Sympathetic nervous system activation, antivenin administration and cardiovascular manifestations of scorpion envenomation

Tako-tsubo cardiomyopathy in clinical toxinology: A systematic review

Tako-tsubo cardiomyopathy (TTC) is a transient left ventricular dysfunction, normally triggered by emotional or physical stress, although it is also associated with to use of drugs, drug abuse, or some intoxications. In addition, TTC has been reported in some case reports derived from the exposure of patients to animal venoms, toxins or poisons, or bacterial infections. However, to date, a systematic assessment of TTC in clinical toxinology is lacking. Therefore the aim of this study was to collect and integrate the available information about TTC in clinical toxinology. After our search strategy, 19 articles were retrieved, resulting in 20 case reports. Most cases occurred in women (75.0%). The venomous species that trigger TTC are bee/wasp, including probable Africanized honey bee and Vespa orientalis (15.0%), scorpions (Tytius serrulatus and Androctonus australis, 15.0%), a spider (Latrodectus tredecimguttatus, 5.0%), snakes (Gloydius blomhofii and Naja nivea, 10.0%), Clostridium sp (C. tetani, C. botulinum and C. difficile, 45.0%) and jellyfish (Pelagia noctiluca and Carukia barnesi, 10.0%). Among the affected people there were two deaths. In all case reports authors diagnosed TTC by using the combination of some of the following strategies: clinical findings, echocardiography, magnetic cardiac resonance, electrocardiogram changes and/or the increased plasma levels of cardiac damage biomarkers. In most cases images were available. We hypothesized the possible mode of action of venoms, toxins or poisons to induce TTC, however other mechanisms may exist, but they have not been described yet. Therefore, further studies are needed. In some cases, venoms, toxins, or poisons might cause catecholamine discharge either directly or indirectly, therefore, this was suggested as the trigger of TTC. Finally, the appearance of TTC should be considered in clinical toxinology.

Amazonian scorpions and scorpionism: integrating toxinological, clinical, and phylogenetic data to combat a human health crisis in the world's most diverse rainfores

Venom from Amazonian scorpions of the genus Tityus contains components capable of eliciting a distinct clinical, mostly neurological, syndrome. This contrasts with the mainly autonomic manifestations produced after envenomation by congeneric southern and northern South American species. Herein, we summarize Pan-Amazonian scorpionism by synthesizing available toxinological, clinical, and molecular data gathered from all affected areas in Amazonia, including Brazil, Ecuador, Colombia, Peru, Venezuela, and French Guiana. We searched multiple databases, as well as our own records, for reports of scorpion envenomations in Amazonia by confirmed Tityus spp., and compared the clinical manifestations. To help uncover clinical and venom relationships among problematic species, we explored phylogenetic relationships with a rate-calibrated analysis of mitochondrial COI data from available species. The possible existence of diversity gradients for venom toxic and immunogenic components despite the predicted strong phylogenetic association among species is underscored by discussed clinical and toxinological findings. A multicentric effort, involving all nations affected by this neglected disease, is urgently needed to offer alternatives for treating and understanding this pathology, including the preparation of neutralizing antibodies with a broad range of efficacy.

Comparison of the Scorpionism Caused by Centruroidesmargaritatus, Tityuspachyurus and Tityus n. sp. aff. metuendus Scorpion Venoms in Colombia

Among other scorpion species, Colombia has two genera of the Buthidae family Centruroides and Tityus, considered to be dangerous to humans. This research shares scientific knowledge aiming to a better understanding about the pathophysiological effects of such venoms. The venom of the three species: Centruroides margaritarus, Tityus pachyurus, and T. n. sp. aff. metuendus with biomedical interest were studied. An initial pre-glycemic sample was taken from ICR mice. They were later intraperitoneally inoculated with doses of 35% and 70% of LD₅₀ of total venom. Poisoning signs were observed during a 6-h period to determine the level of scorpionism. After observation, a second glycemic sample was taken, and a histopathological evaluation of different organs was performed. This work revealed that all three venoms showed considerably notorious histopathological alterations in main organs such as heart and lungs; and inducing multiple organ failure, in relation to the glycemia values, only C. margaritatus and T. n. sp. aff. metuendus showed significant changes through manifestation of hyperglycemia. According to the Colombian scorpionism level; signs were mild to severe affecting the autonomous nervous system.

Mast Cells Modulate the Immune Response and Redox Status of the Gastrointestinal Tract in Induced Venom Pathogenesis

The pathogenesis of Androctonus autralis hector (Aah) scorpion venom involved cellular and molecular mechanisms resulting in multi-organ dysfunction. However, little is reported about the effects of venom on the gastrointestinal axis. Mast cells (MCs) are known to play a crucial role in modulating immune response of the gut. This study aims to investigate the involvement of this cell type in venom-induced gastric and intestinal disorders in a time course (3 and 24h). The obtained results revealed that Aah scorpion venom induced inflammatory cell infiltration as shown by the increase of the myeloperoxidase and eosinophil peroxidase activities. Overexpression of the c-kit receptor (CD117) severely imbalanced the redox status with depletion of antioxidant systemic accompanied by gastrointestinal tissue damage. Moreover, an increased level of lactate dehydrogenase in the serum was correlated with tissue injuries. Pharmacological inhibition of MCs targeting tyrosine kinase (TK) reduces the generation of reactive oxygen species and normalizes catalase, and gluthation S-transferase activities to their physiological levels. In addition, histopathological alterations were restored after pretreatment with c-kit receptor inhibitor associated with a considerable reduction of MC density. Interestingly, obtained results indicate that MCs might be involved in gastric modulation and intestinal inflammation through c-kit signaling following sub-cutaneous Aah venom injection.

