Renal lesions in rhabdomyolysis caused by Pseudechis australis snake myotoxin

In Vitro Toxicity of Chinese Russell’s Viper (Daboia siamensis) Venom and Neutralisation by Antivenoms

Daboia siamensis (Russell’s viper) is a highly venomous and medically important snake in China, as well as much of Asia. There is minimal information on the pharmacological activity of the venom of the Chinese species, and currently no commercially available specific antivenom in China. This has led to the use of non-specific antivenoms to treat D. siamensis envenomation. In this study, the in vitro neurotoxicity and myotoxicity of D. siamensis venom was examined and the efficacy of four antivenoms was investigated, including the recently developed Chinese D. siamensis monovalent antivenom (C-DsMAV) and three commercially available antivenoms (Thai D. siamensis (Thai-DsMAV) monovalent antivenom, Deinagkistrodon acutus monovalent antivenom (DaAV), and Gloydius brevicaudus monovalent antivenom (GbAV). D. siamensis venom (10–30 µg/mL) caused the concentration-dependent inhibition of indirect twitches in the chick biventer cervicis nerve muscle preparation, without abolishing contractile responses to exogenous agonists ACh or CCh, indicating pre-synaptic neurotoxicity. Myotoxicity was also evident at these concentrations with inhibition of direct twitches, an increase in baseline tension, and the partial inhibition of ACh, CCh, and KCl responses. The prior addition of C-DsMAV or Thai-DsMAV prevented the neurotoxic and myotoxic activity of D. siamensis venom (10 µg/mL). The addition of non-specific antivenoms (GbAV and DaAV) partially prevented the neurotoxic activity of venom (10 µg/mL) but failed to neutralize the myotoxic effects. We have shown that D. siamensis venom exhibits in vitro weak presynaptic neurotoxicity and myotoxicity, which can be prevented by the pre-addition of the Chinese and Thai Russell’s viper antivenoms. Non-specific antivenoms were poorly efficacious. There should be further development of a monospecific antivenom against D. siamensis envenomation in China.

Fatal Rattlesnake Envenomation in Northernmost Brazilian Amazon: A Case Report and Literature Overview

Snakebite envenomations are classified as Category A Neglected Tropical Diseases by the World Health Organization. In Brazil, 405 snake species are distributed among 11 families, with the genera Bothrops and Crotalus being the most studied and main responsible for severe and lethal envenomations. In the country, Crotalus genus (i.e., rattlesnakes) is represented by Crotalus durissus species, showing seven different subspecies distributed along the country, including Crotalus durissus ruruima, which inhabits Roraima, the Brazilian nothermost state from Amazon forest. Here, we report a fatal case of a severe envenomation following a rattlesnake bite. The patient presented classic crotalic neurological signs and symptoms such as ptosis, drooling of saliva, sluggishness, macroscopic hematuria, and oliguria, which evolved to acute kidney failure (AKF) and hemodynamic instability. Although the patient was treated with the specific antivenom therapy, the severe envenomation resulted in three cardiac arrests and death of the victim in less than 38 h. This study discusses the causes of the patient death, the features of rattlesnake venom-induced AKF, and shows evidences that the Brazilian crotalic antivenom should be improved to treat rattlesnake envenomations caused by C. d. ruruima venom in Roraima state.

Evaluation of the geographical utility of Eastern Russell's viper (Daboia siamensis) antivenom from Thailand and an assessment of its protective effects against venom-induced nephrotoxicity

BACKGROUND

Daboia siamensis (Eastern Russell's viper) is a medically important snake species found widely distributed across Southeast Asia. Envenomings by this species can result in systemic coagulopathy, local tissue injury and/or renal failure. While administration of specific antivenom is an effective treatment for Russell's viper envenomings, the availability of, and access to, geographically-appropriate antivenom remains problematic in many rural areas. In this study, we determined the binding and neutralizing capability of antivenoms manufactured by the Thai Red Cross in Thailand against D. siamensis venoms from four geographical locales: Myanmar, Taiwan, China and Thailand.

