Thromboelastography Use to Guide Resuscitation and Antivenom Administration after Gaboon Viper Bite.

The Gaboon viper (Bitis gabonica) is an exotic snake native to sub-Saharan Africa. Gaboon viper venom is an extremely toxic hemotoxin, causing severe coagulopathy and local tissue necrosis. These are not aggressive snakes and therefore bites involving humans are rare and there is not a substantial amount of literature documenting how to manage these injuries and resultant coagulopathies. We report a 29-year-old male presenting 3 hours after a Gaboon viper envenomation resulting in coagulopathy requiring massive resuscitation and multiple doses of antivenom. The patient received various blood products based on thromboelastography (TEG) and also underwent early continuous renal replacement therapy (CRRT) to assist in correction of severe acidosis and acute renal failure. The combination of TEG to guide resuscitation, administration of antivenom, and early implementation of CRRT allowed our team to correct venom-induced consumptive coagulopathy and ultimately allow the patient to survive following this extremely deadly Gaboon viper envenomation.

The concept of Big Four: Road map from snakebite epidemiology to antivenom efficacy.

Snake envenomation is a life-threatening disease caused by the injection of venom toxins from the venomous snake bite. Snakebite is often defined as the occupational or domestic hazard mostly affecting the rural population. India experiences a high number of envenoming cases and fatality due to the nation's diversity in inhabiting venomous snakes. The Indian Big Four snakes namely Russell's viper (Daboia russelii), spectacled cobra (Naja naja), common krait (Bungarus caeruleus), and saw-scaled viper (Echis carinatus) are responsible for majority of the snake envenoming cases and death. The demographic characteristics including occupation, stringent snake habitat management, poor healthcare facilities and ignorance of the rural victims are the primary influencers of high mortality. Biogeographic venom variation greatly influences the clinical pathologies of snake envenomation. The current antivenoms against the Big Four snakes are found to be less immunogenic against the venom toxins emphasizing the necessity of alternative approaches for antivenom generation. This review summarizes the burden of snake envenomation in India by the Big Four snakes including the geographic distribution of snake species and biogeographic venom variation. We have provided comprehensive information on snake venom proteomics that has aided the better understanding of venom induced pathological features, summarized the impact of current polyvalent antivenom therapy highlighting the need for potential antivenom treatment for the effective management of snakebites.

The Effectiveness of Antibiotics in Managing Bacterial Infections on Bite Sites following Snakebite Envenomation.

Snakebite envenomation (SBE) is a life-threatening medical emergency with a high mortality rate. Common secondary complications following SBE, such as wound infections, are significant due to their impact on worsening local tissue damage and causing systemic infection. Antivenoms are not effective to treat wound infections following SBE. Moreover, in several rural clinical settings, broad-spectrum antibiotics are often used without clear guidelines or based on limited laboratory data, resulting in undesirable side effects and exacerbated treatment costs. Therefore, robust antibiotic strategies should be developed to tackle this critical issue. Currently, there is limited information available on the bacterial profiles of SBE-induced infections and antibiotic susceptibility. Hence, it is essential to improve the knowledge of bacterial profiles and their antibiotic sensitivity in SBE victims to develop better treatment strategies. This study aimed to address this issue by examining the bacterial profiles of SBE victims with a specific focus on Russell's viper envenomation. The most frequently found bacteria in the bites of SBE victims were Staphylococcus aureus, Klebsiella sp., Escherichia coli, and Pseudomonas aeruginosa. Linezolid, clindamycin, colistin, meropenem, and amikacin were some of the most effective antibiotics for commonly grown bacteria in SBE victims. Similarly, ciprofloxacin, ampicillin, amoxiclave, cefixime, and tetracyclin were the least effective antibiotics for common bacteria found in the wound swabs of SBE victims. These data provide robust guidance for infection management following SBE and offer useful insights to aid in designing effective treatment protocols for SBE with serious wound infections in rural areas where laboratory facilities may not be readily available.

Platelet Desialylation Is a Novel Mechanism and Therapeutic Target in Daboia siamensis and Agkistrodon halys Envenomation-Induced Thrombocytopenia.

