scholarly journals A Genus-Wide Bioactivity Analysis of Daboia (Viperinae: Viperidae) Viper Venoms Reveals Widespread Variation in Haemotoxic Properties

2021 ◽  
Vol 22 (24) ◽  
pp. 13486
Author(s):  
Bianca op den Brouw ◽  
Francisco C. P. Coimbra ◽  
Nicholas R. Casewell ◽  
Syed Abid Ali ◽  
Freek J. Vonk ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Human Plasma ◽  
Dose Response ◽  
Factor X ◽  
African Species ◽  
Human Fibrinogen ◽  
Fibrinogenolytic Activity ◽  
The Many ◽  
Viper Venoms ◽  
Multiple Variants

The snake genus Daboia (Viperidae: Viperinae; Oppel, 1811) contains five species: D. deserti, D. mauritanica, and D. palaestinae, found in Afro-Arabia, and the Russell’s vipers D. russelii and D. siamensis, found in Asia. Russell’s vipers are responsible for a major proportion of the medically important snakebites that occur in the regions they inhabit, and their venoms are notorious for their coagulopathic effects. While widely documented, the extent of venom variation within the Russell’s vipers is poorly characterised, as is the venom activity of other species within the genus. In this study we investigated variation in the haemotoxic activity of Daboia using twelve venoms from all five species, including multiple variants of D. russelii, D. siamensis, and D. palaestinae. We tested the venoms on human plasma using thromboelastography, dose-response coagulometry analyses, and calibrated automated thrombography, and on human fibrinogen by thromboelastography and fibrinogen gels. We assessed activation of blood factors X and prothrombin by the venoms using fluorometry. Variation in venom activity was evident in all experiments. The Asian species D. russelii and D. siamensis and the African species D. mauritanica possessed procoagulant venom, while D. deserti and D. palaestinae were net-anticoagulant. Of the Russell’s vipers, the venom of D. siamensis from Myanmar was most toxic and D. russelli of Sri Lanka the least. Activation of both factor X and prothrombin was evident by all venoms, though at differential levels. Fibrinogenolytic activity varied extensively throughout the genus and followed no phylogenetic trends. This venom variability underpins one of the many challenges facing treatment of Daboia snakebite envenoming. Comprehensive analyses of available antivenoms in neutralising these variable venom activities are therefore of utmost importance.

A Chromogenic Factor X Assay With New Standardized Reagents

1979 ◽  
Author(s):  
P Friberger ◽  
C Lenne
Keyword(s):  
Human Plasma ◽  
Suitable Method ◽  
Chromogenic Substrate ◽  
Factor X ◽  
Normal Human Plasma ◽  
Normal Plasma ◽  
Normal Human

A recently published method for Factor X (FX) assay (1) utilizing Russel's Viper Venom (RVV) and a chromogenic substrate has been further investigated by testing a large number of parameters. This method has been considered as a suitable method for monitoring coumarol treatment (Bergström et al).The conditions for the activation of FX by purified preparations of the RVV have been studied as well as the conditions for FXa determination with a new chromogenic substrate Bz-Ile-Glu(γ-piperidyl)-Gly-Arg-pNA (S-2337). Both purified factors and normal plasma have been used. The effect of plasma inhibitors as well as the selectivity of the method has been studied.The reproducibility and stability of the different reagents and standards have been studied and found to be good.The amount of FXa activity obtained from normal human plasma has been titrated with FXa inhibitors of known purity.1) Aurell L. et al, Thromb. Res., 11, 595 (1977)2) Bergström et al, Thromb. Res., 12, 531 (1978)

Absence of Synergism Between Tissue-Type Plasminogen Activator (t-PA), Single-Chain UrokinaseType Plasminogen Activator (scu-PA) and Urokinase on Clot Lysis in a Plasma Milieu In Vitro

