The scorpion envenoming syndrome: a different perspective. The physiological basis of the role of insulin in scorpion envenoming

When Venom Meets the Heart: A Rare Case of Scorpion Sting-Induced Acute Myocardial Infarction

Scorpion sting cases are everyday encounters in the Emergency Department (ED). However, scorpion sting-induced systemic manifestations are rarely seen. Signs and symptoms of envenomation involve the central nervous system, stimulation of the autonomic nervous system and rarely respiratory and heart failure leading to death. Cardiovascular manifestations are particularly prominent following stings by the Indian red scorpion. This case report is of an 18-year-old male patient who presented to ED with complaints of scorpion sting. Twelve lead electrocardiography (ECG) done was suggestive of acute inferior wall myocardial infarction with raised cardiac markers. He also had autonomic dysfunction in the form of hypertension, hypothermia and priapism. He was treated with an alpha-blocker, dual antiplatelets and analgesics. ECG changes reverted to normal the next day, and he was discharged. So, the anticipation of life-threatening complications of scorpion stings plays a vital role in the treatment and prognosis of patients presenting to ED.

Scorpion venoms and associated toxins as anticancer agents: update on their application and mechanism of action

Cancer remains one of the deadliest non-infectious diseases of the 21^st century, causing millions of mortalities per year worldwide. Analyses of conventional treatments, such as radiotherapy and chemotherapy, have shown not only a lower therapeutic efficiency rate but also plethora of side-effects. Considering the desperate need to identify promising anticancer agents, researchers are in quest to design and develop new tumoricidal drugs from natural sources. Over the past few years, scorpion venoms have shown exemplary roles as pivotal anticancer agents. Scorpion venoms associated metabolites, particularly toxins demonstrated in vitro anticancer attributes against diversified cell lines by inhibiting the growth and progression of the cell cycle, inhibiting metastasis by blocking ion channels such as K⁺ and Cl^- , and/or inducing apoptosis by intrinsic and extrinsic pathways. This review sheds light not only on in vitro anticancer properties of distinct scorpion venoms and their toxins, but also on their mechanism of action for designing and developing new therapeutic drugs in future.

Scorpion Venom-Toxins that Aid in Drug Development: A Review

Scorpion venom components have multifaceted orientation against bacterial, viral, fungal infections and other neuronal disorders. They can modulate the ion channels (K⁺, Na⁺, Cl⁻, Ca²⁺) of our body and this concept has been hypothesized in formulating pharmaceuticals. The triumphant achievement of these venom components as formulated anticancer agent in Phase I and Phase II clinical trials allure researchers to excavate beneficial venom components prohibiting DNA replication in malignant tumor cells. This review brings forth the achievements of Science and Technology in classifying the venom components as therapeutics and further application in drug product development.

Animal toxins and renal ion transport: Another dimension in tropical nephrology

Renal vascular and tubular ion channels and transporters involved in toxin injury are reviewed. Vascular ion channels modulated by animal toxins, which result in haemodynamic alterations and changes in blood pressure, include ENaC/Degenerin/ASIC, ATP sensitive K channels (KATP ), Ca activated K channels (Kca) and voltage gated Ca channels, mostly L-type. Renal tubular Na channels and K channels are also targeted by animal toxins. NHE3 and ENaC are two important targets. NCC and NKCC may be involved indirectly by vasoactive mediators induced by inflammation. Most renal tubular K channels including voltage gated K channels (Kv1), KATP , ROMK1, BK and SK are blocked by scorpion toxins. Few are inhibited by bee, wasp and spider venoms. Due to small envenoming, incomplete block and several compensatory mechanisms in renal tubules, serum electrolyte charges are not apparent. Changes in serum electrolytes are observed in injury by large amount of venom when several channels or transporters are targeted. Envenomings by scorpions and bees are examples of toxins targeting multiple ion channels and transporters.

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.