Complete neutralization of the lethality of Hemiscorpius lepturus crude venom by a novel anti-recombinant phospholipase D1 IgGs

Treatment of scorpion envenomation is a challenging issue since serotherapy is implemented by administration of polyvalent equine antisera. In our previous study we discovered that recombinant phospholipase D1 (Hl-RecPLD1) is responsible for the lethality of Hemiscorpius lepturus (H. lepturus) venom in mice. Accordingly, this study was aimed to investigate the protectivity of purified anti-Hl-RecPLD1 IgG against the lethality or major complications of H. lepturus venom. The neutralization efficiency of purified anti-Hl-RecPLD1 IgGs against sphingomyelinase activities of the crude venom and Hl-RecPLD1 was also assessed. Anti-Hl-RecPLD1 IgGs at optimum amount of 3.7 mg completely neutralized one Lethal Dose 100 (LD₁₀₀) of crude venom in mice. The anti-Hl-RecPLD1 IgGs remarkably reduced the necrosis area from 6.5 to 1 cm² in rabbit derma, induced by the crude venom. The anti-Hl-RecPLD1 IgGs remarkably reduced the sphingomyelinase and hemolytic activities of crude venom as well. In conclusion, a novel rabbit monovalent IgG against Hl-RecPLD1 was able to completely protect the mice against the lethality of H. lepturus crude venom and reduced its toxicity as well. Such monovalent anti-Hl-RecPLD1 IgGs may have potential applications in serotherapy of H. lepturus envenomation.

Venom diversity in the Neotropical scorpion genus Tityus: Implications for antivenom design emerging from molecular and immunochemical analyses across endemic areas of scorpionism

Scorpions of the Neotropical genus Tityus are responsible for most severe envenomations in the Caribbean, South America, and Lower Central America (LCA). Although Tityus is taxonomically complex, contains high toxin polymorphism, and produces variable clinical manifestations, treatment is limited to antivenoms produced against species with restricted distributions. In this study, we explored the compositional and antigenic diversity of Tityus venoms to provide improved guidelines for the use of available antivenoms at a broader geographic scale. We used immunoblotting, competitive ELISA, and in vivo studies to compare reactivity against commercial antivenoms from Brazil, Venezuela, and Mexico, as well as MALDI-TOF mass spectrometry, cDNA sequencing, and phylogenetic analyses to assess venom sodium channel-active toxin (NaTx) content from medically important Tityus populations inhabiting Brazil, Colombia, Costa Rica, Ecuador, Panama, Trinidad and Tobago, and Venezuela. Additionally, we raised rabbit antibodies against Tityus venoms from LCA to test for cross-reactivity with congeneric species. The results suggest that Tityus spp. possess high venom antigenic diversity, underlying the existence of four toxinological regions in Tropical America, based on venom composition and immunochemical criteria: LCA/Colombia/Amazonia (Region I), Venezuela (Region II), southeast South America (Region III), and a fourth region encompassing species related to toxinologically divergent Tityus cerroazul. Importantly, our molecular and cross-reactivity results highlight the need for new antivenoms against species inhabiting Region I, where scorpions may produce venoms that are not significantly reactive against available antivenoms.

Scorpionism by Hemiscorpius spp. in Iran: a review

Scorpions are distributed throughout Iran and the genus Hemiscorpius is particularly important in this region. Hemiscorpius lepturus is the most significant species within the genus in the country. Since scorpionism provoked by Hemiscorpius comprises a medical emergency, the present study is focused on this important issue. In order to perform the present work, a review of the medical and health-related literature was carried out in several databases. The current findings indicate that six species of Hemiscorpius are found in 15 states of Iran, mainly in the south and southwest. Deaths caused by stings were reported only for two species. The morphological characteristics and geographical distribution of H. lepturus in Iran, its venom and the toxic compounds, epidemiologic data and clinical manifestations of envenomation as well as treatment for affected people are herein reviewed and described. H. lepturus venom toxicity differs from other Iranian scorpions regarding duration and severity. Scorpionism is an important public health problem in Iran, especially in southwest and south regions and in urban areas. It is more prevalent in children and young people. H. lepturus venom is primarily a cytotoxic agent and has hemolytic, nephrotoxic and to some extent hepatotoxic activity. The use of polyvalent antivenom to prevent scorpion sting symptoms is recommended. A well-planned health education program might be useful in preventing scorpionism.

Aspidosperma pyrifolium Has Anti-Inflammatory Properties: An Experimental Study in Mice with Peritonitis Induced by Tityus serrulatus Venom or Carrageenan

Scorpions of the genus Tityus are responsible for the majority of envenomation in Brazil, the Tityus serrulatus species being the most common and dangerous in South America. In this approach, we have investigated the ability of the aqueous extract from the leaves of Aspidosperma pyrifolium in reducing carrageenan-induced inflammation and the inflammation induced by T. serrulatus envenomation in mice. We also evaluated the cytotoxic effects of this extract, using the 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl-2H-tetrazolium (MTT) assay and the results revealed that the extract is safe. Analysis by High Performance Liquid Chromatography coupled with Diode Array Detector (HPLC-DAD) and Liquid Chromatography Coupled with Mass Spectrometry with Diode Array Detection (LC-DAD-MS) showed one major chemical component, the flavonoid rutin and phenolics compounds. For in vivo studies in carrageenan-induced peritonitis model, mice received extracts, dexamethasone, rutin or saline, before administration of carrageenan. For venom-induced inflammation model, animals received T. serrulatus venom and were, simultaneously, treated with extracts, antivenom, rutin or saline. The extract and rutin showed a reduction in the cell migration into the peritoneal cavity, and in the same way the envenomated animals also showed reduction of edema, inflammatory cell infiltration and vasodilation in lungs. This is an original study revealing the potential action of A. pyrifolium against inflammation caused by Tityus serrulatus venom and carrageenan, revealing that this extract and its bioactive molecules, specifically rutin, may present potential anti-inflammatory application.

