Toxicon Research Papers - Academia.edu (original) (raw)

Introduction and Objectives: Current standard treatment for patients with spasticity includes botulinum toxin infiltrations at intervals of no less than 3 months. However, in clinical practice, some patients need more closely spaced treatments in order to adequately modulate spastic hypertonia and to ensure their satisfaction. The aim of this study was to investigate whether reduction of intervals between incobotulinumtoxin A (Xeomin) infiltrations results in a significant reduction of treatment clinical efficacy over time or a rise in adverse reactions. Methods: We evaluated the effects of flexible intervals of incobotulinumtoxin A infiltrations (6, 12, 16 weeks) in 28 patients with left spasticity treated for a period of 16 months. We analyzed 3 parameters: patient satisfaction (outcome), Modified Ashworth Scale (MAS), and myotonometry (MYO), which represents a noninvasive way to characterize the viscoelastic properties (tone, elasticity, stiffness) of skeletal muscles. Statistical analysis was performed using one-way ANOVA. Results: Therapeutic effect of infiltration at different time intervals was maintained constant in time (P<0.05). Conclusions: The opportunity to reduce the time between infiltrations is due to the pharmacologic properties of incobotulinumtoxin A, which is free from complexing proteins. Infiltrations administered at flexible intervals (6 to 16 weeks) were well tolerated by patients and modulated the spasticity satisfactorily, allowing a personalized treatment. Last, we found that the therapeutic effect of this new strategy remains constant over time.

- by and +1
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- Toxicon, Pharmacology and pharmaceutical sciences

Two hemolysins, Sticholysin I (St I) and Sticholysin II (St II) were puri®ed from the sea anemone Stichodactyla helianthus combining gel ®ltration and ion exchange chromatography. The amino acid composition of both cytolysins was determined revealing a high proportion of glycine, lysine, tyrosine and non-polar amino acids (alanine, leucine and valine). Cysteine was not found in either polypeptide. Molecular masses of St I and St II were 19401 and 19290 Da, respectively. N-terminal sequence analysis of St I and St II showed a high homology between them suggesting they are isoforms of the same cytolysin. Compared with other sea anemone cytolysins, St I and St II contain a 22 amino acid insertion fragment also present in Eq T II/Tn C and probably in CaT I and Hm T and absent in C III, the major hemolysin previously reported in this anemone. 7

- by Célia Carlini
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- Brazil, Mice, Lectins, Proteins
- by Gavin Laing
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- Toxicon, Pharmacology and pharmaceutical sciences

Spider venom contains a mixture of peptide toxins, some able to kill insects specifically to those considered as important pest. In this study, a peptide toxin produced by the Macrothele gigas spider, Magi 6, was cloned and expressed in tobacco plants, as this toxin has been shown to constitute an effective insecticide. For this purpose, a genetic construction for the cDNA that codifies for Magi 6 was subcloned in a plant expression vector using the 35S promoter and the 5 0 -end leader from tobacco mosaic virus, in order to transform tobacco leaf disks. The resulting plants demonstrated the presence of Magi 6 gene in the tobacco genome using PCR, and transcription of the cDNA was verified by means of RT-PCR. The expression of the Magi 6 peptide in tobacco was demonstrated by Western blot, which exhibited the expected size, thus suggesting a correct processing of the signal peptide. No morphological alterations in the different transgenic lines were observed, nor any change in plant growth. Subsequently, experiments were carried out challenging detached leaves or whole plants with the herbivorous insect Spodoptera frugiperda. The bioassays indicated that the transgenic lines were significantly more resistant than the wild type plants. This work demonstrated that the expression of Magi 6 peptide in transgenic plants conferred resistance to insect attack and opens the possibility of employing this peptide to improve the resistance of diverse plants.