Venom-induced thrombocytopenia (VIT) is one of the most important hemotoxic effects of a snakebite, which is often associated with venom-induced consumptive coagulopathy (VICC). Refractory thrombocytopenia without significant coagulation abnormalities has also been reported after envenomation by some viperid snakes; however, the mechanisms are not well understood and therapeutic strategies are lacking. Here, we found that patients injured by Daboia siamensis or Agkistrodon halys snakes, who were resistant to standard antivenom treatment, had developed coagulopathy-independent thrombocytopenia. Venoms from these viperid snakes, rather than from the elapid snake (Bungarus multicinctus), induced platelet surface expression of neuraminidase-1 (NEU-1), and significantly increased the desialylation of the glycoproteins on human platelets. The desialylated platelets caused by viperid snake venoms were further internalized by macrophages, which resulted in reduced platelet numbers in peripheral blood. Importantly, neuraminidase inhibitor significantly decreased viper venom-induced platelet desialylation, therefore inhibiting platelet phagocytosis by macrophages, and alleviating venom-induced thrombocytopenia. Collectively, these findings support an important role for desialylated platelet clearance in the progression of viper envenomation-induced, coagulopathy-independent thrombocytopenia. Our study demonstrates that the neuraminidase inhibitor may be a potential therapy or adjuvant therapy to treat snakebite-induced thrombocytopenia.

VENOMOUS SNAKEBITES IN CROATIA, CLINICAL PRESENTATION, DIAGNOSIS AND TREATMENT.

Venomous snake bites are recognized as a major public health problem, affecting mostly poor, underdeveloped areas in the tropical and subtropical areas. Every year, more than three million bite cases and about 100,000 deaths are registered worldwide. Over the past years, 632 people have been hospitalized in Croatia with only 3 deaths due to venomous snake bites. Favorable geographic position, warm climate and great biodiversity of Croatia have resulted in the development of a total of 15 species of snakes, of which only 3 are venomous: horned viper (Vipera ammodytes), the common European viper (Vipera berus) and meadow viper (Vipera ursinii macrops). Snake venom envenomation is called ophidism (greek ofis=snake). Snake venoms are complex mixtures of proteins and toxins that have a wide range of toxic effects. The clinical presentation of ophidism is due to hematotoxic, neurotoxic, myotoxic (cardiotoxic) and cytotoxic effects of venom. There is currently no test to identify patients with a systemic spread of the venom, the diagnosis is made by a combination of diagnostic tests, clinical symptoms and sings of systemic envenomation. Ophidism is a medical condition that requires urgent treatment. Following first aid given at the scene, the patient should be transported to the closest medical facility to assess the severity of the clinical presentation in a timely manner and take the necessary treatment measures.

Early Adverse Reactions to Snake Antivenom: Poison Center Data Analysis.

Antivenom is an essential treatment for snake envenomation; however, early adverse reactions (EARs) are major limitations to its use. We performed a retrospective cross-sectional study using Ramathibodi Poison Center data (January 2016 to December 2017) to clarify the incidence and severity of EARs following different F(ab')2 antivenoms. Among 1006 envenomed patients, 684 (68%) received antivenom therapy with a total of 1157 doses, mostly green pit viper antivenom. The overall EAR incidence and rate were 22. 5% (154/684) and 15% (173/1157), respectively. The EAR rate following each type of antivenom was >10%, except for Russell's viper antivenom (2.9%); the severe reaction rate was 2.6% (30/1157). Malayan pit viper bites caused a high incidence of EARs (37.8%) and the highest EAR rate (22.3%). Fifty-two cases developed anaphylaxis. All EARs occurred within 2 h after treatment initiation. No deaths were attributed to EARs. The duration of administration was significantly different between doses of antivenom that induced EARs and those that did not. In conclusion, all types and every dose of antivenom should be infused for 30−60 min. Preparation of resuscitation equipment and continuous clinical observation are crucial for at least 2 h after administration, and prompt treatment should be provided when EARs occur.

Neurotoxicity and Other Clinical Manifestations of a Common European Adder (Vipera berus) Bite in Romania.

