12252-G allele was associated with hospital admission (OR = 1.65 [95% CI; 1.01-2.70], P = 0.04]) and mortality (OR = 2.2 [95% CI; 1.16-4.20], P = 0.01). Patients less than 60 years old had a lower survival probability if they harbor this allele (log-rank test P = 0.002). Plasma levels of IFNγ were significantly lower in a subset of patients with AG/GG genotypes than patients with AA genotype (P = 0.00016). Early identification of these individuals at higher risk of death may inform precision public health response.

Obesity and COVID-19: what makes obese host so vulnerable?

The disease (COVID-19) novel coronavirus pandemic has so far infected millions resulting in the death of over a million people as of Oct 2020. More than 90% of those infected with COVID-19 show mild or no symptoms but the rest of the infected cases show severe symptoms resulting in significant mortality. Age has emerged as a major factor to predict the severity of the disease and mortality rates are significantly higher in elderly patients. Besides, patients with underlying conditions like Type 2 diabetes, cardiovascular diseases, hypertension, and cancer have an increased risk of severe disease and death due to COVID-19 infection. Obesity has emerged as a novel risk factor for hospitalization and death due to COVID-19. Several independent studies have observed that people with obesity are at a greater risk of severe disease and death due to COVID-19. Here we review the published data related to obesity and overweight to assess the possible risk and outcome in Covid-19 patients based on their body weight. Besides, we explore how the obese host provides a unique microenvironment for disease pathogenesis, resulting in increased severity of the disease and poor outcome.

A Trial of Favipiravir and Hydroxychloroquine combination in Adults Hospitalized with moderate and severe Covid-19: A structured summary of a study protocol for a randomised controlled trial

OBJECTIVES

The selected combination was based on limited evidence clinically and in vitro on the efficacy of the Favipiravir and Hydroxychloroquine in SARS-CoV-2. The two medications were listed in many guidelines as treatment options and ongoing trials assessing their efficacy and safety. Thus, we want to prove the clinical effectiveness of the combination as therapy.

TRIAL DESIGN

This is an Open label, multicenter, randomized controlled clinical trial to evaluate the safety and efficacy of novel therapeutic agents in hospitalized adults diagnosed with COVID-19. It is a multicenter trial that will compare Favipiravir plus Hydroxychloroquine combination (experimental arm) to a control arm.

PARTICIPANTS

All study procedures will be conducted in eight centres in Saudia Arabia: King Abdulaziz Medical City National Guard Health Affairs in Riyadh. King Abdulaziz Hospital - Al Ahsa, Saudi Arabia AlMadina General Hospital, Madnia, Saudi Arabia Al-Qatif Central Hospital, Saudi Arabia Imam Abdulrahman Al Faisal Hospital, Dammam, Saudi Arabia King Abdulaziz Medical City, Jeddah, Saudi Arabia King Abdulaziz Hospital, Makkah, Saudi Arabia Imam Abdulrahman Alfaisal Hospital, Riyadh, Saudi Arabia Inclusion Criteria • Should be at least 18 years of age, • Male or nonpregnant female, • Diagnosed with COVID-19 by PCR confirmed SARS-coV-2 viral infection. • Able to sign the consent form and agree to clinical samples collection (or their legal surrogates if subjects are or become unable to make informed decisions).. • Moderate or Severe COVID-19, defined as oxygen saturation (Sao2) of 94% or less while they were breathing ambient air or significant clinical symptoms that require hospital admission. • patients had to be enrolled within 10 days of disease onset. Exclusion Criteria • Patients who are pregnant or breastfeeding. • Will be transferred to a non-study site hospital or discharged from hospital within 72 hours. • Known sensitivity/allergy to hydroxychloroquine or Favipiravir • Current use of hydroxychloroquine for another indication • Prior diagnosis of retinopathy • Prior diagnosis of glucose-6-phosphate dehydrogenase (G6PD) deficiency • Major comorbidities increasing the risk of study drug including: i. Hematologic malignancy, ii. Advanced (stage 4-5) chronic kidney disease or dialysis therapy, iii. Known history of ventricular arrhythmias, iv. Current use of drugs that prolong the QT interval, Severe liver damage (Child-Pugh score ≥ C, AST> 5 times the upper limit), HIV. • The investigator believes that participating in the trial is not in the best interests of the patient, or the investigator considers unsuitable for enrollment (such as unpredictable risks or subject compliance issues). • Clinical prognostic non-survival, palliative care, or in deep coma and no have response to supportive treatment within three hours of admission • Patient with irregular rhythm • Patient with a history of heart attack (myocardial infarction) • Patient with a family history of sudden death from heart attack before the age of 50 • Take other drugs that can cause prolonged QT interval • Patient who is receiving immunosuppressive therapy (cyclosporin) which cannot be switched to another agent or adjusted while using the investigational drug • Gout/history of Gout or hyperuricemia (above the ULN), hereditary xanthinuria or xanthine calculi of the urinary tract.

INTERVENTION AND COMPARATOR

The treatment intervention would be for a maximum of 10 days from randomization and it would be as follows: Favipiravir for 10 days: Administer 1800 mg (9 tablets) by mouth twice daily for one day, followed by 800mg (4 tablets) twice daily (total days of therapy is 10 days) Hydroxychloroquine for 5 days: (400mg) twice daily on day 1; for days 2-5 (200mg) twice daily. Reference Comparator Therapy: Standard of care is defined as: Treatment that is accepted by medical experts as a proper treatment for Covid-19 disease. Standard care comprised of, as necessary, supplemental oxygen, noninvasive and invasive ventilation, antibiotic agents, vasopressor support, renal-replacement therapy, extracorporeal membrane oxygenation (ECMO), and antiviral therapy except Favipiravir. Also, it may include intravenous fluids and medications for symptoms relief .

MAIN OUTCOMES

The primary endpoint is the time to clinical improvement, defined as the time from randomization to an improvement of two points (from the status at randomization) on a seven-category ordinal scale or live discharge from the hospital, whichever came first (14 days from Randomization).

