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Background: Despite conflicting data, intravenous lipid emulsion has emerged as a potential antidote. The "lipid sink" theory suggests that following intravenous administration of lipid, lipophilic drugs are sequestered in the vascular compartment, thereby reducing their tissue concentrations. This study sought to determine if survival is associated with the intoxicant's degree of lipophilicity., Methods: We reviewed all cases in the Toxicology Investigators Consortium's lipid sub-registry between May 2012 through December 2018. Information collected included demographics, exposure circumstances, clinical course, management, disposition, and outcome. The primary outcome was survival after lipid emulsion therapy. Survival was stratified by the log of the intoxicant's octanol-water partition coefficient. We also assessed the association between intoxicant lipophilicity and an increase in systolic blood pressure after lipid emulsion administration., Results: We identified 134 patients, including 81 (60.4%) females. The median age was 40 years (interquartile range 21-75). One hundred and eight (80.6%) patients survived, including 45 (33.6%) with cardiac arrest during their intoxication. Eighty-two (61.2%) were hypotensive, and 98 (73.1%) received mechanical ventilation. There was no relationship between survival and the log of the partition coefficient of the intoxicant on linear analysis ( P  = 0.89) or polynomial model ( P  = 0.10). Systolic blood pressure increased in both groups. The median (interquartile range) systolic blood pressure before lipid administration was 68 (60-78) mmHg for those intoxicants with a log partition coefficient < 3.6 compared with 89 (76-104) mmHg after lipid administration. Among those drugs with a log partition coefficient > 3.6, the median (interquartile range) was 69 (60-84) mmHg before lipid and 89 (80-96) mmHg after lipid administration., Conclusion: Most patients in this cohort survived. Lipophilicity was not correlated with survival or the observed changes in blood pressure. The study did not address the efficacy of lipid emulsion.

Objectives: To assess whether using coronavirus disease 2019 (COVID-19) community activity level can accurately inform strategies for routine testing of facility staff for active severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection., Design: Cross-sectional study., Setting and Participants: In total, 59,930 nursing home staff tested for active SARS-CoV-2 infection in Indiana., Measures: Receiver operator characteristic curves and the area under the curve to compare the sensitivity and specificity of identifying positive cases of staff within facilities based on community COVID-19 activity level including county positivity rate and county cases per 10,000., Results: The detection of any infected staff within a facility using county cases per 10,000 population or county positivity rate resulted in an area under the curve of 0.648 (95% confidence interval 0.601‒0.696) and 0.649 (95% confidence interval 0.601‒0.696), respectively. Of staff tested, 28.0% were certified nursing assistants, yet accounted for 36.9% of all staff testing positive. Similarly, licensed practical nurses were 1.4% of staff, but 4.7% of positive cases., Conclusions and Implications: We failed to observe a meaningful threshold of community COVID-19 activity for the purpose of predicting nursing homes with any positive staff. Guidance issued by the Centers for Medicare and Medicaid Services in August 2020 sets the minimum frequency of routine testing for nursing home staff based on county positivity rates. Using the recommended 5% county positivity rate to require weekly testing may miss asymptomatic infections among nursing home staff. Further data on results of all-staff testing efforts, particularly with the implementation of new widespread strategies such as point-of-care testing, is needed to guide policy to protect high-risk nursing home residents and staff. If the goal is to identify all asymptomatic SARS-Cov-2 infected nursing home staff, comprehensive repeat testing may be needed regardless of community level activity., (Copyright © 2020 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.)

Herein we report the programmable preparation of ultrasensitive surface-enhanced Raman scattering (SERS)-based nanoplasmonic superlattice substrates to assay fentanyl and cocaine (detection and quantification) from 10 μL aliquots of emergency department patient plasma without the need for purification steps. Highly homogeneous three-dimensional (3D) nanoplasmonic superlattices are generated through the droplet evaporation-based self-assembly process of chemically-synthesized, polyethylene glycol thiolate-coated gold triangular nanoprisms (Au TNPs). Close-packed, solid-state 3D superlattice substrates produce electromagnetic hot spots due to near-field plasmonic coupling of Au TNPs, which display unique localized surface plasmonic resonance properties. These uniquely prepared superlattice substrates enable strong SERS enhancement to achieve a parts-per-quadrillion limit of detection using the label-free SERS-based technique. Our reported limit of detection is at least 100-fold better than any known SERS substrates for the drug assay. Importantly, our density functional theory calculations show that a specific electronic interaction between the drug molecule and novel nanoplasmonic superlattice substrates plays a critical role that may trigger achieving this unprecedentedly high sensitivity. Additionally, we show high selectivity of the superlattice substrate in the SERS-based detection of analytes from different patient samples, which do and do not contain target analytes (i.e., fentanyl and/or cocaine). The demonstrated sensitivity and selectivity of 3D superlattice substrates for SERS-based drug analysis in real toxicological samples are expected to advance the field of measurement science, and forensic and clinical toxicology by obviating the need for complicated sample processing steps, long assay times, and the low sensitivity of existing "gold standard" analytical techniques including gas chromatography/mass spectrometry, liquid chromatography/mass spectrometry and enzyme-linked immunosorbent assays. Taken together, we believe that this entirely new and reproducible superlattice substrate for the SERS analysis will aid scientific, forensic, and healthcare communities to battle the drug overdose epidemic in the United States.

Background: In the United States, adolescent suicide attempts are increasing. Indiana has the highest rate of adolescent suicidal ideation in the US. Using the National Poison Data System (NPDS), we analyzed Indiana's increase in suicide attempts by poisoning. Methods: Utilizing NPDS and Toxicall data repositories, we selected 10-19 year-old intentional overdose cases with suspected suicidal intent from 2006-2016. Age, sex, outcome, involved substances and case volume by weekday and month were assessed. Geospatial analysis of the proportion of cases by county was also performed. To determine the association between known social determinants of health and adolescent intentional overdose cases with suspected suicidal intent, we correlated county-wide statistics from the County Health Rankings and Roadmaps dataset from 2010-2016 with the proportion of teen suicide cases by county. Results: Over the eleven years, adolescent intentional overdoses with suspected suicidal intent cases significantly increased starting in 2012 ( p -value < .001). The majority of cases (73.7%) involved females with an average age of 15.96 ± 0.27 years. Monday and Tuesday had the highest rates and Saturday had the lowest. June and July had the lowest case rate while November had the highest. The most commonly involved agents were over-the-counter analgesics and antidepressants. Geospatial analysis shows an increased number of cases in the northern third of the State. Among county statistics analyzed, only violent crime was associated, albeit intermittently, with the 11-year proportion of adolescent intentional overdoses with suspected suicidal intent by county. Conclusions: Intentional overdoses with suspected suicidal intent involving adolescent females are significantly increasing. These rates correlate with the school schedule with summer months and weekends having a lower frequency of calls. We did not find associations between county wide social determinants of care with the exception of violent crime. Further studies are needed to establish the factors that might better predict adolescents at risk for suicide.