Most cases of envenomation by common European vipers (Vipera berus) have not been reported to have neurotoxic manifestations. However, these manifestations have been demonstrated in some cases of envenomation by subspecies of V. berus, found in the Carpathian Basin region of south-eastern Europe. Here, we report the case of a 5-year-old girl from the south of Romania who presented symptoms of neurotoxicity, as well as other systemic and local symptoms, after being bitten by an adder of the V. berus subspecies. Treatment consisted of monovalent antivenom, a corticosteroid, and prophylactic enoxaparin. Neurotoxic manifestations of envenomation as well as other local and systemic symptoms improved within 5 days of treatment. The presented case shows that venom from V. berus subspecies found in the Carpathian Basin can have neurotoxic effects. This case also confirmed the efficacy of monospecific antivenom treatment in bringing about rapid and complete remission, following envenomation.

Ultrasound-Guided Compression Method Effectively Counteracts Russell's Viper Bite-Induced Pseudoaneurysm.

Russell's viper (Daboia russelii), one of the 'Big Four' venomous snakes in India, is responsible for the majority of snakebite-induced deaths and permanent disabilities. Russell's viper bites are known to induce bleeding/clotting abnormalities, as well as myotoxic, nephrotoxic, cytotoxic and neurotoxic envenomation effects. In addition, they have been reported to induce rare envenomation effects such as priapism, sialolithiasis and splenic rupture. However, Russell's viper bite-induced pseudoaneurysm (PA) has not been previously reported. PA or false aneurysm is a rare phenomenon that occurs in arteries following traumatic injuries including some animal bites, and it can become a life-threatening condition if not treated promptly. Here, we document two clinical cases of Russell's viper bites where PA has developed, despite antivenom treatment. Notably, a non-surgical procedure, ultrasound-guided compression (USGC), either alone, or in combination with thrombin was effectively used in both the cases to treat the PA. Following this procedure and additional measures, the patients made complete recoveries without the recurrence of PA which were confirmed by subsequent examination and ultrasound scans. These data demonstrate the development of PA as a rare complication following Russell's viper bites and the effective use of a simple, non-surgical procedure, USGC for the successful treatment of PA. These results will create awareness among healthcare professionals on the development of PA and the use of USGC in snakebite victims following bites from Russell's vipers, as well as other viper bites.

Development and validation of a ligand-binding assay for quantification of the F(ab')2 antivenom of Daboia russelii siamensis in human serum and its application to a phase I clinical study.

Daboia russelii siamensis accounts for most of snakebite mortalities in China, yet, specific treatment against the venom toxins is absent in clinical practice. The F(ab')2 antivenom of Daboia russelii siamensis is manufactured and approved for the clinical trial in China. To satisfy the need for clinical pharmacokinetic research, this study aimed to develop a ligand binding assay (LBA) for the quantification of F(ab')2 antivenom of Daboia russelii siamensis in human serum. A diverse combination of conditions was optimized based on the fitness of the calibration curve and selectivity. The established LBA undergoes thorough method validation according to the guidelines of regulatory authorities. In the calibration range 1.0-64 µg/mL, the correlation coefficient r2 was from 0.9970 to 1.000, indicating good fitness. Accuracy and precision were within ± 20%. Dilution linearity was observed in the ultra-high quality-control (QC) samples (500 µg/mL). In addition, the assay was free from hook effect, the endogenous interferences and exogenous interferences. The QC samples were stable under different handling and storage conditions. The validated assay was successfully applied to a phase I clinical study of the F(ab')2 antivenom of Daboia russelii siamensis in Chinese healthy volunteers. The peak concentrations exhibited dose-proportionality. In conclusion, this study provides a novel and reliable LBA method for the clinical pharmacokinetic research of F(ab')2 antivenom of Daboia russelii siamensis. It will facilitate further clinical trials in treating the snakebite of Daboia russelii siamensis.

Indigenous venomous snakebites in Switzerland: analysis of reports to the National Poisons Information Centre over 22 years.