RANDOMISATION

Eligible participants will be randomized in a 1:1 ratio to either the combination group (Favipiravir and Hydroxychloroquine) or a control group. The patients will be randomized utilizing Web based data entry System with a stratification based on the centre and the ICU admission.

BLINDING (MASKING)

This is an Open label study and only the analyst will be blinded during the study conduct.

NUMBERS TO BE RANDOMISED (SAMPLE SIZE)

Under the classical two arm parallel design the total effective sample sizes needed is 472 subjects (236 subjects per group).

TRIAL STATUS

Protocol version 3.1 (dated 11 Aug 2020), and currently recruitment is ongoing. The date recruitment started was May 21, 2020 and the investigators anticipate the trial will finish recruiting by the end of December 2020.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04392973 , 19 May 2020 FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

Evidence of a wide gap between COVID-19 in humans and animal models: a systematic review

BACKGROUND

Animal models of COVID-19 have been rapidly reported after the start of the pandemic. We aimed to assess whether the newly created models reproduce the full spectrum of human COVID-19.

METHODS

We searched the MEDLINE, as well as BioRxiv and MedRxiv preprint servers for original research published in English from January 1 to May 20, 2020. We used the search terms (COVID-19) OR (SARS-CoV-2) AND (animal models), (hamsters), (nonhuman primates), (macaques), (rodent), (mice), (rats), (ferrets), (rabbits), (cats), and (dogs). Inclusion criteria were the establishment of animal models of COVID-19 as an endpoint. Other inclusion criteria were assessment of prophylaxis, therapies, or vaccines, using animal models of COVID-19.

RESULT

Thirteen peer-reviewed studies and 14 preprints met the inclusion criteria. The animals used were nonhuman primates (n = 13), mice (n = 7), ferrets (n = 4), hamsters (n = 4), and cats (n = 1). All animals supported high viral replication in the upper and lower respiratory tract associated with mild clinical manifestations, lung pathology, and full recovery. Older animals displayed relatively more severe illness than the younger ones. No animal models developed hypoxemic respiratory failure, multiple organ dysfunction, culminating in death. All species elicited a specific IgG antibodies response to the spike proteins, which were protective against a second exposure. Transient systemic inflammation was observed occasionally in nonhuman primates, hamsters, and mice. Notably, none of the animals unveiled a cytokine storm or coagulopathy.

CONCLUSIONS

Most of the animal models of COVID-19 recapitulated mild pattern of human COVID-19 with full recovery phenotype. No severe illness associated with mortality was observed, suggesting a wide gap between COVID-19 in humans and animal models.

SARS-CoV-2 ORF8 and SARS-CoV ORF8ab: Genomic Divergence and Functional Convergence

The COVID-19 pandemic, in the first seven months, has led to more than 15 million confirmed infected cases and 600,000 deaths. SARS-CoV-2, the causative agent for COVID-19, has proved to be a great challenge for its ability to spread in asymptomatic stages and the diverse disease spectrum it has generated. This has created a challenge of unimaginable magnitude, not only affecting human health and life but also potentially generating a long-lasting socioeconomic impact. Both medical sciences and biomedical research have also been challenged, consequently leading to a large number of clinical trials and vaccine initiatives. While known proteins of pathobiological importance are targets for these therapeutic approaches, it is imperative to explore other factors of viral significance. Accessory proteins are one such trait that have diverse roles in coronavirus pathobiology. Here, we analyze certain genomic characteristics of SARS-CoV-2 accessory protein ORF8 and predict its protein features. We have further reviewed current available literature regarding its function and comparatively evaluated these and other features of ORF8 and ORF8ab, its homolog from SARS-CoV. Because coronaviruses have been infecting humans repeatedly and might continue to do so, we therefore expect this study to aid in the development of holistic understanding of these proteins. Despite low nucleotide and protein identity and differentiating genome level characteristics, there appears to be significant structural integrity and functional proximity between these proteins pointing towards their high significance. There is further need for comprehensive genomics and structural-functional studies to lead towards definitive conclusions regarding their criticality and that can eventually define their relevance to therapeutics development.

Summer Hajj pilgrimage in the era of global warming: a call for vigilance and better understanding of the risks

Hajj, one of the largest and most ethnically and geographically diverse annual mass gatherings in the world, presents many of the risk factors for heat-related illnesses. In the era of global warming, these illnesses are a major health threat at the event, especially while Hajj is in the hot cycle.

Permissive underfeeding, cytokine profiles and outcomes in critically ill patients

Background

During critical illness in humans, the effects of caloric restriction on the inflammatory response are not well understood. The aim of this study is to examine the associations of caloric restriction, inflammatory response profiles and outcomes in critically ill patients.

Methods

This is a sub-study of the PermiT trial (Permissive Underfeeding or Standard Enteral Feeding in Critically Ill Adults Trial- ISRCTN68144998). Serum samples were collected on study days 1, 3, 5, 7 and 14 and analyzed for a panel of 29 cytokines. We used principal component analysis to convert possibly correlated variables (cytokine levels) into a limited number of linearly uncorrelated variables (principal components). We constructed repeated measures mixed linear models to assess whether permissive underfeeding compared to standard feeding was associated with difference cytokine levels over time.

Results

A total of 72 critically ill patients were enrolled in this study (permissive underfeeding n = 36 and standard feeding n = 36). Principal component analysis identified 6 components that were responsible for 78% of the total variance. When adjusted to principal components, permissive underfeeding was not associated with 90-day mortality (adjusted odds ratio 1.75, 95% confidence interval 0.44, 6.95, p = 0.43) or with incident renal replacement therapy. The cytokines did not differ with time between permissive underfeeding and standard feeding groups.

Conclusions

The association of permissive underfeeding compared to standard feeding with mortality was not influenced by the inflammatory profile. Permissive underfeeding compared to standard feeding was not associated with differences in the serum levels of cytokines in critically ill patients.

Oxidative stress, caloric intake and outcomes of critically ill patients

BACKGROUND

The aim of this study was to investigate the patterns of oxidative stress in critically ill patients and the association with caloric intake and outcomes.

