Erratum to: The in vitro toxicity of venoms from South Asian Hump-nosed pit vipers (Viperidae: Hypnale)

Hump-nosed pit vipers (Genus Hypnale) are venomous snakes from South India and Sri Lanka. Envenoming by Hypnale species may cause significant morbidity and is characterized by local envenoming and less commonly coagulopathy and acute renal failure. Currently there are three nominal species of this genus: H. hypnale, H. zara and H. nepa. This study investigates the biochemical and pharmacological properties of the venoms from the three Hypnale species in Sri Lanka. The three Hypnale venoms had similar chromatographic profiles using reverse phase high performance liquid chromatography and fractions with procoagulant activity were identified. Hypnale venoms had potent cytotoxicity in cultured rat aorta smooth muscle cells with similar IC50 values. The venoms had weak neurotoxic and myotoxic activity in the isolated chick biventer muscle preparation. They had mild procoagulant activity with close MCC5 values and also phospholipase activity. Locally available polyvalent antivenom did not neutralise any venom effects. The study demonstrates that the three Hypnale venoms are similar and cytotoxicity appears to be the most potent effect, although they have mild procoagulant activity. These findings are consistent with clinical reports

Filter based methods for statistical linear inverse problems

Ill-posed inverse problems are ubiquitous in applications. Understanding of algorithms for their solution has been greatly enhanced by a deep understanding of the linear inverse problem. In the applied communities ensemble-based filtering methods have recently been used to solve inverse problems by introducing an artificial dynamical system. This opens up the possibility of using a range of other filtering methods, such as 3DVAR and Kalman based methods, to solve inverse problems, again by introducing an artificial dynamical system. The aim of this paper is to analyze such methods in the context of the linear inverse problem. Statistical linear inverse problems are studied in the sense that the observational noise is assumed to be derived via realization of a Gaussian random variable. We investigate the asymptotic behavior of filter based methods for these inverse problems. Rigorous convergence rates are established for 3DVAR and for the Kalman filters, including minimax rates in some instances. Blowup of 3DVAR and a variant of its basic form is also presented, and optimality of the Kalman filter is discussed. These analyses reveal a close connection between (iterated) regularization schemes in deterministic inverse problems and filter based methods in data assimilation. Numerical experiments are presented to illustrate the theory

A randomized controlled trial of fresh frozen plasma for coagulopathy in Russell's viper (Daboia russelii) envenoming

Background Russell's viper (Daboia russelii) envenoming is a major health issue in South Asia and causes venom induced consumption coagulopathy (VICC). Objectives We investigated the effect of fresh frozen plasma (FFP) and two antivenom doses in correcting VICC. Methods We undertook an open-label randomized controlled trial in patients with VICC at two Sri Lankan hospitals. Patients with suspected Russell's viper bites and coagulopathy were randomly allocated (1:1) high-dose antivenom (20 vials) or low-dose antivenom (10 vials) plus 4U FFP. The primary outcome was the proportion of patients with an international normalized ratio (INR)<2, 6h post-antivenom. Secondary outcomes included anaphylaxis, major haemorrhage, death and clotting factor recovery. Results From 214 eligible patients, 141 were randomized; 71 to high-dose antivenom, 70 to low-dose antivenom/FFP; five had no post-antivenom bloods. The groups were similar except for a delay of 1h in antivenom administration for FFP patients. 6h post-antivenom 23/69 (33%) patients allocated high-dose antivenom had an INR<2 compared with 28/67 (42%) allocated low-dose antivenom/FFP [absolute difference 8%;95%Confidence Interval:-8% to 25%]. 15 patients allocated FFP did not receive it. Severe anaphylaxis occurred equally frequently in each group. One patient given FFP developed transfusion related acute lung injury. Three deaths occurred in low-dose/FFP patients including one intracranial haemorrhage. There was no difference in recovery rates of INR or fibrinogen, but more rapid initial recovery of factor V and X in FFP patients. Conclusion FFP post-antivenom in Russell's viper bites didn't hasten recovery of coagulopathy. Low-dose antivenom/FFP did not worsen VICC, suggesting low-dose antivenom is sufficient

Current treatment for venom-induced consumption coagulopathy resulting from snakebite

Venomous snakebite is considered the single most important cause of human injury from venomous animals worldwide. Coagulopathy is one of the commonest important systemic clinical syndromes and can be complicated by serious and life-threatening haemorrhage. Venom-induced consumption coagulopathy (VICC) is the commonest coagulopathy resulting from snakebite and occurs in envenoming by Viperid snakes, certain elapids, including Australian elapids, and a few Colubrid (rear fang) snakes. Procoagulant toxins activate the clotting pathway, causing a broad range of factor deficiencies depending on the particular procoagulant toxin in the snake venom. Diagnosis and monitoring of coagulopathy is problematic, particularly in resource-poor countries where further research is required to develop more reliable, cheap clotting tests. MEDLINE and EMBASE up to September 2013 were searched to identify clinical studies of snake envenoming with VICC. The UniPort database was searched for coagulant snake toxins. Despite preclinical studies demonstrating antivenom binding toxins (efficacy), there was less evidence to support clinical effectiveness of antivenom for VICC. There were no placebo-controlled trials of antivenom for VICC. There were 25 randomised comparative trials of antivenom for VICC, which compared two different antivenoms (ten studies), three different antivenoms (four), two or three different doses or repeat doses of antivenom (five), heparin treatment and antivenom (five), and intravenous immunoglobulin treatment and antivenom (one). There were 13 studies that compared two groups in which there was no randomisation, including studies with historical controls. There have been numerous observational studies of antivenom in VICC but with no comparison group. Most of the controlled trials were small, did not use the same method for assessing coagulopathy, varied the dose of antivenom, and did not provide complete details of the study design (primary outcomes, randomisation, and allocation concealment). Non-randomised trials including comparison groups without antivenom showed that antivenom was effective for some snakes (e.g., Echis), but not others (e.g., Australasian elapids). Antivenom is the major treatment for VICC, but there is currently little high-quality evidence to support effectiveness. Antivenom is not risk free, and adverse reactions can be quite common and potentially severe. Studies of heparin did not demonstrate it improved outcomes in VICC. Fresh frozen plasma appeared to speed the recovery of coagulopathy and should be considered in bleeding patients

