The Gaboon viper (Bitis gabonica): its biology, venom components and toxinology

A case of Western Gaboon viper (Bitis rhinoceros) envenomation: Successful treatment with South African Institute for Medical Research (SAIMR) antivenom after North American crotalid antivenom failure

We report a case of Western Gaboon viper (Bitis rhinoceros) envenomation in which the patient's symptoms progressed despite treatment with North American crotalid antivenom but improved after receiving South African Institute for Medical Research (SAIMR) polyvalent antivenom. A 59-year-old man was hospitalized after reportedly being bitten by a Gaboon viper (Bitis gabonica). On arrival, he had normal vital signs, two puncture wounds on his left hand, and edema distal to the wrist. The hospital contacted the local poison center who conveyed that crotalid antivenom would be ineffective and recommended transfer to a snakebite center for species-appropriate antivenom. However, this recommendation was disregarded. Initial laboratory tests 2 hours after envenomation revealed a platelet count of 77 x 109/L; other parameters were normal. He received six vials of crotalid antivenom (CroFab®) followed by three maintenance doses (total 12 vials). The next morning, swelling had progressed proximal to the elbow and platelets decreased to 37 x 109/L. He was subsequently transferred and received SAIMR polyvalent antivenom. Six hours later, his platelets were 130 x 109/L. The next morning, his swelling had significantly improved. He was discharged the following day. After discharge, it was discovered that the snake was a Bitis rhinoceros. Bitis gabonica and Bitis rhinoceros are popular captive snakes in the United States. Bitis rhinoceros was formerly a sub-species of B. gabonica, and they are often referred to interchangeably. Their venoms cause tissue edema, coagulopathy, and in severe cases, hemorrhage, dysrhythmias, and death. Antivenom is not widely available in the United States often necessitating patient transfer or antivenom delivery. This case addresses the question of whether crotalid antivenom, which is ubiquitous in the United States, can treat B. gabonica and B. rhinoceros envenomations and highlights the need for consultation with a poison center to facilitate administration of species-appropriate antivenom.

Real life condition evaluation of Inoserp PAN-AFRICA antivenom effectiveness in Cameroon

BACKGROUND

Snakebites is a serious public health issue but remains a neglected tropical disease. Data on antivenom effectiveness are urgently needed in Africa. We assessed effectiveness of Inoserp PAN-AFRICA (IPA), the recommended antivenom available in Cameroon.

METHODOLOGY/PRINCIPAL FINDINGS

We enrolled 447 patients presenting with snakebite in 14 health facilities across Cameroon. At presentation, cytotoxicity, coagulation troubles and neurotoxicity were graded. We administered two to four vials of antivenom to patients based on hemotoxic or neurotoxic signs. We renewed antivenom administration to patients with persistence of bleedings or neurotoxicity 2 hours after each injection. We defined early improvement as a reduction of the grade of envenomation symptoms 2 hours after first injection. Medium-term effectiveness was investigated looking at disappearance of symptoms during hospitalization. After hospital discharge, a home visit was planned to assess long-term outcomes. Between October 2019 and May 2021, we enrolled 447 (93.7%), including 72% from the savannah regions. The median [IQR] age was 25 [14-40]. Envenomation was diagnosed in 369 (82.6%) participants. The antivenom was administered to 356 patients (96.5%) of whom 256 (71.9%) received one administration. Among these patients, cytotoxic symptoms were observed in 336 (94.4%) participants, coagulation disorders in 234 (65.7%) participants and neurotoxicity in 23 (6.5%) participants. Two hours after the first administration of antivenom, we observed a decrease in coagulation disorders or neurotoxicity in 75.2% and 39.1% of patients, respectively. Complete cessation of bleedings and neurotoxicity occurred in 96% and 93% of patients within 24 hours, respectively. Sequelae have been observed in 9 (3%) patients at the home visit 15 days after hospital admission and 11 (3%) died including one before antivenom injection.

CONCLUSIONS/SIGNIFICANCE

We confirmed good effectiveness of the IPA and highlighted the rapid improvement in bleeding or neurotoxicity after the first administration. Sequential administrations of low doses of antivenom, rigorously assessed at short intervals for an eventual renewal, can preserve patient safety and save antivenom.

TRIAL REGISTRATION

NCT03326492.

Pulmonary involvement from animal toxins: the cellular mechanisms

Venomous animals and their venom have always been of human interest because, despite species differences, coevolution has made them capable of targeting key physiological components of our bodies. Respiratory failure from lung injury is one of the serious consequences of envenomation, and the underlying mechanisms are rarely discussed. This review aims to demonstrate how toxins affect the pulmonary system through various biological pathways. Herein, we propose the common underlying cellular mechanisms of toxin-induced lung injury: interference with normal cell function and integrity, disruption of normal vascular function, and provocation of excessive inflammation. Viperid snakebites are the leading cause of envenomation-induced lung injury, followed by other terrestrial venomous animals such as scorpions, spiders, and centipedes. Marine species, particularly jellyfish, can also inflict such injury. Common pulmonary manifestations include pulmonary edema, pulmonary hemorrhage, and exudative infiltration. Severe envenomation can result in acute respiratory distress syndrome. Pulmonary involvement suggests severe envenomation, thus recognizing these mechanisms and manifestations can aid physicians in providing appropriate treatment.

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.

Untangling interactions between Bitis vipers and their prey using coagulotoxicity against diverse vertebrate plasmas

Venom is a key evolutionary innovation which plays a primary role in prey subjugation by venomous snakes. However, while there is a growing body of literature indicating the composition and activity of snake venoms is under strong natural selection driven by differences in prey physiology, the majority of studies have historically focussed on the activity of snake venoms with regards only towards human or mammalian physiologies. This study aimed to use clotting assays measuring both time and strength of clotting to characterise the coagulotoxic activity of venoms from a taxonomically, morphologically, and ecologically diverse range of Bitis spp. of viperid snakes upon the plasma of model species: amphibian (Cane Toad, Rhinella marina); lizard (Blue-tongue Skink, Tiliqua scincoides); avian (Domestic Chicken, Gallus gallus); and rodent (Brown Rat, Rattus norvegicus). Significant variation in coagulotoxic activity across the different plasmas was observed between species and compared to the known affects upon human plasma. Bitis caudalis was notable in being active on all four plasmas, but in extremely divergent manners: accelerating clotting times and producing strong, stable clots upon amphibian plasma (consistent with true procoagulation); accelerating clotting time but producing weak, unstable clots upon lizard plasma (consistent with pseudo-procoagulation); delaying avian clotting time beyond machine maximum reading time (strong anticoagulation consistent with either inhibition of clotting enzymes or total destruction of fibrinogen, or both); and delaying clotting of rodent plasma (consistent with inhibition of clotting enzymes) and with only weak clots formed (consistent with destruction of fibrinogen). In contrast, the sister species B. peringueyi and B. schneideri displayed activity only upon the lizard plasma, slightly accelerating the clotting times to produce weak, unstable clots (consistent with pseudo-procoagulation). The other dwarf species, B. cornuta, displayed strong anticoagulation upon avian and rodent plasmas, delaying clotting beyond the machine maximum reading time (strong anticoagulation consistent with either inhibition of clotting enzymes or total destruction of fibrinogen, or both). In contrast, the giant species studied (B. gabonica) showed only a very weak pseudo-procoagulant activity upon lizard plasma. The wide range of variation seen within this study highlights the importance of studying venom activity on relevant models when making conclusions about the ecological role of venoms and the extreme limitation in extrapolating animal results to predict potential human clinical effects.

