Viperidae Snakes Research Articles

Clinical and Laboratory Parameters Associated with Acute Kidney Injury in Viper Envenomed Cases

Viper species are distributed allover Egypt. Venomous bites by Viperidae snakes are associated with local and systemic manifestations and may be exacerbated by the development of acute kidney injury (AKI). THE AIM of the study was to assess acute renal injury in cases of envenomations by locally prevalent vipers as regards incidence, clinical and laboratory parameters and final outcome. METHODS: The current study was conducted on all patients, of both sex, admitted in Poison Control Center of Ain Shams University hospitals following envenomation by Viperidae snakes during 2014, 2015, and 2016. Diagnosis was based on history of snake bite with suggestive clinical data. Recorded data included patient characteristics (age, gender, delay time), vital data (heart rate, blood pressure), presence of local signs, bleeding manifestations, laboratory parameters (INR, platelet count, hemoglobin level, BUN and serum creatinine), number of antivenom vials used , duration of hospital stay and survival. Cases were sub-grouped to group I with AKI and group II without AKI. RESULTS: A total of 120 cases of venomous bites by Viperidae snakes were recorded during the study period with mortality of 4.2%. Cases were predominantly males with mean age of 35 +/-14.7years. A subset of 5.8% cases developed AKI which statistically was related to older age, longer delay time, increased incidence of bleeding manifestations and tachycardia, higher values of INR, serum creatinine, and blood urea nitrogen, lower platelet count, higher number of used antivenom vials and longer duration of hospital stay. Gender, hypotension, presence of local manifestations and hemoglobin level were insignificant among AKI. Mortality among AKI cases was statistically linked to old age, prolonged delay time, increased incidence of bleeding manifestations, higher INR values, low platelet count and low hemoglobin level and increased number of used antivenom vials and duration of hospital stay. The incidence of tachycardia, hypotension and local manifestations, serum creatinine and blood urea nitrogen levels were not statistically different among non- survivors. CONCLUSION: Acute renal injury may complicate the course of viper envenomations. Venom hemotoxicity is related to morbidity and mortality especially with older age and longer time between bite to antivenom therapy.

A study of snakebite envenomation cases admitted to egyptian national poisoning center

Introduction: Snakebite is an Egyptian health problem since ancient Egypt. Meanwhile, there is still no controlled geographical and medical studies on locally prevalent snake family intoxication. Aim and Methods: The present study aimed to investigate local snakebites presentations, management, prognosis, and the effect of the polyvalent antivenom, locally produced by the Holding Company for Biological Products and Vaccines (VACSERA) through the year 2015. Results: A total of 87 snakebites caused by venomous and nonvenomous species were recorded. Most cases were middle-aged males. Most cases presented in summer and in the evening time. Two major groups of venomous Egyptian snakes were identified, Viperidae and Elapidae species, based on history, characteristic symptoms, and laboratory findings. Most snakebites (56 cases) were reported to be nonvenomous bites (64.4%). Twenty-one cases (24.1%) of snakebites were reported to be venomous bites by Elapidae snakes and 10 cases (11.5%) were reported to be venomous bites by Viperidae snakes. Antivenom was administered before referral to 37 (42.5%) of cases, and 19 only of them were victims of venomous snakes. Thirty-six (41.3%) patients received antivenom during admission including all cases of the venomous bites and 8.9% of nonvenomous bites' cases. Conclusion: Patients who had moderate or severe symptoms were effectively treated with VACSERA's polyvalent antivenom, with doses related to the severity grading and snake species identification. Additional antivenom doses were repeated on the bases of the clinical condition. Many snakebite victims referred from primary health centers received inadequate or nonnecessary doses of antivenom. No cases of anaphylaxis were recorded. There were no mortalities with current National Center for Clinical and Environmental Toxicology's protocol of treatment.

Soluble P-selectin rescues viper venom-induced mortality through anti-inflammatory properties and PSGL-1 pathway-mediated correction of hemostasis.

