Extensive Variation in the Activities of Pseudocerastes and Eristicophis Viper Venoms Suggests Divergent Envenoming Strategies Are Used for Prey Capture.

Snakes of the genera Pseudocerastes and Eristicophis (Viperidae: Viperinae) are known as the desert vipers due to their association with the arid environments of the Middle East. These species have received limited research attention and little is known about their venom or ecology. In this study, a comprehensive analysis of desert viper venoms was conducted by visualising the venom proteomes via gel electrophoresis and assessing the crude venoms for their cytotoxic, haemotoxic, and neurotoxic properties. Plasmas sourced from human, toad, and chicken were used as models to assess possible prey-linked venom activity. The venoms demonstrated substantial divergence in composition and bioactivity across all experiments. Pseudocerastes urarachnoides venom activated human coagulation factors X and prothrombin and demonstrated potent procoagulant activity in human, toad, and chicken plasmas, in stark contrast to the potent neurotoxic venom of P. fieldi. The venom of E. macmahonii also induced coagulation, though this did not appear to be via the activation of factor X or prothrombin. The coagulant properties of P. fieldi and P. persicus venoms varied among plasmas, demonstrating strong anticoagulant activity in the amphibian and human plasmas but no significant effect in that of bird. This is conjectured to reflect prey-specific toxin activity, though further ecological studies are required to confirm any dietary associations. This study reinforces the notion that phylogenetic relatedness of snakes cannot readily predict venom protein composition or function. The significant venom variation between these species raises serious concerns regarding antivenom paraspecificity. Future assessment of antivenom is crucial.

Mesenchymal Stromal Cell-Based Therapies as Promising Treatments for Muscle Regeneration After Snakebite Envenoming.

Snakebite envenoming is a global neglected disease with an incidence of up to 2.7 million new cases every year. Although antivenoms are so-far the most effective treatment to reverse the acute systemic effects induced by snakebite envenoming, they have a limited therapeutic potential, being unable to completely neutralize the local venom effects. Local damage, such as dermonecrosis and myonecrosis, can lead to permanent sequelae with physical, social, and psychological implications. The strong inflammatory process induced by snake venoms is associated with poor tissue regeneration, in particular the lack of or reduced skeletal muscle regeneration. Mesenchymal stromal cells (MSCs)-based therapies have shown both anti-inflammatory and pro-regenerative properties. We postulate that using allogeneic MSCs or their cell-free products can induce skeletal muscle regeneration in snakebite victims, improving all the three steps of the skeletal muscle regeneration process, mainly by anti-inflammatory activity, paracrine effects, neovascularization induction, and inhibition of tissue damage, instrumental for microenvironment remodeling and regeneration. Since snakebite envenoming occurs mainly in areas with poor healthcare, we enlist the principles and potential of MSCs-based therapies and discuss regulatory issues, good manufacturing practices, transportation, storage, and related-procedures that could allow the administration of these therapies, looking forward to a safe and cost-effective treatment for a so far unsolved and neglected health problem.

Acute Kidney Injury Induced by Bothrops Venom: Insights into the Pathogenic Mechanisms.