Cost of Manufacturing for Recombinant Snakebite Antivenoms

Snakebite envenoming is a neglected tropical disease that affects millions of people across the globe. It has been suggested that recombinant antivenoms based on mixtures of human monoclonal antibodies, which target key toxins of medically important snake venom, could present a promising avenue toward the reduction of morbidity and mortality of envenomated patients. However, since snakebite envenoming is a disease of poverty, it is pivotal that next-generation therapies are affordable to those most in need; this warrants analysis of the cost dynamics of recombinant antivenom manufacture. Therefore, we present, for the first time, a bottom-up analysis of the cost dynamics surrounding the production of future recombinant antivenoms based on available industry data. We unravel the potential impact that venom volume, abundance of medically relevant toxins in a venom, and the molecular weight of these toxins may have on the final product cost. Furthermore, we assess the roles that antibody molar mass, manufacturing and purification strategies, formulation, antibody efficacy, and potential cross-reactivity play in the complex cost dynamics of recombinant antivenom manufacture. Notably, according to our calculations, it appears that such next-generation antivenoms based on cocktails of monoclonal immunoglobulin Gs (IgGs) could be manufacturable at a comparable or lower cost to current plasma-derived antivenoms, which are priced at USD 13-1120 per treatment. We found that monovalent recombinant antivenoms based on IgGs could be manufactured for USD 20-225 per treatment, while more complex polyvalent recombinant antivenoms based on IgGs could be manufactured for USD 48-1354 per treatment. Finally, we investigated the prospective cost of manufacturing for recombinant antivenoms based on alternative protein scaffolds, such as DARPins and nanobodies, and highlight the potential utility of such scaffolds in the context of low-cost manufacturing. In conclusion, the development of recombinant antivenoms not only holds a promise for improving therapeutic parameters, such as safety and efficacy, but could possibly also lead to a more competetive cost of manufacture of antivenom products for patients worldwide.

How do morphological sharpness measures relate to puncture performance in viperid snake fangs?

It makes intuitive sense that you need a sharp tool to puncture through a tough material. The typical approach to evaluating sharpness in biological puncturing tools is to treat morphological measurements as a proxy for puncture ability. However, there are multiple approaches to measuring sharpness, and the relative influence of morphology on function remains unclear. Our goal is to determine what aspects of tip morphology have the greatest impact on puncture ability, using ( a) viper fangs and ( b) engineered punches to isolate the effects of different sharpness measures. Our results indicate that tip included angle is the strongest predictor of puncture performance in both viper fangs and engineered punches. For puncture tools with small included angles, sharpness index (based on the radius of curvature) also affects puncture ability. Finally, we found that punches serve as good predictors of fang performance at small angles and sharpness index values.

Fingerprinting snakes: paleontological and paleoecological implications of zygantral growth rings in Serpentes

We introduce a new non-destructive source of skeletochronological data with applications to species identification, associating disarticulated remains, assessing minimum number of individuals (MNI), and collection management of fossil snakes, but with potential implications for all bony vertebrates, extinct or extant. Study of a diverse sample of Recent henophidian snakes confirms that annual growth cycles (AGCs) visible on the surface of the vertebral zygantrum correspond to lines of arrested growth in osteohistological thin sections and accordingly reflect chronological age. None of the specimens considered here showed signs of remodelling of the zygantrum, suggesting that a complete, unaltered age record is preserved. We tested potential influences on AGCs with a single experimental organism, a male Bogertophis subocularis, that was raised at a controlled temperature and with constant access to mice and water. The conditions in which this individual was maintained, including that it had yet to live through a full reproductive cycle, enabled us to determine that its AGCs reflect only the annual solar cycle, and neither temperature, nor resource availability, nor energy diversion to gametogenesis could explain that it still exhibited lines of arrested growth. Moreover, growth lines in this specimen are deposited toward the end of the growth season in the fall, and not in the winter, during which this individual continued to feed and grow, even though this mid-latitude species would normally be hibernating and not growing. This suggests that growth lines are not caused by hibernation, but reflect the onset of a physiological cycle preparing Bogertophis subocularis for winter rest. That being said, hibernation and reproductive cycle could still influence the amount of time represented by an individual growth line. Growth-line number and AGC spacing-pattern, plus centrum length, are used to estimate MNI of the Early Eocene fossil snake Boavus occidentalis collected from the Willwood Formation over two field seasons during the late 19th century. We identified eight or nine individuals among specimens previously parcelled among two specimen lots collected during those expeditions.

Gaboon viper envenomation: An unexpected injury by non-indigenous snake in South Korea

In recent years, various kinds of non-indigenous snakes have become popular as domestic pets globally. If the snake is highly venomous, this would be a potentially life-threatening emergency for breeders. In such a case, the specific antidote should be administered immediately for saving the life. “Salmusa” genus (e.g. Gloydius genus) is a representative indigenous venomous snake in South Korea. Therefore, only one antidote for the “Salmusa” genus is commercially available in South Korea. The Gaboon viper (Bitis gabonica) inhabits in the rainforests of sub-Saharan Africa. Its venom is very toxic for mammals. Victims of a Gaboon viper bite could result in die unless the appropriate antidote is administered timely. We report a case of a 20-year-old male who completely recovered from a Gaboon viper envenomation after receiving “Salmusa” antivenom (Kovax^®). This report reminds us that establishing an inventory of antidotes for potential toxic non-indigenous organisms is needed to enable successful treatment of emergency situations for public health.