Venomous snakebites are lethal and occur frequently worldwide each year, and receiving the antivenom antibody is currently the most effective treatment. However, the specific antivenom might be unavailable in remote areas. Snakebites by Viperidae usually lead to hemorrhage and mortality if untreated. In the present study, challenges of rattlesnake (Crotalus atrox) venom markedly increased the circulating soluble P-selectin (sP-sel) level, but not P-selectin (P-sel, Selp−/−) mutants, in wild-type mice. Because sP-sel enhances coagulation through the P-selectin ligand 1 (PSGL-1, Selplg) pathway to produce tissue factor–positive microparticles, we hypothesized that increasing the plasma sP-sel level can be a self-rescue response in hosts against snake venom–mediated suppression of the coagulation system. Confirming our hypothesis, our results indicated that compared with wild-type mice, Selp−/− and Selplg−/− mice were more sensitive to rattlesnake venom. Additionally, administration of recombinant sP-sel could effectively reduce the mortality rate of mice challenged with venoms from three other Viperidae snakes. The antivenom property of sP-sel is associated with improved coagulation activity in vivo. Our data suggest that the elevation of endogenous sP-sel level is a self-protective response against venom-suppressed coagulation. The administration of recombinant sP-sel may be developed as a new strategy to treat Viperidae snakebites.

Preclinical efficacy against toxic activities of medically relevant Bothrops sp. (Serpentes: Viperidae) snake venoms by a polyspecific antivenom produced in Mexico

The assessment of the preclinical neutralizing ability of antivenoms in Latin America is necessary to determine their scope of efficacy. This study was aimed at analyzing the neutralizing efficacy of a polyspecific bothropic-crotalic antivenom manufactured by BIRMEX in Mexico against lethal, hemorrhagic, defibrinogenating and in vitro coagulant activities of the venoms of Bothrops jararaca (Brazil), B. atrox (Perú and Colombia), B. diporus (Argentina), B. mattogrossensis (Bolivia), and B. asper (Costa Rica). Standard laboratory tests to determine these activities were used. In agreement with previous studies with bothropic antivenoms in Latin America, a pattern of cross-neutralization of heterologous venoms was observed. However, the antivenom had low neutralizing potency against defibrinogenating effect of the venoms of B. atrox (Colombia) and B. asper (Costa Rica), and failed to neutralize the in vitro coagulant activity of the venom of B. asper (Costa Rica) at the highest antivenom/venom ratio tested. It is concluded that, with the exception of coagulant and defibrinogenating activities of B. asper (Costa Rica) venom, this antivenom neutralizes toxic effects of various Bothrops sp venoms. Future studies are necessary to assess the efficacy of this antivenom against other viperid venoms.

A comparison of five Korean snake species' reproductive organ sizes, Oocatochus rufodorsatus and Rhabdophis tigrinus in Colubridae and Gloydius saxatilis, G. brevicaudus and G. ussuriensis in Viperidae

Characteristics of snake reproductive organs that are relatively less affected by external environmental conditions can be used as an important means of classification; additionally, such characteristics can provide useful information on a spe cies’ reproductive system. In this study, we compared the testis weights, hemipenis lengths and retractor muscle lengths of male Oocatochus rufodorsatus and Rhabdophis tigrinus in Colubridae and Gloydius saxatilis, G. brevicaudus and G. ussuriensis in Viperidae. The snake snout-vent lengths (SVLs) were positively related to the three reproductive organ sizes, but the body weight only exhibited a positive relationship with the testis weight. The three organs did not significantly differ on the left and right sides. The relative testis weights and retractor muscle lengths (divided by the body weight and SVL, respectively) of the Colubridae snakes were greater than for the Viperidae snakes, but the relative hemipenis lengths (divided by SVL) did not differ between the two groups. The relative testis weight of G. saxatilis and the relative retractor muscle lengths of the Viperidae snakes were smaller compared with the Colubridae snakes. The relative hemipenis length of O. rufodorsatus was greater than for R. tigrinus, G. saxatilis and G. brevicaudus. Additional comparisons were not significant. Our results may facilitate further studies on hemipenial morphology and mating competition in Korean snakes. This is the first study on Korean snake reproductive organs.