Acute kidney injury (AKI) following snakebite is common in developing countries and Bothrops genus is the main group of snakes in Latin America. To evaluate the pathogenic mechanisms associated with Bothrops venom nephrotoxicity, we assessed urinary and blood samples of patients after hospital admission resulting from Bothrops snakebite in a prospective cohort study in Northeast Brazil. Urinary and blood samples were evaluated during hospital stay in 63 consenting patients, divided into AKI and No-AKI groups according to the KDIGO criteria. The AKI group showed higher levels of urinary MCP-1 (Urinary monocyte chemotactic protein-1) (median 547.5 vs. 274.1 pg/mgCr; p = 0.02) and urinary NGAL (Neutrophil gelatinase-associated lipocalin) (median 21.28 vs. 12.73 ng/mgCr; p = 0.03). Risk factors for AKI included lower serum sodium and hemoglobin levels, proteinuria and aPTT (Activated Partial Thromboplastin Time) on admission and disclosed lower serum sodium (p = 0.01, OR = 0.73, 95% CI: 0.57⁻0.94) and aPTT (p = 0.031, OR = 26.27, 95% CI: 1.34⁻512.11) levels as independent factors associated with AKI. Proteinuria showed a positive correlation with uMCP-1 (r = 0.70, p < 0.0001) and uNGAL (r = 0.47, p = 0.001). FENa (Fractional Excretion of sodium) correlated with uMCP-1 (r = 0.47, P = 0.001) and uNGAL (r = 0.56, p < 0.0001). sCr (serum Creatinine) showed a better performance to predict AKI (AUC = 0.85) in comparison with new biomarkers. FEK showed fair accuracy in predicting AKI (AUC = 0.92). Coagulation abnormality was strongly associated with Bothrops venom-related AKI. Urinary NGAL and MCP-1 were good biomarkers in predicting AKI; however, sCr remained the best biomarker. FEK (Fractional Excretion of potassium) emerged as another diagnostic tool to predict early AKI. Positive correlations between uNGAL and uMCP-1 with proteinuria and FENa may signal glomerular and tubular injury. Defects in urinary concentrations highlighted asymptomatic abnormalities, which deserve further study.

Pituitary dysfunction in survivors of Russell's viper snake bite envenomation: A prospective study.

PURPOSE: Endocrinal insufficiency caused by vasculotoxic snake envenomation is under-recognized and is mostly confined to a specific geographic area. We conducted a prospective study to determine the prevalence and pattern of pituitary-target gland insufficiencies caused by snake envenomation. MATERIALS AND METHODS: The hormonal evaluation of patients who had suffered from vasculotoxic snake envenomation was done at baseline and at 6 months of follow-up. Those patients with a documented hormonal insufficiency underwent magnetic resonance imaging (MRI) of the hypothalamo-pituitary area. The severity of envenomation was assessed by the acute physiology and chronic health evaluation II (APACHE-II) score, the sepsis-related organ failure assessment (SOFA) score, and the snake bite severity score (SBSS) for all patients. RESULTS: Seventy-six patients were seen during the study period, of which 60 were available for a repeat hormonal evaluation at 6 months, with the majority of patients belonging to the middle age group (mean age, 37.6 ± 14.9 years). The mean lag period at presentation was 32 ± 20 h. Thirty-five patients (46.1%) had coagulopathy, 20 patients (26.3%) had acute kidney injury (AKI), and 8 of 76 patients (10.5%) needed renal replacement therapy (RRT) in the form of hemodialysis. Six patients (out of 41 with vasculotoxic bites) developed chronic hypopituitarism, which was in continuation with the acute hypopituitarism that they developed. Growth hormone and glucocorticoid deficiencies were the most common endocrinopathies observed. The occurrence of hypopituitarism was observed only in patients with a vasculotoxic snake bite (due to Russell's viper); coagulopathy, renal insufficiency, or any of the scoring tools did not predict the occurrence of hypopituitarism. CONCLUSION: Acute asymptomatic and chronic symptomatic or asymptomatic hypopituitarism are important sequelae of viper bite in a small proportion of patients and can occur in the presence of normal pituitary imaging. Routine prospective pituitary hormone screening should be done in all patients within the first 6 months of envenomation by the vasculotoxic snakebite as chronic pituitary dysfunction can often occur in these patients.

On the chemotherapeutic agents localization in tissue by means of snake venoms.

The efficiency of anti-tumour drug strongly depends on its dose. Higher drug doses and exposure times usually result in better treatment. It is why the implementation of high-dose treatment is always attractive. However, most of the drug delivery techniques meet essential limitations. In isolated regional perfusion a tumour can be exposed to high-dose therapeutic influence but the target organ may be isolated from the rest of circulatory system only for a relatively short period of time. During systemic injection of anti-tumour agents dose limitations are dictated by side toxicity danger. Viperidae venoms are known to cause local stagnation of blood flow and blood-tissue exchange processes in the place of snakebite. In present paper we suggest to use Viperidae snake venoms in addition to anti-tumour drugs for regional anti-cancer therapy. We suppose that Viperidae venoms will assist in drug localization. We state that their usage will help in high-dosage therapy implementation.