Venom regeneration in the centipede Scolopendra polymorpha: evidence for asynchronous venom component synthesis

Venom regeneration comprises a vital process in animals that rely on venom for prey capture and defense. Venom regeneration in scolopendromorph centipedes likely influences their ability to subdue prey and defend themselves, and may influence the quantity and quality of venom extracted by researchers investigating the venom's biochemistry. We investigated venom volume and total protein regeneration during the 14-day period subsequent to venom extraction in the North American centipede Scolopendra polymorpha. We further tested the hypothesis that venom protein components, separated by reversed-phase fast protein liquid chromatography (RP-FPLC), undergo asynchronous (non-parallel) synthesis. During the first 48 h, volume and protein mass increased linearly. Protein regeneration lagged behind volume regeneration, with 65–86% of venom volume and 29–47% of protein mass regenerated during the first 2 days. No additional regeneration occurred over the subsequent 12 days, and neither volume nor protein mass reached initial levels 7 months later (93% and 76%, respectively). Centipede body length was negatively associated with rate of venom regeneration. Analysis of chromatograms of individual venom samples revealed that 5 of 10 chromatographic regions and 12 of 28 peaks demonstrated changes in percent of total peak area (i.e., percent of total protein) among milking intervals, indicating that venom proteins are regenerated asynchronously. Moreover, specimens from Arizona and California differed in relative amounts of some venom components. The considerable regeneration of venom occurring within the first 48 h, despite the reduced protein content, suggests that predatory and defensive capacities are minimally constrained by the timing of venom replacement.

Pulmonary effects and complications of snakebites

This review is on the pulmonary complications of snakebites, which can have fatal consequences. We identified three common themes as reported in the literature regarding envenomation: generalized neuromuscular paralysis affecting airway and respiratory muscles, pulmonary edema, and pulmonary hemorrhages or thrombosis due to coagulopathy. Respiratory paralysis and pulmonary edema can be due to either elapid or viper bites, whereas pulmonary complications of coagulopathy are exclusively reported with viper bites. The evidence for each complication, timeline of appearance, response to treatment, and details of pathophysiology are discussed.

New proline-rich oligopeptides from the venom of African adders: Insights into the hypotensive effect of the venoms

BACKGROUND

The snakes from the Bitis genus are some of the most medically important venomous snakes in sub Saharan Africa, however little is known about the composition and effects of these snake venom peptides. Considering that the victims with Bitis genus snakes have exacerbate hypotension and cardiovascular disorders, we investigated here the presence of angiotensin-converting enzyme modulators on four different species of venoms.

METHODS

The peptide fractions from Bitis gabonica gabonica, Bitis nasicornis, Bitis gabonica rhinoceros and Bitis arietans which showed inhibitory activity on angiotensin-converting enzyme were subjected to mass spectrometry analysis. Eight proline-rich peptides were synthetized and their potencies were evaluated in vitro and in vivo.

RESULTS

The MS analysis resulted in over 150 sequences, out of which 32 are new proline-rich oligopeptides, and eight were selected for syntheses. For some peptides, inhibition assays showed inhibitory potentials of cleavage of angiotensin I ten times greater when compared to bradykinin. In vivo tests showed that all peptides decreased mean arterial pressure, followed by tachycardia in 6 out of 8 of the tests.

CONCLUSION

We describe here some new and already known proline-rich peptides, also known as bradykinin-potentiating peptides. Four synthetic peptides indicated a preferential inhibition of angiotensin-converting enzyme C-domain. In vivo studies show that the proline-rich oligopeptides are hypotensive molecules.

GENERAL SIGNIFICANCE

Although proline-rich oligopeptides are known molecules, we present here 32 new sequences that are inhibitors of the angiotensin-converting enzyme and consistent with the symptoms of the victims of Bitis spp, who display severe hypotension.

Variation in venom yield and protein concentration of the centipedes Scolopendra polymorpha and Scolopendra subspinipes

Venom generally comprises a complex mixture of compounds representing a non-trivial metabolic expense. Accordingly, natural selection should fine-tune the amount of venom carried within an animal's venom gland(s). The venom supply of scolopendromorph centipedes likely influences their venom use and has implications for the severity of human envenomations, yet we understand very little about their venom yields and the factors influencing them. We investigated how size, specifically body length, influenced volume yield and protein concentration of electrically extracted venom in Scolopendra polymorpha and Scolopendra subspinipes. We also examined additional potential influences on yield in S. polymorpha, including relative forcipule size, relative mass, geographic origin (Arizona vs. California), sex, time in captivity, and milking history. Volume yield was linearly related to body length, and S. subspinipes yielded a larger length-specific volume than S. polymorpha. Body length and protein concentration were uncorrelated. When considering multiple influences on volume yield in S. polymorpha, the most important factor was body length, but yield was also positively associated with relative forcipule length and relative body mass. S. polymorpha from California yielded a greater volume of venom with a higher protein concentration than conspecifics from Arizona, all else being equal. Previously milked animals yielded less venom with a lower protein concentration. For both species, approximately two-thirds of extractable venom was expressed in the first two pulses, with remaining pulses yielding declining amounts, but venom protein concentration did not vary across pulses. Further study is necessary to ascertain the ecological significance of the factors influencing venom yield and how availability may influence venom use.

Snake velvet black: hierarchical micro- and nanostructure enhances dark colouration in Bitis rhinoceros

The West African Gaboon viper (Bitis rhinoceros) is a master of camouflage due to its colouration pattern. Its skin is geometrically patterned and features black spots that purport an exceptional spatial depth due to their velvety surface texture. Our study shades light on micromorphology, optical characteristics and principles behind such a velvet black appearance. We revealed a unique hierarchical pattern of leaf-like microstructures striated with nanoridges on the snake scales that coincides with the distribution of black colouration. Velvet black sites demonstrate four times lower reflectance and higher absorbance than other scales in the UV-near IR spectral range. The combination of surface structures impeding reflectance and absorbing dark pigments, deposited in the skin material, provides reflecting less than 11% of the light reflected by a polytetrafluoroethylene diffuse reflectance standard in any direction. A view-angle independent black structural colour in snakes is reported here for the first time.