- by Gabriel Iturriaga and +3
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- Genetics, Tobacco, Spiders, Insect Resistance

Centaurea solstitialis (yellow star thistle) has been proven to cause equine nigropallidal encephalomalacia in horses. Over the last fifty years, nigropallidal encephalomalacia has been of interest to human medicine due to the possible connection with Parkinson's disease. Previous studies indicated the presence of neurotoxic nitrogenous compounds in polar extracts of the plant. In order to give a more detailed description of the nitrogen-containing fraction of C. solstitialis, various samples were collected at different development stages. Different aliquots of the same aqueous extract were directly derivatized with ophthaldialdehyde and dansyl chloride and analyzed separately by reversed-phase HPLC. A complete profile of the free nitrogenous fraction of C. solstitialis was given and results obtained with the two derivatization procedures were compared. No particularly high level of free aspartic and glutamic acids, two potent neuroexcitotoxic amino acids, were found in polar extracts of the plant. Tyramine resulted to be the most important biologically active amine present in C. solstitialis (with a mean concentration of 2.0 mg/100 g of dry weight). q

- by LANFRANCO CONTE
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- Nitrogen, Neurotoxins, High Pressure Liquid Chromatography, Amino Acids

The accidental contact with Lonomia obliqua caterpillar causes local and systemic symptoms (such as fibrinogen depletion), leading, in some cases, to serious clinical complications (acute renal failure and intracranial haemorrhage). Fortunately, a successful therapeutical approach using anti-Lonomic serum, produced in horses against L. obliqua's bristle extract, has already been put in place. However, a global view of immunogenic toxins involved in the coagulation disorders could help to elucidate the envenoming process. In the present study, our aim was to identify bristle extract's immunogenic components, especially those related to the haemostasis, coupling proteomics and immunochemical approaches (bidimensional electrophoresis, mass spectrometry and immunoblotting). The bidimensional map of bristle extract showed a broad profile of 157 silver-stained spots, where at least 153 spots were immunochemically revealed. Twenty-four of these spots were submitted to sequencing by mass spectrometry and three different categories of proteins were identified: lipocalins, cuticle proteins and serpins. From these protein families, it was observed that the most abundant was the lipocalin family, specifically represented by different isoforms of Lopap (a prothrombin activator protein), reinforcing its relevance during envenoming. Peptide sequences of several other immunochemically revealed spots showed no correspondence to any known sequence and were classified as unknown proteins. These proteins could represent new immunogenic molecules and/or toxins. The sequences presented in this article can be used for oligonucleotide design aiming the amplification of cDNAs coding for new molecules using L. obliqua bristles' cDNA libraries or isolated RNAs as template. r

- by Jonas Ramos
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- Mass Spectrometry, Proteomics, Lepidoptera, Acute renal failure
- by Linda Jahnke
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- Microbiology, Technology, Environmental microbiology, Kinetics

G. ROJAS, J. M. JIM~NEZ and J. M. GUTII~RREZ. Caprylic acid fractionation of hyperimmune horse plasma: description of a simple procedure for antivenom production. Toxicon 32, 351-363, 1994.--A simple methodology for hyperimmune horse plasma fractionation, based on caprylic acid precipitation, is described. Optimal conditions for fractionation were studied; the method gives best results when concentrated caprylic acid was added to plasma, whose pH had been adjusted to 5.8, until a final caprylic acid concentration of 5% was reached. The mixture was vigorously stirred during caprylic acid addition and then for 60 min; afterwards the mixture was filtered. Non-immunoglobulin proteins precipitated in these conditions, whereas a highly enriched immunoglobulin preparation was obtained in the filtrate, which was then dialysed to remove caprylic acid before the addition of NaC1 and phenol. Thus, antivenom was produced after a single precipitation step followed by dialysis. In order to compare this methodology with that based on ammonium sulfate fractionation, a sample of hyperimmune plasma was divided into two aliquots which were fractionated in parallel by both methods. It was found that caprylic acid-fractionated antivenom was superior in terms of yield, production time, albumin/globulin ratio, turbidity, protein aggregates, electrophoretic pattern and neutralizing potency against several activities of Bothrops asper venom. Owing to its efficacy and simplicity, this method could be of great value in antivenom and antitoxin production laboratories.