INTRODUCTION: Two venomous snakes, the asp viper (Vipera aspis) and the common adder (Vipera berus) are native to Switzerland. Bites by both vipers cause mainly local effects, but systemic envenomation is possible. METHODS: We analysed all calls concerning indigenous venomous snakebites recorded at the Swiss National Poisons Information Centre between 1997 and 2018, including all cases with identification by a herpetologist, and/or with compatible symptoms and circumstances of the exposure. RESULTS: During the study period, 1,364 cases concerned snakebites. One third (466; 34%) were attributed to indigenous vipers. In 243 (52%) patients, medical follow-up information was available, with good causality between exposure and symptoms in 219 (90%) patients. Vipera aspis was identified in 77 of the cases (35%), Vipera berus in 54 (25%), and not further specified vipers in 88 (40%). In over two thirds of the 219 cases (155, 71%) adult patients were affected (male 109, female 46; median age 43 years [range 16-90]). Sixty-four patients were children (male 47, female 16; median age 11 years [range 1.3-15.9]). The highest occurrence of bites was in the summer months. In the majority of patients, the clinical course was mild (94; 43%) or moderate (80; 36%); a lower proportion was either asymptomatic (17; 8%) or exhibited severe symptoms (28; 13%). There were no fatalities reported. The most frequent symptoms were local effects at the bite site with mild (100; 46%) to moderate (56; 25%) swelling, pain (65; 30%) and redness (51; 23%). Gastrointestinal symptoms including nausea (31; 14%), vomiting (47; 22%) and abdominal pain (25; 11%) were also common. Other systemic symptoms included cardiovascular effects (e.g., hypotension (20; 9%) or shock [6; 3%]), neurotoxicity (e.g., visual impairment [5; 2.3%]) and haematotoxicity (e.g., coagulopathy [11; 5%]). Seven (3.2%) patients developed anaphylactic reactions. Antivenom was administered in only 20% (24 with moderate and 19 with severe symptoms) with good resolution of symptoms. The mean duration of hospitalization was 2 days (0-12 days). CONCLUSION: Snakebites in Switzerland can result in severe symptoms, sometimes necessitating antivenom treatment.

How to Achieve Standardization? Diluted Russell Viper Venom Test for Lupus Anticoagulant Detection in a Chinese Female Population.

On an international scale, guidelines and proposals for lupus anticoagulant detection have been published over the last 20 years, but until now, standardization has not been completely realized. The aim of this study was to evaluate the different ways of interpreting the results of lupus anticoagulant detection for standardization. A retrospective review of 15 447 instances of lupus anticoagulant detection by the diluted Russell Viper Venom test for female patients presenting with problems relating to the areas of reproduction, gynecology and obstetrics was performed. Lupus anticoagulant data were compared between different departments, months, reagent lots and cutoffs. Significant differences were found in patient data between different reagent lots, especially between lots of screening reagents (monthly average: highest 37.96 s vs lowest 33.88 s) and in the positive rates of lupus anticoagulant by different detection cutoffs (47.58% by using LA1/LA2 > 1.20 without normalization as a cutoff in Lot 1 vs 1.52% by using LA1 > 44 s as a cutoff in Lot 3). Compared with the cutoff using the value above the 99th percentile of LA1 for the healthy donors per lot, the cutoff using integrated tests with normalization had the smaller deviation of positive rate between different reagent lots. Pregnant women had higher LA1/LA2 levels than nonpregnant women. Based on the results, normalization is needed because there are significant lot-to-lot variations. Integrated tests with normalization might be a better standard by which to confirm lupus anticoagulant. Pregnant women should have population-specific cutoffs because they have higher LA1/LA2 levels.

Lebetin 2, a Snake Venom-Derived B-Type Natriuretic Peptide, Provides Immediate and Prolonged Protection against Myocardial Ischemia-Reperfusion Injury via Modulation of Post-Ischemic Inflammatory Response.

Myocardial infarction (MI) followed by left ventricular (LV) remodeling is the most frequent cause of heart failure. Lebetin 2 (L2), a snake venom-derived natriuretic peptide, exerts cardioprotection during acute myocardial ischemia-reperfusion (IR) ex vivo. However, its effects on delayed consequences of IR injury, including post-MI inflammation and fibrosis have not been defined. Here, we determined whether a single L2 injection exerts cardioprotection in IR murine models in vivo, and whether inflammatory response to ischemic injury plays a role in L2-induced effects. We quantified infarct size (IS), fibrosis, inflammation, and both endothelial cell and cardiomyocyte densities in injured myocardium and compared these values with those induced by B-type natriuretic peptide (BNP). Both L2 and BNP reduced IS, fibrosis, and inflammatory response after IR, as evidenced by decreased leukocyte and proinflammatory M1 macrophage infiltrations in the infarcted area compared to untreated animals. However, only L2 increased anti-inflammatory M2-like macrophages. L2 also induced a higher density of endothelial cells and cardiomyocytes. Our data show that L2 has strong, acute, prolonged cardioprotective effects in post-MI that are mediated, at least in part, by the modulation of the post-ischemic inflammatory response and especially, by the enhancement of M2-like macrophages, thus reducing IR-induced necrotic and fibrotic effects.