Low-Level Laser Therapy (904 nm) Counteracts Motor Deficit of Mice Hind Limb following Skeletal Muscle Injury Caused by Snakebite-Mimicking Intramuscular Venom Injection.

Myotoxins present in Bothrops venom disrupt the sarcolemma of muscle fibers leading to the release of sarcoplasmic proteins and loss of muscle homeostasis. Myonecrosis and tissue anoxia induced by vascularization impairment can lead to amputation or motor functional deficit. The objective of this study was to investigate the dynamic behavior of motor function in mice subjected to injection of Bothrops jararacussu venom (Bjssu) and exposed to low-level laser therapy (LLLT). Male Swiss mice received Bjssu injection (830 µg/kg) into the medial portion of the right gastrocnemius muscle. Three hours later the injected region was irradiated with diode semiconductor Gallium Arsenide (GaAs- 904 nm, 4 J/cm²) laser following by irradiation at 24, 48 and 72 hours. Saline injection (0.9% NaCl) was used as control. Gait analysis was performed 24 hours before Bjssu injection and at every period post-Bjssu using CatWalk method. Data from spatiotemporal parameters Stand, Maximum Intensity, Swing, Swing Speed, Stride Length and Step Cycle were considered. The period of 3 hours post venom-induced injury was considered critical for all parameters evaluated in the right hindlimb. Differences (p<0.05) were concentrated in venom and venom + placebo laser groups during the 3 hours post-injury period, in which the values of stand of most animals were null. After this period, the gait characteristics were re-established for all parameters. The venom + laser group kept the values at 3 hours post-Bjssu equal to that at 24 hours before Bjssu injection indicating that the GaAs laser therapy improved spatially and temporally gait parameters at the critical injury period caused by Bjssu. This is the first study to analyze with cutting edge technology the gait functional deficits caused by snake envenoming and gait gains produced by GaAs laser irradiation. In this sense, the study fills a gap on the field of motor function after laser treatment following snake envenoming.

Comparative Studies of Structural and Functional Properties of Snake Venom Metalloproteinases.

Snake venom metalloproteinases (SVMPs) induces local and systemic effects on patients suffering from snakebite, degrading extracellular matrix (ECM) proteins such as collagen, gelatin, elastin, laminin, fibronectin, nidogen (entactin), and thrombospondin that cause local hemorrhage and tissue damage. They cleave or activate coagulation factors such as fibrinogen, fibrin, prothrombin, factor V, factor IX, factor X and protein C that bring about systemic coagulopathy. SVMPs and their truncated forms cleave or interfere with platelet adhesive proteins such as vWF, fibrinogen and collagen, and cleave or interfere with platelet receptors such as GPVI, alpha2beta1, GPIb, GPIX, and GPIIbIIIa that result in platelet aggregation defect. SVMPs induce cancer cell line to form morphological changes and apoptosis in vitro concordant with skin necrosis after snakebite in some cases. These local effects caused by SVMPs have no certain treatments, even with commercial anti-venom. SVMPs researches are focusing on their inhibitors, measurement and replacement of blood coagulation factor defects, or anti-cancer drug.

Clinical effects and antivenom use for snake bite victims treated at three US hospitals in Afghanistan.

OBJECTIVE: Annually, more than 100,000 US and international military and civilian personnel work in Afghanistan within terrain harboring venomous snakes. Current literature insufficiently supports Afghan antivenom treatment and stocking guidelines. We report the clinical course and treatments for snakebite victims presenting to US military hospitals in Afghanistan. METHODS: All snakebite victims presenting to 3 US military emergency departments between July 2010 and August 2011 in northern and southern Afghanistan were examined via chart review. Case information included patient demographics, snake description, bite details and complications, laboratory results, antivenom use and adverse effects, procedures performed, and hospital course. RESULTS: Of 17 cases, median patient age was 20 years (interquartile range [IQR], 12-30), 16 were male, and 82% were Afghans. All bites were to an extremity, and median time to care was 2.8 hours (IQR, 2-5.8). On arrival, 8 had tachycardia and none had hypotension or hypoxia. A viper was implicated in 5 cases. Ten cases received at least 1 dose of polyvalent antivenom, most commonly for coagulopathy, without adverse effects. Six received additional antivenom, 6 had an international normalized ratio (INR) > 10, and none developed delayed coagulopathy. Three received blood transfusions. Hospital stay ranged from 1 to 4 days. None required vasopressors, fasciotomy, or other surgery, and none died. All had resolution of marked coagulopathies and improved swelling and pain on discharge. CONCLUSIONS: We report the largest series of snake envenomations treated by US physicians in Afghanistan. Antivenom was tolerated well with improvement of coagulopathy and symptoms. All patients survived with minimal advanced interventions other than blood transfusion.