- by Gustavo Rojas
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- Snake venoms, Mice, Horses, Chemical Precipitation

J. M. Delaney and R. M. Wilkins. Toxicity of microcystin-LR, isolated from Microcystis aeruginosa, against various insect species. Toxicon 33, 771-778, 1995.-Microcystin-LR (MC-LR), isolated from the cyanobacterium Microcystis aeruginosa Kuetzing emend. Elenkin strain CCAP 1450/4 was tested for biological activity against four species of insect and the invertebrate Artemia salina. The efficacy of pesticidal activity was compared with various insecticides. The 24 hr LD,, value for third instar diamond-backed moth, Plutella xylostella, on ingestion from a treated leaf surface was 1 .O pg cm', compared with a 72 hr LD,, value for rotenone of 2..0 pg cm-*. The 24 hr LD, values of MC-LR and malathion on intrathoracic injection into adult house flies (Musca domestica) were 0.5 and 3.7 mg kg-l, respectively. MC-LR had no effect on M. domestica when applied topically at dosages up to 32 mg kg-'. MC-LR and malathion gave 24 hr LD, values of 4.7 and 13.1 mg kg-', respectively when injected into third instar cotton leafworm (Spodoptera littoralis). In fourth instar cabbage white butterfly larvae (Pieris brassicae) MC-LR injected gave 24 and 48 hr ~a,,, values of 3.9 and 1.9 mg kg-', respectively, whilst the 24 and 48 hr LD~ values for carbofuran were 0.4 and 0.3 mg kg-', respectively. An immersion bioassay with l-day-old brine shrimp larvae (Artemia salina) gave 24 hr LD,, values of 3.8 pgml-' for MC-LR and 1.8 pgrnl-' for carbofuran. MC-LR has appreciable insect toxicity, comparable to the three insecticides tested. The toxin look 24-48 hr to exert its full lethal effect in insects, much longer than the l-3 hr it takes in mammals. The potential use of MC-LR as an insecticide is discussed.

- by Richard Wilkins
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- Artemia, Insects, Cyclic peptides, Marine Toxins

A method is described which produces a high, permanent antibody response following a single injection of venom. Animals (mice, rabbits, sheep) were given intravenous, subcutaneous or orally administered Nigerian Echis carinatus (carpet viper) venom which had been incorporated into sphingomyelin-cholesterol liposomes whose membranes had been stabilized by cross-linking adjacent molecules of sphingomyelin using osmium tetroxide. Before use the preparations were thoroughly dialysed to remove any unbound osmium tetroxide. Antibody levels were estimated using enzyme immunoassay. Venom treated in this way and administered i.v. or s.c. produced a powerful, sustained and protective antibody response lasting for the lifetime of a mouse. We also report the development of significant antibody responses after oral administration of liposome-entrapped but not free venom.

- by James Iddon
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- Antibodies, Mice, Sheep, Cholesterol

Central effects of scorpion venom toxins have been neglected, due both to the common belief that scorpion venoms act by targeting peripheral organs and also to the misunderstanding that these peptides do not cross the brain-blood barrier (BBB). Determining whether scorpion neurotoxicity is restricted to peripheral actions or whether a central mechanism may be partly responsible for systemic manifestations could be crucial in clinical therapy trends. The present study therefore aims to assess histopathological damages in some organs (heart, kidney, liver, and lungs) and the related biochemical impairments, together with a neurobehavioral investigation following an intracerebroventricular (i.c.v) micro-injection of Hottentotta gentili (Scorpiones, Buthidae) venom (0.47 μg/kg). I.c.v. injection of venom produced focal fragmentation of myocardial fibers, while lungs showed rupture of the alveolar structure. Concurrently, there was a significant rise in the serum enzymes levels of ASAT, ALAT, CPK and LDH. Meanwhile, we observed behavioral alterations such as a hypoactivity, and in addition the venom seems to have a marked anxiogenic-like effect. The present investigation has brought new experimental evidence of a peripheral impact of central administration of H. gentili venom, such impact was manifested by physiological and behavioral disturbances, the last of these appearing to reflect profound neuro-modulatory action of H. gentili venom.