Endocannabinoid signaling mechanisms in the substantia nigra pars reticulata modulate GABAergic nigrotectal pathways in mice threatened by urutu-cruzeiro venomous pit viper

The substantia nigra pars reticulata (SNpr) is rich in γ-aminobutyric acid (GABA)-ergic neurons and connected to the mesencephalic tectum (MT) structures, such as the superior colliculus and dorsal periaqueductal gray matter. The SNpr presents a high density of cannabinoid receptors (CBRs), suggesting a possible regulatory role that is played by endocannabinoids (eCBs) in the ventral mesencephalon. The present study investigated the involvement of SNpr eCB mechanisms in nigrotectal pathways in the expression of defensive behavior associated with instinctive fear and panic reactions in mice that are confronted with the venomous Viperidae snake Bothrops alternatus. The localization of CB1 receptors (CB1RS) and synaptophysin glycoprotein in the SNpr was also evaluated. Administration of the GABAA receptor antagonist bicuculline in the MT increased defensive responses to the snake that are related to panic, such as freezing and non-oriented escape reactions, sometimes toward the snake itself. Mice that were pretreated with anandamide (5 or 50pmol) in the SNpr, followed by an injection of physiological saline or bicuculline in the MT, exhibited significant decreases in the expression of alertness, freezing, and escape responses. Immunofluorescence showed the presence of fibers that were rich in CB1RS and synaptophysin in the SNpr, indicating that these receptors appear to be located mainly in presynaptic terminals in the striatonigral pathway. These findings suggest that eCB mechanisms in the SNpr facilitate the activity of nigrotectal GABAergic pathways, modulating the activity of striatonigral links during the elaboration and organization of innate fear and panic-like responses in threatening situations.

Novel antagonists of nicotinic acetylcholine receptors--proteins from venoms of Viperidae snakes.

Novel antagonists of nicotinic acetylcholine receptors--proteins from venoms of Viperidae snakes.

Does defensive posture increase mimetic fidelity of caterpillars with eyespots to their putative snake models?

Abstract Organisms often evolve behaviours that increase or reinforce the protection from predators afforded by their morphological defences. For example, mimetic animals may adopt postures or locomotory behaviours that emulate a characteristic feature of their model to increase predator deception. Caterpillars with eyespots are thought to mimic snakes, and when threatened many of these caterpillars adopt a posture that appears to enhance this resemblance. Herein we evaluate the quantitative strength of evidence of behavioural mimicry in the caterpillars of 14 species by comparing how closely a series of putative snake-mimicking caterpillars resemble snakes while at rest and when threatened. Specifically, we quantified the head morphology and eye position of a range of snake species, as well as the shape of the apparent head (i.e. anterior body segments) and position of eyespots in caterpillars resting or in their defensive posture. This allowed us to objectively examine evidence for an increased resemblance to either snakes generally, or to Viperidae snakes specifically, upon adopting the defensive posture. Widening the anterior body segments during the defensive posture typically made caterpillars appear more viper-like as opposed to more snake-like in general. Enhanced resemblance to vipers upon mounting the defensive posture was apparent only from the dorsal view. Laterally, caterpillars more closely resembled snakes in the resting posture and shifting to the defensive posture instead reduced mimetic fidelity. Overall we found evidence for behavioural mimicry in all 14 species examined. We highlight that objectively quantifying mimetic fidelity can help identify key features involved in deception.