Background: A variety of plants contain cardiac glycosides. This has resulted in many of them being used to commit suicide. In southeast Asia, Cerebera odollam (pong-pong or suicide tree) is frequently used for suicidal ingestion. Seeds, or kernels, of this plant can cause hyperkalemia, heart block, and death due to the effects of its cardiac glycosides., Case Report: We describe six cases of pong-pong seed ingestion reported to US poison centers. The most common symptoms were vomiting and bradycardia. Three patients survived and three died. All patients who died had heart block, serum digoxin levels > 1.0 ng/mL, and were treated with anti-digoxin immune FAB. Anti-digoxin immune FAB may be ineffective in a large pong-pong seed ingestion. Patients ingesting pong-pong seeds who develop a potassium level > 8.0 meq/L or have a digoxin level > 1.0 ng/mL may be at a higher risk for death. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The apparent ease of acquiring C. odollam seeds on the Internet makes knowledge of it important, as it can be used as a means to commit suicide. The apparent failure of digoxin immune FAB to treat toxicity from pong-pong is important, as other lifesaving techniques, such as extracorporeal membrane oxygenation, might be needed in severely toxic patients., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Introduction: The determination of fatigue and exhaustion in experimental animals is complicated by the subjective nature of the measurement. Typically, it requires an observer to watch exercising animals, e.g. rats running on the treadmill, and to identify the time of the event. In this study, we hypothesized that automatic analysis of the time-averaged position of a rat on a treadmill could be an objective way for estimating times to fatigue and exhaustion. To test this hypothesis, we compared these times measured by a human observer to the results of an automated video tracking system., Methods: Rats, previously familiarized to running on the treadmill, ran at a fixed speed with zero incline, until exhaustion. The experiments were performed at either room temperature (24 °C) or in a hot environment (32 °C). Each experiment was video recorded. A trained observer estimated the times to fatigue and exhaustion. Then, video tracking software was used to determine the position of the animals on the treadmill belt. The times to fatigue and exhaustion were determined, based on the position on the treadmill using predefined criteria., Results: Manual scores and the average position on the treadmill had significant correlation. Both the observer and the automated video tracking determined that exercise in a hot environment, compared with the exercise at room temperature, results in shorter times to exhaustion and fatigue. Also, estimates of times made by the observer and the automated video tracking were not statistically different from each other., Discussion: A similarity between the estimates of times to fatigue and exhaustion made by the observer and the automated technique suggests that video tracking of rodents running on a treadmill can be used to determine both parameters in experimental studies. Video tracking technique allows for a more objective measure and would allow for an increased performance in experimentation. The Supplemental information to this manuscript contains an Excel file, which includes the code in Virtual Basic with freeware license, to process and visualize running data and automatically estimate the times to fatigue and exhaustion. Instructions for the software are also included., Competing Interests: The authors declare there are no competing interests.

Stimulants cause hyperthermia, in part, by increasing heat generation through exercise. Stimulants also delay the onset of fatigue and exhaustion allowing animals to exercise longer. If used in a warm environment, this combination (increased exercise and decreased fatigue) can cause heat stroke. The dorsomedial hypothalamus (DMH) is involved in mediating locomotion from stimulants. Furthermore, inhibiting the DMH decreases locomotion and prevents hyperthermia in rats given stimulants in a warm environment. Whether the DMH is involved in mediating exercise-induced fatigue and exhaustion is not known. We hypothesized that disinhibiting neurons in the dorsomedial hypothalamus (DMH) would delay the onset of fatigue and exhaustion in animals exercising in a warm environment. To test this hypothesis, we used automated video tracking software to measure fatigue and exhaustion. In rats, using wearable mini-pumps, we demonstrated that disinhibiting the DMH, via bicuculline perfusion (5 µM), increased the duration of exercise in a warm environment as compared to control animals (25 ± 3 min vs 15 ± 2 min). Bicuculline-perfused animals also had higher temperatures at exhaustion (41.4 ± 0.2 °C vs 40.0 ± 0.4 °C). Disinhibiting neurons in the DMH also increased the time to fatigue. Our data show that the same region of the hypothalamus that is involved in mediating locomotion to stimulants, is also involved in controlling exhaustion and fatigue. These findings have implications for understanding the cause and treatment of stimulant-induced-hyperthermia., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The clinical manifestation of drug-induced abnormalities in thermoregulation occurs across a variety of drug mechanisms. The aim of this chapter is to review two of the most common drug-induced hyperthermic states, serotonin syndrome and neuroleptic malignant syndrome. Clinical features, pathophysiology, and treatment strategies will be discussed, in addition to differentiating between these two syndromes and differentiating them from other hyperthermic or febrile syndromes. Our goal is to both review the current literature and to provide a practical guide to identification and treatment of these potentially life-threatening illnesses. The diagnostic and treatment recommendations made by us, and by other authors, are likely to change with a better understanding of the pathophysiology of these syndromes., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Vital parameters of living organisms exhibit circadian rhythmicity. Although rats are nocturnal animals, most of the studies involving rats are performed during the day. The objective of this study was to examine the circadian variability of the body temperature responses to methamphetamine. Body temperature was recorded in male Sprague-Dawley rats that received intraperitoneal injections of methamphetamine (Meth, 1 or 5 mg/kg) or saline at 10 AM or at 10 PM. The baseline body temperature at night was 0.8°C higher than during the day. Both during the day and at night, 1 mg/kg of Meth induced monophasic hyperthermia. However, the maximal temperature increase at night was 50% smaller than during the daytime. Injection of 5 mg/kg of Meth during the daytime caused a delayed hyperthermic response. In contrast, the same dose at night produced responses with a tendency toward a decrease of body temperature. Using mathematical modeling, we previously showed that the complex dose dependence of the daytime temperature responses to Meth results from an interplay between inhibitory and excitatory drives. In this study, using our model, we explain the suppression of the hyperthermia in response to Meth at night. First, we found that the baseline activity of the excitatory drive is greater at night. It appears partially saturated and thus is additionally activated by Meth to a lesser extent. Therefore, the excitatory component causes less hyperthermia or becomes overpowered by the inhibitory drive in response to the higher dose. Second, at night the injection of Meth results in reduction of the equilibrium body temperature, leading to gradual cooling counteracting hyperthermia.