Ending the drought: new strategies for improving the flow of affordable, effective antivenoms in Asia and Africa

The development of snake antivenoms more than a century ago should have heralded effective treatment of the scourge of snakebite envenoming in impoverished, mostly rural populations around the world. That snakebite still exists today, as a widely untreated illness that maims, kills and terrifies men, women and children in vulnerable communities, is a cruel anachronism. Antivenom can be an effective, safe and affordable treatment for snakebites, but apathy, inaction and the politicisation of public health have marginalised both the problem (making snakebite arguably the most neglected of all neglected tropical diseases) and its solution. For lack of any coordinated approach, provision of antivenoms has been pushed off the public health agenda, leading to an incongruous decline in demand for these crucial antidotes, excused and fed by new priorities, an absence of epidemiological data, and a poor regulatory framework. These factors facilitated the infiltration of poor quality products that degrade user confidence and undermine legitimate producers. The result is that tens of thousands are denied an essential life-saving medicine, allowing a toll of human suffering that is a summation of many individual catastrophes. No strategy has been developed to address this problem and to overcome the intransigence and inaction responsible for the global tragedy of snakebite. Attempts to engage with the broader public health community through the World Health Organisation (WHO), GAVI, and other agencies have failed. Consequently, the toxinology community has taken on a leadership role in a new approach, the Global Snakebite Initiative, which seeks to mobilise the resources, skills and experience of scientists and clinicians for whom venoms, toxins, antivenoms, snakes and snakebites are already fields of interest. Proteomics is one such discipline, which has embraced the potential of using venoms in bio-discovery and systems biology. The fields of venomics and antivenomics have recently evolved from this discipline, offering fresh hope for the victims of snakebites by providing an exciting insight into the complexities, nature, fundamental properties and significance of venom constituents. Such a rational approach brings with it the potential to design new immunising mixtures from which to raise potent antivenoms with wider therapeutic ranges. This addresses a major practical limitation in antivenom use recognised since the beginning of the 20th century: the restriction of therapeutic effectiveness to the specific venom immunogen used in production. Antivenomic techniques enable the interactions between venoms and antivenoms to be examined in detail, and if combined with functional assays of specific activity and followed up by clinical trials of effectiveness and safety, can be powerful tools with which to evaluate the suitability of current and new antivenoms for meeting urgent regional needs. We propose two mechanisms through which the Global Snakebite Initiative might seek to end the antivenom drought in Africa and Asia: first by establishing a multidisciplinary, multicentre, international collaboration to evaluate currently available antivenoms against the venoms of medically important snakes from specific nations in Africa and Asia using a combination of proteomic, antivenomic and WHO-endorsed preclinical assessment protocols, to provide a validated evidence base for either recommending or rejecting individual products; and secondly by bringing the power of proteomics to bear on the design of new immunising mixtures to raise Pan-African and Pan-Asian polyvalent antivenoms of improved potency and quality. These products will be subject to rigorous clinical assessment. We propose radically to change the basis upon which antivenoms are produced and supplied for the developing world. Donor funding and strategic public health alliances will be sought to make it possible not only to sustain the financial viability of antivenom production partnerships, but also to ensure that patients are relieved of the costs of antivenom so that poverty is no longer a barrier to the treatment of this important, but grossly neglected public health emergency.

Two incidents of venomous snakebite on juvenile blue and Sykes monkeys (Cercopithecus mitis stuhlmanni and C. m. albogularis)

Although rarely observed, predation is thought to be an important factor in the evolution of primate life histories and behavior. Here I describe two incidents of snake predation on Cercopithecus mitis guenons from Kenya. The first case involved a juvenile blue monkey (Cercopithecus mitis stuhlmanni) in the Kakamega Forest, which died following a bite by a Gaboon viper (Bitis gabonica gabonica). The snake's attempts to ingest its prey were unsuccessful. In the second incident, a juvenile Sykes monkey (Cercopithecus mitis albogularis) at Gede Ruins National Monument died suddenly after suffering symptoms that are characteristic of bites inflicted by black mambas (Dendroaspis polylepis). In both cases circumstantial evidence suggests that attacks occurred during extended play sessions in dense vegetation on or near the ground. If so, the observations support the hypothesis that play may be a costly activity.

Elucidation of trends within venom components from the snake families Elapidae and Viperidae using gel filtration chromatography

Research into snake venom components has intensified over the last number of decades, particularly that work directed towards the discovery of novel agents with potential applications in clinical therapy. In the present study we report, for the first time, defined patterns observed in the G-50 chromatographic elution profiles from 30 snake venoms taken from Elapidae and Viperidae families, as well as previously unreported patterns within subfamilies of these snake species. Development of this chromatographic technique thus offers a rapid method for the general classification of snakes within these families as well as providing insights into hitherto uncharacterised trends within the venoms of snake subfamilies that have opened new avenues for further investigation.

Gaboon viper (Bitis gabonica) envenomation resulting from captive specimens--a review of five cases

BACKGROUND

Five cases of illegitimate bite by captive specimens of the Gaboon viper (Bitis gabonica) snake have demonstrated the dangers of keeping exotic African snakes in captivity.

CASE SERIES

Four cases necessitated hospitalization for the bite and were characterized by progressive swelling of the affected limb, local necrosis and hemorrhagic edema near the wound, chest tightness and prolonged coagulation times. However, platelet counts were not altered. All patients received antivenom and had uneventful recovery, except for one who underwent amputation of a distal phalanx and one who required debridement. In the fifth case, the patient died without being able to summon help.

DISCUSSION

The results of this case series emphasize the need for extreme care to be exercised with the captivity of exotic snakes, such as the Gaboon viper. The increasing popularity of this snake as a captive pet predicates the need for private collectors to have a pre-existing treatment strategy with their local emergency centers. Such arrangements may facilitate the treatment of envenomation by this snake.

Snake Venomics of Bitis gabonica gabonica. Protein Family Composition, Subunit Organization of Venom Toxins, and Characterization of Dimeric Disintegrins Bitisgabonin-1 and Bitisgabonin-2

The protein composition of the venom of the East African Gaboon viper (Bitis gabonica gabonica) was analyzed using RP-HPLC, N-terminal sequencing, MALDI-TOF peptide mass fingerprinting, and CID-MS/MS. In total, 35 proteins of molecular masses in the range of 7-160 kDa and belonging to 12 toxin families were identified. The most abundant proteins were serine proteinases (26.4%), Zn2+-metalloproteinases (22.9%), C-type lectin-like proteins (14.3%), PLA2s (11.4%), and bitiscystatin (9.8%). Other protein classes, that is, bradykinin-potentiating peptides, dimeric disintegrins, Kunitz-type inhibitor, DC-fragments, sv-VEGF, CRISP, and L-amino acid oxidase, comprised between 1.3 and 3.4% of the total venom proteome. Only 11 venom-secreted proteins matched any of the previously reported 22 partial or full-length venom gland transcripts. In addition, venome and transcriptome depart in their relative abundances of different toxin families. The proteomic characterization of purified B. gabonica gabonica proteins run under nonreducing and reducing SDS-PAGE conditions revealed their aggregation state and subunit composition. Multimeric proteins included heterodimeric disintegrins, homodimeric sv-VEGF-A, heterodimeric (alphabeta) and tetrameric (alphabeta)4 C-type lectins, and multimeric PIII Zn2+-metalloproteinases. Determination of the complete primary structure and subunit composition of the two major dimeric disintegrins, bitisgabonin-1 and bitisgabonin-2, showed that each comprised a distinct RGD- and MLD-bearing subunit and a common, N-terminal-blocked, RGD-containing subunit identical to the disintegrin domain of the PII Zn2+-metalloproteinase 4. Cell adhesion inhibition assays showed that bitisgabonin-1 (RGD-RGD) is a potent inhibitor of integrin alpha5beta1, whereas bitisgabonin-2 (MLD-RGD) is a better antagonist of integrins alpha4beta1 and alpha9beta1.