The snake venom rhodocytin from Calloselasma rhodostoma- a clinically important toxin and a useful experimental tool for studies of C-type lectin-like receptor 2 (CLEC-2).

The snake venom, rhodocytin, from the Malayan viper, Calloselasma rhodostoma, and the endogenous podoplanin are identified as ligands for the C-type lectin-like receptor 2 (CLEC-2). The snakebites caused by Calloselasma rhodostoma cause a local reaction with swelling, bleeding and eventually necrosis, together with a systemic effect on blood coagulation with distant bleedings that can occur in many different organs. This clinical picture suggests that toxins in the venom have effects on endothelial cells and vessel permeability, extravasation and, possibly, activation of immunocompetent cells, as well as effects on platelets and the coagulation cascade. Based on the available biological studies, it seems likely that ligation of CLEC-2 contributes to local extravasation, inflammation and, possibly, local necrosis, due to microthrombi and ischemia, whereas other toxins may be more important for the distant hemorrhagic complications. However, the venom contains several toxins and both local, as well as distant, symptoms are probably complex reactions that cannot be explained by the effects of rhodocytin and CLEC-2 alone. The in vivo reactions to rhodocytin are thus examples of toxin-induced crosstalk between coagulation (platelets), endothelium and inflammation (immunocompetent cells). Very few studies have addressed this crosstalk as a part of the pathogenesis behind local and systemic reactions to Calloselasma rhodostoma bites. The author suggests that detailed biological studies based on an up-to-date methodology of local and systemic reactions to Calloselasma rhodostoma bites should be used as a hypothesis-generating basis for future functional studies of the CLEC-2 receptor. It will not be possible to study the effects of purified toxins in humans, but the development of animal models (e.g., cutaneous injections of rhodocytin to mimic snakebites) would supplement studies in humans.

Acute pituitary insufficiency and hypokalaemia following envenoming by Russell's viper (Daboia russelii) in Sri Lanka: Exploring the pathophysiological mechanisms.

Russell's viper envenoming is associated with a high incidence of morbidity and mortality. Hypopituitarism following envenoming by Russell's vipers is a well recognized sequel in Burma and parts of India but has been reported only once in Sri Lanka. Hypokalaemia following envenoming by Russell's viper has not been described. Here we describe the association of acute pituitary insufficiency and hypokalaemia following Russell's viper envenoming in Sri Lanka and review the literature in order to understand its pathophysiological basis. A previously healthy 21-year-old man was envenomed by a Russell's viper and treated with antivenom. Ten hours after the bite, he developed persistent hypotension, which responded promptly to intravenous dexamethasone. His hormone profiles were consistent with hypocortisolism secondary to acute pituitary insufficiency. He also developed hypokalaemia. Analysis of urine and serum electrolytes suggested redistribution of potassium in to the cells rather than renal loss. Hypotension and hypoglycaemic coma are life-threatening manifestations of acute pituitary insufficiency. Therefore prompt steroid administration in these setting is life saving. Awareness of these complications among physicians would help to make prompt diagnosis and initiate immediate life saving treatment.

Tityus zulianus venom induces massive catecholamine release from PC12 cells and in a mouse envenomation model.