Antitumoral Potential of Tunisian Snake Venoms Secreted Phospholipases A2

Phospholipases type A2 (PLA2s) are the most abundant proteins found in Viperidae snake venom. They are quite fascinating from both a biological and structural point of view. Despite similarity in their structures and common catalytic properties, they exhibit a wide spectrum of pharmacological activities. Besides being hydrolases, secreted phospholipases A2 (sPLA2) are an important group of toxins, whose action at the molecular level is still a matter of debate. These proteins can display toxic effects by different mechanisms. In addition to neurotoxicity, myotoxicity, hemolytic activity, antibacterial, anticoagulant, and antiplatelet effects, some venom PLA2s show antitumor and antiangiogenic activities by mechanisms independent of their enzymatic activity. This paper aims to discuss original finding against anti-tumor and anti-angiogenic activities of sPLA2 isolated from Tunisian vipers: Cerastes cerastes and Macrovipera lebetina, representing new tools to target specific integrins, mainly, α5β1 and αv integrins.

The complete mitochondrial DNA sequence of Crotalus horridus (timber rattlesnake)

The complete mitogenome of the timber rattlesnake (Crotalus horridus) was completed using Sanger sequencing. It is 17,260 bp with 13 protein-coding genes, 21 tRNAs, two rRNAs and two control regions. Gene synteny is consistent with other snakes with the exception of a missing redundant tRNASer. This mitogenome should prove to be a useful addition of a well-known member of the Viperidae snake family.

Venomous Snakebites

More than 5 million people are bitten by venomous snakes annually and more than 100 000 of them die. In Europe, one person dies due to envenomation every 3 years. There is only one venomous snake species in Lithuania – the common adder (Vipera berus) – which belongs to the Viperidae family; however, there are some exotic poisonous snakes in the zoos and private collections, such as those belonging to the Elapidae family (cobras, mambas, coral snakes, etc.) and the Crotalidae subfamily of the Viperidae family (pit vipers, such as rattlesnakes). Snake venom can be classified into hemotoxic, neurotoxic, necrotoxic, cardiotoxic, and nephrotoxic according to the different predominant effects depending on the family (i.e., venom of Crotalidae and Viperidae snakes is more hemotoxic and necrotoxic, whereas venom of Elapidae family is mainly neurotoxic). The intoxication degree is estimated according to the appearance of these symptoms: 1) no intoxication (“dry” bite); 2) mild intoxication (local edema and pain); 3) moderate intoxication (pain, edema spreading out of the bite zone, and systemic signs); 4) severe intoxication (shock, severe coagulopathy, and massive edemas). This topic is relevant because people tend to make major mistakes providing first aid (e.g., mouth suction, wound incision, and application of ice or heat). Therefore, this article presents the essential tips on how first aid should be performed properly according to the “Guidelines for the Management of Snake-Bites” by the World Health Organization (2010). Firstly, the victim should be reassured. Rings or other things must be removed preventing constriction of the swelling limb. Airway/breathing must be maintained. The bitten limb should be immobilized and kept below heart level to prevent venom absorption and systemic spread. Usage of pressure bandage is controversial since people usually apply it improperly. Incision, mouth suction, or excision should not be performed; neither a tourniquet nor ice or heat should be applied. A doctor must monitor respiratory rate, blood pressure, heart rate, renal function, fluid balance, and coagulation status. The only specific treatment method is antivenin – serum with antibodies against antigens of snake venom. Antivenins against pit vipers used in the United States are Antivenin Crotalidae Polyvalent (ACP) and a more purified and hence causing less adverse reactions – Crotalidae Polyvalent Immune Fab (CroFab). In Europe, a polyvalent antiserum against Viperidae family snakes (including the common adder) can be used. Antivenins often may cause severe hypersensitivity reactions because of their protein nature. The bite of the common adder (the only poisonous snake in such countries as Lithuania and Great Britain) relatively rarely results in death; thus, considering the risk of dangerous reactions the antivenin causes itself, the usage of it is recommended to be limited only to life-threatening conditions.