Sexual dimorphism in venom of Bothrops jararaca(Serpentes: Viperidae)

Bothrops jararaca is an abundant snake in Brazil, and its venom has been studied exhaustively. The species exhibits adult size dimorphism in which female are larger. We registered the growth in Snout-Vent Length and weight of one litter (with 11 females and 12 males). We compared growth curves and venom profile between male and female of B. jararaca in order to establish the relationship of those characters and sex. Their venoms were analyzed when they were 36 months old, concerning SDS PAGE, protein content, proteolytic, hyaluronidasic, phospholipasic, blood-clotting, edematogenic, hemorrhagic, myotoxic activities, and lethality. Differences in the growth curves of the females and the males were significantly different after the 12th month of age, with the females growing faster. Females produced five times more venom than males. The electrophoretic patterns were variable: the venom from males had more protein bands than females. Venom composition varied significantly between males and females. Venom from females is more potent for hyaluronidasic, hemorrhagic, and lethality activities, whereas venom from males is more potent for coagulant, phospholipasic, and myotoxic activities. The variability of proteolytic and edematogenic activities were not significant. The important sexual dimorphism in body size and mass, amount of venom produced, and venom composition in B. jararaca may reflect a divergence in niche partitioning.

Adenosine in the venoms from viperinae snakes of the genus Bitis: Identification and quantitation using LC/MS and CE/MS

Snake venoms are rich sources of toxic proteins and small molecules. This study was directed at molecules of molecular mass below 1 kDa. Thirty different venoms, of either neurotoxic or haemorrhagic type, were fractionated using size-exclusion chromatography. Only venoms of the Puff adder (Bitis arietans), Gaboon viper (Bitis gabonica), and Rhinoceros viper (Bitis nasicornis) exhibited large absorbance peaks at lambda(280 nm) in the total volume range of the chromatographic column indicating the presence of abundant low molecular mass material. Analysis of fractions containing this material using both HPLC and capillary electrophoresis interfaced with electrospray ion-trap mass spectrometry unequivocally established that the bioactive nucleoside, adenosine, was the major component. The concentrations of adenosine found (Puff adder--97.7 x 10(-6) mol L(-1); Gaboon viper--28.0 x 10(-6) mol L(-1); and Rhinoceros viper-56.8 x 10(-6) mol L(-1)) were above those required to activate all known sub-types of adenosine receptors. Adenosine may thus act at the site of envenomation causing local vasodilatation and may play a role in the subsequent systemic hypotension observed.

Epidemiology of snakebite in Eshowe, KwaZulu-Natal, South Africa

Three hundred and thirty-three patients admitted to Eshowe Hospital with snakebite were analysed. Forty-one were non-envenomed, 282 exhibited painful progressive swelling (PPS), seven showed progressive weakness (PW), and there were three cases of minor envenomations that were unclassifiable. Offending dead venomous snakes included Naja mossambica (Mozambique spitting cobra), Bitis arietans (puff adder), Atractaspis bibronii (stiletto snake), Causus rhombeatus (common night adder) and Dendroaspis polylepis (black mamba). Most bites occurred on the leg in the wet summer months during the first three decades of the patients' lives. The majority of patients used a first-aid measure. The snake was most commonly sighted if the patient was bitten on an upper limb or above the ankle. Severe envenomation was associated with quicker arrival at hospital, and multiple bites occurred more frequently in sleeping patients. Non-envenomation following snakebites was more common in winter, in adult females, and if the patient was bitten proximally on a limb or on a hand. Patients with PPS developed bite site complications (42), compartment syndromes (4), femoral vessel entrapment (1), deep vein thrombosis (1), and respiratory complications (4). Severe swelling was associated with spring and early summer, proximal limb bites and children who were most at risk of necrosis. Fingers and hands were most prone to necrosis and permanent disability. Four patients with PW developed respiratory failure. Antivenom was administered to 12 patients, five of whom developed an acute adverse reaction. There was one death.

Influences on venom yield in Australian tigersnakes (Notechis scutatus) and brownsnakes (Pseudonaja textilis: Elapidae, Serpentes)

The rates at which venomous animals produce venoms are of obvious biological and medical importance, but factors influencing those rates remain poorly understood. We gathered data on venom yield (wet mass of venom) and percentage solids (dry mass of the venom divided by wet mass) for 53 eastern brownsnakes (Pseudonaja textilis) and 36 mainland tigersnakes (Notechis scutatus) over a 4-year period at Venom Supplies Pty. Ltd, a commercial venom production facility in South Australia. Tigersnakes yielded about threefold more venom (by wet mass) than brownsnakes, but with slightly lower percentage solids. Both species showed significant geographic variation in percentage solids. Venom yields varied as a function of the snake's sex and geographic origin, but these effects were secondary consequences of geographic and sex-based differences in body size. Relative head size affected venom yield in brownsnakes but not tigersnakes. Overall, the amount of venom that a snake produced during milking was affected by its species, its geographic origin, its body size and relative head size, and by the time of year that it was milked, as well as by interactions among these factors. Body size was the most important effect on venom yield, with yields increasing more rapidly with size in brownsnakes than in tigersnakes. Research at the intersection of snake ecology and venom characteristics has great potential, but will require a genuinely interdisciplinary approach.