Background: For children worldwide, diarrhea is the second leading cause of death. These deaths are preventable by fluid resuscitation. Nasogastric tubes (NGs) have been shown to be equivalent to intravenous fluids for rehydration and recommended by the World Health Organization (WHO) for use in severe dehydration. Despite this, NGs are rarely used for rehydration in Kenya. Our objective was to evaluate clinicians' adherence to rehydration guidelines and to identify barriers to the use of NGs for resuscitating dehydrated children., Methods: A case-based structured survey was administered to pediatric care providers in western Kenya to determine their choices for alternative rehydration therapies when oral rehydration and intravenous fluids fail. Providers then participated in a qualitative, semi-structured interview to identify barriers to using nasogastric tubes for rehydration. Analysis included manual, progressive coding of interview transcripts to identify emerging central themes., Results: Of 44 participants, only four (9%) followed WHO guidelines that recommend quickly switching to NG for rehydration in their case responses. Participants identified that placing intravenous lines in dehydrated children is a challenge. However, when discussing NG use, many believed NGs are not effective for rehydration. Other participants' concerns surrounded knowledge and training regarding guidelines as well as not having NGs available., Discussion: Healthcare providers in western Kenya do not report using NGs for rehydration in accordance with WHO guidelines for diarrheal illness with severe dehydration. Barriers to the use of NG tubes were lack of knowledge and availability. Education and implementation of guidelines using NG tubes for rehydration may improve outcomes of children suffering from diarrheal illness with severe dehydration., Competing Interests: The authors declare there are no competing interests.

The corticotropin-releasing hormone (CRH) plays an important role in mediating physiological response to stress and is thought to be involved in the development of various psychiatric disorders. In this paper, we compare the differences between the effect of intraperitoneal (i.p.) and intraarterial (i.a.) administration of the non-peptide CRH 1 antagonist CP-154,526 (CP) (10 and 20mg/kg) on plasma adrenocorticotropic hormone levels (ACTH), heart rate, MAP, and c-Fos expression in the paraventricular nucleus of the hypothalamus. Intraperitoneal, but not i.a., injection of CP resulted in an increase in plasma ACTH (from 105±13 to 278±51pg/ml after 20mg/kg). This effect was accompanied by a dramatic increase in c-Fos expression in cells immunoreactive for CRH in the paraventricular nucleus of the hypothalamus. When the drug was administered i.p., CP-induced activation of the HPA appears to mask the inhibitory effect of CP on stress-induced ACTH secretion, an effect which was readily apparent when the drug was given i.a. Intraperitoneal administration of CP also increased the baseline MAP which may account for previous reports that treatment with this drug attenuated the increases associated with stress. CP given by either route had no effect on baseline heart rate or stress-induced tachycardia. Thus, in all studies in which CP 154,526 is given, the route of delivery must be given careful consideration., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The importance of exercise is increasingly emphasized for maintaining health. However, exercise itself can pose threats to health such as the development of exertional heat shock in warm environments. Therefore, it is important to understand how the thermoregulation system adjusts during exercise and how alterations of this can contribute to heat stroke. To explore this we measured the core body temperature of rats (Tc) running for 15 min on a treadmill at various speeds in two ambient temperatures (Ta = 25°C and 32°C). We assimilated the experimental data into a mathematical model that describes temperature changes in two compartments of the body, representing the muscles and the core. In our model the core body generates heat to maintain normal body temperature, and dissipates it into the environment. The muscles produce additional heat during exercise. According to the estimation of model parameters, at Ta = 25°C, the heat generation in the core was progressively reduced with the increase of the treadmill speed to compensate for a progressive increase in heat production by the muscles. This compensation was ineffective at Ta = 32°C, which resulted in an increased rate of heat accumulation with increasing speed, as opposed to the Ta = 25°C case. Interestingly, placing an animal on a treadmill increased heat production in the muscles even when the treadmill speed was zero. Quantitatively, this "ready-to-run" phenomenon accounted for over half of the heat generation in the muscles observed at maximal treadmill speed. We speculate that this anticipatory response utilizes stress-related circuitry., (Copyright © 2015 the American Physiological Society.)

Yohimbine is a prototypical alpha2-adrenergic receptor antagonist. Due to its relatively high selectivity, yohimbine is often used in experiments whose purpose is to examine the role of these receptors. For example, yohimbine has been employed at doses of 1-5 mg/kg to reinstate drug-seeking behavior after extinction or to antagonize general anesthesia, an effects presumably being a consequence of blocking alpha2-adrenergic receptors. In this report we characterized dose-dependent autonomic and behavioral effects of yohimbine and its interaction with an antagonist of 5-HT1A receptors, WAY 100,635. In low doses (0.5-2 mg/kg i.p.) yohimbine induced locomotor activation which was accompanied by a tachycardia and mild hypertension. Increasing the dose to 3-4.5 mg/kg reversed the hypertension and locomotor activation and induced profound hypothermia. The hypothermia as well as the suppression of the locomotion and the hypertension could be reversed by the blockade of 5-HT1A receptors with WAY 100635. Our data confirm that yohimbine possesses 5-HT1A properties, and demonstrated that in doses above 1mg/kg significantly activate these receptors., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

The objective of this study was to characterize the acute clinical effects, laboratory findings, complications, and disposition of patients presenting to the hospital after abusing synthetic cathinone. We conducted a retrospective multicenter case series of patients with synthetic cathinone abuse by searching for the terms bath salts, MDPV, methylenedioxypyrovalerone, mephedrone, methcathinone, methylone, methedrone, and cathinone within the "agent" field of a national clinical toxicology database (ToxIC). The medical records of these patients were obtained and abstracted by investigators at each study site. Patients with confirmatory testing that identified a synthetic cathinone in either blood or urine were included in the series. Patients who had either an undetectable synthetic cathinone test or no confirmatory testing were excluded. A data abstraction sheet was used to obtain information on each patient. We entered data into an Excel spreadsheet and calculated descriptive statistics. We identified 23 patients with confirmed synthetic cathinone exposure--all were positive for methylenedioxyprovalerone (MDPV). Eighty-three percent were male and 74 % had recreational intent. The most common reported clinical effects were tachycardia (74 %), agitation (65 %), and sympathomimetic syndrome (65 %). Acidosis was the most common laboratory abnormality (43 %). Seventy-eight percent of patients were treated with benzodiazepines and 30 % were intubated. Ninety-six percent of patients were hospitalized and 87 % were admitted to the ICU. The majority (61 %) of patients was discharged home but 30 % required inpatient psychiatric care. There was one death in our series. The majority of patients presenting to the hospital after abusing MDPV have severe sympathomimetic findings requiring hospitalization. A number of these patients require inpatient psychiatric care after their acute presentation.