METHODS

In this pre-planned sub-study of the PermiT (Permissive Underfeeding versus Target Enteral Feeding in Adult Critically Ill Patients Trial- ISRCTN68144998), we included patients expected to stay in the ICU for ≥14 days. Serum samples were collected on days 1, 3, 5, 7 and 14 of enrollment. We measured total anti-oxidant capacity (TAC), protein carbonyl concentration (a measure of protein oxidation) and 8-hydroxy-7,8-dihydro-2'-deoxyguanosine (8-OHdG) (a measure of DNA oxidation). We used principal component analysis (PCA) and hierarchical cluster analysis (HCA) to group patients according to oxidative stress.

RESULTS

Principal component analysis identified 2 components that were responsible for 79% of the total variance, and cluster analysis grouped patients in three statistically distinct clusters. Majority of patients 78.6% (44/55) were included in cluster 1 with lowest TAC, protein carbonyl and 8-OHdG levels and cluster 2 which accounted for 16.1% (9/55) of patients had the highest levels of TAC and intermediate levels of protein carbonyl levels. Cluster 3 patients 5.4% (3/56) had the highest protein carbonyl levels. Incident renal replacement therapy was highest in cluster 2 (4/8, 50.0%), compared to cluster 1 (4/42, 9.5%) and cluster 3 (1/3, 33.3%, p 0.01). When adjusted to oxidative stress cluster membership, permissive underfeeding was not associated with 90-day mortality (adjusted odds ratio, aOR 1.37, 95% CI 0.36, 5.25, p 0.64) but was associated significantly with lower incident renal replacement therapy (aOR 0.02, 95% CI < 0.001, 0.57, p 0.02).

CONCLUSIONS

There are different distinct patterns of oxidative stress in critically ill patients. Incident renal replacement therapy was different among the three clusters. Our data suggest a protective effect of permissive underfeeding on incident renal replacement therapy that may differ by clusters of oxidative stress.

Activation of Coagulation and Fibrinolysis in Heatstroke

Hemorrhagic diathesis and widespread microthrombosis are common in heatstroke. To assess the early stages of coagulopathy in heatstroke, thrombin-antithrombin III (TAT), fibrin monomers, plasmin-a2-antiplasmin (PAP), plasminogen and D-Dimer were measured in 16 heatstroke patients (means ± SE rectal temperature 42.3 ± 0.2° C) pre- and postcooling and compared with 8 heatstressed and 23 normal controls.

Comparing heatstroke patients with normal controls, TAT, fibrin monomers, PAP and D-Dimer were elevated to (median (range)) 16.5 (4-1000) versus 3.5 (2-7.2) Μg/l p<0.001,16 (4-113) versus 2 (2-9) nM p<0.001; 3300 (1000-36500) versus 255 (136-462) Μg/l p<0.001 and 0.72 (0.22-64.8) versus 0.15 (0.05-0.25) Μg/ml p<0.01 respectively. Plasminogen decreased to 81% (34-106); PAP, TAT and D-Dimer correlated significantly with hyperthermia (r = 0.577, p = 0.02; r = 0.635, p = 0.01; r = 0.76, p = 0.003). Postcooling PAP decreased to 545 (260-850) Μg/1 p<0.005, TAT 10 (6-70) |ig/l, and fibrin monomers 22 (18-86) nM remained unchanged. Heatstressed controls showed mild but significant increase in all markers.

Activation of coagulation and fibrinolysis occurs early and is profound and sustained in heatstroke. Cooling seems to attenuate the activation of fibrinolysis only, however, this requires confirmation in a larger study population.

Feasibility of Using Convalescent Plasma Immunotherapy for MERS-CoV Infection, Saudi Arabia

Efficacy testing will be challenging because of the small pool of donors with sufficiently high antibody titers.

We explored the feasibility of collecting convalescent plasma for passive immunotherapy of Middle East respiratory syndrome coronavirus (MERS-CoV) infection by using ELISA to screen serum samples from 443 potential plasma donors: 196 patients with suspected or laboratory-confirmed MERS-CoV infection, 230 healthcare workers, and 17 household contacts exposed to MERS-CoV. ELISA-reactive samples were further tested by indirect fluorescent antibody and microneutralization assays. Of the 443 tested samples, 12 (2.7%) had a reactive ELISA result, and 9 of the 12 had reactive indirect fluorescent antibody and microneutralization assay titers. Undertaking clinical trials of convalescent plasma for passive immunotherapy of MERS-CoV infection may be feasible, but such trials would be challenging because of the small pool of potential donors with sufficiently high antibody titers. Alternative strategies to identify convalescent plasma donors with adequate antibody titers should be explored, including the sampling of serum from patients with more severe disease and sampling at earlier points during illness.

Heatstroke

Heatstroke is an acute medical emergency that is always fatal if left untreated. The diagnosis of heatstroke should be considered in any hyperthermic patient with altered mental status during a heat wave or following vigorous muscle exertion. Heat can damage the structure and function of essential macromolecules, including proteins, membrane lipids, and nucleic acids, and thereby lead to multiple-organ failure, culminating in death. The cytotoxic effect of heat is a function of degree and duration of hyperthermia; thus, an early diagnosis and prompt initiation of cooling are paramount to halt progression to tissue damage and death.