Snake venoms and the hemostatic system

Snake venoms are complex mixtures containing many different biologically active proteins and peptides. A number of these proteins interact with components of the human hemostatic system. This review is focused on those venom constituents which affect the blood coagulation pathway, endothelial cells, and platelets. Only highly purified and well characterized snake venom proteins will be discussed in this review. Hemostatically active components are distributed widely in the venom of many different snake species, particularly from pit viper, viper and elapid venoms. The venom components can be grouped into a number of different categories depending on their hemostatic action. The following groups are discussed in this review: (i) enzymes that clot fibrinogen; (ii) enzymes that degrade fibrin(ogen); (iii) plasminogen activators; (iv) prothrombin activators; (v) factor V activators; (vi) factor X activators; (vii) anticoagulant activities including inhibitors of prothrombinase complex formation, inhibitors of thrombin, phospholipases, and protein C activators; (viii) enzymes with hemorrhagic activity; (ix) enzymes that degrade plasma serine proteinase inhibitors; (x) platelet aggregation inducers including direct acting enzymes, direct acting non-enzymatic components, and agents that require a cofactor; (xi) platelet aggregation inhibitors including: alpha-fibrinogenases, 5'-nucleotidases, phospholipases, and disintegrins. Although many snake venoms contain a number of hemostatically active components, it is safe to say that no single venom contains all the hemostatically active components described here. Several venom enzymes have been used clinically as anticoagulants and other venom components are being used in pre-clinical research to examine their possible therapeutic potential. The disintegrins are an interesting group of peptides that contain a cell adhesion recognition motif, Arg-Gly-Asp (RGD), in the carboxy-terminal half of their amino acid sequence. These agents act as fibrinogen receptor (integrin GPIIb/IIIa) antagonists. Since this integrin is believed to serve as the final common pathway leading to the formation of platelet-platelet bridges and platelet aggregation, blockage of this integrin leads to inhibition of platelet aggregation regardless of the stimulating agent. Clinical trials suggest that platelet GPIIb/IIIa blockade is an effective therapy for the thrombotic events and restenosis frequently accompanying cardiovascular and cerebrovascular disease. Therefore, because of their clinical poten tial, a large number of disintegrins have been isolated and characterized.

A study on the venom yield of venomous snake species from Argentina

A study on the venom yield of snakes from Argentina over a three year period was carried out on adult specimens of Bothrops alternatus (n = 74); Bothrops neuwiedii (n = 127); Bothrops ammodytoides (n = 30); Bothrops moojeni (n = 14); Bothrops jararaca (n = 14); B. jararacussu (n = 6); Crotalus durissus terrificus (n = 120) and Micrurus spp. (n = 6) as well as with 12 specimens of newborn C. d. terrificus kept in captivity. While for each species there was a positive correlation between venom yield and number of snakes milked, the correlation with the snake's body weights after individual milkings was even better, suggesting that the size of the snakes is more important in determining the venom yield than the number of snakes milked or the specimen's sex. Individual milkings indicated that, in addition to the snake size, when the amount of venom is normalized per 100 g body weight there is a species specific difference in venom yield. It follows the order B. jararacussu > B. moojeni approximately = B. jararaca approximately = B. alternatus > B. neuwiedii> Micrurus spp approximately = B. ammodytoides> C. d. terrificus. Although the venom yield per 100 g body weight of newborn C. d. terrificus specimens is 2-fold higher than that of adults, no correlation was observed between venom yield and body weight.

The Gaboon viper, Bitis gabonica: hemorrhagic, metabolic, cardiovascular and clinical effects of the venom

The effects of Bitis gabonica venom have been studied in several animal species, including the monkey, dog, rabbit, rat and guinea pig. Further information has been provided by observations on the effects of snake bite in man. Bitis gabonica venom exerts a number of cytotoxic and cardiovascular effects: cytotoxic effects include widespread hemorrhage, caused by the presence of two hemorrhagic proteins. These hemorrhagins bring about separation of vascular endothelial cells and extravasation of blood into the tissue spaces. Metabolic alterations include decreased oxygen utilization by tissues and increased plasma glucose and lactate concentrations. Metabolic non-compensated acidosis has also been seen in the rat as a consequence of the cytotoxicity of the venom. Cardiovascular effects include disturbances in atrio-ventricular conduction and reduction in amplitude and duration of the action potential brought about by a decreased calcium membrane conductance. A progressive decrease in myocardial contractility can also be attributed to the decreased calcium conductance, which together with the severe acidosis may cause death in experimental animals. A severe, though reversible, vasodilatation was observed after envenomation due to unidentified compounds in the venom. In man, envenomation causes a variable clinical picture depending on the time course and severity of envenomation. Frequently seen effects include hypotension, hemorrhage at the site of the bite and elsewhere and disseminated intravascular coagulation. Envenomation can be satisfactorily treated with antivenom.

Isolation and characterisation of two haemorrhagic proteins (HTa and HTb) from the venom of Bitis gabonica (Gaboon viper)

Two distinct haemorrhagic proteinases, HTa and HTb, were isolated from the venom of Bitis gabonica by gel filtration and ion-exchange chromatography with native mol. wts of 180,000 and 111,000, respectively. After reduction with dithiothreitol, smaller mol. wts of 77,600 and 69,200 were recorded for HTa and HTb, suggesting that under native conditions the haemorrhagins exist as dimeric molecules. Both toxins possessed caseinolytic and collagenase activity although HTa was 15-36 times more potent than HTb with respect to collagenase activity. No zinc could be detected in the toxins; however, dialysis against ethylenediamine tetracetic acid (EDTA) reduced caseinolytic activity, suggesting the dependence of the latter on other metal ions. HTa and HTb had a marked effect on the intrinsic cascade coagulation mechanism (factors IX, XI and XII) but no effect on the final common coagulation pathway (factor X and prothrombin). Light and electron microscopical studies demonstrated that both HTa and HTb caused organ-specific lesions, with the lungs, diaphragm and body wall muscle being most affected. HTa caused widespread haemorrhage whilst HTb caused discrete focal lesions near the site of injection and elsewhere. However, both toxins appeared to cause capillary rupture by the separation of cells from one another and both caused cell detachment and cell death of bovine endothelial cells cultured in vitro, consonant with the massive disruption of capillaries seen in vivo.

Effect of bilineobin, a thrombin-like proteinase from the venom of common cantil (Agkistrodon bilineatus)

A thrombin-like proteinase, named bilineobin, was isolated from Agkistrodon bilineatus venom by Sephadex G-75, DEAE-Sephacel and Heparin-Sepharose CL-6B column chromatography. The purified enzyme has a mol. wt of 57,000 and catalysed the hydrolysis of arginine esters and thrombin substrates Boc-Val-Pro-Arg-MCA and Boc-Asp(OBz)-Pro-Arg-MCA. Although bilineobin converted fibrinogen into fibrin resulting in the production of fibrinopeptides, the activity was relatively low (0.65 NIH units/mg). Fibrinopeptides released upon hydrolysis by this proteinase were identified as fibrinopeptide A (FpA) and fibrinopeptide B (FpB) by measuring fast atom bombardment (FAB) mass spectra and amino acid sequence. This indicates that bilineobin hydrolyses the Arg(19)-Gly(20) bond in the A alpha chain and the Arg(21)-Gly(22) bond in the B beta chain of the bovine fibrinogen molecule. Kinetic study of FpA and FpB release reveals that bilineobin has a preference for cleaving the B beta chain. In addition, bilineobin is resistant to thrombin inhibitors such as hirudin. These suggest that the mechanism of action of bilineobin is similar but not identical to that of thrombin. It was demonstrated that the NH2-terminal region of bilineobin has significant similarities in sequence with thrombin-like proteinases from other snake venoms; however, only three residues were common with thrombin up to residue number 24.