Role of some vasoactive mediators in scorpion envenomed children: Possible relation to envenoming outcome

Scorpion envenomation causes an autonomic storm resulting in changes in the vasoactive mediators' levels which lead to myocardial damage, cardiovascular disturbances, peripheral circulatory failure, pulmonary edema, multi-system-organ-failure and death. The study aimed to determine the circulating levels of adrenaline, noradrenaline, angiotensin converting enzyme (ACE), Angiotensin II (Ang II), kallikrein enzyme, nitric oxide (NO), aldosterone, and electrolytes Na⁺, K⁺ and Ca⁺² in scorpion envenomed children and to evaluate the potential relation between these vasoactive mediators, the severity of scorpion envenoming and the clinical outcome of envenomed children. Forty envenomed children (22 mild and 18 severe cases) along with 10 healthy control children were enrolled in the study. The circulating levels of adrenaline, noradrenaline, Ang II, ACE, kallikrein enzyme, and NO were determined by ELISA, and spectrophotometric assays on admission and 24 h later. On admission, serum aldosterone, and electrolytes; Na⁺, K⁺ and Ca⁺² were determined by RIA, Flame photometer and Flame atomic absorption respectively. All envenomed children showed significant surge of adrenaline, noradrenaline, ACE, Ang II, aldosterone, NO and Na⁺, that concomitantly faced by significant reduction in kallikrein, K⁺ and Ca⁺² on admission. Twenty four hours later, all envenomed children continued to show significant elevation of ACE, Ang II and NO. The severely envenomed children showed considerable reduction in circulating levels of adrenaline, noradrenaline, ACE and Ang II, while dramatic increase in kallikrein activity was reported in comparison to mildly envenomed children after 24 h of medical care. Also, NO exhibited considerable accumulation in non survivors, on admission, that was persistent for the subsequent 24 h and was accompanied by high kallikrein, low catecholamines and Ang II levels compared to survivors. Finally, the hypertensive cases showed substantial higher levels of catecholamine, ACE and Ang II, 24 h after admission. These findings indicated that, disturbances of the studied vasoactive mediators were common in scorpion envenomed children and may account for several inflammatory manifestations and clinical outcome. ACE inhibitors could be considered as possible therapeutic agent in victims with prominent increase in ACE and Ang II while kallikrein inhibitor and antioxidants may be effective in the treatment of late hypotensive ones.

Involvement of Cholinergic and Adrenergic Receptors in Pathogenesis and Inflammatory Response Induced by Alpha-Neurotoxin Bot III of Scorpion Venom

Bot III neurotoxin is the most lethal α neurotoxin purified from Buthus occitanus tunetanus scorpion venom. This toxin binds to the voltage-gated sodium channel of excitable cells and blocks its inactivation, inducing an increased release of neurotransmitters (acetylcholine and catecholamines). This study aims to elucidate the involvement of cholinergic and adrenergic receptors in pathogenesis and inflammatory response triggered by this toxin. Injection of Bot III to animals induces an increase of peroxidase activities, an imbalance of oxidative status, tissue damages in lung parenchyma, and myocardium correlated with metabolic disorders. The pretreatment with nicotine (nicotinic receptor agonist) or atropine (muscarinic receptor antagonist) protected the animals from almost all disorders caused by Bot III toxin, especially the immunological alterations. Bisoprolol administration (selective β1 adrenergic receptor antagonist) was also efficient in the protection of animals, mainly on tissue damage. Propranolol (non-selective adrenergic receptor antagonist) showed less effect. These results suggest that both cholinergic and adrenergic receptors are activated in the cardiopulmonary manifestations induced by Bot III. Indeed, the muscarinic receptor appears to be more involved than the nicotinic one, and the β1 adrenergic receptor seems to dominate the β2 receptor. These results showed also that the activation of nicotinic receptor leads to a significant protection of animals against Bot III toxin effect. These findings supply a supplementary data leading to better understanding of the mechanism triggered by scorpionic neurotoxins and suggest the use of drugs targeting these receptors, especially the nicotinic one in order to counteract the inflammatory response observed in scorpion envenomation.

Clinical update on scorpion envenoming

Scorpion stings are currently the leading cause of venom-related injury to humans in Brazil and are a significant public health problem globally. Only scorpions of the Tityus genus are of medical importance in Brazil, and Tityus serrulatus is responsible for the most serious envenomations and deaths. The toxic effects of scorpion envenomation are due to a massive release of sympathetic and parasympathetic neurotransmitters; the severity is related to cardiac and hemodynamic changes, with cardiogenic shock and pulmonary edema contributing to the main causes of death. The pathophysiology of cardiac involvement has been discussed for decades and has been attributed to adrenergic discharge and a possible toxic effect of venom on the myocardium, while acute pulmonary edema may have a cardiogenic and/or non-cardiogenic origin. Currently, the clinical data point to catecholamine excess as the cause for reversible scorpion cardiomyopathy . These data include electrocardiographic changes, profiling of cardiac enzymes and troponin I, echocardiographic data with global or regional left ventricle dysfunction, and myocardial perfusion alterations compatible with spasm in the coronary microcirculation. Furthermore, recent data on cardiac magnetic resonance imaging findings, which are similar to those observed for stress-induced cardiomyopathy, have also been linked to catecholamine excess. The efficiency of antivenom serum treatment is controversial in the literature. Our experience in Brazil is that the management of patients with systemic manifestations of scorpion stings is based on three approaches, all of which are extremely important. These include symptomatic treatment, antivenom serum, and cardiorespiratory support.

Effects of Tityus stigmurus (Thorell 1876) (Scorpiones: Buthidae) venom in isolated perfused rat kidneys

ABSTRACT Scorpions belonging to the Tityus genus are of medical interest in Brazil. Among them, Tityus stigmurus is the main scorpion responsible for stings in the Northeast region. After a sting, the scorpion venom distributes rapidly to the organs, reaching the kidneys quickly. However, there are few studies concerning the renal pathophysiology of scorpion poisoning. In this study, we evaluated the effects of T. stigmurus venom (TsV) on renal parameters in isolated rat kidneys. Wistar rats (n = 6), weighing 250-300 g, were perfused with Krebs-Henseleit solution containing 6 g/100 mL bovine serum albumin. TsV at 0.3 and 1.0 μg/mL was tested, and the effects on perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), and electrolyte excretion were analyzed. Effects were observed only at TsV concentration of 1.0 μg/mL, which increased PP (controlPP40' = 92.7 ± 1.95; TsVPP40' = 182.0 ± 4.70* mmHg, *p < 0.05), RVR (controlRVR40' = 3.28 ± 0.23 mmHg; TstRVR40' = 6.76 ± 0.45* mmHg, *p < 0.05), UF (controlUF50' = 0.16 ± 0.04; TstUF50' = 0.60 ± 0.10* mL/g/min,*p < 0.05), GFR and electrolyte excretion, with histological changes that indicate renal tubular injury. In conclusion, T. stigmurus venom induces a transient increase in PP with tubular injury, both of which lead to an augmented electrolyte excretion.