METHODOLOGY/PRINCIPLE FINDINGS

The D. siamensis monovalent antivenom displayed extensive recognition and binding to proteins found in D. siamensis venom, irrespective of the geographical origin of those venoms. Similar immunological characteristics were observed with the Hemato Polyvalent antivenom, which also uses D. siamensis venom as an immunogen, but binding levels were dramatically reduced when using comparator monovalent antivenoms manufactured against different snake species. A similar pattern was observed when investigating neutralization of coagulopathy, with the procoagulant action of all four geographical venom variants neutralized by both the D. siamensis monovalent and the Hemato Polyvalent antivenoms, while the comparator monovalent antivenoms were ineffective. These in vitro findings translated into therapeutic efficacy in vivo, as the D. siamensis monovalent antivenom was found to effectively protect against the lethal effects of all four geographical venom variants preclinically. Assessments of in vivo nephrotoxicity revealed that D. siamensis venom (700 μg/kg) significantly increased plasma creatinine and blood urea nitrogen levels in anaesthetised rats. The intravenous administration of D. siamensis monovalent antivenom at three times higher than the recommended scaled therapeutic dose, prior to and 1 h after the injection of venom, resulted in reduced levels of markers of nephrotoxicity and prevented renal morphological changes, although lower doses had no therapeutic effect.

CONCLUSIONS/SIGNIFICANCE

This study highlights the potential broad geographical utility of the Thai D. siamensis monovalent antivenom for treating envenomings by the Eastern Russell's viper. However, only the early delivery of high antivenom doses appears to be capable of preventing venom-induced nephrotoxicity.

Non-neurotoxic activity of Malayan krait (Bungarus candidus) venom from Thailand

Background

Envenoming by kraits (genus Bungarus) is a medically significant issue in South Asia and Southeast Asia. Malayan krait (Bungarus candidus) venom is known to contain highly potent neurotoxins. In recent years, there have been reports on the non-neurotoxic activities of krait venom that include myotoxicity and nephrotoxicity. However, research on such non-neurotoxicity activities of Malayan krait venom is extremely limited. Thus, the aim of the present study was to determine the myotoxic, cytotoxic and nephrotoxic activities of B. candidus venoms from northeastern (BC-NE) and southern (BC-S) Thailand in experimentally envenomed rats.

Methods

Rats were administered Malayan krait (BC-NE or BC-S) venom (50 μg/kg, i.m.) or 0.9% NaCl solution (50 μL, i.m.) into the right hind limb. The animals were sacrificed 3, 6 and 24 h after venom administration. The right gastrocnemius muscle and both kidneys were collected for histopathological analysis. Blood samples were also taken for determination of creatine kinase (CK) and lactate dehydrogenase (LDH) levels. The human embryonic kidney cell line (HEK-293) was used in a cell proliferation assay to determine cytotoxic activity.

Results

Administration of BC-NE or BC-S venom (50 μg/kg, i.m.) caused time-dependent myotoxicity, characterized by an elevation of CK and LDH levels. Histopathological examination of skeletal muscle displayed marked muscle necrosis and myofiber disintegration 24 h following venom administration. Both Malayan krait venoms also induced extensive renal tubular injury with glomerular and interstitial congestion in rats. BC-NE and BC-S venoms (100–0.2 μg/mL) caused concentration-dependent cytotoxicity on the HEK-293 cell line. However, BC-NE venom (IC₅₀ = 8 ± 1 μg/mL; at 24 h incubation; n = 4) was found to be significantly more cytotoxic than BC-S venom (IC₅₀ = 15 ± 2 μg/mL; at 24 h incubation; n = 4). In addition, the PLA₂ activity of BC-NE venom was significantly higher than that of BC-S venom.

Conclusions

This study found that Malayan krait venoms from both populations possess myotoxic, cytotoxic and nephrotoxic activities. These findings may aid in clinical diagnosis and treatment of envenomed patients in the future.