Scorpion envenomation is a public health problem in Venezuela, mainly produced by Tityus discrepans (TD) and Tityus zulianus (TZ). Accidents by these two species differ clinically. Thus, TZ envenomation is associated with high mortality in children due to cardiopulmonary disorders, as a result of, excessive amounts of plasma catecholamines (Epinephrine) release from adrenal medulla, probably via the voltage-gated sodium-channel activated by specific scorpion toxins. This Epi release is, in part responsible, for some of the envenomation clinical consequences, resembling those described for patients presenting catecholamine-releasing tumors (pheochromocytoma). In this work, BALB/c mice and rat pheochromocytoma-derived PC12 cells were used to provide in vivo and in vitro models, respectively, on which the basis for the TZ-mediated catecholamine release mechanism could be elucidated. In mice, TZ venom increased, at 1h post-injection, the Epi plasma levels in 4000%, which remained elevated for 24h. A significant rise in plasma levels of the catecholamine catabolite 3-Methoxy-4-Hydroxy-Phenyl-Glycol (MHPG) was also observed. In [(3)H]dopamine-loaded PC12 cells, TZ venom potentiated the carbamylcholine (CC)-mediated release of [(3)H]dopamine, as shown by the leftward shift in the CC-dose-response curves. Moreover, TZ venom also displayed the maximal [(3)H]dopamine releasing activity compared to TD venom, with significant reduction of the EC50 for CC. The nicotinic-acetylcholine receptor (nAChR) blocker hexamethonium induced a significant inhibition of the [(3)H]dopamine release produced by CC in PC12 cells but the TZ-elicited release of [(3)H]dopamine was 70% hexamethonium-insensitive, suggesting unidentified TZ toxins affecting other regulatory mechanisms of catecholamine secretion.

Therapeutic potential of peptides with neutralizing ability towards the venom and toxin (CaTx-I) of crotalus adamanteus.

The CaTx-I (PLA2) toxin of Crotalus adamanteus venom is responsible for most of the symptoms observed during envenomation. Synthetic peptides were designed and screened for venom (0.8 µg/ml) and CaTx-I (0.1 µM) inhibition at varying doses of the peptide (10000- 0.0001 µM) using a Cayman chemical human secretory phospholipase A2 (sPLA2, Type II) assay kit. Further, in vitro neutralization studies were evaluated by a fixed dose of peptide (1 µM) against venom (0.8 µg/ml) and toxin (0.1 µM). Among the linear peptides (PIP-18, cyclic C and PIP59-67) that showed potent neutralizing effects against the venom/toxin of C. adamanteus. PIP-18 [IC50, 1.23 µM] and cyclic C [IC50, 1.27 µM] peptides possessed the strongest inhibitory effect against CaTx-I. A fixed dose of CaTx-I (75 µg/kg) was administered intraperitoneally (i.p.) into mice followed by an i.p. injection of peptides PIP-18 and cyclic C at (6 µg/mouse), venom (150 µg/kg) and toxin CaTx-I alone served as references. Mice treated with PIP-18 and cyclic C showed a very strong neutralizing effect and markedly reduced mortality compared to the control after 24 h. The CA venom and CaTx-I injected mice showed severe toxicity after 24 h. Peptides PIP-18 and cyclic C were non-hemolytic at 100 µM. They produced a significant decrease in lipid peroxidase (LPx) and enhancement of superoxide dismutase (SOD), catalase (CAT) and Glutathione-s-transferase (GST) levels indicating their antioxidant property against venom-induced changes in mice. This study confirmed the potent snake venom neutralizing properties of peptides.

Hyponatraemia, rhabdomyolysis, alterations in blood pressure and persistent mydriasis in patients envenomed by Malayan kraits (Bungarus candidus) in southern Viet Nam.