Striatal direct pathway modulates response time in execution of conditional discrimination

The substantia nigra pars reticulata (SNpr) is rich in γ-aminobutyric acid (GABA)-ergic neurons and connected to the mesencephalic tectum (MT) structures, such as the superior colliculus and dorsal periaqueductal gray matter. The SNpr presents a high density of cannabinoid receptors (CBRs), suggesting a possible regulatory role that is played by endocannabinoids (eCBs) in the ventral mesencephalon. The present study investigated the involvement of SNpr eCB mechanisms in nigrotectal pathways in the expression of defensive behavior associated with instinctive fear and panic reactions in mice that are confronted with the venomous Viperidae snake Bothrops alternatus. The localization of CB1 receptors (CB1RS) and synaptophysin glycoprotein in the SNpr was also evaluated. Administration of the GABAA receptor antagonist bicuculline in the MT increased defensive responses to the snake that are related to panic, such as freezing and non-oriented escape reactions, sometimes toward the snake itself. Mice that were pretreated with anandamide (5 or 50 pmol) in the SNpr, followed by an injection of physiological saline or bicuculline in the MT, exhibited significant decreases in the expression of alertness, freezing, and escape responses. Immunofluorescence showed the presence of fibers that were rich in CB1RS and synaptophysin in the SNpr, indicating that these receptors appear to be located mainly in presynaptic terminals in the striatonigral pathway. These findings suggest that eCB mechanisms in the SNpr facilitate the activity of nigrotectal GABAergic pathways, modulating the activity of striatonigral links during the elaboration and organization of innate fear and panic-like responses in threatening situations.

Venom peptide analysis of Vipera ammodytes meridionalis (Viperinae) and Bothrops jararacussu (Crotalinae) demonstrates subfamily-specificity of the peptidome in the family Viperidae

Snake venom peptidomes are valuable sources of pharmacologically active compounds. We analyzed the peptidic fractions (peptides with molecular masses < 10,000 Da) of venoms of Vipera ammodytes meridionalis (Viperinae), the most toxic snake in Europe, and Bothrops jararacussu (Crotalinae), an extremely poisonous snake of South America. Liquid chromatography/mass spectrometry (LC/MS), direct infusion electrospray mass spectrometry (ESI-MS) and matrix-assisted desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) were applied to characterize the peptides of both snake venoms. 32 bradykinin-potentiating peptides (BPPs) were identified in the Crotalinae venom and their sequences determined. 3 metalloproteinase inhibitors, 10 BPPs and a Kunitz-type inhibitor were observed in the Viperinae venom peptidome. Variability in the C-terminus of homologous BPPs was observed, which can influence the pharmacological effects. The data obtained so far show a subfamily specificity of the venom peptidome in the Viperidae family: BPPs are the major peptide component of the Crotalinae venom peptidome lacking Kunitz-type inhibitors (with one exception) while the Viperinae venom, in addition to BPPs, can contain peptides of the bovine pancreatic trypsin inhibitor family. We found indications for a post-translational phosphorylation of serine residues in Bothrops jararacussu venom BPP (S[combining low line]QGLPPGPPIP), which could be a regulatory mechanism in their interactions with ACE, and might influence the hypotensive effect. Homology between venom BPPs from Viperidae snakes and venom natriuretic peptide precursors from Elapidae snakes suggests a structural similarity between the respective peptides from the peptidomes of both snake families. The results demonstrate that the venoms of both snakes are rich sources of peptides influencing important physiological systems such as blood pressure regulation and hemostasis. The data can be used for pharmacological and medical applications.

Amblyomma rotundatum (Koch, 1844) (Acari: Ixodidae) two-host life-cycle on Viperidae snakes

Amblyomma rotundatum is an ixodid tick that infests ectothermic animals and reproduces exclusively by parthenogenesis. This tick has been frequently reported to infest reptiles and amphibians, under natural conditions and sometimes in captivity. It was described in Brazil and several other countries of South, Central and North America. Although many studies have reported aspects of its biology, none of them has used regularly either ophidian as hosts, or controlled temperature, humidity and luminosity for parasitic stages. The objective of this experiment was to study the life cycle of A. rotundatum feeding on Viperidae snakes under room controlled conditions at 27 ± 1 °C temperature, 85 ± 10% relative humidity and 12:12 hours photoperiod for parasitic stages, and under B.O.D incubator conditions at 27 ± 1 °C temperature, 85 ± 10% relative humidity and scotophase for non-parasitic stages. The total duration of the life cycle ranged from 56 to 163 days (mean of 105 days). Two-host life cycle was observed for most of the ixodid population studied.