Middle East Respiratory Syndrome

Between September 2012 and January 20, 2017, the World Health Organization (WHO) received reports from 27 countries of 1879 laboratory-confirmed cases in humans of the Middle East respiratory syndrome (MERS) caused by infection with the MERS coronavirus (MERS-CoV) and at least 659 related deaths. Cases of MERS-CoV infection continue to occur, including sporadic zoonotic infections in humans across the Arabian Peninsula, occasional importations and associated clusters in other regions, and outbreaks of nonsustained human-to-human transmission in health care settings. Dromedary camels are considered to be the most likely source of animal-to-human transmission. MERS-CoV enters host cells after binding the dipeptidyl peptidase 4 (DPP-4) receptor and the carcinoembryonic antigen–related cell-adhesion molecule 5 (CEACAM5) cofactor ligand, and it replicates efficiently in the human respiratory epithelium. Illness begins after an incubation period of 2 to 14 days and frequently results in hypoxemic respiratory failure and the need for multiorgan support. However, asymptomatic and mild cases also occur. Real-time reverse-transcription–polymerase-chain-reaction (RT-PCR) testing of respiratory secretions is the mainstay for diagnosis, and samples from the lower respiratory tract have the greatest yield among seriously ill patients. There is no antiviral therapy of proven efficacy, and thus treatment remains largely supportive; potential vaccines are at an early developmental stage. There are multiple gaps in knowledge regarding the evolution and transmission of the virus, disease pathogenesis, treatment, and prospects for a vaccine. The ongoing occurrence of MERS in humans and the associated high mortality call for a continued collaborative approach toward gaining a better understanding of the infection both in humans and in animals. MERS-CoV was first identified in September 2012 in a patient from Saudi Arabia who had hypoxemic respiratory failure and multiorgan illness. Subsequent cases have included infections in humans across the Arabian Peninsula, occasional importations and associated clusters in other regions, and outbreaks of nonsustained human-to-human transmission in health care settings (Fig. 1).

Heat stroke

Heat stroke is a life-threatening condition clinically diagnosed as a severe elevation in body temperature with central nervous system dysfunction that often includes combativeness, delirium, seizures, and coma. Classic heat stroke primarily occurs in immunocompromised individuals during annual heat waves. Exertional heat stroke is observed in young fit individuals performing strenuous physical activity in hot or temperature environments. Long-term consequences of heat stroke are thought to be due to a systemic inflammatory response syndrome. This article provides a comprehensive review of recent advances in the identification of risk factors that predispose to heat stroke, the role of endotoxin and cytokines in mediation of multi-organ damage, the incidence of hypothermia and fever during heat stroke recovery, clinical biomarkers of organ damage severity, and protective cooling strategies. Risk factors include environmental factors, medications, drug use, compromised health status, and genetic conditions. The role of endotoxin and cytokines is discussed in the framework of research conducted over 30 years ago that requires reassessment to more clearly identify the role of these factors in the systemic inflammatory response syndrome. We challenge the notion that hypothalamic damage is responsible for thermoregulatory disturbances during heat stroke recovery and highlight recent advances in our understanding of the regulated nature of these responses. The need for more sensitive clinical biomarkers of organ damage is examined. Conventional and emerging cooling methods are discussed with reference to protection against peripheral organ damage and selective brain cooling.

Feasibility, safety, clinical, and laboratory effects of convalescent plasma therapy for patients with Middle East respiratory syndrome coronavirus infection: a study protocol

As of September 30, 2015, a total of 1589 laboratory-confirmed cases of infection with the Middle East respiratory syndrome coronavirus (MERS-CoV) have been reported to the World Health Organization (WHO). At present there is no effective specific therapy against MERS-CoV. The use of convalescent plasma (CP) has been suggested as a potential therapy based on existing evidence from other viral infections. We aim to study the feasibility of CP therapy as well as its safety and clinical and laboratory effects in critically ill patients with MERS-CoV infection. We will also examine the pharmacokinetics of the MERS-CoV antibody response and viral load over the course of MERS-CoV infection. This study will inform a future randomized controlled trial that will examine the efficacy of CP therapy for MERS-CoV infection. In the CP collection phase, potential donors will be tested by the enzyme linked immunosorbent assay (ELISA) and the indirect fluorescent antibody (IFA) techniques for the presence of anti-MERS-CoV antibodies. Subjects with anti-MERS-CoV IFA titer of ≥1:160 and no clinical or laboratory evidence of MERS-CoV infection will be screened for eligibility for plasma donation according to standard donation criteria. In the CP therapy phase, 20 consecutive critically ill patients admitted to intensive care unit with laboratory-confirmed MERS-CoV infection will be enrolled and each will receive 2 units of CP. Post enrollment, patients will be followed for clinical and laboratory outcomes that include anti-MERS-CoV antibodies and viral load. This protocol was developed collaboratively by King Abdullah International Medical Research Center (KAIMRC), Gulf Cooperation Council (GCC) Infection Control Center Group and the World Health Organization—International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC-WHO) MERS-CoV Working Group. It was approved in June 2014 by the Ministry of the National Guard Health Affairs Institutional Review Board (IRB). A data safety monitoring board (DSMB) was formulated. The study is registered at http://www.clinicaltrials.gov (NCT02190799).

Severe neurologic syndrome associated with Middle East respiratory syndrome corona virus (MERS-CoV)

BACKGROUND

Since the identification of the first case of infection with the Middle East respiratory syndrome corona virus (MERS-CoV) in Saudi Arabia in June 2012, the number of laboratory-confirmed cases has exceeded 941 cases globally, of which 347 died. The disease presents as severe respiratory infection often with shock, acute kidney injury, and coagulopathy. Recently, we observed three cases who presented with neurologic symptoms. These are so far the first reported cases of neurologic injury associated with MERS-CoV infection.

METHODS

Data was retrospectively collected from three patients admitted with MERS-CoV infection to Intensive Care unit (ICU) at King Abdulaziz Medical City, Riyadh. They were managed separately in three different wards prior to their admission to ICU.

FINDING

The three patients presented with severe neurologic syndrome which included altered level of consciousness ranging from confusion to coma, ataxia, and focal motor deficit. Brain MRI revealed striking changes characterized by widespread, bilateral hyperintense lesions on T2-weighted imaging within the white matter and subcortical areas of the frontal, temporal, and parietal lobes, the basal ganglia, and corpus callosum. None of the lesions showed gadolinium enhancement.

INTERPRETATION

CNS involvement should be considered in patients with MERS-CoV and progressive neurological disease, and further elucidation of the pathophysiology of this virus is needed.

Clinical characteristics, sepsis interventions and outcomes in the obese patients with septic shock: an international multicenter cohort study

Introduction

Data are sparse as to whether obesity influences the risk of death in critically ill patients with septic shock. We sought to examine the possible impact of obesity, as assessed by body mass index (BMI), on hospital mortality in septic shock patients.