BJ-PRO-7A and BJ-PRO-10C induce vasodilatation and inotropic effects in normotensive and hypertensive rats: Role of nitric oxide and muscarinic receptors.

Bj-PRO-7a and Bj-PRO-10c belong to a family of proline-rich oligopeptides (PROs) identified in Bothrops jararaca (Bj) crude venom. Previous studies have shown an antihypertensive effect evoked by theses peptides. However, the mechanisms underlying the direct effects on vessels and heart remain to be unraveled. Thus, we investigated the effect of the Bj-PRO-7a and Bj-PRO-10c in the aorta and coronary arteries and in cardiac contractility in normotensive (Wistar) and hypertensive (SHR) rats. Pre-constricted aortic rings were exposed to increasing concentrations of Bj-PROs in presence or absence of muscarinic type 1 receptor antagonist (Pirenzepine), nonselective muscarinic receptor antagonist (Atropine), nitric oxide synthase inhibitor (L-NAME), guanylyl cyclase inhibitor (ODQ), adenylyl cyclase inhibitor (MDL), or argininosuccinate synthetase inhibitor (MDLA). The effects of Bj-PROs in the cardiac contractility and coronary vasomotricity were evaluated using Langendorff perfused heart preparation. The rat hearts were perfused with Bj-PRO-7a or Bj-PRO-10c in absence or presence of L-NAME, ODQ or MDL. Both Bj-PROs induced endothelium-dependent vasorelaxation in aortic rings from Wistars and SHRs. These effects were inhibited by L-NAME, ODQ or MDL. Atropine and Pirenzepine blocked the vasorelaxant effect of Bj-PRO-7a in aorta from both strains. MDLA inhibited the Bj-PRO-10c-induced vasorelaxation in aortic rings from SHR, but not Wistar. The Bj-PRO-7a induced coronary vasodilation only in SHR. L-NAME, ODQ and MDL inhibited this effect. Bj-PRO-10c induced coronary vasodilatation in both strains, which was blocked by L-NAME, ODQ and MDL. Bj-PRO-7a decreased the dP/dt max in Wistar hearts and the dP/dt min in Wistar and SHR hearts. These effects were abolished by L-NAME. Bj-PRO-10c decreased dP/dt max and dP/dt min in hearts from normotensive and hypertensive animals, which were abolished in the presence of L-NAME, MDL and ODQ. In summary, the Bj-PROs induced endothelium-dependent vasorelaxation in rat thoracic aorta, coronary vasodilation and negative inotropic effects through mechanisms mediated by activation of nitric oxide pathway.

Vipers of the Middle East: A Rich Source of Bioactive Molecules.

Snake venom serves as a tool of defense against threat and helps in prey digestion. It consists of a mixture of enzymes, such as phospholipase A2, metalloproteases, and l-amino acid oxidase, and toxins, including neurotoxins and cytotoxins. Beside their toxicity, venom components possess many pharmacological effects and have been used to design drugs and as biomarkers of diseases. Viperidae is one family of venomous snakes that is found nearly worldwide. However, three main vipers exist in the Middle Eastern region: Montivipera bornmuelleri, Macrovipera lebetina, and Vipera (Daboia) palaestinae. The venoms of these vipers have been the subject of many studies and are considered as a promising source of bioactive molecules. In this review, we present an overview of these three vipers, with a special focus on their venom composition as well as their biological activities, and we discuss further frameworks for the exploration of each venom.

Targeting α1 inserted domain (I) of α1ß1 integrin by Lebetin 2 from M. lebetina transmediterranea venom decreased tumorigenesis and angiogenesis.