The contribution of exercise to hyperthermia mediated by MDMA is not known. We recently showed that inhibiting the dorsomedial hypothalamus (DMH) attenuated spontaneous locomotion and hyperthermia and prevented deaths in rats given MDMA in a warm environment. The goal of this study was to confirm that restoring locomotion through a treadmill would reverse these effects thereby confirming that locomotion mediated by the DMH contributes to MDMA-mediated hyperthermia. Rats were randomized to receive bilateral microinjections, into the region of the DMH, of muscimol (80pmol/100nl) or artificial CSF followed by a systemic dose of either MDMA (7.5mg/kg, i.v.) or saline. Immediately after the systemic injection, rats were placed on a motorized treadmill maintained at 32°C. Rats were exercised at a fixed speed (10m/min) until their core temperature reached 41°C. Our results showed that a fixed exercise load abolished the decreases in temperature and mortality, seen previously with inhibition of the DMH in freely moving rats. Therefore, locomotion mediated by neurons in the DMH is critical to the development of hyperthermia from MDMA., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Experimental Data: Orexinergic neurotransmission is involved in mediating temperature responses to methamphetamine (Meth). In experiments in rats, SB-334867 (SB), an antagonist of orexin receptors (OX1R), at a dose of 10 mg/kg decreases late temperature responses (t > 60 min) to an intermediate dose of Meth (5 mg/kg). A higher dose of SB (30 mg/kg) attenuates temperature responses to low dose (1 mg/kg) of Meth and to stress. In contrast, it significantly exaggerates early responses (t < 60 min) to intermediate and high doses (5 and 10 mg/kg) of Meth. As pretreatment with SB also inhibits temperature response to the stress of injection, traditional statistical analysis of temperature responses is difficult., Mathematical Modeling: We have developed a mathematical model that explains the complexity of temperature responses to Meth as the interplay between excitatory and inhibitory nodes. We have extended the developed model to include the stress of manipulations and the effects of SB. Stress is synergistic with Meth on the action on excitatory node. Orexin receptors mediate an activation of on both excitatory and inhibitory nodes by low doses of Meth, but not on the node activated by high doses (HD). Exaggeration of early responses to high doses of Meth involves disinhibition: low dose of SB decreases tonic inhibition of HD and lowers the activation threshold, while the higher dose suppresses the inhibitory component. Using a modeling approach to data assimilation appears efficient in separating individual components of complex response with statistical analysis unachievable by traditional data processing methods.

Background: Exertional heat stroke is a devastating condition that can cause significant morbidity and mortality. Rapid cooling is the most effective means of treating heat stroke, but little is published on the safety and logistics of cooling patients on site at a major sporting event., Purpose: To describe an on-site exertional heat stroke treatment protocol and to compare the outcomes of patients treated on site to those transferred to hospitals., Study Design: Descriptive epidemiological study., Methods: Using race-day medical records and ambulance run sheets, patients who developed exertional heat stroke at the Indianapolis half-marathon from 2005 to 2012 were identified. Exertional heat stroke was defined as runners with a core temperature measured with a rectal thermometer greater than 102° F and altered mental status. Clinical information and patient outcomes were abstracted from the race medical tent and hospital charts by 3 separate trained reviewers using structured methods and a data collection form. Two reviewers, using a RedCAP database and dual-data entry, abstracted records for each patient. A third arbitrated all discrepancies between reviewers. Clinical signs, treatments, and outcomes were calculated using descriptive statistics, and data were grouped and compared for patients treated on site or transferred to local hospitals for treatment., Results: Over 235,000 athletes participated in the event over the 8-year period, with 696 seeking medical care. A total of 32 heat stroke victims were identified during the study period; of these, 22 were treated on site. Of these, 68% were treated with cold-water immersion and 59% were discharged home from the race. Ten exertional heat stroke patients were transported from the race course to local hospitals. None of them underwent cold-water immersion, and 40% of them were subsequently discharged home. No patients in the study died., Conclusion: On-site treatment of athletes who develop exertional heat stroke appears to be both safe and effective. On-site treatment may decrease the local burden of critically ill patients to emergency departments during large athletic events., (© 2015 The Author(s).)

Objective. Mobile phones have been successfully used for Emergency Department (ED) patient follow-up in developed countries. Mobile phones are widely available in developing countries and may offer a similar potential for follow-up and continued care of ED patients in low and middle-income countries. The goal of this study was to determine the percentage of families with mobile phones presenting to a pediatric ED in western Kenya and rate of response to a follow-up phone call after discharge. Methods. A prospective, cross-sectional observational study of children presenting to the emergency department of a government referral hospital in Eldoret, Kenya was performed. Documentation of mobile phone access, including phone number, was recorded. If families had access, consent was obtained and families were contacted 7 days after discharge for follow-up. Results. Of 788 families, 704 (89.3%) had mobile phone access. Of those families discharged from the ED, successful follow-up was made in 83.6% of cases. Conclusions. Mobile phones are an available technology for follow-up of patients discharged from a pediatric emergency department in resource-limited western Kenya.

This editorial summarizes Temperature's special issue entitled "Temperature and Toxicology with a Focus on Drugs of Abuse" (2014, volume 1, issue 3), dedicated to the multiple recent discoveries related to the thermoregulatory effects of xenobiotics. Several basic and clinical studies on xenobiotic-induced hyperthermia are reported that propose novel mechanisms and treatments.