Methods

We performed a nested cohort study within a retrospective database of patients with septic shock conducted in 28 medical centers in Canada, United States and Saudi Arabia between 1996 and 2008. Patients were classified according to the World Health Organization criteria for BMI. Multivariate logistic regression analysis was performed to evaluate the association between obesity and hospital mortality.

Results

Of the 8,670 patients with septic shock, 2,882 (33.2%) had height and weight data recorded at ICU admission and constituted the study group. Obese patients were more likely to have skin and soft tissue infections and less likely to have pneumonia with predominantly Gram-positive microorganisms. Crystalloid and colloid resuscitation fluids in the first six hours were given at significantly lower volumes per kg in the obese and very obese patients compared to underweight and normal weight patients (for crystalloids: 55.0 ± 40.1 ml/kg for underweight, 43.2 ± 33.4 for normal BMI, 37.1 ± 30.8 for obese and 27.7 ± 22.0 for very obese). Antimicrobial doses per kg were also different among BMI groups. Crude analysis showed that obese and very obese patients had lower hospital mortality compared to normal weight patients (odds ratio (OR) 0.80, 95% confidence interval (CI) 0.66 to 0.97 for obese and OR 0.61, 95% CI 0.44 to 0.85 for very obese patients). After adjusting for baseline characteristics and sepsis interventions, the association became non-significant (OR 0.80, 95% CI 0.62 to 1.02 for obese and OR 0.69, 95% CI 0.45 to 1.04 for very obese).

Conclusions

The obesity paradox (lower mortality in the obese) documented in other populations is also observed in septic shock. This may be related in part to differences in patient characteristics. However, the true paradox may lie in the variations in the sepsis interventions, such as the administration of resuscitation fluids and antimicrobial therapy. Considering the obesity epidemic and its impact on critical care, further studies are warranted to examine whether a weight-based approach to common therapeutic interventions in septic shock influences outcome.

Non-communicable health risks during mass gatherings

Mass gatherings (MGs) have been associated with high rates of morbidity and mortality from non-communicable diseases, accidents, and terrorist attacks, thus posing complex public health challenges. We assessed the health risks and public health responses to MGs to identify an evidence-based framework for public health interventions. Human stampedes and heat-related illnesses are the leading causes of mortality. Minor traumatic injuries and medical complaints are the main contributors to morbidity and, particularly, the need for on-site medical care. Infrastructure, crowd density and mood, weather, age, and sex determine the risks to health. Many predictive models for deployment of medical resources are proposed, but none have been validated. We identified the risks for mortality and morbidity during MGs, most efficient public health interventions, and need for robust research into health risks for non-communicable diseases during MGs.

[Breast hypertrophy: preliminary study in Dakar]

The management of breast hypertrophy has become a new and increasing need in Senegal. The files of 47 patients presenting with breast hypertrophy were collated over twelve years. The mean age was 33,9 years. Three surgical techniques were used. The average sternal notch to nipple measurement was 33 cm. Surgery was performed on twenty-two patients, or 42 breast. The surgical technique of Mac Kissock was used in 50% of the cases, the inferior pedicle technique in 13.6% of the cases and the technique of Thorek in 36.4% of the cases. The average weight of tissue removed was 1.3 kg per breast. Our rate of post-operative complications was 9.5% , mostly suppurations. Close to 91% of the patients expressed being satisfied with the aesthetic result obtained. The surgery of breast hypertrophy is increasing in our activity.

sRAGE in diabetic and non-diabetic critically ill patients: effects of intensive insulin therapy

Introduction

Hyperglycemia represents an independent prognostic factor in critically ill non-diabetic patients but not in those with diabetes. In this context, there is an ongoing debate on the benefit of an intensive insulin therapy, particularly in diabetic patients. We tested the hypothesis that expression of the receptor for advanced glycation end-products (RAGE), an important signal transduction receptor that elicits long-lasting nuclear factor kappa B (NF-κB) activation, may underlie this difference. RAGE expression is regulated by multiple ligands, including high mobility group box-1 (HMGB-1), and is reflected by its released soluble form (sRAGE).

Methods

A predesigned analysis was conducted of prospectively collected samples from 76 hyperglycemic critically ill patients (33 type-2 diabetes, 43 non-diabetes) aged ≥18 years with blood glucose of > 6.1 mmol/L enrolled in a randomized controlled trial comparing intensive insulin therapy with conventional insulin therapy. sRAGE and its ligand HMGB-1 together with IL-6, and soluble thrombomodulin (as markers of inflammation and endothelial cell injury, respectively) were evaluated in ICU, at Days 1, 3, 5 and 7. Plasma samples from 18 healthy subjects were used as controls.

Results

Both diabetic and non-diabetic hyperglycemic patients showed increased plasma sRAGE, HMGB-1 and soluble thrombomodulin levels at the time of admission to ICU. Plasma IL-6 concentration was only increased in non-diabetic patients. Plasma levels of sRAGE were higher in diabetic compared with non-diabetic patients. Intensive insulin therapy resulted in a significant decrease of sRAGE and thrombomodulin at Day 7, in diabetic but not in non-diabetic patients. Circulating sRAGE levels correlated positively with IL-6 and soluble thrombomodulin levels and inversely with HMGB-1. Multivariate regression analysis demonstrated that sRAGE remains independently correlated with HMGB-1 only in diabetic patients. Neither sRAGE nor any inflammatory markers are associated with mortality.

Conclusions

These findings support the hypothesis that sRAGE release, time-course and response to intensive insulin therapy differ between hyperglycemic diabetic and non-diabetic critically ill patients. Whether this difference underlies the dissimilarity in clinical outcome of hyperglycemia in these two conditions warrants further studies.