Pharmacokinetics and pharmacodynamics of the myotoxic venom of Pseudechis australis (mulga snake) in the anesthetised rat

CONTEXT

Myotoxicity is a common clinical effect of snake envenoming and results from either local or systemic myotoxins in snake venoms. Although numerous myotoxins have been isolated from snake venoms, there has been limited study on the relationship between the time course of venom concentrations (pharmacokinetics) and the time course of muscle injury measured as a rise in creatine kinase (CK) (pharmacodynamics).

OBJECTIVE

The aim of this study was to develop an in vivo model of myotoxicity to investigate the time course of myotoxicity and the effect of antivenom.

MATERIALS AND METHODS

Anesthetised rats were administered Pseudechis australis (mulga snake) venom either through i.v., i.m. or s.d. route, including a range of doses (5-100 μg/kg). Serial blood samples were collected for measurement of venom using enzyme immunoassay and measurement of CK and creatinine. Antivenom was administered before, 1 and 6 h after venom administration to investigate its effect on muscle injury. Plots of venom and CK versus time were made and the area under the curve (AUC) was calculated.

RESULTS

There was a significant dose-dependent increase in CK concentration after administration of P. australis venom, which was greatest for i.v. administration. Timed measurement of venom concentrations showed a rapid absorption through s.d. and i.m. routes and a delayed rise in CK concentrations following any route. Antivenom prevented myotoxicity shown by a decrease in the CK AUC, which was most effective if given earliest. There was a rise in creatinine following i.v. venom administration.

CONCLUSION

The study shows the delayed relationship between venom absorption and the rise in CK, consistent with the delayed onset of myotoxicity in human envenoming. Antivenom prevented myotoxicity more effectively if given earlier.

Selenium inhibits renal oxidation and inflammation but not acute kidney injury in an animal model of rhabdomyolysis

Acute kidney injury (AKI) is a manifestation of rhabdomyolysis (RM). Extracellular myoglobin accumulating in the kidney after RM promotes oxidative damage, which is implicated in AKI.

AIM

To test whether selenium (Se) supplementation diminishes AKI and improves renal function.

RESULTS

Dietary selenite increased Se in the renal cortex, as demonstrated by X-ray fluorescence microscopy. Experimental RM-stimulated AKI as judged by increased urinary protein/creatinine, clusterin, and kidney injury molecule-1 (KIM-1), decreased creatinine clearance (CCr), increased plasma urea, and damage to renal tubules. Concentrations of cholesterylester (hydro)peroxides and F₂-isoprostanes increased in plasma and renal tissues after RM, while aortic and renal cyclic guanidine monophosphate (cGMP; marker of nitric oxide (NO) bioavailability) decreased. Renal superoxide dismutase-1, phospho-P65, TNFα gene, MCP-1 protein, and the 3-chloro-tyrosine/tyrosine ratio (Cl-Tyr/Tyr; marker of neutrophil activation) all increased after RM. Dietary Se significantly decreased renal lipid oxidation, phospho-P65, TNFα gene expression, MCP-1 and Cl-Tyr/Tyr, improved NO bioavailability in aorta but not in the renal microvasculature, and inhibited proteinuria. However, CCr, plasma urea and creatinine, urinary clusterin, and histopathological assessment of AKI remained unchanged. Except for the Se++ group, renal angiotensin-receptor-1/2 gene/protein expression increased after RM with parallel increases in MEK1/2 inhibitor-sensitive MAPkinase (ERK) activity.

INNOVATION

We employed synchrotron radiation to identify Se distribution in kidneys, in addition to assessing reno-protection after RM.

CONCLUSION

Se treatment has some potential as a therapeutic for AKI as it inhibits oxidative damage and inflammation and decreases proteinuria, albeit histopathological changes to the kidney and some plasma and urinary markers of AKI remain unaffected after RM.