1986 ◽  
Vol 56 (01) ◽  
pp. 035-039 ◽  
Author(s):  
D Collen ◽  
F De Cock ◽  
E Demarsin ◽  
H R Lijnen ◽  
D C Stump
Keyword(s):  
Human Plasma ◽  
Plasminogen Activator ◽  
Dose Response ◽  
Fibrinolytic System ◽  
Tissue Type ◽  
Clot Lysis ◽  
Single Chain ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator

SummaryA potential synergic effect of tissue-type plasminogen activator (t-PA), single-chain urokinase-type plasminogen activator (scuPA) or urokinase on clot lysis was investigated in a whole human plasma system in vitro. The system consisted of a human plasma clot labeled with 125I-fibrinogen, immersed in titrated whole human plasma, to which the thrombolytic agents were added. Clot lysis was quantitated by measurement of released 125I, and activation of the fibrinolytic system in the surrounding plasma by measurements of fibrinogen and α2-antiplasmin.t-PA, scu-PA and urokinase induced a dose-dependent and time-dependent clot lysis; 50 percent lysis after 2 h was obtained with 5 nM t-PA, 20 nM scu-PA and 12 nM urokinase. At these concentrations no significant activation of the fibrinolytic system in the plasma was observed with t-PA and scu-PA, whereas urokinase caused significant α2-antiplasmin consumption and concomitant fibrinogen degradation. The shape of the dose-response curves was different; t-PA and urokinase showed a log linear dose-response whereas that of scu-PA was sigmoidal.

A Hitherto Undescribed Naturally Occurring Plasma Antagonist of Activated Factor X Inhibitor (Antithrombin III)

1979 ◽  
Author(s):  
E. T. Yin ◽  
W. J. Salsgiver ◽  
O. Tangen
Keyword(s):  
Equilibrium State ◽  
Human Plasma ◽  
Antithrombin Iii ◽  
Circumstantial Evidence ◽  
Incubation Mixture ◽  
Factor X ◽  
Normal Human Plasma ◽  
Plasma Component ◽  
Naturally Occurring ◽  
Normal Human

Circumstantial evidence suggested that normal human plasma contained a substance regulating the neutralization of F.Xa by F.Xa inhibitor(XaI), (Yin et.al.,Adv.Exper. Med. & Biol., 52 : 239, 1975, Plenum Press, N.Y.).This plasma component has now been isolated and partially purified in our laboratory, and tentatively designated as “Anti-XaI”.In experiments employing purified components, when Anti-XaI was incubated at 37°C with F.Xa, Xal and heparin for two minutes at pH7.5, the amount of F.Xa inhibited was inversely proportional to the Anti-XaI concentration. But, when the F.Xa was replaced by thrombin in the incubation mixture, the neutralization of thrombin clotting activity was undisturbed.Anti-XaI was found to be neither PF3 nor PF4.These and other data strongly suggest that the “Antithrombin III pathway” is more complex than currently believed to be. In circulating blood an equilibrium state must exist between Anti-XaI and XaI.Under certain conditions when the Anti-XaI activity is predominant the rate of F.Xa neutralization bv XaI then becomes slower than the activation of prothrombin to thrombin by F.Xa.

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

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 112
Author(s):  
Bianca op den Brouw ◽  
Francisco C. P. Coimbra ◽  
Lachlan A. Bourke ◽  
Tam Minh Huynh ◽  
Danielle H. W. Vlecken ◽  
...  
Keyword(s):  
Prey Capture ◽  
Anticoagulant Activity ◽  
Protein Composition ◽  
Coagulation Factors ◽  
Arid Environments ◽  
Factor X ◽  
Venom Protein ◽  
Research Attention ◽  
Future Assessment ◽  
Viper Venoms

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

scholarly journals Pharmacological Characterisation of Pseudocerastes and Eristicophis Viper Venoms Reveal Anticancer (Melanoma) Properties and a Potentially Novel Mode of Fibrinogenolysis