- by HIND FEREHAN and +1
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- Toxicon, Pharmacology and pharmaceutical sciences

Polyvalent antivenin was prepared against the Egyptian snake venons N~a Julje, N.tt;grlcollis, Cerastes eerastu and C. vipers, and tested by neutralization and immunodiffusion tests. The antivenin was of high potency against the Egyptian snake venons, especially C. ceraatea and C. vlpera, followed by F .chls carirruut, E. coloratur, N. /ulje, N. rt{gricollis and Walterinneaia aegyptia. The titre against the African and hidiaa cobra venons, N. nivea, N. hgje (Ethiopian) and N. rtgja was lower, while poor or no effect was shown against Bittyarietaru, B. galinnlea and 7ümeruurw flavovirldtr venons. The polyvalent serum prepared in horses not previously immunized, was comparable to sera obtained by using horses, which were previously immunized against a single venom. However, the latter sera, still maintained their higher titre against the original sensitizing venom. Comparison of polyvalent and monovaknt N. nigricollir aativwtina, revealed that while the polyvalent serum was of belles effectiveness against the Egyptian viper venons especially txtastes vanoma, more protection was provided by the nonovaknt serum against the raja venons .

- by Humberto González
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- Snakes, Rats, Lethal Dose, Venoms

A simple and sensitive in situ method for monitoring the occurrence of toxic algal blooms and shellfish contamination events has been developed. The technique involves the passive adsorption of biotoxins onto porous synthetic resin filled sachets (SPATT bags) and their subsequent extraction and analysis. The success of the method is founded on the observation that during algal blooms significant amounts of toxin, including the low polarity lipophilic compounds such as the pectenotoxins and the okadaic acid complex toxins, are dissolved in the seawater. The results of field trials during Dinophysis acuminata and Protoceratium reticulatum blooms are presented. These data prove the concept and demonstrate that the technique provides a means of forecasting shellfish contamination events and predicting the net accumulation of polyether toxins by mussels. As an early warning method it has many advantages over current monitoring techniques such as shellfish-flesh testing and phytoplankton ...

- by Andy Selwood
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- Genetics, Water, Mass Spectrometry, Eutrophication

Botulinum neurotoxins induce a prolonged muscle paralysis by specifically blocking the release of neuronal transmitters from peripheral nerve junctions. Potency testing of toxin and antitoxin therapies is entirely dependent on mouse lethality bioassay which is associated with extreme suffering of large numbers of animals to ensure high precision. The mouse phrenic nerve-diaphragm assay is an ex vivo assay that closely mimics in vivo respiratory paralysis offering substantial refinement and reduction in the number of animals used. A range of botulinum antitoxin standards, one licenced product and experimental antitoxins were tested for neutralising potency using ex vivo hemidiaphragm assay and compared with in vivo determined activities. Overall, there was an excellent agreement between neutralising activity detected by the two assay systems and for each toxin serotype using only 4–7 replicates for each product (almost perfect concordance for type A antitoxins: ρ = 0.997, and substantial concordance for type B antitoxins: ρ = 0.991 and type E antitoxins: ρ = 0.964, respectively). These findings confirm that the mouse nerve-diaphragm preparation can provide a functional ex vivo replacement assay for specific, sensitive and precise assessment of toxin and antitoxin activity.

- by Russell G A Jones
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- Peripheral Nerve, Botulinum Toxin, Toxicon
- by L Bruce Pearce
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- Mice, PARALYSIS, Clinical Study, Mechanism of action

The effects of Indian red scorpion Buthus tmnulus venom in vivo and in vitro. Toxicon 30, 1157Toxicon 30, -1164Toxicon 30, , 1992.-The Indian red scorpion Buthus tmnulus (or Mesobuthus tumulus) can cause fatal envenoming, but its mechanism of action is unclear. Venom was tested in vivo in anaesthetized rats and in vitro on isolated cardiac and skeletal muscle preparations . In vivo, the venom caused marked rhythmical fluctuations in blood pressure proceding cardiovascular collapse and death. On sheep Purkinje fibres, venom could induce spontaneous action potentials and cause prolongation of action potential duration. In chick biventer cervicis and mouse triangularis sterni preparations, venom enhanced the release of acetylcholine and induced repetitive firing of nerve action potentials in response to single shock stimulation. High concentrations caused stimulation then block of neuromuscular transmission. The main effects of Buthus tumulus venom are likely to be due to toxins that affect the opening of Na+ channels in nerves and muscles. This will cause an increase in the release of neurotransmitters in the peripheral nervous system, which may produce cardiovascular abnormalities and respiratory paralysis.