Through the recent development of knowledge in biotechnology and bioinformatics, snake venoms are widely used to develop new drugs to treat diseases such as hypertension and cancer. We have previously reported that Lebetin 2 isolated from Macrovipera lebetina transmediterranea venom displays a potent anti-platelet activity and exerts a cardioprotective effect in ischemia-reperfusion (IR) injury model. Here, we report that Lebetin 2 possess an anti-tumor effect by targeting the integrin receptor function. It was thus able to inhibit both adhesion and migration of pheochromocytoma cells (PC12) and α1ß1 integrin-expressing CHO cells (CHO-α1) to type I and IV collagens. Moreover, this peptide affects proliferation of PC12 cells by modulating AKT phosphorylation. Furthermore, Lebetin 2 exhibits a potent anti-angiogenic effect as assessed in vitro and ex vivo, using both the embryo chick chorioallantoic membrane model (CAM) and rat aortic ring assay. Interestingly, the interaction mode of Lebetin 2 with the integrin α1ß1, assessed in silico, showed that the peptide represents a steric obstruction preventing the collagen from enforcing the interactions with the integrin.

Lebein, a snake venom disintegrin, suppresses human colon cancer cells proliferation and tumor-induced angiogenesis through cell cycle arrest, apoptosis induction and inhibition of VEGF expression.

Lebein, is an heterodimeric disintegrin isolated from Macrovipera lebetina snake venom that was previously characterized as an inhibitor of ADP-induced platelet aggregation. In this study, we investigated the effect of Lebein on the p53-dependent growth of human colon adenocarcinoma cell lines. We found that Lebein significantly inhibited LS174 (p53wt), HCT116 (p53wt), and HT29 (p53mut) colon cancer cell viability by inducing cell cycle arrest through the modulation of expression levels of the tumor suppression factor p53, cell cycle regulating proteins cyclin D1, CDK2, CDK4, retinoblastoma (Rb), CDK1, and cyclin-dependent kinase inhibitors p21 and p27. Interestingly, Lebein-induced apoptosis of colon cancer cells was dependent on their p53 status. Thus, in LS174 cells, cell death was associated with PARP cleavage and the activation of caspases 3 and 8 while in HCT116 cells, Lebein induced caspase-independent apoptosis through increased expression of apoptosis inducing factor (AIF). In LS174 cells, Lebein triggers the activation of the MAPK ERK1/2 pathway through induction of reactive oxygen species (ROS). It also decreased cell adhesion and migration to fibronectin through down regulation of α5ß1 integrin. Moreover, Lebein significantly reduced the expression of two angiogenesis stimulators, Vascular Endothelial Growth Factor (VEGF) and Neuropilin 1 (NRP1). It inhibited the VEGF-induced neovascularization process in the quail embryonic CAM system and blocked the development of human colon adenocarcinoma in nude mice. Overall, our work indicates that Lebein may be useful to design a new therapy against colon cancer. © 2016 Wiley Periodicals, Inc.

Lebecetin, a C-type lectin, inhibits choroidal and retinal neovascularization.

Angiogenesis is a cause of visual impairment and blindness in the wet form of age-related macular degeneration and in ischemic retinopathies. Current therapies include use of anti-VEGF agents to reduce choroidal neovascularization (CNV) and edema. These treatments are effective in most cases, but spontaneous or acquired resistance to anti-VEGF and possible adverse effects of long-term VEGF inhibition in the retina and choroid highlight a need for additional alternative therapies. Integrins αvß3 and αvß5, which regulate endothelial cell proliferation and stabilization, have been implicated in ocular angiogenesis. Lebecetin (LCT) is a 30-kDa heterodimeric C-type lectin that is isolated from Macrovipera lebetina venom and interacts with α5ß1- and αv-containing integrins. We previously showed that LCT inhibits human brain microvascular endothelial cell adhesion, migration, proliferation, and tubulogenesis. To evaluate the inhibitory effect of LCT on ocular angiogenesis, we cultured aortic and choroidal explants in the presence of LCT and analyzed the effect of LCT on CNV in the mouse CNV model and on retinal neovascularization in the oxygen-induced retinopathy model. Our data demonstrate that a single injection of LCT efficiently reduced CNV and retinal neovascularization in these models.-Montassar, F., Darche, M., Blaizot, A., Augustin, S., Conart, J.-B., Millet, A., Elayeb, M., Sahel, J.-A., Réaux-Le Goazigo, A., Sennlaub, F., Marrakchi, N., Messadi, E., Guillonneau, X. Lebecetin, a C-type lectin, inhibits choroidal and retinal neovascularization.