In vitro neurotoxic effects of Pseudechis spp. venoms: A comparison of avian and murine skeletal muscle preparations

Two common in vitro skeletal muscle preparations used for the study of venom neurotoxicity are the indirectly stimulated chick isolated biventer cervicis nerve-muscle preparation and the rat isolated phrenic nerve-diaphragm preparation. The aim of the current study was to compare the in vitro neurotoxicity of six Pseudechis spp. (Black snakes) venoms in both avian (chicken) and mammalian (rat) skeletal muscle preparations to determine differences in sensitivity. All Pseudechis spp. venoms significantly inhibited indirect twitches, in both preparations, indicating the presence of post synaptic neurotoxins. The inhibitory effects of all venoms were more rapid in the avian preparation, except for Pseudechis colletti venom where no significant difference was seen between the murine and avian muscles. Time taken to produce 50% reduction in stimulated twitches (i.e. t(50)) was markedly shorter in the avian preparation. We have shown that the avian in vitro preparation is more sensitive to the neurotoxic activity of Pseudechis spp. than the murine preparation. This difference is likely to be due to species differences in the interaction between the neurotoxins and the nicotinic receptor binding sites as well as differences in the 'safety factor' between the preparations.

Phenolic antioxidants tert-butyl-bisphenol and vitamin E decrease oxidative stress and enhance vascular function in an animal model of rhabdomyolysis yet do not improve acute renal dysfunction

Rhabdomyolysis (RM) caused by severe burn releases extracellular myoglobin (Mb) that accumulates in the kidney. Extracellular Mb is a pro-oxidant. This study tested whether supplementation with tert-butyl-bisphenol (BP) or vitamin E (Vit E, as α-tocopherol) at 0.12% w/w in the diet inhibits acute renal failure (ARF) in an animal model of RM. After RM-induction in rats, creatinine clearance decreased (p < 0.01), proteinuria increased (p < 0.001) and renal-tubule damage was detected. Accompanying ARF, biomarkers of oxidative stress (lipid oxidation and hemeoxygenase-1 (HO-1) gene and protein activity) increased in the kidney (p < 0.05). Supplemented BP or Vit E decreased lipid oxidation (p < 0.05) and HO-1 gene/activity and restored aortic cyclic guanylyl monophosphate in control animals (p < 0.001), yet ARF was unaffected. Antioxidant supplementation inhibited oxidative stress, yet was unable to ameliorate ARF in this animal model indicating that oxidative stress in kidney and vascular cells may not be causally related to renal dysfunction elicited by RM.

Snakebite nephrotoxicity in Asia

Snakebites have the highest incidence in Asia and represent an important health problem. Clinical renal manifestations include proteinuria, hematuria, pigmenturia, and renal failure. Nephropathy usually is caused by bites by snakes with hemotoxic or myotoxic venoms. These snakes are Russell's viper, saw-scaled viper, hump-nosed pit viper, green pit viper, and sea-snake. Renal pathologic changes include tubular necrosis, cortical necrosis, interstitial nephritis, glomerulonephritis, and vasculitis. Hemodynamic alterations caused by vasoactive mediators and cytokines and direct nephrotoxicity account significantly for the development of nephropathy. Hemorrhage, hypotension, disseminated intravascular coagulation, intravascular hemolysis, and rhabdomyolysis enhance renal ischemia leading to renal failure. Enzymatic activities of snake venoms account for direct nephrotoxicity. Immunologic mechanism plays a minor role.

Snakebite nephropathy (Review Article)

There is a broad clinical spectrum of renal involvement in snakebite. Besides the local and systemic symptoms, clinical renal manifestations vary from mild proteinuria, haematuria, pigmenturia to acute renal failure. Bites by haemotoxic snakes and myotoxic snakes are the common causes of renal involvement especially acute renal failure. Therefore, renal failure is often associated with haemorrhagic diathesis, intravascular haemolysis and rhabdomyolysis. Renal pathological changes include mesangiolysis, glomerulonephritis, vasculitis, tubular necrosis, interstitial nephritis and cortical necrosis. Tubular necrosis is an important pathological counterpart of acute renal failure. Haemodynamic alterations induced by cytokines and vasoactive mediators leading to renal ischaemia are important in the pathogenesis of acute renal failure. Haemolysis, intravascular coagulation and rhabdomyolysis are important contributing factors. Direct nephrotoxicity can be induced by the venom through metalloproteases and phosphilipase A2. Immunologic mechanism plays a minor role in the pathogenesis of the renal lesion.