Background: Synthetic cathinones are popularly referred to in the media as "bath salts." Through the direct and indirect activation of the sympathetic nervous system, smoking, snorting, or injecting synthetic cathinones can result in tachycardia, hypertension, hyperthermia, myocardial infarction, and death., Objective: The chemical structures and names of bath salts identified by the Ohio Attorney General's Bureau of Criminal Investigation are presented. Based on their common pharmacophores, we review the history, pharmacology, toxicology, detection methods, and clinical implications of synthetic cathinones. Through the integration of this information, the pharmacological basis for the management of patients using synthetic cathinones is presented., Discussion: Synthetic cathinones activate central serotonergic and dopaminergic systems contributing to acute psychosis and the peripheral activation of the sympathetic nervous system. The overstimulation of the sympathetic nervous system contributes to the many toxicities reported with bath salt use. The pharmacological basis for managing these patients is targeted at attenuating the activation of these systems., Conclusions: Treatment of patients presenting after using bath salts should be focused on reducing agitation and psychosis and supporting renal perfusion. The majority of successfully treated synthetic cathinones cases have used benzodiazepines and antipsychotics along with general supportive care., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The central mechanisms through which MDMA mediates life-threatening hyperthermia when taken in a warm environment are not well described. It is assumed that MDMA alters normal thermoregulatory circuits resulting in increased heat production through interscapular brown adipose tissue (iBAT) and decreased heat dissipation through cutaneous vasoconstriction. We studied the role of the dorsomedial hypothalamus (DMH) and medullary raphe pallidus (mRPa) in mediating iBAT, tail blood flow, and locomotor effects produced by MDMA. Rats were instrumented with guide cannulas targeting either the DMH or the mRPa-brain regions involved in regulating iBAT and cutaneous vascular beds. In all animals, core temperature and locomotion were recorded with surgically implanted telemetric transmitters; and additionally either iBAT temperature (via telemetric transmitter) or tail artery blood flow (via tail artery Doppler cuff) were also recorded. Animals were placed in an environmental chamber at 32°C and microinjected with either control or the GABA agonist muscimol (80pmol) followed by an intravenous injection of saline or MDMA (7.5 mg kg -1 ). To prevent undue suffering, a core temperature of 41°C was chosen as the surrogate marker of mortality. Inhibition of the DMH, but not the mRPa, prevented mortality and attenuated hyperthermia and locomotion. Inhibition of either the DMH or the mRPa did not affect iBAT temperature increases or tail blood flow decreases. While MDMA increases iBAT thermogenesis and decreases heat dissipation through cutaneous vasoconstriction, thermoregulatory brain regions known to mediate these effects are not involved. Rather, the finding that inhibiting the DMH decreases both locomotion and body temperature suggests that locomotion may be a key central contributor to MDMA-evoked hyperthermia.

Amphetamine (Amp) increases exercise duration. It is thought to do so by masking fatigue, but there have been very few studies looking at the effect of amphetamine on VO 2MAX and running economy. Furthermore, it is unknown if amphetamine's effect on exercise duration occurs in a warm environment. We conducted separate experiments in male Sprague-Dawley rats testing the effect of amphetamine on maximal oxygen consumption (VO 2MAX ) (n=12), running economy (n=12), and exercise duration (n=24) in a warm environment. For VO 2MAX and running economy, rats were randomized to either amphetamine at 1 mg/kg (Amp-1) or 2 mg/kg (Amp-2). Animals served as their own controls in a crossover design with the administration order counter-balanced. To study the effect of amphetamine on exercise duration, we conducted run-to-exhaustion treadmill testing on rats in a 32°C environment following administration of Amp-1, Amp-2, or Saline. Compared to control, Amp-2 increased VO 2MAX (by 861 ± 184 ml/kg/hr, p =0.005) and the time to VO 2MAX (by 2.5 ± 0.8 min, p =0.03). Amp-1 had no effect on VO 2MAX but increased the time to VO 2MAX (by 1.7 ± 0.5 min, p =0.03). Neither dose improved running economy. In the warm, only rats in the Amp-1 group (+9.4 min, p =0.02) had an increased time to exhaustion. Compared to control (41.6 ± 0.3°C), both amphetamine doses had higher temperatures at exhaustion: Amp-1 (42.0 ± 0.2°C) and Amp-2 (42.1 ± 0.2°C). Our results suggest that ergogenic effect of amphetamine occurs by masking fatigue but this effect may be offset in the warm with higher doses., Competing Interests: There are no conflicts of interest, financial or otherwise, declared by the authors.

Acute and chronic complications from the substituted amphetamine 3,4-methylenedioxymethamphetamine (MDMA) are linked to activation of the hypothalamic-pituitary-adrenal (HPA) axis. How MDMA activates the HPA axis is not known. HPA responses to stress are known to be mediated through the paraventricular (PVH) hypothalamus and to involve serotonin-1a (5-HT1A) receptors. We sought to determine if the PVH and 5-HT1A receptors were also involved in mediating HPA responses to MDMA. Rats were pretreated with either saline or a 5-HT1A antagonist, WAY-100635 (WAY), followed by a systemic dose of MDMA (7.5mg/kg i.v.). Animals pretreated with WAY had significantly lower plasma ACTH concentrations after MDMA. To determine if neurons in the PVH were involved, and if their involvement was mediated by 5-HT1A receptors, rats implanted with guide cannulas targeting the PVH were microinjected with the GABAA receptor agonist muscimol, aCSF, or WAY followed by MDMA. Compared to aCSF, microinjections of muscimol significantly attenuated the MDMA-induced rise in plasma ACTH (126 vs. 588pg/ml, P=<0.01). WAY had no effect. Our data demonstrates that neurons in the PVH, independent of 5-HT1A receptors, mediate ACTH responses to MDMA., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Objectives: The objective was to ascertain whether acetaminophen (APAP) concentrations less than 100 μg/mL obtained between 1 and 4 hours after acute ingestion accurately predict a nontoxic 4-hour concentration., Methods: The authors performed a multicenter, prospective cohort study involving five emergency departments (EDs) participating in the ToxIC Research Network. Data were collected from May 2009 to December 2011. Patients with APAP concentrations <100 μg/mL drawn between 1 and 4 hours after acute ingestions, and concentrations drawn 4 or more hours after ingestions, were included in the study. Exclusion criteria included initial concentration >100 μg/mL, initial APAP concentration drawn prior to 1 hour, two undetectable APAP concentrations, the second concentration drawn prior to 4 hours, and unknown time of ingestion. Toxic concentrations 4 or more hours after ingestion were defined as concentrations that plotted above the 150 μg/mL line on the Rumack-Matthew nomogram., Results: Data were collected on 83 patients who met inclusion criteria. Of the 83 patients with APAP concentrations <100 μg/mL between 1 and 4 hours, one patient (1.2%) had a ≥ 4-hour toxic concentration. Negative predictive value (NPV) for an APAP concentration <100 μg/mL obtained between 1 and 4 hours after an acute ingestion was 98.8% (95% confidence interval [CI] = 93.5% to 99.8%)., Conclusions: An APAP concentration of <100 μg/mL obtained between 1 and 4 hours after ingestion has a high NPV for excluding toxic ingestion. We do not recommend reliance on concentrations obtained between 1 and 4 hours to exclude toxicity, because of a potential false-negative rate of 6.5%., (© 2013 by the Society for Academic Emergency Medicine.)