Between 1998 and 2007, 42 patients admitted to Choray hospital, Ho Chi Minh City, and to two hospitals in adjacent regions in southern Viet Nam brought the Malayan kraits (Bungarus candidus) that had been responsible for biting them. Half of the patients had been bitten while they were asleep. Fang marks and numbness were the only local features of the bites. Common signs of neurotoxic envenoming included bilateral ptosis, persistently dilated pupils, limb weakness, breathlessness, hypersalivation, dysphonia and dysphagia. Thirty patients (71.4%) required endotracheal intubation of whom all but one were mechanically ventilated. Fourteen patients (33.3%) developed hypertension, 13 (31.0%) shock, 31 (73.8%) hyponatraemia (plasma sodium concentration < 130 mEq/l) and 30 (71.4%) showed evidence of mild rhabdomyolysis (peak plasma creatine kinase concentration 1375 +/- 140 micro/l). None developed acute kidney injury. All the patients were treated with a new monospecific B. candidus antivenom. There were no fatalities. Hyponatraemia has been reported previously in victims of Chinese kraits (Bungarus multicinctus) in northern Viet Nam and rhabdomyolysis in patients envenomed by B. niger in Bangladesh. These features of envenoming pose new problems for the management of krait bite cases in South east Asia and should stimulate a search for the causative venom toxins.

Snake venomics and antivenomics of Crotalus durissus subspecies from Brazil: assessment of geographic variation and its implication on snakebite management.

We report the comparative proteomic and antivenomic characterization of the venoms of subspecies cascavella and collilineatus of the Brazilian tropical rattlesnake Crotalus durissus. The venom proteomes of C. d. collilineatus and C. d. cascavella comprise proteins in the range of 4-115 kDa belonging to 9 and 8 toxin families, respectively. Collilineatus and cascavella venoms contain 20-25 main toxins belonging to the following protein families: disintegrin, PLA(2), serine proteinase, cysteine-rich secretory protein (CRISP), vascular endothelial growth factor-like (VEGF), L-amino acid oxidase, C-type lectin-like, and snake venom metalloproteinase (SVMP). As judged by reverse-phase HPLC and mass spectrometry, cascavella and collilineatus share about 90% of their venom proteome. However, the relative occurrence of the toxin families departs among the two C. durissus subspecies venoms. The most notable difference is the presence of the myotoxin crotamine in some C. d. collilineatus specimens (averaging 20.8% of the total proteins of pooled venom), which is absent in the venom of C. d. cascavella. On the other hand, the neurotoxic PLA(2) crotoxin represents the most abundant protein in both C. durissus venoms, comprising 67.4% of the toxin proteome in C. d. collilineatus and 72.5% in C. d. cascavella. Myotoxic PLA(2)s are also present in the two venoms albeit in different relative concentrations (18.1% in C. d. cascavella vs. 4.6% in C. d. collilineatus). The venom composition accounts for the clinical manifestations caused by C. durissus envenomations: systemic neurotoxicity and myalgic symptoms and coagulation disturbances, frequently accompanied by myoglobinuria and acute renal failure. The overall compositions of C. d. subspecies cascavella and collilineatus venoms closely resemble that of C. d. terrificus, supporting the view that these taxa can be considered geographical variations of the same species. Pooled venom from adult C.d. cascavella and neonate C.d. terrificus lack crotamine, whereas this skeletal muscle cell membrane depolarizing inducing myotoxin accounts for approximately 20% of the total toxins of venom pooled from C.d. collilineatus and C.d. terrificus from Southern Brazil. The possible relevance of the observed venom variability among the tropical rattlesnake subspecies was assessed by antivenomics using anti-crotalic antivenoms produced at Instituto Butantan and Instituto Vital Brazil. The results revealed that both antivenoms exhibit impaired immunoreactivity towards crotamine and display restricted ( approximately 60%) recognition of PLA(2) molecules (crotoxin and D49-myotoxins) from C. d. cascavella and C. d. terrificus venoms. This poor reactivity of the antivenoms may be due to a combination of factors: on the one hand, an inappropriate choice of the mixture of venoms for immunization and, on the other hand, the documented low immunogenicity of PLA(2) molecules. C. durissus causes most of the lethal snakebite accidents in Brazil. The implication of the geographic variation of venom composition for the treatment of bites by different C. durissus subspecies populations is discussed.