Synthetic Peptides Derived from the C-Terminal Region of Lys49 Phospholipase A2 Homologues from Viperidae Snake Venoms: Biomimetic Activities and Potential Applications

Lys49-phospholipase A(2) homologues constitute a large family of toxins present in the venoms of viperid snake species, which despite lacking catalytic activity, cause significant skeletal muscle necrosis. The main structural determinants of this toxic effect have been experimentally mapped to a region near their C-terminus (115-129), which combines cationic and hydrophobic/aromatic amino acid residues. Short (13-mer) synthetic peptides representing this C-terminal region can mimick several of the effects of Lys49 PLA(2) homologues. In addition to their ability to damage muscle cells, these peptides display antibacterial, antiendotoxic, antifungal, antiparasite, and antitumor activities, as well as VEGF-receptor 2 (KDR)-binding and heparin-binding properties. Modifications of their sequences have shown possibilities to enhance their effects upon prokaryotic cells, while decreasing toxicity for eukaryotic cells. This review presents an updated summary on the biomimetic actions exerted by such peptides, and highlights their potential value as molecular tools or as drug leads in diverse biomedical areas.

Autolysis at the disintegrin domain of patagonfibrase, a metalloproteinase from Philodryas patagoniensis (Patagonia Green Racer; Dipsadidae) venom

Patagonfibrase is a 57.5-kDa hemorrhagic metalloproteinase isolated from the venom of Philodryas patagoniensis (Patagonia Green Racer), a South American rear-fanged snake. Herein we demonstrate that patagonfibrase undergoes autolysis at its pH optimum (7.5) and at 37 °C, primarily producing a ∼ 32.6 kDa fragment composed of disintegrin-like and cysteine-rich domains, as identified by mass spectrometry and N-terminal sequencing. The autolysis site for production of this fragment is similar to that observed for metalloproteinases from front-fanged Viperidae snake venoms. In the presence of Ca 2+, patagonfibrase was only partially autolysed, giving rise mainly to one fragment of ∼ 52.2 kDa. In addition, calcium markedly enhanced the azocaseinolytic activity of patagonfibrase. Our findings contribute to the understanding of the structural and mechanistic bases of this family of metalloenzymes that are widely distributed among snake venoms, demonstrating that important post-translational modifications such as proteolysis can also contribute to the diversity and complexity of proteins found in rear-fanged snake venoms.

Neutralization of local and systemic toxicity of Daboia russelii venom by Morus alba plant leaf extract

Antivenom therapy is the current best therapy available for the treatment of fatal snake envenomation. However, the antivenom offers less or no protection against local effects such as extensive edema, hemorrhage, dermo-, myonecrosis and inflammation at the envenomed region. Viperidae snakes are highly known for their violent local effects and such effects have been commonly treated with plant extracts without any scientific validation in rural India. In this investigation Morus alba plant leaf extract has been studied against the Indian Vipera/Daboia russelii venom induced local and systemic effects. The extract completely abolished the in vitro proteolytic and hyaluronolytic activities of the venom. Edema, hemorrhage and myonecrotic activities were also neutralized efficiently. In addition, the extract partially inhibited the pro-coagulant activity and completely abolished the degradation of Aalpha chain of human fibrinogen. Thus, the extract processes potent antisnake venom property, especially against the local and systemic effects of Daboia russelii venom.