- by Bernice Man and +2
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- Mice, Sheep, Anesthesia, Heart

Honey badgers (Mellivora capensis) prey upon and survive bites from venomous snakes (Family: Elapidae), but the molecular basis of their venom resistance is unknown. The muscular nicotinic cholinergic receptor (nAChR), targeted by snake α-neurotoxins, has evolved in some venom-resistant mammals to no longer bind these toxins. Through phylogenetic analysis of mammalian nAChR sequences, we show that honey badgers, hedgehogs, and pigs have independently acquired functionally equivalent amino acid replacements in the toxin-binding site of this receptor. These convergent amino acid changes impede toxin binding by introducing a positively charged amino acid in place of an uncharged aromatic residue. In venom-resistant mongooses, different replacements at these same sites are glycosylated, which is thought to disrupt binding through steric effects. Thus, it appears that resistance to snake venom α-neurotoxin has evolved at least four times among mammals through two distinct biochemical mec...

- by Sharon Jansa
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- Convergent Evolution, Toxicon

Pha1b is a potent toxin obtained from the spider Phoneutria nigriventer that blocks neuronal voltage-sensitive Ca 2þ channels. This study compared the antiallodynic effects of Pha1b, u-conotoxin MVIIA and morphine in mice and their side effects in rats. Mechanical allodynia was measured in mice receiving single intrathecal administration of Pha1b, u-conotoxin MVIIA or morphine before or after the incisional plantar procedure. The effect of the treatments on cardiovascular profile and global neurological were evaluated in rats. The expression of pro or anti-inflammatory cytokines of human polymorph mononuclear cells was also evaluated.

- by Carine Vieira
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- Pain, Polymorphism, Cytokines, Performance Assessment
- by Bruno Lomonte
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- Toxicon

Saxitoxin (STX) is a low molecular weight neurotoxin mainly produced by certain marine dinoflagellates that, along with its family of similarly related paralytic shellfish toxins, may cause the potentially fatal intoxication known as paralytic shellfish poisoning. Illness and fatality rates are low due to the effective monitoring programs that determine when toxins exceed the established regulatory action level and effectuate shellfish harvesting closures accordingly. Such monitoring programs rely on the ability to rapidly screen large volumes of samples. Many of the screening assays currently available employ antibodies or live animals. This research focused on developing an analytical recognition element that would eliminate the challenges associated with the limited availability of antibodies and the use of animals. Here we report the discovery of a DNA aptamer that targets STX. Concentration-dependent and selective binding of the aptamer to STX was determined using a surface plasmon resonance sensor. Not only does this work represent the first reported aptamer to STX, but also the first aptamer to any marine biotoxin. A novel strategy of using a toxin-protein conjugate for DNA aptamer selection was successfully implemented to overcome the challenges associated with aptamer selection to small molecules. Taking advantage of such an approach could lead to increased diversity and accessibility of aptamers to low molecular weight toxins, which could then be incorporated as analytical recognition elements in diagnostic assays for foodborne toxin detection. The selected STX aptamer sequence is provided here, making it available to any investigator for use in assay development for the detection of STX.

- by Katrina Campbell
- •
- Protein Folding, Calibration, Surface plasmon resonance, Proteins
- by Daniel Truong
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- Evidence Based Medicine, Evidence Based Practice, Face, Treatment Outcome