Acute myocarditis and pulmonary edema due to scorpion sting

Objective: To present a case of a serious manifestation of scorpion sting, which was not reported before in Qatar, review the literature, and compare with previously reported similar cases.

Case presentation and intervention: A young male patient was admitted to CCU with a clinical picture of acute toxic myocarditis and cardiogenic shock with abnormal ECG and elevated cardiac markers after a scorpion sting to his right big toe. Thorough investigations, including echocardiography, cardiac MRI and right heart catheterization, supported the diagnosis. Coronary angiography was normal. Patient was managed conservatively with supportive measures, mechanical ventilation, IV fluids, inotropic agents, steroids, antibiotics and Prazocin. Over 9 days of hospital course, patient gradually improved, was successfully extubated, and was discharged in a stable condition.

Conclusion: Toxic myocarditis (with myocardial damage), pulmonary edema and cardiogenic shock are reported manifestations of scorpion venom intoxication.

Characterizing Tityus discrepans scorpion venom from a fractal perspective: Venom complexity, effects of captivity, sexual dimorphism, differences among species

A characteristic of venom elution patterns, shared with many other complex systems, is that many their features cannot be properly described with statistical or euclidean concepts. The understanding of such systems became possible with Mandelbrot's fractal analysis. Venom elution patterns were produced using the reversed phase high performance liquid chromatography (HPLC) with 1 mg of venom. One reason for the lack of quantitative analyses of the sources of venom variability is parametrizing the venom chromatograms' complexity. We quantize this complexity by means of an algorithm which estimates the contortedness (Q) of a waveform. Fractal analysis was used to compare venoms and to measure inter- and intra-specific venom variability. We studied variations in venom complexity derived from gender, seasonal and environmental factors, duration of captivity in the laboratory, technique used to milk venom.

Study of severe scorpion envenoming following subcutaneous venom injection into dogs: Hemodynamic and concentration/effect analysis

To evaluate the dose-effects of Androctonus australis hector (Aah) venom injected subcutaneously on hemodynamics and neurohormonal secretions, 10 anesthetized and ventilated mongrel dogs, were split in two groups (n = 5/group). Subcutaneous injection was done with either 0.2 mg/kg or 0.125 mg/kg of the purified G50 scorpion toxic fraction. Hemodynamic parameters using right heart catheter were recorded and plasma concentrations of catecholamine, troponin, and serum toxic fraction were measured sequentially from baseline to 120 min. We identified the dose of toxic fraction evoking characteristic hemodynamic perturbation of severe envenomation, the time-lapse to envenomation, and the associated plasma level. The injection of 0.125 mg/kg toxic fraction was not associated with significant variations in hemodynamic parameters, whereas the 0.2 mg/kg dose caused envenomation characterized by significant increase in plasma catecholamines, increased pulmonary artery occluded pressure, mean arterial pressure, and systemic vascular resistance (p < 0.05), in association with sustained decline in cardiac output (p < 0.001). Envenomation occurred by the 30th minute, and the corresponding concentration of toxic fraction was 1.14 ng/ml. The current experiment allowed the identification of the sub-lethal dose (0.2 mg/kg) of the toxic fraction of Aah administered by the subcutaneous route. Two parameters with potential clinical relevance were also uncovered: the time-lapse to envenomation and the corresponding concentration of toxic fraction.

Androctonus australis hector venom contributes to the interaction between neuropeptides and mast cells in pulmonary hyperresponsiveness

Lung injury and respiratory distress syndrome are frequent symptoms observed in the most severe cases of scorpion envenomation. The uncontrolled transmigration of leukocyte cells into the lung interstitium and alveolar space and pulmonary edema may be the cause of death. Mast cells can release various inflammatory mediators known to be involved in the development of lung edema following scorpion venom injection. The present study was designed to determine the evidence of neurokinin 1 (NK1) receptor and the involvement of mast cell activation to induce pulmonary edema and to increase vascular permeability after Androctonus australis hector (Aah) venom administration. To this end, mast cells were depleted using compound 48/80 (C48/80). Furthermore, the involvement of tachykinin NK1 receptors expressed on mast cell membranes was elucidated by their blocking with an antagonist. On the other hand, the ability of Aah venom to increase vascular permeability and to induce edema was also assessed by measuring the amount of Evans blue dye (EBD) extravasation in bronchoalveolar lavage (BAL) fluid and in the lungs of mice. Pulmonary edema, as assessed by the levels of EBD extravasation, was completely inhibited in compound 48/80-treated animals. Depletion by stimuli non-immunological C48/80 component markedly reduced induced inflammatory response following the venom administration. The mast cells seem to play an important role in the development of lung injury and the increase of vascular permeability in mice following the subcutaneous administration of Aah scorpion venom through the NK1 receptor.

Systemic responses following brain injuries and inflammatory process activation induced by a neurotoxin of Androctonus scorpion venom

OBJECTIVE

Kaliotoxin 2 (KTX2), a neurotoxin isolated from Androctonus australis hector scorpion venom, presents a high affinity with the voltage-gated potassium channels. The targets of KTX2 in the brain and its toxic effects on the cerebral cortex have been extensively studied; however, its deleterious systemic effects on other organ systems have not yet been investigated. Inflammatory response induced by KTX2 is supported by cytokine release which could provoke multiple organ dysfunction and diverse biological disorders in mammals. The possibility that inflammatory response and brain injuries induced by KTX2 may lead to functional disturbances, e.g. in the pancreas and the liver, were investigated. The contribution of IL-6 and TNF-α to the modulation of pathophysiological effects induced by KTX2 was also tested.

METHODS

NMRI mice were injected by the intracerebroventricular route with a sublethal dose of KTX2 or saline solution. Inflammatory response and oxidative stress were assessed in sera and tissue homogenates. Biomarkers of pancreatic and hepatic functions and the correlation with tissue damage in the brain, liver and pancreas were also analyzed.

RESULTS

The obtained results revealed that KTX2 injection induced an inflammatory process activation and imbalanced redox status. It also induced severe alterations in cerebral cortex, hepatic and pancreatic tissues associated with a significant increase in pancreatic and hepatic pathological biomarkers. Cytokine antagonists injected 30 min prior to KTX2 led to a significant reduction of all disturbances induced by KTX2.