Accidental envenoming by a Gaboon viper (Bitis gabonica): the haemostatic disturbances observed and investigation of in vitro haemostatic properties of whole venom

We report the successful treatment of envenoming by the Gaboon viper (Bitis gabonica) and include results of in vitro investigations of the haemostatic properties of the whole venom. The patient was admitted to casualty soon after the bite with chest tightness, dizziness, nausea and swelling at the site of the bite and was treated immediately with polyspecific antivenom, hydrocortisone, chlorpheniramine and antibiotics. Results of haemostatic investigations were essentially normal on admission but on day 3 the thrombin time became prolonged and was associated with significant hypofibrinogenaemia and elevated D-dimers. Factors V and VIII, antithrombin III and protein C levels and platelet number were not significantly reduced. The haemostatic disturbances persisted for more than 24 h despite treatment with blood products (16 units of cryoprecipitate, 2 units of fresh frozen plasma and 6 units of platelet concentrate). Resolution of the abnormalities occurred only after administration of a further dose of antivenom. The period of hypofibrinogenaemia occurred at a time when venom antigen was undetectable in plasma by enzyme-linked immunosorbent assay. Studies in vitro with whole venom and a panel of amidolytic substrates commonly employed for measurement of haemostatic proteins revealed significant activity of venom with substrates sensitive to kallikrein and plasmin. The venom inhibited washed platelet aggregation induced by collagen, thrombin, arachidonic acid and the calcium ionophore A23187 in a dose-dependent manner.

A comparative study of the biological properties of venoms of some old world vipers (subfamily viperinae)

1. The hemorrhagic, procoagulant, anticoagulant, phosphodiesterase, hyaluronidase, alkaline phosphomonoesterase, 5'-nucleotidase, arginine ester hydrolase, phospholipase A, L-amino acid oxidase and protease activities of 30 samples of venoms from nine species (12 taxa) of the old world vipers (Subfamily Viperinae) including snakes from the genera Bitis, Causus, Cerastes, Echis, Eristicophis and Pseudocerastes, were determined and the Sephadex G-75 gel filtration patterns for some of the venoms were also examined. 2. Examination of the biological properties of the venoms of the Viperinae tested indicates the presence of common venom biological characteristics at the various phylogenic levels. 3. Venoms of most species of the Viperinae examined exhibited characteristic biological properties at the species level, and this allows the differentiation of the Viperinae species by differences in their biological properties. 4. Particularly useful for this purpose, are the effects of venom on kaolin-cephalin clotting time of platelet poor rabbit plasma and the Sephadex G-75 gel filtration pattern and arginine ester hydrolase activity of the venom.

Acidotic effect of gaboon viper (Bitis gabonica) venom in the urethane-anaesthetized rat

1. Intravenous venom (4 mg/kg) caused a non-compensated metabolic acidosis. 2. Bicarbonate concentration, base excess, standard base excess and pH all fell dramatically. 3. A respiratory impairment occurred characterized by pulmonary oedema and a fall in arterial pO2. 4. Acidosis occurred soon after venom when pO2 was still normal, indicating that changes in tissue metabolism contributed to the acidosis independently of reduced oxygen availability.

Comparison of the physiological effects in rabbits of gaboon viper (Bitis gabonica) venoms from different sources

The cardiovascular, respiratory and metabolic effects of B. gabonica venoms obtained from specimens originating from Ghana, Togo, Nigeria, Uganda and Tanzania were examined in anaesthetized rabbits. Intravenous injection of all venoms (0.125-2.0 mg/kg) induced hypotension. Nigeria venom was the least potent in this respect. Following doses of all venoms there was a brief bradycardia and a transient increase in respiratory rate and depth. At high doses (greater than or equal to 1.0 mg/kg), all venoms induced severe ST depression and T wave inversion. In addition, Togo venom, and to a lesser extent Tanzania and Ghana venoms, were potent in inducing extrasystoles. None of the venoms produced any significant changes in haematocrit, plasma proteins or arterial blood gas and pH levels. All venoms increased blood glucose and lactate levels by 1.3-2.1 fold and 2.2-4.0 fold respectively while the respiratory quotient remained unchanged. Togo venom was significantly (P less than 0.05) more lethal than the other venoms. The pattern of haemorrhage observed at post-mortem was the same for all venoms with the heart, ureters, adrenals, kidneys, lungs, stomach and intestines being the most affected. When combined on a subspecies basis, the results suggest that there are no significant differences in the physiological effects of venoms representing B. g. rhinoceros (West African gaboon viper) and B. g. gabonica (East African gaboon viper).

Acid-base, plasma lactate and glucose changes in the rabbit following administration of Gaboon viper (Bitis gabonica) venom

The acid-base and metabolic effects of Bitis gabonica venom administered intravenously to the anaesthetised rabbit were studied. Doubling doses of venom from 0.125 mg/kg to 1.0 mg/kg were used. Venom caused progressive and significant increases in plasma glucose and plasma lactate levels although oxygen consumption only became significantly lower after the fourth dose. Standard base excess (SBE) became significantly more negative after the third dose of venom and the fall in pH became significant at the same point. The results indicate that venom induces a metabolic acidosis in the rabbit and because the acidosis occurs in the absence of any fall in arterial PO2, it cannot be considered a consequence of impaired pulmonary ventilation. The reduction in oxygen uptake is likely to occur at a cellular level with a shift from aerobic to anaerobic metabolism hence the increase in plasma lactate levels. However, the magnitude of the acidosis is unlikely to be the principal cause of death under experimental conditions.