Endocrinological and biochemical changes of scorpionism in children in Upper Egypt

AIM

The aim of this study was to determine some endocrinological and biochemical changes of scorpionism in children in Upper Egypt. In addition, it aimed to find any possible relationship between these changes and the severity of scorpionism.

PATIENTS AND METHODS

The present study was carried out at two university hospitals in Upper Egypt and included 42 children with envenomation and 20 apparently healthy children as controls. In all subjects, levels were measured of noradrenaline, aldosterone, insulin and cortisol, and some biochemical parameters and electrolytes including nitric oxide (NO), creatine phosphokinase (CPK), Na+ and K+.

RESULTS

Na+, NO and CPK levels were significantly higher in children with envenomation compared with the controls. Also, there was a significant reduction in K+ in patients compared with controls. Children with severe envenomation had significantly higher levels of noradrenaline, cortisol and aldosterone compared with the controls and mild cases. However, insulin levels were significantly decreased in severe cases of scorpionism compared with mild ones. Moreover, hyperglycemia was detected in all patients with envenomation compared with controls, with significantly higher blood glucose levels among children with severe envenomation compared with mild cases.

CONCLUSION

Endocrinological changes were common in all children with scorpion envenomation and more obvious in cases of severe envenomation. The released mediators may account for several inflammatory manifestations such as pulmonary edema, myocardial failure, systemic inflammatory response syndrome and multiple organ failure. The use of insulin is recommended in cases of severe envenomation to improve the outcome.

NMR-based metabonomics survey in rats envenomed by Hemiscorpius lepturus venom

About 1% of scorpion stings in Iran have been reported in cities and more than 5% in rural areas. The genus Hemiscorpous lepturus belongs to the family Hemiscorpiidae that is endemic in the south-western province of Khoozestan and other parts of western Iran. Although this species is responsible for only 10% of the reported stings, it is also responsible for 95% of mortalities. The heavy cytotoxic and neurotoxic venomous effects of scorpion sting may cause serious disorders such as erythema, purpuric changes, bulla, necrosis and ulcer, either alone or in combination. The toxic effects of H. lepturus venom cause vast changes in both primary and secondary metabolites of the victim, which finally lead to death if not treated early enough. Metabolomics is the systematic study of chemical fingerprints resulting from cytotoxic and pathogenic reactions of cells. We studied the toxic mechanism of H. lepturus venom on metabolome profiling of the victims along with biochemical pathways, organs and physiological detectable effects of this venom by the help of (1)H NMR. Our results showed that pyrimidine, histidine and tyrosine metabolisms, and steroid hormone biosynthesis were the most affected pathways. The major action of the crude venom is on the pancreas, and also on the nerve cells, spleen and mitochondria, causing acute seizures, which resemble the early markers of myocardial injury and seizure disorders.

[2013 update about arthropod envenomations in French Guyana]

French Guiana, by its geographical situation, its climate and its biodiversity, is often called "the green hell". Indeed, this French department of America shelters a wildlife rich, abundant among which many species of arthropods, some of which are responsible for envenomations. These accidents consist of scorpion's or hymenoptera's stings or spider's bites. The associated clinical aspect is variable, from simple pain to circulatory collapse, or lung oedema. However, symptomatology is generally mild; four deaths associated to arthropod envenomations have been reported in the past 25 years. This article focuses on envenomations in French Guiana, describing favoring human behavior, risks and venoms associated with the main related animal species.