Hsp-72, a candidate prognostic indicator of heatstroke

Exposure of rats to environmental heat enhances the expression of heat shock protein-72 (Hsp-72) in most of their organs proportionally to heat stress severity. Pre-induction or over-expression of Hsp-72 prevents organ damage and lethality, suggesting that heat shock proteins (Hsps) may have a pathogenic role in this condition. We investigated the expression profile of Hsps in baboons subjected to environmental heat stress until the core temperature attained 42.5 degrees C (moderate heatstroke) or occurrence of hypotension associated with core temperature > or = 43.5 degrees C (severe heatstroke). Western blot analysis demonstrated a differential induction of Hsp-72 among organs of heat-stressed animals with the highest induction in the liver and the lowest in lung. Hsp-60 and Hsc-70 expression was similar between control and heat-stressed animals. ELISA studies indicated a marked release of Hsp-72 into the circulation of baboons with severe heatstroke with a peak at 24 h post-heatstroke onset and remained sustained up to 72 h. Hsp-72 release was not associated with core temperature or systolic blood pressure, but correlated with markers of liver, myocardium, and skeletal muscle tissue necrosis. Non-survivors displayed significantly higher Hsp-72 levels than survivors. No Hsp-60 was detected in the circulation. These findings add further evidence that increased expression of Hsp-72 may be an important component of the host response to severe heatstroke. They also suggest that extracellular Hsp-72 is a marker of multiple organs tissue damage. Whether extracellular Hsp-72 plays a role in the host immune response to heat stress merits further studies.

Recombinant activated protein C attenuates endothelial injury and inhibits procoagulant microparticles release in baboon heatstroke

OBJECTIVE

We tested the hypothesis that the antithrombotic and cytoprotective effects of recombinant human activated protein C (rhAPC) protect baboons against the lethal effects of heatstroke.

METHODS AND RESULTS

Fourteen anesthetized baboons assigned randomly to rhAPC (n=7) or control group (n=7) were heat-stressed in a prewarmed incubator at 44 to 47 degrees C until systolic blood pressure fell below 90 mm Hg, which signaled severe heatstroke. rhAPC was administered intravenously (24 microg/kg/h) for 12 hours at onset of heatstroke. Heat stress induced coagulation and fibrinolysis activation as evidenced by a significant increase from baseline levels in plasma levels of thrombin-antithrombin (TAT) complexes, tissue plasminogen activator, and D-dimer. Heat stress elicited cell activation/injury as assessed by the release of interleukin (IL)-6, soluble thrombomodulin, and procoagulant microparticles (MPs). rhAPC did not significantly reduce heatstroke-induced thrombin generation, and D-dimer and had no effect on fibrinolytic activity. In contrast, rhAPC infusion attenuated significantly the plasma rise of IL-6 and inhibited the release of soluble thrombomodulin and MPs as compared with control group. No difference in survival was observed between rhAPC-treated and control group.

CONCLUSIONS

rhAPC given to heatstroke baboons provided cytoprotection, but had no effect on heatstroke-induced coagulation activation and fibrin formation. Inhibition of MPs by rhAPC suggested a novel mechanism of action for this protein.

Microvascular injury, thrombosis, inflammation, and apoptosis in the pathogenesis of heatstroke: a study in baboon model

OBJECTIVE

Severe heatstroke is a leading cause of morbidity and mortality during heat waves. The pathogenesis of tissue injury, organ failure, and death in heatstroke is not well understood.

METHODS AND RESULT

We investigated the pathways of heatstroke-induced tissue injury and cell death in anesthetized baboons (Papio hamadyras) subjected to environmental heat stress until core temperature attained 42.5 degrees C (moderate heatstroke; n = 3) or onset of severe heatstroke (n = 4) signaled by a fall in systolic blood pressure to < 90 mm Hg and rise in core temperature to 43.1+/-0.1 degrees C. Three sham-heated animals served as controls. Light and electron microscopy revealed widespread hemorrhage and thrombosis, transmural migration of leukocytes, and microvascular endothelium injury in severe heatstroke. Immunohistology and ultrastructural analysis demonstrated increased staining of endothelial von Willebrand factor (vWF), tissue factor (TF), and endothelial leukocyte-platelet interaction. Extensive apoptosis was noted in spleen, gut, and lung, and in hematopoeitic cells populating these organs. Double-labeling studies colocalized active caspase-3 and TF with apoptotic cells. Findings in sham-heated animals were unremarkable.

CONCLUSIONS

These data suggested that microvascular injury, thrombosis, inflammation, and apoptosis may play an important role in the pathogenesis of heatstroke injury.

Cooling and hemodynamic management in heatstroke: practical recommendations

Introduction

Although rapid cooling and management of circulatory failure are crucial to the prevention of irreversible tissue damage and death in heatstroke, the evidence supporting the optimal cooling method and hemodynamic management has yet to be established.

Methods

A systematic review of all clinical studies published in Medline (1966 to 2006), CINAHL (Cumulative Index to Nursing & Allied Health Literature) (1982 to 2006), and Cochrane Database was performed using the OVID interface without language restriction. Search terms included heatstroke, sunstroke, and heat stress disorders.

Results

Fourteen articles reported populations subjected to cooling treatment for classic or exertional heatstroke and included data on cooling time, neurologic morbidity, or mortality. Five additional articles described invasive monitoring with central venous or pulmonary artery catheters. The four clinical trials and 15 observational studies covered a total of 556 patients. A careful analysis of the results obtained indicated that the cooling method based on conduction, namely immersion in iced water, was effective among young people, military personnel, and athletes with exertional heatstroke. There was no evidence to support the superiority of any one cooling technique in classic heatstroke. The effects of non-invasive, evaporative, or conductive-based cooling techniques, singly or combined, appeared to be comparable. No evidence of a specific endpoint temperature for safe cessation of cooling was found. The circulatory alterations in heatstroke were due mostly to a form of distributive shock associated with relative or absolute hypovolemia. Myocardial failure was found to be rare.

Conclusion

A systematic review of the literature failed to identify reliable clinical data on the optimum treatment of heatstroke. Nonetheless, the findings of this study could serve as a framework for preliminary recommendations in cooling and hemodynamic management of heatstroke until more evidence-based data are generated.

Prognostic Factors in Heat Wave–Related DeathsA Meta-analysis

BACKGROUND

Although identifying individuals who are at increased risk of dying during heat waves and instituting protective measures represent an established strategy, the evidence supporting the components of this strategy and their strengths has yet to be evaluated. We conducted a meta-analysis of observational studies on risk and protective factors in heat wave-related deaths.