CONCLUSION

In addition to its significant toxicity on the central nervous system, KTX2 can also affect pancreatic and hepatic functions, probably by an indirect mechanism involving activation of the inflammatory response with release of IL-6 and TNF-α.

Neutralizing effects of Mimosa tenuiflora extracts against inflammation caused by Tityus serrulatus scorpion venom

Scorpion bite represents a significant and serious public health problem in certain regions of Brazil, as well as in other parts of the world. Inflammatory mediators are thought to be involved in the systemic and local immune response induced by Tityus serrulatus scorpion envenomation. The aim of this study was to evaluate the effect of extracts of Mimosa tenuiflora on model envenomation. In mice, the envenomation model is induced by Tityus serrulatus venom. Previous treatment of mice with fractions from M. tenuiflora was able to suppress the cell migration to the peritoneal cavity. The treatment of mice with M. tenuiflora extracts also decreased the levels of IL-6, IL-12, and IL-1β. We concluded that the administration of the extract and fractions resulted in a reduction in cell migration and showed a reduction in the level of proinflammatory cytokines. This study demonstrates, for the first time, the anti-inflammatory effect of aqueous extract from the Mimosa tenuiflora plant on T. serrulatus venom.

Effects of atropine and propranolol on lung inflammation in experimental envenomation: comparison of two buthidae venoms

Background

Previous works had shown that scorpion venom induced neurotransmitter elevation and an inflammatory response associated with various anatomo-pathological modifications. The most dangerous scorpions species in Algeria responsible for these effects are Androctonus australis hector (Aah) and Androctonus amoreuxi (Aam).

Results

Comparison of the physiopathological effects induced by the two venoms showed differences in the kinetic of cytokine release and in lung injury.

The lung edema was only observed in response to Aah venom and it was correlated with cell infiltration. In order to better understand the involved mechanism in inflammatory response, we used two antagonists, atropine (non-selective muscarinic antagonist) and propranolol (β adrenergic antagonist), which lead to a decrease of cell infiltration but has no effect on edema forming.

Conclusion

These results suggest another pathway in the development of lung injury following envenomation with Aam or Aah venom.

Neuropathophysiological effect and immuno-inflammatory response induced by kaliotoxin of androctonus scorpion venom

OBJECTIVE

Kaliotoxin (KTX) is a neurotoxin purified from Androctonus scorpion venom. Purification and pharmacological and immunological characterization of this neurotoxin has been extensively studied, but its biological effects have not. The ability of KTX to induce neuropathophysiological and immuno-inflammatory effects was investigated.

METHODS

NMRI mice were injected with a sublethal dose of KTX (20 ng/20 g of body weight) or saline solution via the intra-cerebro-ventricular route. Tissue damage and immunological biomarkers such as eosinophil peroxidase (EPO), myeloperoxidase (MPO), and nitric oxide (NO) were analyzed in serum, brain, lung, and heart tissue. Protein levels, LDH, and CPK activities were also determined in serum 24 h after injection.

RESULTS

In this study, KTX injection induced severe alterations in the cerebral cortex, myocardium, and pulmonary parenchyma. Tissue damage was correlated with seric increase in creatine kinase and lactate dehydrogenase activities. KTX also induced an immuno-inflammatory response distinguished by cell infiltration characterized by a significant increase in EPO and MPO activities in the brain, heart, and lungs. This infiltration was also associated with an increase in albumin, α-, β-, and γ-globulin fractions, and NO release.

CONCLUSION

KTX binding to its targets in CNS (Kv1.1 and Kv1.3 channels) may induce severe modifications in the structure and function of various organs associated with the activation of immuno-inflammatory reactions.

Neurological effects of venomous bites and stings: snakes, spiders, and scorpions

Snake and spider bites, as well as scorpion sting envenoming, are neglected diseases affecting millions of people all over the world. Neurological complications vary according to the offending animal, and are often directly related to toxic effects of the venom, affecting the central nervous system, the neuromuscular transmission, the cardiovascular system, or the coagulation cascade. Snake bite envenoming may result in stroke or muscle paralysis. Metalloproteinases and other substances (common in vipers and colubrids) have anticoagulant or procoagulant activity, and may induce ischemic or hemorrhagic strokes. The venom of elapids is rich in neurotoxins affecting the neuromuscular transmission at either presynaptic or postsynaptic levels. The clinical picture of scorpion sting envenoming is dominated by muscle weakness associated with arterial hypertension, cardiac arrythmias, myocarditis, or pulmonary edema. These manifestations occur as the result of release of catecholamines into the bloodstream or due to direct cardiac toxicity of the venom. Cerebrovascular complications have been reported after the sting of the Indian red scorpion. Intracranial hemorrhages occur in the setting of acute increases in arterial blood pressure related to sympathetic overstimulation, and cerebral infarctions are related to either cerebral hypoperfusion, consumption coagulopathy, vasculitis, or cardiogenic brain embolism. Three main syndromes result from spider bite envenoming: latrodectism, loxoscelism, and funnel-web spider envenoming. Latrodectism is related to neurotoxins present in the venom of widow spiders. Most cases present with headache, lethargy, irritability, myalgia, tremor, fasciculation, or ataxia. Loxoscelism is caused by envenoming by spiders of the family Sicariidae. It may present with a stroke due to a severe coagulopathy. The venom of funnel-web spiders also has neurotoxins that stimulate neurotransmitter release, resulting in sensory disturbances and muscle paralysis. Proper management of the envenomed patient, including prompt transport to the hospital, correction of the hemostatic disorder, ventilatory support, and administration of antivenom, significantly reduce the risk of neurological complications which, in turn, reduce the mortality and improve the functional outcome of survivors.