The drug with perhaps the greatest impact on the practice of Psychiatry is Methamphetamine. By increasing the extracellular concentrations of dopamine while slowly damaging the dopaminergic neurotransmission, Meth is a powerfully addictive drug whose chronic use preferentially causes psychiatric complications. Chronic Meth users have deficits in memory and executive functioning as well as higher rates of anxiety, depression, and most notably psychosis. It is because of addiction and chronic psychosis from Meth abuse that the Meth user is most likely to come to the attention of the practicing Psychiatrist/Psychologist. Understanding the chronic neurologic manifestations of Meth abuse will better arm practitioners with the diagnostic and therapeutic tools needed to make the Meth epidemic one of historical interest only., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Introduction: Cream of tartar (potassium bitartrate) has a long history as a cooking aid and medicinal purgative. Despite containing large amounts of potassium, there are no well-documented cases of it causing toxicity. We report two cases in which intentional ingestions of cream of tartar resulted in life-threatening hyperkalemia. In addition, we briefly review the use of cream of tartar as a historical purgative., Case Reports: In both cases, individuals ingested a large quantity of cream of tartar in an effort to "clean themselves out". They manifested similar initial symptoms (vomiting), abnormal serum potassium (>8.0 mmol/L), and EKG's with peaked T waves. Both patients were treated for hyperkalemia and recovered without complication. A search for articles on an academic internet database failed to identify any cases specifically dealing with ill effects of potassium bitartrate and numerous websites continue to purport its beneficial health effects., Conclusion: Ingestion of cream of tartar can potentially result in life-threatening hyperkalemia.

Study Objective: Validated methods for weight estimation of children are readily available in developed countries; however, their utility in developing countries with higher rates of malnutrition and infectious disease is unknown. The goal of this study is to determine the validity of a height-based estimate, the Broselow tape, compared with age-based estimations among pediatric patients in Western Kenya., Methods: A prospective cross-sectional study of all sick children presenting to the emergency department of a government referral hospital in Eldoret, Kenya, was performed. Measured weight was compared with predicted weights according to the Broselow tape and commonly used advanced pediatric life support (APLS) and Nelson's age-based formulas. A Bland-Altman analysis was used to determine agreement between each method and actual weight. The method for weight prediction was determined a priori to be equivalent to the actual weight if the 95% confidence interval for the mean percentage difference between the predicted and actual weight was less than 10%., Results: Nine hundred sixty-seven children were included in analysis. The overall mean percentage difference for the actual weight and Broselow predicted weight was -2.2%, whereas APLS and Nelson's predictions were -5.2% and -10.4%, respectively. The overall agreement between Broselow color zone and actual weight was 65.5%, with overestimate typically occurring by only 1 color zone., Conclusion: The Broselow tape and APLS formula predict the weights of children in western Kenya. According to its better performance, ease of use, and provision of drug dosing and equipment size, the Broselow tape is superior to age-based formulas for estimation of weight in Kenyan children., (Copyright © 2012. Published by Mosby, Inc.)

We recently discovered that inhibiting neurons in the dorsomedial hypothalamus (DMH) attenuated hyperthermia, tachycardia, hypertension, and hyperactivity evoked by the substituted amphetamine 3, 4-methylenedioxymethamphetamine (MDMA). Neurons that synthesize orexin are also found in the region of the DMH. As orexin and its receptors are involved in the regulation of heart rate and temperature, they would seem to be logical candidates as mediators of the effects evoked by amphetamines. The goal of this study was to determine if blockade of orexin-1 receptors in conscious rats would suppress cardiovascular and thermogenic responses evoked by a range of methamphetamine (METH) doses. Male Sprague-Dawley rats (n=6 per group) were implanted with telemetric transmitters measuring body temperature, heart rate, and mean arterial pressure. Animals were randomized to receive pretreatment with either the orexin-1 receptor antagonist SB-334867 (10mg/kg) or an equal volume of vehicle. Thirty minutes later animals were given intraperitoneal (i.p.) injections of either saline, a low (1mg/kg), moderate (5mg/kg) or high (10mg/kg) dose of METH. Pretreatment with SB-334867 significantly attenuated increases in body temperature and mean arterial pressure evoked by the moderate but not the low or high dose of METH. Furthermore, animals treated with SB-334867, compared to vehicle, had lower temperature and heart rate increases after the stress of an i.p. injection. In conclusion, temperature and cardiovascular responses to a moderate dose of METH and to stress appear to involve orexin-1 receptors. The failure to affect a low and a high dose of METH suggests a complex pharmacology dependent on dose. A better understanding of this may lead to the knowledge of how monoamines influence the orexin system and vice versa., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Microinjections are a major tool in modern neuroscience. Microinjection techniques in conscious animals typically involve four steps: (1) animal adapts to experimental setup; (2) injection system is filled and the microinjector is carefully inserted; (3) a drug solution is injected; (4) 1-2 min later the microinjector is carefully removed. Steps 2 and 4 are difficult to perform in rodents without disturbing the animal. This disruption can cause stress and accompanying tachycardia and hyperthermia - unwanted artifacts in physiological research. To reduce these effects, we altered the traditional approach. Our procedure of microinjection consisted of the following steps: (1) we filled the injection setup and fixed the microinjector in its guide cannula; (2) allowed an animal to adapt to the setup; (3) performed an experiment including microinjection(s); (4) removed the microinjector after the experiment was complete. The key change we incorporated was a 1m long piece of tubing with a small internal diameter; it allowed us to inject nanoliter volumes through the injector which had been placed into the guide cannula in advance. This way we avoided the usual manipulations related to microinjection, and minimized extraneous disturbances to the rat. In this report we describe the details of this technique in conscious rats and provide examples of the effects and the reproducibility of a 100 nL drug injection on cardiovascular function., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Methamphetamine abuse has reached epidemic proportions in the United States. The repetitive use of methamphetamine causes massive and sustained elevations in central monoamines. These elevations, particularly in dopamine, can cause changes in the function of the central nervous system that can manifest as a variety of neurologic disorders. This article focuses on these disorders, such as neurocognitive disorders and mental illness, including drug-induced psychosis; motor disorders, including the possible risk of Parkinson's disease, the development of choreoathetoid movements, and punding; and changes in the physical appearance of the methamphetamine users, including dental caries., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The medial preoptic area (mPOA) of the hypothalamus has long been thought to play an important role in both fever production and thermoregulation. Microinjections of prostaglandin E2 (PgE2) or the GABA(A) agonist muscimol into the mPOA cause similar increases in body temperature, heart rate, and blood pressure. Microinjections of these compounds however evoke different behavioral responses with muscimol increasing and PgE2 having no effect on locomotion. The purpose of this study was to determine the role of orexin-1 receptors in mediating these dissimilar responses. Systemic injections of the orexin-1 receptor antagonist SB-334867 reduced temperature and cardiovascular responses produced by microinjections of muscimol, but had no effect on either response produced by PgE2. SB-334867 did not significantly decrease locomotion evoked by microinjections of muscimol into the mPOA. These data suggest that there are two central nervous system circuits involved in increasing body temperature, heart rate and blood pressure: one circuit activated by muscimol, involving orexin neurons, and a separate orexin-independent circuit activated by PgE2., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Context: Adolescents are at risk to abuse opioid analgesics for many reasons, including inaccurate perception of risk and increased drug availability. In 2000, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) released pain management standards that emphasized pain control as a patient rights issue. This focus on analgesia may have increased both the prescribing and use of opioid analgesics, thereby increasing availability., Objective: Using data from a US poison center, this study aims to compare the number of adolescent opioid cases and their outcome severity before and after the 2000 JCAHO pain initiative., Methods: Retrospective case series of opioid exposures involving persons 12-18 years of age reported to a US poison center from 1994 to 2007. The main outcome measure was the number of adolescent opioid cases reported for 1994-2000 compared to 2001-2007. Secondary outcomes included outcome severity, number of cases involving specific opioids, and correlation between the number of cases and the amount of opioids distributed to the state., Results: There were 1634 adolescent opioid-related cases with 187 cases developing medical complications. Compared with 1994-2000, the rate ratio of cases involving adolescents and opioid analgesics for the years 2001-2007 was 1.69 (95% CI: 1.53, 1.86), and these cases were 2.84 (95% CI: 2.06, 3.91) times more likely to have had medical complications. Medical complications involving methadone (p =0.001) increased after the JCAHO initiative, while complications related to codeine (p =0.001) and propoxyphene (p =0.030) decreased. There were 15 deaths in 2001-2007 and none in 1994-2000 (p =0.012). Lastly, there was a correlation between the rate of adolescent opioid cases and the amount of opioids distributed to the state (r(2) =0.90; p < 0.001)., Conclusion: In the 7 years following the JCAHO pain standards, there was an increase in the number and severity of adolescent opioid-related poison center cases. The increase correlates with statewide availability of opioids. These data may prove useful in drug education and prevention programs targeting adolescents.