Indian red scorpion venom-induced augmentation of cardio-respiratory reflexes and pulmonary edema involve the release of histamine

Pulmonary edema is a consistent feature of Mesobuthus tamulus (MBT) envenomation. Kinins, prostaglandins and other inflammatory mediators are implicated in it. Since, histamine also increases capillary permeability, this study was undertaken to evaluate whether MBT venom utilizes histamine to produce pulmonary edema and augmentation of cardio-respiratory reflexes evoked by phenylbiguanide (PBG). Blood pressure, respiratory excursions and ECG were recorded in urethane anaesthetized adult rats. Injection of PBG (10 μg/kg) produced apnoea, hypotension and bradycardia and the responses were augmented after exposure to venom (100 μg/kg). There was increased pulmonary water content in these animals. Pretreatment with pheniramine maleate (H₁ antagonist, 3 mg/kg) blocked both venom-induced augmentation of PBG response and pulmonary edema. In another series, compound 48/80 (mast cell depletor) was treated for 4 days then the PBG responses were elicited as before. At the end of the experiments, mast cells were counted from the peritoneal fluid. The venom-induced pulmonary edema and the augmentation of PBG reflex were not observed in compound 48/80 treated animals. Further, mast cells in the peritoneal fluid were absent in this group as compared to vehicle treated group (29 ± 7.9 cells/mm³). These observations indicate that venom-induced pulmonary edema and augmentation of PBG reflexe are mediated through mast cells by involving H₁ receptors.

Scorpion envenomation among children: clinical manifestations and outcome (analysis of 685 cases)

Our objective was to characterize both epidemiologically and clinically manifestations after severe scorpion envenomation and to define simple factors indicative of poor prognosis in children. We performed a retrospective study over 13 years (1990-2002) in the medical intensive care unit (ICU) of a university hospital (Sfax-Tunisia). The diagnosis of scorpion envenomation was based on a history of scorpion sting. The medical records of 685 children aged less than 16 years who were admitted for a scorpion sting were analyzed. There were 558 patients (81.5%) in the grade III group (with cardiogenic shock and/or pulmonary edema or severe neurological manifestation [coma and/or convulsion]) and 127 patients (18.5%) in the grade II group (with systemic manifestations). In this study, 434 patients (63.4%) had a pulmonary edema, and 80 patients had a cardiogenic shock; neurological manifestations were observed in 580 patients (84.7%), 555 patients (81%) developed systemic inflammatory response syndrome (SIRS), and 552 patients (80.6%) developed multi-organ failure. By the end of the stay in the ICU, evolution was marked by the death in 61 patients (8.9%). A multivariate analysis found the following factors to be correlated with a poor outcome: coma with Glasgow coma score ≤ 8/15 (odds ratio [OR] = 1.3), pulmonary edema (OR = 2.3), and cardiogenic shock (OR = 1.7). In addition, a significant association was found between the development of SIRS and heart failure. Moreover, a temperature > 39°C was associated with the presence of pulmonary edema, with a sensitivity at 20.6%, a specificity at 94.4%, and a positive predictive value at 91.7%. Finally, blood sugar levels above 15 mmol/L were significantly associated with a heart failure. In children admitted for severe scorpion envenomation, coma with Glasgow coma score ≤ 8/15, pulmonary edema, and cardiogenic shock were associated with a poor outcome. The presence of SIRS, a temperature > 39°C, and blood sugar levels above 15 mmol/L were associated with heart failure.

Assessment of biochemical and hematological parameters in rats injected with Tityus serrulatus scorpion venom

The aim of this work was to evaluate the hematological changes induced by Tityus serrulatus venom (TsV). Blood of Wistar rats was collected 0.5, 2, 6 and 24 h after i.p. injection of TsV (0.5 mg/kg) or saline (controls). Two additional groups were injected with 0.67 mg/kg and 0.25 mg/kg of TsV and the blood was collected after 0.5 and 2 h, respectively. The results showed an increase on hematocrit (Ht), red blood cells (RBC) count, hemoglobin concentration (Hb), albumin and total protein, mainly 2-6 h after envenoming. Increase in serum activities of amylase, creatine kinase and aspartate aminotransferase were also observed, indicating tecidual damages. Hyperglycemia was observed at all times analyzed, as a consequence of catecholamine release. No significant changes were detected in the urea, [Na(+)] and [Ca(2+)], but an increase of [Mg(2+)], [K(+)] and conductivity was observed. TsV induced a reduction of erythrocytes osmotic fragility as consequence of dehydration and increase in plasma electrolytes concentration, as evidenced by its higher conductivity. This study demonstrated that TsV is able to induce severe hematological changes, that appear within the first hours after envenoming, justifying the seeking of medical attention as soon as possible to avoid worsening of clinical symptoms.