Ts6 and Ts2 from Tityus serrulatus venom induce inflammation by mechanisms dependent on lipid mediators and cytokine production

Inflammatory mediators are thought to be involved in the systemic and local immune response induced by the Tityus serrulatus scorpion envenomation. New functional aspects of lipid mediators have recently been described. Here, we examine the unreported role of lipid mediators in cell recruitment to the peritoneal cavity after an injection with Ts2 or Ts6 toxins isolated from the T. serrulatus scorpion venom. In this report, we demonstrate that following a single intraperitoneal (i.p.) injection of Ts2 or Ts6 (250 μg/kg) in mice, there was an induction of leukocytosis with a predominance of neutrophils observed at 4, 24, 48 and 96 h. Moreover, total protein, leukotriene (LT)B(4), prostaglandin (PG)E(2) and pro-inflammatory cytokine levels were increased. We also observed an increase of regulatory cytokines, including interleukin (IL)-10, after the Ts2 injection. Finally, we observed that Ts2 or Ts6 injection in 5-lipoxygenase (LO) deficient mice and in wild type (WT) 129sv mice pre-treated with LTs and PGs inhibitors (MK-886 and celecoxib, respectively) a reduction the influx of leukocytes occurs in comparison to WT. The recruitment of these cells demonstrated a phenotype characteristic of neutrophils, macrophages, CD4 and CD8 lymphocytes expressing GR1+, F4/80+, CD3+/CD4+ and CD3+/CD8+, respectively. In conclusion, our data demonstrate that Ts2 and Ts6 induce inflammation by mechanisms dependent on lipid mediators and cytokine production. Ts2 may play a regulatory role whereas Ts6 exhibits pro-inflammatory activity exclusively.

Chagas heart disease: report on recent developments

Chagas disease, caused by the parasite Trypanosoma cruzi, is an important cause of cardiac disease in endemic areas of Latin America. It is now being diagnosed in nonendemic areas because of immigration. Typical cardiac manifestations of Chagas disease include dilated cardiomyopathy, congestive heart failure, arrhythmias, cardioembolism, and stroke. Clinical and laboratory-based research to define the pathology resulting from T. cruzi infection has shed light on many of the cellular and molecular mechanisms leading to these manifestations. Antiparasitic treatment may not be appropriate for patients with advanced cardiac disease. Clinical management of Chagas heart disease is similar to that used for cardiomyopathies caused by other processes. Cardiac transplantation has been successfully performed in a small number of patients with Chagas heart disease.

Heminecrolysin, a potential immunogen for monospecific antivenom production against Hemiscorpius lepturus scorpion

Serotherapy against Hemiscorpius (H.) lepturus scorpion sting is based on the administration of equine polyvalent antivenom prepared against a mixture of six venoms. In a previous study, we reported the identification of Heminecrolysin, a 33 kDa H. lepturus venom protein endowed with a sphingomyelinase D, hemolytic and dermonecrotic activities. We aimed herein to investigate the capacity of Heminecrolysin to generate antibodies able to neutralize the major physiopathological properties of H. lepturus envenomation, e.g. hemolysis and dermonecrosis. The efficiency of anti-Heminecrolysin antibodies was compared to that of anti-whole venom. Our results demonstrated that Heminecrolysin elicits high levels of specific IgGs. Anti-Heminecrolysin, similarly to anti-whole venom antibodies, totally inhibited H. lepturus hemolytic effect when up to 5 times the half maximal effective concentration of venom were used. Phosphatidylserine exposure on the external lipid monolayer of human red blood cells treated with whole venom was also fully blocked by both anti-sera. Experimental envenomation of rabbits showed that anti-Heminecrolysin antibodies were as potent as anti-H. lepturus antibodies to neutralize dermonecrotic effects when up to 4 times the minimal necrotic dose of venom were injected. However, inflammatory reaction was better controlled with anti-whole venom sera. In conclusion, Heminecrolysin elicits protective antibodies of comparable potency to those elicited by immunization with whole venom.

Effect of purified Russell's viper venom-factor X activator (RVV-X) on renal hemodynamics, renal functions, and coagulopathy in rats

Acute renal failure (ARF) is the most frequent and a serious complication in victims of Russell's viper snakebites. Russell's viper venom-factor X activator (RVV-X) has been identified as a main procoagulant enzyme involving coagulopathy, which might be responsible for changes in renal hemodynamics and renal functions. Here, we purified RVV-X from crude Russell's viper venom to study renal hemodynamics, renal functions, intravascular clot, and histopathological changes in Sprague-Dawley rats. Changes in renal hemodynamics and renal functions were evaluated by measuring the mean arterial pressure, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), effective renal blood flow (ERBF), renal vascular resistance (RVR), and fractional excretion of electrolytes. After 10 min, rats receiving both crude venom and purified RVV-X decreased GFR, ERPF, and ERBF and increased RVR. These changes correlated to renal lesions. Along with the determination of intravascular clot, rats injected with purified RVV-X increased the average D-dimer level and reached a peak at 10 min, declined temporarily, and then reached another peak at 30 min. The temporal association between clots and renal dysfunction was observed in rats within 10 min after the injection of purified RVV-X. These findings suggested RVV-X as a major cause of renal failure through intravascular clotting in the renal microcirculation.

Immune cells recruitment and activation by Tityus serrulatus scorpion venom

Despite several studies showed that the Tityus serrulatus scorpion venom (Tsv) induces an inflammatory response, just a few have investigated the effect of the venom on the immune response. Therefore, the aim of this study was to evaluate alterations of venom application on lymphoid organs and on the recruitment and activation of cells and also on the cytokine production. Swiss male mice (2-3 months, 20-25 g) received a non-lethal dose of crude Tsv (200 μg/kg), diluted in sterile PBS by subcutaneous route. Control animals received only sterile PBS. The animals were sacrificed after 30, 120 and 360 min. The inflammatory parameters studied were skin histology at the site of venom application, leukocyte count, and blood cytokine levels (IL-6, IL-10, and TNF-α). Inguinal lymph node, spleen and bone marrow cellularity was determined for evaluation of the Tsv effect on immune system organs. The results showed that Tsv caused no local inflammation, but it induced an increase of blood neutrophils and serum IL-6, TNF-α and IL-10. After 360 min of envenomation there was a reduction in the cells number from peritoneum and spleen, but there was an increase in the cell number from lymph nodes. In conclusion, the Tsv induces systemic alterations characterized by changes in the cell number in lymphoid organs, increase pro and anti-inflammatory cytokines.

Scorpion envenomation and antivenom therapy

Scorpion envenomation is a dangerous and common global event that can result in a variety of toxic clinical effects. These are typically managed with supportive care or antivenom. Antivenom use is controversial because of conflicting evidence of effectiveness for adrenergic toxicity. However, both controlled and uncontrolled studies have shown that antivenom is effective in resolving neuromotor toxicity associated with envenomations by the scorpions of genus Centruroides.