Although anesthetic doses of urethane increase plasma levels of ACTH, the exact mechanism through which this occurs is unclear. We theorized that these increases might be a consequence of an increased systemic osmolality owing to the large doses of urethane usually employed. To evaluate this possibility, we measured plasma osmolality and ACTH in a total of six rats after graded infusions of urethane (N=3 rats) or equimolar amounts of mannitol (N=3 rats). Rats received infusions at 15 min intervals up to a cumulative dose equivalent to an anesthetic dose for urethane (1.4 g/kg). Blood samples (0.35 ml) were withdrawn at baseline and 10 min after each infusion. Urethane and mannitol produced significant and equivalent increases in plasma osmolality. However, only urethane evoked increases in plasma ACTH which were maximal (252+/-55 pg/ml from a baseline of 27+/-7 pg/ml) after a cumulative dose of 1 g/kg. Thus, increases in plasma ACTH seen after anesthetic doses of urethane are unlikely to be a consequence of its effect on plasma osmolality., (Copyright 2010 Elsevier Ireland Ltd. All rights reserved.)

Of the known elements, nearly 80% are either metals or metalloids. The highly reactive nature of most metals result in their forming complexes with other compounds such oxygen, sulfide and chloride. Although this reactivity is the primary means by which they are toxic, many metals, in trace amounts, are vital to normal physiological processes; examples include iron in oxygen transport, manganese and selenium in antioxidant defense and zinc in metabolism. With these essential metals toxicity occurs when concentrations are either too low or too high. For some metals there are no physiological concentrations that are beneficial; as such these metals only have the potential to cause toxicity. This chapter focuses on four of these: arsenic, mercury, lead and thallium.

Introduction: Tacrolimus is an immunosuppressant widely used in recipients of solid organ transplants to prevent rejection. Toxicity is usually reported in transplant patients. We report the first case of tacrolimus toxicity in a non-transplant patient., Case Report: A 42 year-old, 48 kg woman complained of neck pain following a motor vehicle collision and was admitted for observation. On examination, her pulse was 112 beats/minute and her blood pressure 188/134 mmHg. Because the hypertension and tachycardia might be ethanol withdrawal, she was admitted and treated with multivitamins, folate, and thiamine in her maintenance fluids. She was discharged after 4 days in hospital. The day after her discharge, she was asked to return after it was discovered that she had inadvertently received tacrolimus (total of 400 mg) instead of thiamine. She was admitted with non-oliguric renal failure and metabolic acidosis. A tacrolimus concentration 27 hours after her last exposure was 96.8 ng/mL (therapeutic 5 to 20 ng/mL). Treatment was supportive and she was discharged after 4 days without sequellae., Discussion: Our patient's tacrolimus dose was 2.1 mg/kg/day for 4 days (therapeutic 0.03 to 0.05 mg/kg/day). Her tacrolimus elimination half-life was 16.5 hours, compared to a mean half-life in healthy volunteers of 34.2 +/- 7.7 hours., Conclusion: Clinical toxicity, similar to that seen in transplant patients, can develop in non-transplant patients following intravenous administration of supra-therapeutic doses of tacrolimus.

Introduction: Ingestion of a small amount of concentrated hydrogen peroxide can cause cerebral air gas embolism (CAGE). Hyperbaric oxygen therapy (HBOT) is the standard of care in the treatment of CAGE. We report a case of CAGE after accidental ingestion of 33%hydrogen peroxide treated with HBOT resulting in reversal of both the clinical and radiologic abnormalities., Case Report: A 48 year-old male took two sips of 33% hydrogen peroxide. A short time later, he developed hematemesis, left sided hemiplegia, confusion, and left homonymous hemianopsia. Initial laboratory studies, chest x-ray, and brain CT were normal. MRI demonstrated areas of restricted diffusion and T2 hyper intensities in multiple vascular territories consistent with ischemia due to CAGE. Eighteen hours after arrival, the patient underwent HBOT at 3 atmospheres absolute (ATA) for 30 minutes and 2.5 ATA for 60 minutes with clinical improvement. Follow-up MRI at six months demonstrated resolution of the hyper intensities., Discussion: A search of MEDLINE from 1950 to present revealed only two cases of CAGE from ingestion of concentrated hydrogen peroxide treated with HBOT. Both cases, similar to ours, had complete resolution of symptoms. Of the seven reported cases of CAGE from hydrogen peroxide that did not undergo HBOT, only in one patient was there a report of symptom resolution., Conclusion: Ingestion of even a small amount of concentrated hydrogen peroxide can result in cerebral air gas embolism. Hyperbaric oxygen therapy may be of benefit in reversing the symptoms and preventing permanent neurological impairment.