Scorpion venom and the inflammatory response

Scorpion venoms consist of a complex of several toxins that exhibit a wide range of biological properties and actions, as well as chemical compositions, toxicity, and pharmacokinetic and pharmacodynamic characteristics. These venoms are associated with high morbility and mortality, especially among children. Victims of envenoming by a scorpion suffer a variety of pathologies, involving mainly both sympathetic and parasympathetic stimulation as well as central manifestations such as irritability, hyperthermia, vomiting, profuse salivation, tremor, and convulsion. The clinical signs and symptoms observed in humans and experimental animals are related with an excessive systemic host inflammatory response to stings and stings, respectively. Although the pathophysiology of envenomation is complex and not yet fully understood, venom and immune responses are known to trigger the release of inflammatory mediators that are largely mediated by cytokines. In models of severe systemic inflammation produced by injection of high doses of venom or venoms products, the increase in production of proinflammatory cytokines significantly contributes to immunological imbalance, multiple organ dysfunction and death. The cytokines initiate a cascade of events that lead to illness behaviors such as fever, anorexia, and also physiological events in the host such as activation of vasodilatation, hypotension, and increased of vessel permeability.

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.

Serum levels of IL-6 and its soluble receptor, TNF-α and chemokine RANTES in scorpion envenomed children: Their relation to scorpion envenomation outcome

During the present study, 30 children in Upper Egypt (less than 12 years old) were admitted to Pediatric Intensive Care Unit because of scorpion envenomation. They were compared with 20 apparently normal children of matching age and sex as controls. The victims and controls were subjected to complete clinical examination and full blood picture. The serum levels of interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), regulated upon activation normal T cells expressed and secreted (RANTES ) and tumour necrosis factor-alpha (TNF-alpha) were determined once for the controls and twice for the victims, the first sample on admission and the second sample after 24h. All victims showed significantly higher mean values of IL-6, sIL-6R, RANTES, TNF-alpha, and leucocytic count both on admission and on the follow up when compared with controls. According to the clinical manifestations of envenomation, 40% of the victims had a mild envenomation manifestation, while 60% of them had severe manifestations. The severely envenomed children showed significantly higher mean values of IL-6, sIL-6R, TNF-alpha, RANTES and leucocytic count both on admission and on the follow up samples when compared with the mild cases. The non-survival victims (five victims) showed significantly higher mean values of IL-6, sIL-6R, TNF-alpha, RANTES and leucocytic count both on admission and on the follow up samples in comparison to the survivals. Furthermore, those fatal cases showed a non-significant decline in the serum levels of IL-6, sIL-6R, TNF-alpha, RANTES and leucocytic count on the following up samples, while the survivals showed a significant decline in the serum levels of these parameters on the following up samples. In conclusion, these data revealed that IL-6, sIL-6R, TNF-alpha and chemokine, RANTES are involved in the pathogenesis of scorpion envenomation and correlated with its severity.

Insulin-like effects of Bauhinia forficata aqueous extract upon Tityus serrulatus scorpion envenoming