Efficacy and safety of scorpion antivenom plus prazosin compared with prazosin alone for venomous scorpion (Mesobuthus tamulus) sting: randomised open label clinical trial

OBJECTIVE

Envenomation by Mesobuthus tamulus scorpion sting can result in serious cardiovascular effects. Scorpion antivenom is a specific treatment for scorpion sting. Evidence for the benefit of scorpion antivenom and its efficacy compared with that of commonly used vasodilators, such as prazosin, is scarce. We assessed the efficacy of prazosin combined with scorpion antivenom, compared with prazosin alone, in individuals with autonomic storm caused by scorpion sting.

DESIGN

Prospective, open label randomised controlled trial.

SETTING

General hospital inpatients (Bawaskar Hospital and Research Centre Mahad Dist-Raigad Maharashtra, India).

PARTICIPANTS

Seventy patients with grade 2 scorpion envenomation, older than six months, with no cardiorespiratory or central nervous system abnormalities.

INTERVENTION

Scorpion antivenom plus prazosin (n=35) or prazosin alone (n=35) assigned by block randomisation. Treatment was not masked. Analysis was by intention to treat.

MAIN OUTCOME MEASURES

The primary end point was the proportion of patients achieving resolution of the clinical syndrome (sweating, salivation, cool extremities, priapism, hypertension or hypotension, tachycardia) 10 hours after administration of study drugs. Secondary end points were time required for complete resolution of clinical syndrome, prevention of deterioration to higher grade, doses of prazosin required overall and within 10 hours, and adverse events. The study protocol was approved by the independent ethics committee of Mumbai.

RESULTS

Mean (SD) recovery times in hours for the prazosin plus scorpion antivenom group compared with the prazosin alone groups were: sweating 3 (1.1) v 6.6 (2.6); salivation 1.9 (0.9) v 3 (1.9); priapism 4.7 (1.5) v 9.4 (1.5). Mean (SD) doses of prazosin in the groups were 2 (2.3) and 4 (3.5), respectively. 32 patients (91.4%, 95% confidence interval 76.9% to 97.8%) in the prazosin plus antivenom group showed complete resolution of the clinical syndrome within 10 hours of administration of treatment compared with eight patients in the prazosin group (22.9%, 11.8% to 39.3%). Patients from the antivenom plus prazosin group recovered earlier (mean 8 hours, 95% CI 6.5 to 9.5) than those in the control group (17.7 hours, 15.4 to 19.9; mean difference -9.7 hours, -6.9 to -12.4). The number of patients whose condition deteriorated to a higher grade was similar in both groups (antivenom plus prazosin four of 35, prazosin alone five of 35). Hypotension was reported in fewer patients in the antivenom plus prazosin group (12 of 35, 34.3%) than in the prazosin group (19 of 35, 54.3%), but the difference was not statistically significant. No difference was noted in change in blood pressure and pulse rate over time between two groups.

CONCLUSION

Recovery from scorpion sting is hastened by simultaneous administration of scorpion antivenom plus prazosin compared with prazosin alone.

TRIAL REGISTRATION NUMBER

CTRI/2010/091/000584 (Clinical Trials Registry India).

Specific activation of human neutrophils by scorpion venom: a flow cytometry assessment

Acute lung injury following envenomation by Tityus scorpion species is due in part to activation of the inflammatory response leading to release of cytotoxic leukocyte-derived products, including cytokines and possibly reactive oxygen species (ROS). Tityus zulianus envenomation in Venezuela produces cardiorespiratory complications and death by lung injury whereas stings by Tityus discrepans produce mainly gastrointestinal and pancreatic alterations. To ascertain the role played by granulocytes in the envenomation by T. zulianus (TzV) and T. discrepans (TdV), human peripheral blood neutrophils, eosinophils, and monocytes were exposed to scorpion venoms (0.001-5 μg/mL) and the kinetics (5-15 min) of peroxide production determined by flow cytometry, using 2',7'-dichlorodihydrofluorescein diacetate (succinimidyl ester) as a fluorescent substrate. TzV induced a significantly (p<0.01) more potent increase in peroxide production in neutrophils (for 5 and 10 min of incubation), and to a lesser extent in monocytes (5-15 min), compared to TdV. TzV induced necrosis in neutrophils at doses higher than 5 μg/mL. No effect was observed on eosinophils, suggesting that TzV specifically targets neutrophil intracellular ROS production. The TzV-stimulated pathway is protein kinase C-dependent because it was almost completely (>90%) abolished by staurosporine. The stimulatory effect is associated with the lowest molecular mass venom peptides as gel filtration fractions TzII and TzIII significantly enhanced peroxide production. The combined used of the intracellular ROS agonist, phorbol myristate acetate (PMA), and TzV produced a modest but significant increase in peroxide production suggesting the possibility of overlapping signaling cascades amongst PMA and TzV. Up-regulation of intracellular neutrophil ROS production may be an important in vivo target for TzV which could have a role to play in the cardiorespiratory complications elicited after envenomation by this species.

Tityus fasciolatus envenomation induced cardio-respiratory alterations in rats

The present study characterized envenomation in young rats by Tityus fasciolatus, an endemic scorpion to Central Brazilian and state of Minas Gerais. Electrocardiographic examinations were performed prior to treatment and every 5 min during the first 30 min after envenomation. The cardiac blood profile [creatine kinase, CK isoenzyme MB, lactate dehydrogenase, aspartate aminotransferase and troponina] together with macroscopic and microscopic alterations in the lungs and heart were evaluated. Envenomated animals showed ECG changes suggesting electrolytic imbalance, myocarditis and venom interference on the conduction tissue. Biochemical analyses indicated myocardial damage with high levels of CK, CK-MB and LDH. Macroscopic and microscopic findings included detection of pulmonary haemorrhages. In conclusion, T. fasciolatus venom leads to acute cardio-respiratory changes in young rats.