Introduction: Few cases of mercury sequestration in the appendix appear in the literature. Based on these, both prophylactic appendectomy and non-surgical management have been recommended. We report a case in which a patient with mercury retained in the appendix was managed conservatively without developing mercurialism or appendicitis., Case Report: A 43-year-old man ingested approximately one tablespoon of elemental mercury after an argument with his wife. An initial abdominal radiograph showed mercury in the pylorus of the stomach and a follow-up x-ray at 72 hours showed mercury localized to the appendix. The patient was treated as an outpatient and examined several times over a 37-day period. He never developed signs of appendicitis. On a follow-up examination 7 months after the ingestion, he was radiographically free of mercury. Periodically throughout his clinical course, blood mercury levels were obtained. Only one, 6 days after ingestion, showed an elevated mercury level of 68 mcg/L (reference range <10 mcg/L). Despite this, the patient never developed signs or symptoms of mercury poisoning., Conclusion: Patients in whom elemental mercury is retained in the appendix, who are without symptoms and have normal gastric mucosa, may be conservatively managed without surgery.

When given systemically to rats and humans, the drug of abuse 3,4 methylenedioxymethamphetamine (ecstasy, MDMA) elicits hyperthermia, hyperactivity, tachycardia, and hypertension. Chemically stimulating the dorsomedial hypothalamus (DMH), a brain region known to be involved in thermoregulation and in stress responses, causes similar effects. We therefore tested the hypothesis that neuronal activity in the DMH plays a role in MDMA-evoked sympathetic and behavioral responses by microinjecting artificial CSF or muscimol, a neuronal inhibitor, into the DMH prior to intravenous infusion of saline or MDMA in conscious rats. Core temperature, heart rate, mean arterial pressure and locomotor activity were recorded by telemetry every minute for 120 min. In rats previously microinjected with CSF, MDMA elicited significant increases from baseline in core temperature (+1.3+/-0.3 degrees C), locomotion (+50+/-6 counts/min), heart rate (+142+/-16 beats/min), and mean arterial pressure (+26+/-3 mmHg). Microinjecting muscimol into the DMH prior to MDMA prevented increases in core temperature and locomotion and attenuated increases in heart rate and mean arterial pressure. These results indicate that neuronal activity in the DMH is necessary for the sympathetic and behavioral responses evoked by MDMA.

When given in a warm environment MDMA (3,4-methylenedioxymethamphetamine, ecstasy) causes hyperthermia by increasing interscapular brown adipose tissue (iBAT) heat production and decreasing heat loss via cutaneous vasoconstriction. When given in a cold environment, however, MDMA causes hypothermia by an unknown mechanism. This paper addresses these mechanisms and in addition examines whether antagonists at 5-HT(1A) and D(2) receptors reduce the hypothermic action of MDMA. Male Sprague-Dawley rats instrumented with a Doppler probe for measuring tail blood flow, and probes for measuring core and iBAT temperatures, were placed in a temperature-controlled chamber. The chamber temperature was reduced to 10 degrees C and vehicle (0.5 ml Ringer), the 5-HT(1A) antagonist WAY 100635 (0.5 mg/kg), the D(2) antagonist spiperone (20 mug/kg), or the combination of Way 100635 and spiperone were injected s.c. Thirty minutes later the antagonists were injected again along with MDMA (10 mg/kg) or vehicle. MDMA reduced core body temperature by preventing cold-elicited iBAT thermogenesis and by transiently reversing cold-elicited cutaneous vasoconstriction. Pretreatment with WAY 100635 prevented MDMA induced increases in tail blood flow, and briefly attenuated MDMA's effects on iBAT and core temperature. While spiperone alone failed to affect any of the parameters, the combination of spiperone and WAY 100635 decreased MDMA-mediated hypothermia by attenuating both the effects on tail blood flow and iBAT thermogenesis. MDMA's prevention of cold-induced iBAT thermogenesis appears to have a central origin as it rapidly reverses cold-induced increases in iBAT sympathetic nerve discharge in anesthetized rats. Our results demonstrate that MDMA in a cold environment reduces core body temperature by inhibiting iBAT thermogenesis and tail artery vasoconstriction and suggest that mechanisms by which this occurs include the activation of 5-HT1A and dopamine D2 receptors.

The popular drug of abuse 3,4-methylenedioxymethamphetamine (MDMA) has complex interactions with thermoregulatory systems, resulting in either hyperthermia or hypothermia. MDMA induces hypothermia when given to animals housed at a low ambient temperature. In this study we report that MDMA (7.5 mg/kg i.p.) given at normal ambient temperatures of 24 to 25 degrees C caused, in conscious freely moving rats, hypothermia (mean decrease from baseline of 1.1 +/- 0.06 degrees C at 40 min). Pretreating animals with a 0.5 mg/kg i.p. dose of the 5-hydroxytryptamine 1A (5-HT(1A)) antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide (WAY 100635) not only prevented MDMA-induced hypothermia, but resulted in the development of hyperthermia (mean temperature increase from baseline of 0.74 +/- 0.2 degrees C at 120 min). After treatment with WAY 100635, MDMA also elicited an enhanced tachycardia (mean increases in heart rate from baseline of 110 +/- 16 beats/min at 90 min). To identify the location of 5-HT(1A) receptors responsible for hypothermia induced by MDMA, we first investigated the role of 5-HT(1A) receptors in the rostral raphe pallidus (rRP) in decreases in temperature evoked by the known 5-HT(1A) agonist 8-hydroxy-2-di-n-propylamino-tetralin (DPAT). Microinjections of 0.5 nmol of WAY 100635 into the rRP significantly attenuated DPAT (0.2 mg/kg i.p.)-elicited hypothermia. In parallel experiments, we found that microinjections of WAY 100635 into the rRP, while significantly augmenting MDMA-mediated tachycardia, did not alter body temperature. These results demonstrate that although hypothermia mediated by both MDMA and DPAT shares a common dependence on the activation of 5-HT(1A) receptors, the location of these receptors is different for each drug.

Normal thermogenesis requires a complex interaction between systems that generate and dissipate heat. Serving as director of thermogenesis, the hypothalamus activates the sympathetic nervous system along with the thyroid and adrenal glands to respond to changes in body temperature. Working in concert, these systems result in heat generation by uncoupling of oxidative phosphorylation, combined with impaired heat dissipation through vasoconstriction. In this article, the authors discuss serotonin and sympathomimetic syndromes, neuroleptic malignant syndrome,and malignant hyperthermia and how these syndromes affect the hypothalamic and sympathetic nervous systems, resulting at times in severe hyperthermia. Current treatment recommendations and future trends in treatment are also discussed.