Interspecific variation in venom composition and toxicity of Brazilian snakes from Bothrops genus

The genus Bothrops spp. is responsible for 90% of envenomation by snakes in Brazil, and the standard treatment for snakebites is the antivenom therapy. The anti-bothropic serum produced by Butantan Institute is prepared by the hyperimmunization of horses with a pool of venoms from Bothrops alternatus, Bothrops jararaca, Bothrops jararacussu, Bothrops moojeni and Bothrops neuwiedi. In this study, the biochemical and biological characteristics of the venoms from nineteen snakes of the genus Bothrops, responsible for human accidents in Brazil, were analysed. Venoms, particularly from Crotalidae and Viperidae snakes, are rich sources of serine proteases and metalloproteases and the ability of the Brazilian anti-bothropic serum to neutralize the proteolytic activity of these venoms were also tested. The results obtained here show the existence of a large range of variation in the composition and activities in Bothrops spp. toxins and demonstrate that the anti-bothropic serum is not able to fully neutralize the toxic activities of all analysed venoms. These suggest that for the preparation of a fully effective therapeutic anti-bothropic serum, other venoms should be included in the immunization mixture.

Catalytically inactive phospholipase A2 homologue binds to vascular endothelial growth factor receptor-2 via a C-terminal loop region

VEGF (vascular endothelial growth factor) regulates neovascularization through binding to its receptor KDR (kinase insert domain-containing receptor; VEGF receptor-2). We recently identified a catalytically inactive PLA(2) (phospholipase A(2)) homologue (KDR-bp) in the venom of eastern cottonmouth (Agkistrodon piscivorus piscivorus) as a third KDR-binding protein, in addition to VEGF(165) and tissue inhibitor of metalloproteinase-3. KDR-bp binds to the extracellular domain of KDR with a K(d) of 10(-8) M, resulting in specific blockade of endothelial cell growth induced by VEGF(165). Inactive PLA(2) homologues are widely distributed in the venoms of Viperidae snakes and are known to act as myotoxins. In the present study, we demonstrated that KDR-binding ability is a common characteristic for inactive PLA(2) homologues in snake venom, but not for active PLA(2)s such as neurotoxic and platelet aggregation-modulating PLA(2)s. To understand better the KDR and KDR-bp interaction, we resolved the binding region of KDR-bp using eight synthetic peptides designed based on the structure of KDR-bp. A synthetic peptide based on the structure of the C-terminal loop region of KDR-bp showed high affinity for KDR, but other peptides did not, suggesting that the C-terminal loop region of KDR-bp is involved in the interaction with KDR. The results of the present study provide insight into the binding of inactive PLA(2) homologues to KDR, and may also assist in the design of novel anti-KDR molecules for anti-angiogenic therapy.

10.1007/s11827-008-1003-x

Snake venoms contain a vast array of toxic polypeptide components interacting with a variety of cell targets. Thus, Elapidae snake venoms contain α-neurotoxins with very high affinity for nicotinic acetylcholine receptors (nAChRs) and a few toxins able to suppress the activity of Ca2+ and K+ channels. Experimental evidence for the presence of nAChR antagonists and voltage-gated ionic channel blockers in venoms of Viperidae snakes is very scarce. In this study, effects of crude venoms of seven snake species (Vipera nikolskii, Echis multisquamatus, Gloydius saxatilis, Bitis arietans, Vipera renardi, Vipera lebetina, and Naja kaouthia) on nAChRs and voltage-gated Ca2+ channels were studied for the first time. The experiments were carried out on isolated identified neurons of the fresh-water mollusc Lymnaea stagnalis using voltage-clamp and intracellular perfusion techniques. All Viperidae snake venoms under study blocked nAChRs and voltage-gated Ca2+ channels. The potency of these venoms against nAChRs was significantly lower in comparison with N. kaouthia venom which is rich of α-neurotoxins; however, the extent of Ca2+ channel block by venoms of Viperidae snakes and N. kaouthia was similar. The data obtained suggest that Viperidae snake venoms tested in this study contain peptides with affinity both for nAChRs and for voltage-gated Ca2+ channels.