Neurotoxic effects of venoms from seven species of Australasian black snakes (Pseudechis): efficacy of black and tiger snake antivenoms

1. Pseudechis species (black snakes) are among the most widespread venomous snakes in Australia. Despite this, very little is known about the potency of their venoms or the efficacy of the antivenoms used to treat systemic envenomation by these snakes. The present study investigated the in vitro neurotoxicity of venoms from seven Australasian Pseudechis species and determined the efficacy of black and tiger snake antivenoms against this activity. 2. All venoms (10 microg/mL) significantly inhibited indirect twitches of the chick biventer cervicis nerve-muscle preparation and responses to exogenous acetylcholine (ACh; 1 mmol/L), but not to KCl (40 mmol/L), indicating activity at post-synaptic nicotinic receptors on the skeletal muscle. 3. Prior administration of either black or tiger snake antivenom (5 U/mL) prevented the inhibitory effects of all Pseudechis venoms. 4. Black snake antivenom (5 U/mL) added at t90 (i.e. the time-point at which the original twitch height was reduced by 90%) significantly reversed the effects of P. butleri (28+/-5%), P. guttatus (25+/-8%) and P. porphyriacus (28+/-10%) venoms. Tiger snake antivenom (5 U/mL) added at the t90 time-point significantly reversed the neurotoxic effects of P. guttatus (51+/-4%), P. papuanus (47+/-5%) and P. porphyriacus (20+/-7%) venoms. 5. We show, for the first time, the presence of neurotoxins in the venom of these related snake species and that this activity is differentially affected by either black snake or tiger snake antivenoms.

The efficacy of two antivenoms against the in vitro myotoxic effects of black snake (Pseudechis) venoms in the chick biventer cervicis nerve-muscle preparation

Neurotoxicity is rarely seen following human systemic envenoming by Australasian black snakes (genus Pseudechis) with myotoxicity being the most prominent feature following bites by some species. This study investigated the in vitro myotoxicity of venoms from seven species of Australasian Pseudechis and determined the efficacy of CSL black and tiger snake antivenoms. All Pseudechis venoms (10 microg/ml) significantly inhibited direct twitches of the chick biventer cervicis nerve-muscle preparation (p<0.05, one-way ANOVA). Prior addition of black snake antivenom (5 U/ml) prevented the inhibitory effects of all Pseudechis venoms (p<0.05, one-way ANOVA), except Pseudechis butleri. Prior addition of tiger snake antivenom (5 U/ml) prevented the venom-induced reduction in direct twitches to Notechis scutatus venom and all Pseudechis venoms (p<0.05, one-way ANOVA), with the exception of Pseudechis australis and Pseudechis colletti venoms. Black or tiger snake antivenom (5 U/ml) added 1 h after the addition of venom inhibited further reduction of direct twitches by N. scutatus and most Pseudechis venoms, but did not significantly restore twitch height. PLA2 activity was found in all venoms with the following rank order: Pseudechis porphyriacus>P. australis>Pseudechis papuanus>P. butleri>Pseudechis guttatus> or =Pseudechis pailsii>P. colletti>N. scutatus. The results of the present study suggest that Australasian Pseudechis venoms possess variable myotoxic activity. The ability of black or tiger snake antivenom to prevent or inhibit further venom-induced effects varied across the genus.

Clinical toxinology--where are we now?