Preparation and properties of starch xanthide encased powdered natural rubber

Starch xanthide encased powdered natural rubber was produced by oxidatively co- precipitating the mixture of starch xanthate solution and natural rubber field latex under vigorous stirring. The resulting finely divided wet powdered rubber particles were separated by filtration and then converted to free-flowing powders by oven drying. The level of encapsulation as well as the properties of the resulting powder was highly dependent on the strength and the amount of the Starch Xanthate (SX) solution. The lower and the upper limits of Degree of Substitution (DS) of SX examined were 0.07 and 0.35 and the results suggested that the intermediate DS levels were more effective. The physical properties of the final vulcanizates were examined and found to be comparable with the rubbers available in the market

Antivenom cross neutralisation in a suspected Asian pit viper envenoming causing severe coagulopathy

There is evidence of cross-neutralisation between common toxin groups in snake venoms and therefore the potential for antivenoms to be effective against species they are not raised against. Here we present a 49 year old female bitten by an unknown pit-viper in Nepal. She developed a venom induced consumption coagulopathy with an unrecordable international normalised ratio and undetectable fibrinogen. On return to Australia 5 days post-bite she was treated successfully with one antivenom raised against Malayan pit viper and green pit viper venoms (Haemato-polvalent antivenom from Thailand) and then subsequently with another antivenom raised against American pit-viper venoms (Antivipmyn). Presumed pit viper venom was detected in patient sera with an enzyme immunoassay against Hypnale hypnale venom. There was increased absorbance before antivenom compared to non-envenomed control samples, which then decreased after the administration of each antivenom. The recurrence of venom detected by enzyme immunoassay between antivenom doses was accompanied by a recurrence of the coagulopathy. Cross reactivity between the unknown venom and both antivenoms was supported by the fact that no venom was detected in the pre-antivenom samples after they were incubated in-vitro with both antivenoms. This case and investigation of the venom and antivenoms suggest cross-neutralisation between pit vipers, including pit vipers from different continents

Use of immunoturbidimetry to detect venom-antivenom binding using snake venoms

Introduction: Immunoturbidimetry studies the phenomenon of immunoprecipitation of antigens and antibodies in solution, where there is the formation of large, polymeric insoluble immunocomplexes that increase the turbidity of the solution. We used immunoturbidimetry to investigate the interaction between commercial snake antivenoms and snake venoms, as well as cross-reactivity between different snake venoms. Methods: Serial dilutions of commercial snake antivenoms (100 μl) in water were placed in the wells of a microtitre plate and 100 μl of a venom solution (50 μg/ml in water) was added. Absorbance readings were taken at 340 nm every minute on a BioTek ELx808 plate reader at 37 °C. Limits imposed were a 30 minute cut-off and 0.004 as the lowest significant maximum increase. Reactions with rabbit antibodies were carried out similarly, except that antibody dilutions were in PBS. Results: Mixing venom and antivenom/antibodies resulted in an immediate increase in turbidity, which either reached a maximum or continued to increase until a 30 minute cut-off. There was a peak in absorbance readings for most Australian snake venoms mixed with the corresponding commercial antivenom, except for Pseudonaja textilis venom and brown snake antivenom. There was cross-reactivity between Naja naja venom from Sri Lanka and tiger snake antivenom indicated by turbidity when they were mixed. Mixing rabbit anti-snake antibodies with snake venoms resulted in increasing turbidity, but there was not a peak suggesting the antibodies were not sufficiently concentrated. The absorbance reading at pre-determined concentrations of rabbit antibodies mixed with different venoms was able to quantify the cross-reactivity between venoms. Indian antivenoms from two manufacturers were tested against four Sri Lankan snake venoms (Daboia russelli, N. naja, Echis carinatus and Bungarus caeruleus) and showed limited formation of immunocomplexes with antivenom from one manufacturer. Discussion: The turbidity test provides an easy and rapid way to compare and characterise interactions between antivenoms and snake venoms

Antivenom for snake venom-induced neuromuscular paralysis

To assess the effects of antivenom on neuromuscular paralysis in people with neurotoxic snake envenoming

Summary of snakes known to cause venom-induced consumption coagulopathy, the procoagulant toxin, and the factor deficiencies that have been reported (with permission from WikiToxin).

<p>aPTT – activated partial thromboplastin time, CT – clotting time, VCT – venous clotting time, FDP – fibrinogen degradation products, PLA₂ – phospholipase A₂, PT – prothrombin time, TLE – thrombin like enzymes, WBCT – whole blood clotting time, WBCT20 – 20 minutes whole blood clotting time, FII – factor II, FV – factor V, FX – factor X, FDP – fibrinogen degradation products; PTA – prothrombin activator; SVMP – snake venom metalloproteinase; NR – not reported;</p><p>* A SVMP has been isolated from <i>D. typus</i> venom but its function (? PTA, FX activator, TLE) is unclear and only fibrinogen has been measured in patients.</p><p>Summary of snakes known to cause venom-induced consumption coagulopathy, the procoagulant toxin, and the factor deficiencies that have been reported (with permission from WikiToxin).</p