Ciguatera is a significant food borne disease caused by potent polyether toxins known as ciguatoxins, which accumulate in the flesh of ciguateric fish at risk levels above 0.1 ppb. The management of ciguatera has been hindered by the lack of analytical methods to detect and quantify clinically relevant levels of ciguatoxin in easily prepared crude extracts of fish. Here we report a ciguatoxin rapid extraction method (CREM) that allows the rapid preparation of fish flesh extracts for the detection and quantification of ciguatoxin by gradient reversed-phase liquid chromatography-tandem mass spectrometry (LC/MS/MS). CREM-LC/MS/MS delivers a linear response to P-CTX-1 spiked into fish prior to extraction. A similar response was obtained for P-CTX-1 spiked after extraction, indicating >95% extraction efficiency was achieved overall and 85% at the limit of quantification (0.1 ppb). Using this approach, levels !0.1 ppb P-CTX-1 could be detected and quantified from an extract of 2 g fish flesh, making it suitable as a confirmatory assay for suspect ciguateric carnivorous fish in the Pacific Ocean. The approach is designed to simplify the extraction and analysis of multiple samples per day.

- by Alun Jones
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- HPLC, Solid Phase Extraction, Meat, Tandem Mass Spectrometry

The effects of Karenia brevis (Wilson clone) on larval survival and development of the northern quahog, Mercenaria mercenaria, eastern oyster, Crassostrea virginica and bay scallop, Argopecten irradians, were studied in the laboratory. Larvae were exposed to cultures of whole and lysed cells, with mean total brevetoxin concentrations of 53.8 and 68.9 mg L À1 , respectively. Survival of early (3-day-old) larvae was generally over 85% for all shellfish species at K. brevis densities of 100 cells ml À1 or less, and not significantly different between whole and lysed culture. At 1000 cells ml À1 , survival was significantly less in lysed culture than whole culture for both M. mercenaria and C. virginica. Survival of late (7-day-old) larvae in all three species was not significantly affected by K. brevis densities of 1000 cells ml À1 or less. At 5000 cells ml À1 , however, survival was reduced to 37%, 26% and 19% for A. irradians, M. mercenaria and C. virginica, respectively. Development of C. virginica and M. mercenaria larvae was protracted at K. brevis densities of 1000 cells ml À1 . These results suggest that blooms of K. brevis, and particularly their associated brevetoxins, may have detrimental consequences for Florida's shellfisheries by disrupting critical larval processes. Special attention should be paid to blooms of K. brevis where these shellfish occur naturally or where aquaculture and restoration activities are either ongoing or planned. r

- by SANDRA MOTE
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- Bivalvia, Marine Toxins, Larva, Larvae

fatality due to ingestion of the crab Demania reynaudii that contained a palytoxin-like toxin. Toxicon 26, 105-107, 1988.-Clinical accounts of a human fatality resulting from ingestion of the crab Demania reynaudii are documented. The causative toxin was suggested to be palytoxin on the basis of dose-death time relationships and chromatographic properties.

- by angel alcala
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- Death, Crustacea, Toxicity, Heart rate

Canatoxin (CNTX) is a variant form of urease isolated from Canavalia ensiformis (Leguminosaea) seeds. A possible role in the plant defense was proposed for CNTX, due to its toxicity upon feeding to the beetle Callosobruchus maculatus, and the hematophagous bug, Rhodnius prolixus. The toxic effect is caused by a canatoxin-derived peptide (w10 kDa) formed by insect cathepsin-like digestive enzymes. In order to evaluate their potential as bioinsecticides, the effects of CNTX and its peptide were evaluated on a phytophagous hemipteran insect Dysdercus peruvianus, a pest of cotton culture. For the bioassays, the insects fed on gelatin capsules containing powdered cotton seeds, mixed with the freeze-dried protein and other test materials and were observed for survival rate, weight gain and molting. Ingestion of canatoxin, or a recombinant 10 kDa peptide derived from it, severely affected young forms of the insects, delaying their development or leading to their death. In contrast, adults were insensitive to diets containing higher concentrations of canatoxin. Cathepsin-like proteinases predominated and showed distinct pattern of enzymatic activities in midguts homogenates according to the developmental stage of the insect, a fact which may explain the different susceptibility of nymphs as compared to adult D. peruvianus. The data presented confirm the potential use of canatoxin-like proteins and derived peptides as bioinsecticides. q

- by Fernanda Mulinari and +1
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- Brazil, Survival Analysis, Heteroptera, PLANT DEFENSE