2021 ◽  
Vol 22 (13) ◽  
pp. 6896
Author(s):  
Bianca op den Brouw ◽  
Parviz Ghezellou ◽  
Nicholas R. Casewell ◽  
Syed Abid Ali ◽  
Behzad Fathinia ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Serine Proteases ◽  
Human Melanoma ◽  
Snake Venoms ◽  
Lead Compounds ◽  
Bioactive Properties ◽  
Fibrinogenolytic Activity ◽  
Pharmacological Potential ◽  
Hydrolysis Of ◽  
Viper Venoms

Venoms are a rich source of potential lead compounds for drug discovery, and descriptive studies of venom form the first phase of the biodiscovery process. In this study, we investigated the pharmacological potential of crude Pseudocerastes and Eristicophis snake venoms in haematological disorders and cancer treatment. We assessed their antithrombotic potential using fibrinogen thromboelastography, fibrinogen gels with and without protease inhibitors, and colourimetric fibrinolysis assays. These assays indicated that the anticoagulant properties of the venoms are likely induced by the hydrolysis of phospholipids and by selective fibrinogenolysis. Furthermore, while most fibrinogenolysis occurred by the direct activity of snake venom metalloproteases and serine proteases, modest evidence indicated that fibrinogenolytic activity may also be mediated by selective venom phospholipases and an inhibitory venom-derived serine protease. We also found that the Pseudocerastes venoms significantly reduced the viability of human melanoma (MM96L) cells by more than 80%, while it had almost no effect on the healthy neonatal foreskin fibroblasts (NFF) as determined by viability assays. The bioactive properties of these venoms suggest that they contain a number of toxins suitable for downstream pharmacological development as candidates for antithrombotic or anticancer agents.

scholarly journals CLIMATE CHANGE CHALLENGES FACING SRI LANKA: A LITERATURE REVIEW

2021 ◽  
Author(s):  
S.P.M. Dasandara ◽  
◽  
U. Kulatunga ◽  
M.J.B. Ingirige ◽  
T. Fernando ◽  
...  
Keyword(s):  
Climate Change ◽  
Sri Lanka ◽  
Literature Review ◽  
Climate Change Impacts ◽  
Future Research ◽  
Mitigation And Adaptation ◽  
Adverse Weather ◽  
Temperature Levels ◽  
Earth’S Climate ◽  
The Many

The earth’s climate has changed throughout history and climate change can be identified as an inevitable phenomenon which is being experienced by the whole world. When considering the Sri Lankan context, it is no different to the global context in that the country’s climate has already changed. Sri Lanka, being an island state, is vulnerable to many climate change impacts including high-temperature levels, adverse weather events, sea level rising, and changes in precipitation patterns. The many challenges that arise from these climate-related issues are projected to continue through this century and beyond. Thus, climate change mitigation and adaptation have become the most appropriate ways to restrain these climate change challenges in Sri Lanka. It is paramount to get a broad understanding of how disastrous these climate change challenges are, prior to implementing appropriate responses to overcome them. This urges the need for conducting an in-depth investigation of prevailing climate change challenges in Sri Lanka. Thus, this study presents the prevailing climate change challenges facing Sri Lanka through a conceptual framework, that has been developed based on the existing literature. The developed framework reveals how these prevailing climate changes can lead to a number of challenges. These challenges were identified under three main categories as economic, social, and environmental challenges. The knowledge generated through this literature review will be the focus of future research.

scholarly journals Taxonomic Results of the BRYOTROP Expedition to Zaire and Rwanda 29. Thuidiaceae, Thuidium

1995 ◽  
Vol 10 (1) ◽  
pp. 199-199
Author(s):  
A. Touw
Keyword(s):  
African Species ◽  
The Many

For a revision of the African species see Touw (1976). The scarcity of Thuidium samples among the expedition’s collections is most surprising and inexplicable, considering the size of the expedition, the range of habitats and altitudes explored, and the many Thuidium collections made by others in this part of Africa.

Sign in / Sign up

Export Citation Format

Share Document