Isolation and characterization of a serine proteinase with thrombin-like activity from the venom of the snake Bothrops asper

A serine proteinase with thrombin-like activity was isolated from the venom of the Central American pit viper Bothrops asper. Isolation was performed by a combination of affinity chromatography on aminobenzamidine-Sepharose and ion-exchange chromatography on DEAE-Sepharose. The enzyme accounts for approximately 0.13 percent of the venom dry weight and has a molecular mass of 32 kDa as determined by SDS-PAGE, and of 27 kDa as determined by MALDI-TOF mass spectrometry. Its partial amino acid sequence shows high identity with snake venom serine proteinases and a complete identity with a cDNA clone previously sequenced from this species. The N-terminal sequence of the enzyme is VIGGDECNINEHRSLVVLFXSSGFL CAGTLVQDEWVLTAANCDSKNFQ. The enzyme induces clotting of plasma (minimum coagulant dose = 4.1 µg) and fibrinogen (minimum coagulant dose = 4.2 µg) in vitro, and promotes defibrin(ogen)ation in vivo (minimum defibrin(ogen)ating dose = 1.0 µg). In addition, when injected intravenously in mice at doses of 5 and 10 µg, it induces a series of behavioral changes, i.e., loss of the righting reflex, opisthotonus, and intermittent rotations over the long axis of the body, which closely resemble the `gyroxin-like' effect induced by other thrombin-like enzymes from snake venoms.

Adder bites. A report of 68 cases.

BACKGROUND AND AIMS: The adder (Vipera Berus) is the only venomous snake that exists naturally in Scandinavia. The aim of this study is to estimate the severity of adder bites, to form a general picture of symptoms of bites and to find out how effective the present treatment methods of adder bites are. MATERIAL AND METHODS: 68 true adder bites treated in Turku University Hospital during the years 1995-2000 were reviewed retrospectively. RESULTS: There were no deaths in this material. A bite caused severe symptoms to 10% of the patients. The symptoms were moderate in 21%, mild in 34% and minor in 35% of the cases. Children under 10 years were the proportionally biggest age group and severe poisonings were most frequent among small children. Rapidly progressive oedema, gastrointestinal symptoms, hypotension and early leucocytosis were signs of more severe poisonings. Antivenom therapy with specific ovine Fab antivenom proved to be an effective and safe treatment in severe poisonings. CONCLUSIONS: An adder bite may also cause severe symptoms for adults. All patients should be observed at least few hours after the bite and parental fluid therapy should be started at an early stage. In the treatment of severe poisonings an antivenom therapy should be considered. Rapidly progressive symptoms and early leucocytosis may serve as a warning signal for higher probability of severe reactions.

Ophidian envenomation strategies and the role of purines.

Snake envenomation employs three well integrated strategies: prey immobilization via hypotension, prey immobilization via paralysis, and prey digestion. Purines (adenosine, guanosine and inosine) evidently play a central role in the envenomation strategies of most advanced snakes. Purines constitute the perfect multifunctional toxins, participating simultaneously in all three envenomation strategies. Because they are endogenous regulatory compounds in all vertebrates, it is impossible for any prey organism to develop resistance to them. Purine generation from endogenous precursors in the prey explains the presence of many hitherto unexplained enzyme activities in snake venoms: 5'-nucleotidase, endonucleases (including ribonuclease), phosphodiesterase, ATPase, ADPase, phosphomonoesterase, and NADase. Phospholipases A(2), cytotoxins, myotoxins, and heparinase also participate in purine liberation, in addition to their better known functions. Adenosine contributes to prey immobilization by activation of neuronal adenosine A(1) receptors, suppressing acetylcholine release from motor neurons and excitatory neurotransmitters from central sites. It also exacerbates venom-induced hypotension by activating A(2) receptors in the vasculature. Adenosine and inosine both activate mast cell A(3) receptors, liberating vasoactive substances and increasing vascular permeability. Guanosine probably contributes to hypotension, by augmenting vascular endothelial cGMP levels via an unknown mechanism. Novel functions are suggested for toxins that act upon blood coagulation factors, including nitric oxide production, using the prey's carboxypeptidases. Leucine aminopeptidase may link venom hemorrhagic metalloproteases and endogenous chymotrypsin-like proteases with venom L-amino acid oxidase (LAO), accelerating the latter. The primary function of LAO is probably to promote prey hypotension by activating soluble guanylate cyclase in the presence of superoxide dismutase. LAO's apoptotic activity, too slow to be relevant to prey capture, is undoubtedly secondary and probably serves principally a digestive function. It is concluded that the principal function of L-type Ca(2+) channel antagonists and muscarinic toxins, in Dendroaspis venoms, and acetylcholinesterase in other elapid venoms, is to promote hypotension. Venom dipeptidyl peptidase IV-like enzymes probably also contribute to hypotension by destroying vasoconstrictive peptides such as Peptide YY, neuropeptide Y and substance P. Purines apparently bind to other toxins which then serve as molecular chaperones to deposit the bound purines at specific subsets of purine receptors. The assignment of pharmacological activities such as transient neurotransmitter suppression, histamine release and antinociception, to a variety of proteinaceous toxins, is probably erroneous. Such effects are probably due instead to purines bound to these toxins, and/or to free venom purines.