METHODS

Using the OVID interface, we searched Medline (1966-2006) and CINHAL (1982-2006) databases. The Web sites of the World Health Organization, Institut National de Veille Sanitaire, and Centers for Disease Control and Prevention were also visited. The search terms included heat wave, heat stroke, heatstroke, sunstroke, and heat stress disorders. Eligible studies were case-control or cohort studies. Odds ratios (ORs) and information on study quality were abstracted by 2 investigators independently. Six case-control studies involving 1065 heat wave-related deaths were identified.

RESULTS

Being confined to bed (OR, 6.44; 95% confidence interval [CI], 4.5-9.2), not leaving home daily (OR, 3.35; 95% CI, 1.6-6.9), and being unable to care for oneself (OR, 2.97; 95% CI, 1.8-4.8) were associated with the highest risk of death during heat waves. Preexisting psychiatric illness (OR, 3.61; 95% CI, 1.3-9.8) tripled the risk of death, followed by cardiovascular (OR, 2.48; 95% CI, 1.3-4.8) and pulmonary (OR, 1.61; 95% CI, 1.2-2.1) illness. Working home air-conditioning (OR, 0.23; 95% CI, 0.1-0.6), visiting cool environments (OR, 0.34; 95% CI, 0.2-0.5), and increasing social contact (OR, 0.40; 95% CI, 0.2-0.8) were strongly associated with better outcomes. Taking extra showers or baths (OR, 0.32; 95% CI, 0.1-1.1) and using fans (OR, 0.60; 95% CI, 0.4-1.1) were associated with a trend toward lower risk of death.

CONCLUSION

The present study identified several prognostic factors that could help to detect those individuals who are at highest risk during heat waves and to provide a basis for potential risk-reducing interventions in the setting of heat waves.

GLUCOCORTICOIDS DO NOT PROTECT AGAINST THE LETHAL EFFECTS OF EXPERIMENTAL HEATSTROKE IN BABOONS

The mortality and neurological morbidity in heatstroke have been attributed to the host's inflammatory responses to heat stress, suggesting that anti-inflammatory therapy may improve outcome. We tested the hypothesis that a high dose of dexamethasone protects baboons against the lethal effects of heatstroke. Ten anesthetized baboons (Papio hamadryas) were assigned randomly to dexamethasone (n = 5) or control group (n = 5). Dexamethasone (2 mg/kg i.v.) was administered in four divided doses every 6 h starting immediately before heat stress and continuing during cooling. All animals were heat-stressed in a prewarmed neonatal incubator at 44 degrees C to 47 degrees C until systolic blood pressure fell less than 90 mmHg and then cooled passively at the ambient temperature. Mortality and neurological morbidity were noted, and biochemical markers of tissue injury/organ dysfunction were determined. Circulating interleukin (IL) 6 and complement components (C3 and C4) were measured sequentially. All heat-stressed animals had systemic inflammation indicated by increased plasma IL-6 and decreased C3 and C4 levels. Dexamethasone attenuated the complement system activation and maintained a higher plasma concentration of IL-6, with a significant augmentation of arterial blood pressure. Dexamethasone did not prevent the occurrence of severe heatstroke but unexpectedly aggravated significantly the tissue injury and multiorgan system dysfunction. Two animals (40%) in the control group and one in the steroid group survived (P > 0.05). Dexamethasone failed to protect the baboons from the lethal effects of heatstroke. These results do not support clinical testing of corticosteroids as beneficial in preventive or therapeutic strategies for the treatment of heatstroke in humans.

EXPERIMENTAL HEATSTROKE IN BABOON: ANALYSIS OF THE SYSTEMIC INFLAMMATORY RESPONSE

The objective of this study was to analyze the pattern of the inflammatory response to heatstroke in an experimental baboon model with a view to identifying potential target for therapeutic interventions. Blinded analysis of plasma collected from 12 juvenile baboons (Papio hamadryas) in heatstroke was used. Eight anesthetized animals were heat-stressed in an incubator at 44 degrees C to 47 degrees C until rectal temperature was 42.5 degrees C (moderate heatstroke; n = 4) or systolic arterial pressure fell to <90 mmHg (severe heatstroke; n = 4) and were allowed to recover at room temperature. Four sham-heated animals served as a control group. We performed sequential measurement of cytokines. The rectal temperature on completion of heat stress was 42.5 degrees C +/- 0.0 degrees C and 43.3 degrees C +/- 0.1 degrees C in moderate and severe heatstroke, respectively. Heat stress elicited early, simultaneous release of anti-inflammatory cytokines and chemokines (IL-10, IL-1ra, sTNFr I and II, and IL-8). Circulating levels of IL-12p40 were significantly decreased, whereas TNFalpha, IL-1beta, and IL-4 were below the detection limit in all animals. No baboon survived severe heatstroke; there was neurological morbidity without mortality in moderate heatstroke. Nonsurvivors displayed significantly greater activity/alterations in inflammation markers than survivors. Sham-heated animals had no evidence of inflammation activation. These results show that heatstroke activates complex systemic inflammatory and regulatory responses associated with outcome. Further definition of this ambivalent response is needed before identification of target of successful modulation may become possible.

Inflammatory, hemostatic, and clinical changes in a baboon experimental model for heatstroke

The mortality and neurological morbidity in heatstroke have been attributed to the host's inflammatory and hemostatic responses to heat stress, suggesting that immunomodulation may improve outcome. We postulated that an experimental baboon model of heatstroke will reproduce human responses and clinical outcome to allow testing of new therapeutic strategies. Eight anesthetized juvenile baboons (Papio hamadryas) were subjected to heat stress in an incubator maintained at 44-47 degrees C until rectal temperature attained 42.5 degrees C (moderate heatstroke; n = 4) or systolic arterial pressure fell to <90 mmHg (severe heatstroke; n = 4) and were allowed to recover at room temperature. Four sham-heated animals served as a control group. Rectal temperature at the end of heat stress was 42.5 +/- 0.0 and 43.3 +/- 0.1 degrees C, respectively. All heat-stressed animals had systemic inflammation and activated coagulation, indicated by increased plasma IL-6, prothrombin time, activated partial thromboplastin time, and D-dimer levels, and decreased platelet count. Biochemical markers and/or histology evidenced cellular injury/dysfunction: plasma levels of thrombomodulin, creatinine, creatine kinase, lactic dehydrogenase, and alanine aminotransferase were increased, and varying degrees of tissue damage were present in liver, brain, and gut. No baboon with severe heatstroke survived. Neurological morbidity but no mortality was observed in baboons with moderate heatstroke. Nonsurvivors displayed significantly greater coagulopathy, inflammatory activity, and tissue injury than survivors. Sham-heated animals had an uneventful course. Heat stress elicited distinct patterns of inflammatory and hemostatic responses associated with outcome. The baboon model of heatstroke appears suitable for testing whether immunomodulation of the host's responses can improve outcome.