Severe scorpion envenomation in children: Management in pediatric intensive care unit

BACKGROUND

Scorpion envenomation is a common public health problem worldwide and children are at greater risk of developing severe cardiac, respiratory and neurological complications. The aim of this study was to evaluate the effects of antivenin and/or prazosin use on prognosis of scorpion-envenomed children admitted to pediatric intensive care unit (PICU).

METHODS

The standardized medical records of 45 children hospitalized with severe scorpion sting in PICU were retrospectively evaluated. General characteristics of the children, clinical and laboratory findings, treatment approaches and prognosis were evaluated.

RESULTS

The mean age of the patients were 6.1 +/- 4.1 years ranging between 4 month and 15 years. Male to female ratio was 1.8. Thirty-three (71.1%) cases of scorpion stings came from rural areas. Twenty-six (57.8%) of the patients were stung by Androctonus crassicauda. The most common sting localization was the foot-leg (55.6%). The mean duration from the scorpion sting to hospital admission was 4.5 +/- 2.6 hours. The most common findings at presentation were cold extremities (95.5%), excessive sweating (91.1%) and tachycardia (77.7%). The mean leukocyte count, and serum levels of glucose, lactate dehydrogenase, creatine phosphokinase and international normalized ratio were found above the normal ranges. Prazosin was used in all patients, dopamine in 11 (24.4%) and Na-nitroprusside in 4 (8.8%) patients. Two children died (4.4%) due to pulmonary oedema. These children, in poor clinical status at hospital admission, needed mechanical ventilation, and death occurred despite use of antivenin and prazosin in both of them.

CONCLUSION

The current management of children with severe scorpion envenomation consists of administration of specific antivenom and close surveillance in a PICU, where vital signs and continuous monitoring enable early initiation of therapy for life-threatening complications. The aggressive medical management directed at the organ system specifically can be effective. Our data indicated that when admission to hospital is late, the beneficial effect of antivenom and/or prazosin is questionable in severe scorpion stings.

Asymmetric pulmonary edema after scorpion sting: a case report

A 12-year-old boy was referred with acute asymmetric pulmonary edema (APE) four-hour after scorpion sting to Emergency department. On admission, the main clinical manifestations were: dyspnea, tachypnea, and tachycardia. Chest x-ray revealed APE predominantly on the right hemithorax. The patient was treated with oxygen, intravenous frusemide and digoxin and discharged on the sixth hospital day in a good condition. This case report emphasizes the occurrence of asymmetric pulmonary edema after severe scorpion envenomation within few hours immediately after the sting.

A new venomous scorpion responsible for severe envenomation in Argentina: Tityus confluens

In Argentina the scorpions of medical importance belong to the genus Tityus (T.), particularly the species T. trivittatus, the only scorpion whose sting is recognized to be associated with severe human envenoming and death. This genus is distributed from the north of the Patagonian region to the center and some provinces in the north of the country. During the period 2003-2006 four children died following scorpion stings, of which one was certainly and three were probably by T. confluens. In 2006, in the province of Tucumán, a girl died by scorpion envenoming and the scorpion responsible for the death, found in her shoe, was T. confluens. We thus studied the toxicity of venom gland homogenates from T. confluens from the provinces of Jujuy and Catamarca, and of crude venom from specimens from Catamarca and the province of La Rioja. The lethal potencies of the telson homogenates were 7.0 and 18.6microg/g for Jujuy and Catamarca, respectively, while the lethal potency of the crude venom was 0.7microg/g. Injected mice showed generalized congestion and hepatic lesions. Pancreatic damage was observed in some animals. Lungs showed congestion and foci of hemorrhage and mild edema. The heart showed injury in the muscular fibers. The venom showed high reactivity against anti-T. trivittatus antivenom and against two anti-T. serrulatus antivenoms. The anti-T. trivittatus antivenom neutralized the lethal activity of T. confluens venom. In addition, the venom reacted very slightly against an anti-Centruroides antivenom. Therefore, the stings of this scorpion must be considered of risk for humans to the same degree as the stings of T. trivittatus.

Antigenic cross-reactivity between sixteen venoms from scorpions belonging to six genera

Venoms of 15 scorpion species from Venezuela and one from Brazil were compared in their antigenic cross-reactivity with specific F(ab')2 against Tityus discrepans (Td-antibodies), using the method of King and collaborators (1). Our results show that Tityus venoms cross-reactivity (shared epitopes) with the venoms of other species within the genus tended to be less for a greater distance between the habitat of the species. A nonparametric linear regression of free Td-antibody binding to T. discrepans venom immobilized to a solid phase in the presence of other Tityus venoms versus distance showed binding = a + b x log10 (distance) where: median (95% confidence interval) for a = 0.92 (7.43, 9.80) and b = 17.20 (4.15, 22.57) binding/log10(Km); Spearman rS = 0.783 with associated P = 0.006. Our results show that toxins from different Tityus species, targeting mammalian Na+ and K+ channels, are antigenically very similar. Venoms from species from other genera such as Centruroides, Broteas, Diplocentrus, Chactas, and Rhopalurus did not cross-react with Td-antibodies.

Pathophysiological effects of Androctonus australis hector scorpion venom: tissue damages and inflammatory response

In this study, the effects of sublethal dose of Androctonus australis hector (Aah) venom on the enzymatic activities (creatine phospho-kinase and lactate dehydrogenase) and histopathological changes of heart and lungs' organs were determined 24h following envenoming NMRI mice. The effects of Aah venom on the lytic activity of the complement system, plasma cytokine rates (IL1-beta, IL-6, TNF-alpha, IL-4 and IL-10) and the peripheral blood cell infiltration were also studied. Microscopically, treated animals showed severe myocardial edema, hemorrhages and necroses and severe acute bronchopneumonia with alveolar edema and hemorrhages. High serum levels of lactate dehydrogenase and creatine kinase correlate to the tissue lesions. The results showed fast kinetics of production of pro-inflammatory (IL1-beta, IL-6, TNF-alpha) and anti-inflammatory (IL-4 and IL-10) cytokines at 30min in blood sera. An increase in serum lytic activity of envenomed animals and leucocytosis in peripheral blood with predominance of mononuclear and neutrophil cells were also observed. In conclusion, the results reported in the present study suggest that pathophysiological manifestations of Aah envenomation may be mediated sequentially or simultaneously by cytokines and the complement system, which in turn activate leukocyte to produce tissue damage.