Toxinology in Brazil developed specially during the 19th and 20th centuries. A very brief description of the main contributions made by pioneer toxinologists is presented here in an attempt to give an idea of the evolution of toxinology in our country, from its first steps until the XVI World Congress of the International Society on Toxinology, held in Recife, Brazil

- by Célia Carlini
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- Toxicology, Brazil, Biodiversity, Scientific Societies

Some California ground squirrels (Spermophilus beecheyi) show limited necrosis following envenomation by northern Pacific rattlesnakes (Crotalus viridis oreganus). This study demonstrates that S. beecheyi blood sera inhibits venom proteases. Sera from rattlesnake-abundant habitats inhibited C. v. oreganus venom more effectively than venom from two allopatric rattlesnake species, C. v. viridis and C. atrox, suggesting evolutionary specialization. The pattern of inhibition among squirrel populations corresponds best with history of rattlesnake predation, in contrast to current rattlesnake density.

- by James Biardi and +2
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- Coevolution, Chemical Ecology, Adaptation, Biological Sciences

The improvement of the immunotherapeutic treatment of envenomations requires a better knowledge of the pharmacological actions of the scorpion venom and of the mechanism of its in vivo neutralization by antivenom. In the present work, we determined the toxicokinetic parameters of the toxic fraction of Androctonus australis garzonii venom in the absence and after antivenom immunotherapy, in experimentally envenomed rabbits. After subcutaneous injection of the scorpion venom, toxins showed a fast and complete resorption from the site of injection associated with a simultaneous distribution in a large extracellular compartment and with an important body clearance. The precocious intravenous injection of an appropriate antivenom dose was shown to induce an immediate, complete and durable neutralization of toxins, as well as their rapid redistribution from the peripheric compartment to the vascular one. On the contrary, the intramuscular injection of the same antivenom dose produced a slower and partial redistribution of toxins, leading to a delayed neutralization of the venom. The intravenous injection of smaller antivenom doses induced transient decreases of circulating toxins, indicating that a minimal antivenom dose has to be administered to allow an efficient and durable neutralization of the venom. We concluded also that this minimal effective dose of antivenom has to be injected precociously, by intravenous route, to achieve an efficient immunotherapy. q

- by Valerie CHOUMET
- •
- Pharmacokinetics, Mice, Page, Steady state

Mortality due to snake envenomation is not a major problem in the United States with approximately 8–12 deaths per year, but envenomation is a serious problem that can result in functional disability, loss of extremities, and a costly recovery. Physicians encounter different clinical situations with each new snakebite victim because of the geographical variations in snake venoms. The best and most acceptable form of treatment is the use of antivenom; however, it must be administered as soon as possible since it is not so effective at reducing local signs of envenomation such as necrosis. The antivenom in the United States is in short supply, expensive and may not even be the most effective for neutralizing all North American snake venoms. In this study, we tested two antivenoms. The first was a Crotalidae Polyvalent Fab fragment with Ovine origin (FabO) manufactured in London, and the second was Antivipmyn, a Mexican manufactured antivenom that is F(ab′)2 fragment produced in horse (Fab2H). The efficacy of the two antivenoms was tested with 15 different snake venoms found in North America. Three different assays were used to test the efficacy of the antivenoms, the in vivo serum protection test (ED50), antihemorrhagic and anticoagulant. The Fab2H antivenom was most effective in neutralizing the hemorrhagic activity of 78% of the hemorrhagic venoms used in this study. In the ED50 assay, the Fab2H antivenom was effective in neutralizing all venoms used in this study, while FabO neutralized all but C. m. molossus venom. However, in most cases, FabO required less antivenom than Fab2H antivenom to neutralize three LD50.

- by JoHn PèRez
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- Comparative Study, Fibrinogen, Sheep, United States
- by Frederic Dorandeu
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- Toxicon

and sharing with colleagues.