Isolation and characterization of a fibrinogen-clotting enzyme from venom of the snake, Lachesis muta muta (Peruvian bushmaster)

A fibrinogen-clotting enzyme from the venom of the Peruvian bushmaster snake was purified to homogeneity by gel filtration on Sephadex G-100 followed by DEAE-cellulose ion-exchange chromatography using a linear ionic strength gradient with NaCl. The specific activity of the enzyme was 866 NIH U/mg, representing a 55-fold purification, with a recovery of 45%. The amino acid composition was Asx30, Thr14, Ser15, Glx33, Pro23, Gly22, Ala15, Val22, Cys18, Met3, Ile18, Leu23, Tyr2, Phe13, His8, Lys11, Arg11. The total carbohydrate content was 13.4%, comprised of 3.4% hexose, 8.7% hexosamine and 1.3% sialic acid. The enzyme was active against the synthetic amide substrate alpha-N-benzoyl-DL-arginine-p-nitroanilide (BAPNA) and against the ester substrates alpha-N-benzoyl-L-arginine ethyl ester (BAEE) and tosyl-L-arginine methyl ester (TAME). Kinetic parameters for TAME esterolysis were: Vmax, 135 mumoles/min/mg and Km, 2.5 x 10(-4) M. The pH optimum was 8.0. Vmax for BAPNA amidolysis was 0.363 mumoles/min/mg and Km, 7.5 x 10(-5) M. Enzyme activity was reduced by diethylpyrocarbonate and by photo-oxidation, suggesting that the enzyme is a serine protease with a histidine residue involved in the active site. The enzyme released fibrinopeptide A rapidly from purified human fibrinogen and fibrinopeptide B more slowly. Factor XIII was not activated and the clotting activity was not inhibited by heparin. A dose of 50 micrograms/kg brought about defibrinogenation in anaesthetized rats but rabbits were unaffected. A dose of 80 micrograms/kg defibrinogenated conscious rats after 5 hr. There were no hypotensive or haemorrhagic effects.

Adder bites in Aldershot

Each summer cases of adder bite occur in Aldershot and its surrounding areas. Many of these are brought to the Cambridge Military Hospital. This paper reports three cases that together illustrate the commonest clinical signs and symptoms. These include rapid swelling, malaise and anxiety. An important diagnostic indication is an early and marked leucocytosis. Treatment regimes are also reviewed with the advice ultimately being to "admit and monitor". The danger of early resort to antivenom is also examined and the principles of both treatment and first aid are developed.

The effects of gaboon viper (Bitis gabonica) venom on voltage-clamped single heart cells

The effects of crude B. gabonica venom on single ventricular myocytes from guinea-pig hearts were studied using the patch clamp technique in the 'whole cell' mode. Irreversible effects on the membrane currents, which became prominent within 15 min of venom application, were: (1) a decrease in the time invariant current (associated with the inward rectifying K+ current), most clearly seen over a voltage range negative to the resting membrane potential; and (2) a decrease in the peak inward current (associated with the Ca2+ current) elicited by steplike depolarizations from a holding potential of -40 mV. A transient increase in the peak inward current, which preceded its eventual decline, was also noticed; it peaked 6-10 min after the venom was applied. Application of the venom to unclamped, stimulated cells resulted in a shortening of the plateau phase and disturbances of the repolarization phase of action potentials. An early transient prolongation and elevation of the plateau was observed, occurring with the same time course of the transient increase in the peak inward current. No signs of damage to the cell membrane integrity, neither electrical (appearance of a leakage current) nor morphological (surface blebs, loss of striation pattern and of rodlike shape in the isolated myocytes), accompanied the effects observed on ionic currents and action potential activity, supporting the hypothesis of a selective cardiotoxic action of B. gabonica venom.

Evidence for the presence of histamine in Gaboon viper (Bitis gabonica) venom

Venom from B. gabonica produced a dose-dependent contraction of both isolated guinea-pig ileum and rabbit aortic strip preparations. The venom-induced contraction was not antagonised by pretreatment with atropine, phentolamine, methysergide or indomethacin, however, it was blocked by the prior addition of chlorpheniramine or cyproheptadine. Upon exhaustive dialysis of the venom, the dialysate contracted both preparations, while the dialysed venom had no effect. Paper and thin-layer chromatography of the venom showed a spot with an Rf value corresponding to authentic histamine. Biological assay of the crude venom on the guinea-pig ileum showed that it contained the equivalent of 2-10 micrograms of histamine per mg dry weight of crude venom. pA2 values for chlorpheniramine using either the venom or histamine as agonists were not significantly different.

An isoelectric focusing study of seasonal variation in rattlesnake venom proteins

Adult specimens of seven southern Pacific rattlesnakes (Crotalus viridis helleri), four northern black-tailed rattlesnakes (Crotalus molossus molossus), and six western diamondback rattlesnakes (Crotalus atrox) were housed under controlled light and temperature and milked of venom monthly for 20 months. Ambient conditions were modelled to simulate seasonal change. Weighed amounts of lyophilized venom from each snake were compared chronologically for variation in isoelectric focusing patterns, using natural and immobilized gradients. No variation in patterns was evident over this time period for any individual snake. However, intraspecific differences were obvious in the venom samples. The pattern seems indicative of a species, however, concentration of various protein constituents seems individual and genetically "fingerprinted'. Unlike other physiological functions that demonstrate cyclicity in response to temperature and photoperiod, concentration ratios of venom components appear to be constant regardless of external cues. These findings may further emphasize the medical importance of treating snakebite victims symptomatically as individuals. A variation exists in the components of venoms of any given species, as well as in the physiological sensitivities of humans to a venom.

The effects of Gaboon viper (Bitis gabonica) venom on the electrical and mechanical activity of the guinea-pig myocardium

The effects of Bitis gabonica venom were tested on guinea-pig heart, using both Langendorff preparations and isolated atrial strips or papillary muscles. In the self-paced whole heart, a single passage of 50 micrograms of venom per ml produced in sequence: irregularities of the A-V conduction and decrease of the contractile strength, progressive failure to relax and systolic arrest of the heart. Pretreatment with atropine reduced but did not abolish these effects. Venom recycled through the heart was effective at a much lower dose. The relationship between resting membrane potential and [K+]o was unaffected by envenomation, suggesting that the action of the venom cannot be ascribed to a loss of ionic selectivity of the cell membrane. The peak amplitude of action potentials declined in papillary muscle exposed to venom at physiological [K+]o, while in atrial cells it was affected only at higher [K+]o. Maximum upstroke rate of the action potential vs. resting potential at different [K+]o gave a sigmoid relationship, characterized by a higher upper asymptote as compared to controls, and by a shift of the curve towards more negative voltage values. A marked shortening of the action potential duration, paralleled by a decrease in time to peak tension, was recorded as well. 'Slow' action potentials, elicited in 20 mM K+ solution, were completely abolished within 10 min of perfusion with venom. These results are consistent with the hypothesis that the venom interacts with both transmembrane Ca2+ inflow and Ca2+ binding at the external side of the cell membrane. A transient positive inotropic effect induced by the venom was observed in papillary muscle and in atropinized atrium. This effect was abolished by previous administration of reserpine to the animal or by addition of propranolol to the perfusing solution, suggesting a venom-induced release of both adrenergic and cholinergic transmitters from nerve endings within the cardiac tissue.