Scorpion envenoming causes an intense autonomic discharge, leading to a massive release of neurotransmitters, giving rise to several pathophysiological effects. In this work we report the effects of a Bauhinia forficata aqueous extract (BfAE) upon hyperglycemia, glycogenolysis, increase of plasma catecholamines, lethality and changes in serum insulin and plasma electrolytes induced by Tityus serrulatus scorpion venom (TSV). We compare them with the effects of the regular insulin therapy. The following treatments were performed: TSV (500 microg/kg, i.p.); BfAE (1g/kg, p.o.), 24, 12 and 1 h before and immediately after TSV or saline and insulin in a single dose (1.5 IU/kg, s.c.) after TSV. BfAE reduces the fast hyperglycemia induced by TSV, but it is deprived of hypoglycemic activity. The extract also did not reduce either the intense glycogenolysis or the release of catecholamines and did not stimulate the release of endogenous insulin, although causing changes in the electrolyte plasma levels similarly to insulin. Although BfAE and insulin antagonize some effects of TSV, they should be avoided in the treatment of Tityus serrulatus envenoming, since they enhance the lethality of the venom.

Protective effects of aprotinin on respiratory and cardiac abnormalities induced by Mesobuthus tamulus venom in adult rats

Role of aprotinin (kallikrein-kinin synthesis inhibitor) in preventing the cardio-respiratory toxicity induced by Mesobuthus tamulus (BT) venom was evaluated. The effects of BT venom (5 mg/kg) on mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), lung compliance and pulmonary water content were examined. BT venom produced alterations in MAP, HR and RR. The MAP changes were seen as an immediate fall (within 2 s) followed by a rise and subsequent progressive fall. The HR was decreased drastically after venom and never returned to initial value. The respiratory changes were manifested as prolonged apnea with intermittent shallow breathing. The animals died within 30-60 min. In these animals, the lung compliance was decreased as compared to saline treated controls and there was significant increase in pulmonary water content. In aprotinin pre-treated group, there was decrease in MAP, HR and RR within 2 s which returned to pre-venom level within 15 min and remained at that level thereafter. The animals survived for the period of observation (i.e. up to 120 min). The compliance and pulmonary water content in these animals were similar to control animals. The results indicate that aprotinin protects against the BT venom-induced cardio-pulmonary toxicity.

Dysregulation of apoptosis in scorpion envenomed children: its reflection on their outcome

In the present study, 46 children in Upper Egypt (less than 13 years old) were admitted to the Pediatric Intensive Care Unit for scorpion envenomation. They were compared with 20 apparently healthy children of matching age and sex as controls. Out of the studied victims, 25 children (54%) showed signs of severe envenomation and multiple organ dysfunction (MOD), while 21 victims (46%) showed signs of mild envenomation. The serum levels of apoptotic markers, soluble Fas (sFas), soluble Fas ligand (sFasL) and Bcl-2, were determined for both victims and controls. In addition, the serum levels of nitric oxide (NO) and lipid peroxides (LPO) were also measured. Scoring of MOD was evaluated using Logistic Organ Dysfunction System Score (LODS) for the severely envenomed victims. All victims (both severe and mild cases) showed significantly higher mean levels of sFas, LPO and NO and significantly lower serum levels of Bcl-2 in comparison to the controls. The level of sFasL was not detectable in the sera of the healthy control group. The case fatality rate was 15%. The severely envenomed children with MOD as well as the non-survivors showed significantly higher serum levels of sFas, sFasL, LPO and NO and significantly lower serum levels of Bcl-2 in comparison to the mild envenomed victims and the surviving victims of severe cases, respectively. The LODS score of the severely envenomed victims showed significant positive correlations with sFas and LPO and significant negative correlation with Bcl-2. In all victims, a significant positive correlation was detected between sFas and NO. On the other hand, Bcl-2 was significantly negatively correlated with both sFas and LPO. In conclusion, our study revealed that scorpion envenomation can increase apoptosis as shown by up-regulation of sFas/sFasL system and down-regulation of Bcl-2 that was associated by elevation of LPO and NO. This dysregulation of apoptosis was increased with the severity of scorpion envenomation and its extent increased as MOD score and outcome increased. Therefore, sFas and Bcl-2 may be of value in predicting the outcome of these cases. The increase of the extent of apoptosis detected in this study seems to play a role in the outcome of scorpion envenomation, and hence, should be taken into consideration for strategies of therapeutic regimen.