Antagonization of TNF attenuates systemic hemodynamic manifestations of envenomation in a rat model of Vipera aspis snakebite.

OBJECTIVES: Tumor necrosis factor (TNF) has been reported as a mediator of local tissue injury following snake envenomation in an intact rat model. We investigated whether systemic release of TNF occurs following Vipera aspis envenomation. We further analyzed the possible connection between envenomation-related hemodynamic depression and TNF antagonization (TNF antibodies or soluble TNF receptor). DESIGN: A prospective, randomized, controlled experimental study using a rat model for snake envenomation. SETTINGS: A medical university hospital research laboratory. INTERVENTION: Eighty rats (300-400 g) were divided into four groups (n = 20): control and three experimental groups. Intramuscular injection of V. asis 500 microg/kg was administered to the three experimental groups: venom only (group 1), venom and 40 microg anti-TNF antibodies (group 2), venom and 250 microg soluble TNF receptor (p55-R; group 3). Hemodynamic parameters were monitored up to 4 h following venom injection. MEASUREMENTS AND RESULTS: A significant hemodynamic deterioration (reduction in heart rate and blood pressure) occurred 30 min following venom injection in group 1 compared to groups 2 and 3, where hemodynamic parameters remained stable throughout the 4 h observation period. Serum levels of TNF were detected 15 min after venom injection and peaked after 2 h at 485+/-12 pg/ml. CONCLUSIONS: The hemodynamic consequences of intramuscular injection of V. aspis venom can be blunted in a rat by systemic antagonization of TNF activity prior to venom injection. The poisonous hemodynamic effects of the V. aspis venom might be caused by systemic release of TNF.

Xanthine oxidase and tumor necrosis factor alpha: possible mediators of remote tissue injury after viper envenomation.

BACKGROUND: Tumor necrosis factor is associated with various local and systemic inflammatory sequelae following snakebite. Xanthine oxidase is a principal mediator of remote tissue injury (e.g., lungs, heart, liver). OBJECTIVE: To investigate in a snakebite-like animal model the as yet unexplored role of TNF and XO in mediating organ damage following snakebite. METHODS: Sprague-Dawley rats were injected intramuscularly with a non-lethal 500 micrograms/kg dose of Vipera aspis venom (n = 10) or saline (n = 10). Blood pressure and heart rate were continuously monitored, TNF-alpha was measured in the blood, and total XO + xanthine dehydrogenase activity was assessed in various tissues. Lung histology and permeability indices were analyzed. RESULTS: Venom injection caused a significant (P < 0.05) reduction in both heart rate and invasive arterial pressure. The blood circulating TNF levels were significantly higher in the intoxicated group (P < 0.05 vs. saline group), with changes seen at 30 minutes from intoxication in both groups. Total XO + XDH activity in the kidney, lung and liver of the venom-injected group was significantly (P < 0.05) higher than in the saline group, while the activity in the heart was similar. CONCLUSIONS: The mediation of remote organ and hemodynamic changes following intramuscular injection of a non-lethal dose of Vipera aspis venom can be attributed partly to TNF and partly to XO. More research is needed to better understand the role of either compound and the time frame of their activity before specific antagonists can be introduced for snakebite management.