Acid-base alterations in heatstroke

OBJECTIVE

To analyze the acid-base balance during heatstroke.

DESIGN

Retrospective study.

SETTING

Heatstroke Center, Makkah, Saudi Arabia.

PATIENTS

Hundred nine consecutive heatstroke patients (mean age 55 +/- 12 years) with rectal temperature from 40 to 43.4 degrees C following exposure to hot weather.

INTERVENTION

Arterial blood gases collected prospectively and analyzed using 95% confidence limits established by controlled experimental studies. Severity of heatstroke on admission assessed by Simplified Acute Physiology Score and Organ System Failure score.

RESULTS

Metabolic acidosis was the predominant acid-base change followed by respiratory alkalosis (81 and 55% of the patients, respectively). The prevalence of metabolic acidosis (but not respiratory alkalosis) was significantly associated with the degree of hyperthermia: 63, 95 and 100% at 41, 42 and 43 degrees C, respectively (p < 0.0001). Patients with metabolic acidosis had a large anion gap (24 +/- 5). Arterial partial pressure of oxygen (PaO2), systolic blood pressure and Organ System Failure score were similar with or without metabolic acidosis. Although the acute physiology score was higher in patients with, than without, metabolic acidosis (15.7 +/- 3.7 vs 9.8 +/- 4.4, p < 0.001), there was no significant difference in neurologic morbidity and mortality (7.9 vs 1.1%, 5.6 vs 0%, p = 0.776 and 0.581, respectively).

CONCLUSION

We conclude that metabolic acidosis is the predominant response in heatstroke.

Differential effects of in vitro and in vivo hyperthermia on the production of interleukin-10

OBJECTIVE

To determine whether hyperthermia activates an anti-inflammatory response.

DESIGN

A prospective study.

SETTING

Heatstroke Center, Makkah, and King Faisal Specialist Hospital, Riyadh, Saudi Arabia.

PATIENTS

Twenty-five heatstroke patients pre-cooling (rectal temperature 42.4 +/- 0.8 degrees C) (group 1) and 13 normothermic heat-stressed subjects were studied (group 2). Twelve of the 25 heatstroke patients were also studied post-cooling (group 3). Mononuclear cells from six healthy blood donors resting at 24 degrees C were used for in vitro study.

INTERVENTIONS

Mononuclear cells were cultured at a concentration of 1 x 10(6)/ml without and with lipopolysaccharide (LPS) added at concentration of 10, 100, and 1000 ng/ml. The cells were incubated for 24 h at 37, 39, 41, and 43 degrees C. ELISA was used to measure IL-10 in the supernatant and plasma from heatstroke and heat-stressed subjects.

RESULTS

All patients in group 1, 40% of group 2, and 37% of group 3, showed elevation of IL-10 (1289 +/- 2519, 248 +/- 393, and 172 +/- 226 pg/ml, respectively) compared with normal control levels, (< 100 pg/ml) P < 0.05. IL-10 level on admission did not correlate with degree of hyperthermia. During 24 h incubation at 37 degrees C without LPS, no IL-10 was detected, whereas with 10 ng/ml LPS, monocytes released 658 +/- 291 pg IL-10/10(6) cells. At 39 degrees C and 41 degrees C IL-10 release was decreased to 225 +/- 114, and 245 +/- 90 pg/10(6) cells, respectively; and was completely inhibited at 43 degrees C (67 +/- 10 pg/10(6) cells), P < 0.0001.

CONCLUSION

Heat-stress with and without hyperthermia is associated with anti-inflammatory response in vivo. However, it does not seem to be the direct effect of heat on monocytes, suggesting that other environmental or genetic factors may be involved.

Hematopoietic colony-stimulating factors for neutropenic patients in the ICU

OBJECTIVE

To assess whether adjunct hematopoietic colony-stimulating factor (H-CSF) accelerates neutrophil recovery and improves survival.

DESIGN

A retrospective study.

SETTING

Medical/surgical intensive care unit (ICU).

PATIENTS

30 neutropenic patients admitted to the ICU and treated with H-CSF. Controls were the preceding 30 neutropenic patients not treated with H-CSF.

MEASUREMENTS AND RESULTS

Patient admission characteristics were reviewed. Endpoints were neutrophil recovery ( > 1.0 x 10(9)/l), length of ICU stay and survival. Depth and duration of neutropenia (0.267 +/- 0.04 x 10(9)/l for 12 +/- 1.7 days vs 0.293 +/- 0.05 x 10(9)/l for 15 +/- 1.9 days; p = 0.67 and 0.21), and the Acute Physiology and Chronic Health Evaluation II and organ system failure scores were similar. Systemic candidiasis was lower in the H-CSF group (20 vs 3 %; p > 0.05). In 11 (36.6 %) and 10 (33.3 %) patients neutrophil count recovered ( > 1.0 x 10(9)/l); H-CSF did not reduce the duration of neutropenia (7.8 +/- 1.4 vs 5.7 +/- 1.3 days; p = 0. 28), the length of ICU stay (7.8 +/- 1.1 vs 8.9 +/- 1.5 days; p = 0. 55) or improve survival (23 vs 10 %; p = 0.168).

CONCLUSION

H-CSF for treatment of neutropenia in patients admitted to the ICU did not accelerate neutrophil recovery or improve survival.