Viper Venom Botox: The Molecular Origin and Evolution of the Waglerin Peptides Used in Anti-Wrinkle Skin Cream.

The molecular origin of waglerin peptides has remained enigmatic despite their industrial application in skin cream products to paralyse facial muscles and thus reduce the incidence of wrinkles. Here we show that these neurotoxic peptides are the result of de novo evolution within the prepro region of the C-type natriuretic peptide gene in Tropidolaemus venoms, at a site distinct from the domain encoding for the natriuretic peptide. It is the same region that yielded the azemiopsin peptides from Azemiops feae, indicative of a close relationship of this toxin gene between these two genera. The precursor region for the molecular evolution is a biodiversity hotspot that has yielded other novel bioactive peptides with novel activities. We detail the diversity of components in this and other species in order to explore what characteristics enable it to be such a biodiscovery treasure trove. The unusual function of Tropidolaemus venoms may have been selected for due to evolutionary pressures brought about by a high likelihood of prey escape.

A fatal outcome due to pulmonary hemorrhage following Russell's viper bite.

Russell's viper (RV) envenomation causes local effects, coagulopathy, thrombosis, rhabdomyolysis, acute kidney injury, and neurological manifestations. Although coagulopathy and endothelial destruction causing local and mucosal surface bleeding is known, isolated severe pulmonary hemorrhage is not commonly reported. We report a previously healthy 18-year-old male who had bilateral severe pulmonary hemorrhages, which resulted in a fatal outcome following RV bite. This diagnosis was supported by persistent alveolar shadows, with minimum improvement despite hemodialysis without heparin, mixed acidosis and endotracheal tube bleeding. Other bleeding manifestations were absent. Polyvalent antivenom was administered in lieu of prolonged whole blood clotting time. Thrombocytopenia and mildly deranged clotting parameters were noted. Pulmonary hemorrhages were significant enough to require transfusion. This case highlights the importance of suspecting pulmonary hemorrhages in patients with alveolar shadows and desaturation following RV bite despite the absence of other bleeding manifestations in light of failure of optimum therapy including hemodialysis.

Inhibitory effects of polypeptides derived from a snake venom C-type lectin, aggretin, on tumor cell-induced platelet aggregation.

BACKGROUND AND OBJECTIVES: Podoplanin, a transmembrane sialoglycoprotein, is expressed by lymphatic endothelial cells and many tumor cells, and is involved in tumor cell-induced platelet aggregation and tumor metastasis. A recent study found that C-type lectin-like receptor 2 (CLEC-2) is a physiologic receptor for podoplanin. Previous studies showed that aggretin, a snake venom-derived protein, activates platelets by targeting platelet CLEC-2. We hypothesized that the C-terminal fragment of aggretin may bind to platelet CLEC-2 and displace podoplanin, in turn exerting antitumor metastatic effects. METHODS AND RESULTS: Aggretin α-chain C-terminus (residues 106-136; AACT) prolonged the lag phase of platelet aggregation induced by aggretin in human washed platelets, indicating that AACT may target the binding site of CLEC-2. HepG2 cells, which are podoplanin-expressing hepatoma cells, induced platelet aggregation with a lag phase. Pretreatment with AACT inhibited platelet aggregation and prolonged the lag phase induced by HepG2 cells. This inhibitory effect was also found with another hepatocarcinoma cell line, HuH-7. AACT inhibited the interaction between HuH-7 cells and platelets, and a specific binding assay demonstrated that CLEC-2 was the binding site for AACT on platelets. In addition, the invasive ability of HepG2 cells was abolished by AACT in a chick embryo chorioallantoic membrane model. Furthermore, formation of lung metastases after intravenous administration of HuH-7 cells was significantly reduced when mice were treated with AACT. CONCLUSIONS: AACT interacts with CLEC-2 of platelets, leading to interference with platelet aggregation and the subsequent metastatic potential of tumor cells. These results suggest that aggretin AACT is a potential candidate for the treatment of tumor metastasis through CLEC-2 blockade.