Clinical toxinology encompasses a broad range of medical conditions resulting from envenomation by venomous terrestrial and marine organisms, and also poisoning from ingestion of animal and plant toxins. Toxin-related disease is an important cause of morbidity and mortality worldwide, particularly in the tropical and subtropical continents. Snake bite is the single most important toxin-related disease, causing substantial mortality in many parts of Africa, Asia, and the Americas. The most important snake families are Viperidae and Elapidae, causing a range of clinical effects including local necrosis, neurotoxicity, coagulopathy and hemorrhage, myotoxicity and renal toxicity. These effects vary according to geography and group of snake. Arachnid envenomation results mainly in morbidity, particularly scorpion stings which can cause severe systemic envenomation. Spider bite is far less of a problem, and the majority of medically important cases can be attributed to widow spiders (Latrodectus spp.) and recluse spiders (Loxosceles spp.). Marine-related envenomations are common, but severe effects are less so. Plant and mushroom poisoning occur in most parts of the world, but the types and methods of poisoning vary considerably between continents. Management of toxin-related disease is often difficult, and in many cases meticulous supportive care is all that is available. The mainstay of treatment is the use of antivenoms for many envenomations and poisoning, although these do not exist for all dangerous organisms. Unfortunately antivenoms are not an economically viable product, so development and manufacture of these agents have been limited. This is now further worsened by a current shortage of antivenom. There is a need for improvement in the preventionand management of toxin-related disease. This will require well-designed studies to define the extent of the problem, initiatives to improve the prevention and management of these conditions, and development of new, and continuation of current, antivenom supplies.

Overview of tropical nephrology

Tropical nephrology covers renal diseases commonly seen in the tropics and elsewhere and specific tropical renal diseases seen mostly or only in the tropical area. Emphasis in this article is placed on the latter category, which includes renal involvement in tropical infectious diseases, natural toxin poisoning, and environmental renal problems. Pathologically, all renal structures can be affected. There is, therefore, a broad spectrum of pathologic changes, and clinical renal manifestations vary from mild urinary sediment changes to acute renal failure. Inflammatory processes plays an essential role in the pathogenesis of renal involvement in infection and toxin groups. Both models share the same inflammatory pathways through cytokines, chemokines, and mediators. Hemodynamic alterations, immune response, and direct nephrotoxicity are involved in the development of renal lesions.

Myoglobinuria

Myoglobinuria refers to an abnormal pathologic state in which an excessive amount of myoglobin is found in the urine, imparting a cola-like hue, usually in association with myonecrosis and a clinical picture of weakness, myalgias, and edema. Myoglobinuria is produced by multiple causes: any condition that accelerates the use or interferes with the availability of oxygen or energy substrates to muscle cells can result in myoglobinuria, as can events that produce direct muscle injury, either mechanical or chemical. Acute renal failure is the most serious complication, which can be prevented by prompt, aggressive treatment. In patients surviving acute attacks, recovery of muscle and renal function is usually complete.

Purification, properties, and amino acid sequence of a hemoglobinuria-inducing phospholipase A(2), MiPLA-1, from Micropechis ikaheka venom

Dark-colored urine is one of the clinical symptoms of envenomation by Micropechis ikaheka (New Guinea small-eyed snake). We have purified a phospholipase A(2), MiPLA-1, which induces dark-colored urine in experimental mice, to homogeneity. The analysis of the dark-colored urine by electrophoresis and N-terminal sequence determination indicated that the color of mouse urine is due to hemoglobin in the urine but not myoglobin. MiPLA-1 is the first hemoglobinuria-inducing toxin. Insignificant hemolytic activity of MiPLA-1 indicates that hemoglobinuria is not due to lysis of erythrocytes by MiPLA-1. This suggests that hemoglobinuria induced by MiPLA-1 may be due to kidney leakage caused by unknown mechanisms. MiPLA-1 also showed other biological effects, including myotoxicity as well as anticoagulant and antiplatelet effects. Structural studies show that MiPLA-1 is a basic protein with a molecular mass of 14041.60 +/- 1.78 as determined by electrospray mass spectrometry. We have determined the complete amino acid sequence of MiPLA-1. It is a 124-amino-acid protein with a "pancreatic loop" and belongs to group IB phospholipase A(2) enzymes. Two short segments flanked by proline brackets are found in the sequence of MiPLA-1. These segments are on the surface of the molecule and hence may be involved in protein-protein recognition.