- by Joan Fuchs
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- Primary Health Care, Toxicology, Treatment Outcome, Spiders

Struan Sutherland was the doyen of medical research in the field of envenomation and the ultimate authority on the medical management of envenomated victims in Australia for almost 3 decades. In 1981 as Head of Immunology Research of Commonwealth Serum Laboratories (CSL), he produced an antivenom against the Sydney Funnel-web Spider (Atrax robustus)-an accomplishment that had defied numerous previous attempts. Struan also invented the pressure-immobilisation technique of first-aid for snake bite. This ingenious, simple but safe and effective technique revolutionised first-aid management of snake bite and of some other types of envenomation. It made redundant the use of tourniquets and other dangerous first-aid treatments. Similarly, he helped to develop a snake venom detection kit, which enables doctors working at a victim's bedside to ascertain which snake was responsible and which antivenom should be administered. He had a very wide range of research interests and was a prodigious researcher publishing over 200 scientific and medical articles, numerous chapters in books and the standard Australian medical textbook on the management of envenomation, Australian Animal Toxins. He made major contributions to the understanding of the venoms of Australia's remarkable range of fauna including snakes, spiders, Blue-ringed octopus, ants, jellyfish and stinging fish. Struan served the medical fraternity and the public selflessly. He was always available to doctors, or to anybody, to give advice at any hour of the day or night, on management of envenomated victims.

- by James Tibballs
- •
- Australia, Bites and Stings, Toxicon

biochemical activities of Vipera berus (European viper) venom. Toxicon 31, 743-753, 1993.-Vipera berus is widely distributed throughout the northern part of Europe and Asia. Characterization of several toxic effects of its venom in the mouse, as well as of in vitro enzymatic activities was performed. Vipera berus venom displayed in vitro proteolytic, fibrinolytic, anticoagulant, and phospholipase AZ activities . The i.p. LD s p Of the venom for Swiss mice was 0.86 aug/g (95% confidence limits 0.71-1.01 hg/g). Sïgnificant local tissue-damaging effects, including edema, hemorrhage and myonecrosis, were observed . The local edema was characterized by rapid onset, reaching a maximum after 0.~1 hr, and with dose-dependent persistence. The hemorrhagic potency was measured by a skin tent, giving a minimum hemorrhagic dose value of 3.2 hg. The venom also induced a moderate local myonecrosis, evidenced by histological evaluation of injected tissue (gastrocnemius), and by biochemical parameters (increase of plasma creatine kinase activity, and decrease of muscle residual MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide)-reducing activity). Characterization of the venom by SDS-polyacrylamide gel electrophoresis revealed 10 (reduced) or 11 (unreduced) main protein bands, which were further analyzed in relation to mol. wt and relative concentration by densitometry . A rabbit antiserum to V. berus venom recognized all main venom bands by immunoblotting. This antiserum cross-reacted to a variable extent with several crotaline venoms, as assessed by enzyme immunoassay.

- by Bruno Lomonte
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- Antibodies, Mice, Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis, Edema
- by McHardy Smith
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- Sodium channel, Gating, Voltage-Gated Sodium Channels, Toxicon

and sharing with colleagues.

Six novel peptides (named bactridines) were isolated from Tityus discrepans scorpion venom. From mass spectrometry molecular masses were 6916, 7362, 7226, 7011, 7101 and 7173 Da (bactridines 1-6). Bactridines 1 and 2 were sequenced by Edman degradation. The sequences and in silico analysis, indicated that they are positively charged polypeptides comprised of 61 and 64 amino acids (AA), respectively, bactridine 1 and bactridine 2 containing 4 disulfide bridges. Bactridine 1 was only toxic to cockroaches and crabs, and bactridine 2-6 were only toxic to mice. Bactridine 1 has a 78% sequence identity with ardiscretin. Ardisctretin is an insect specific sodium toxin which also produces a small depolarization and induces repetitive firing in squid axons resembling those of DDT [1,10(pchlorobenzyl) 2-trichloretane] in its ability to slow down action potential, to induce repetitive firing. Measured as the minimal inhibitory concentration, bactridines had high antibacterial activity against a wide range of Gram positive and Gram negative bacteria.

- by victor salazar
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- Mass Spectrometry, Fluorescence, Fluorescent Dyes and Reagents, Gram Positive

Optimization of caprylic acid precipitation of equine plasma non-immunoglobulin proteins for antivenom preparation was achieved by regression analysis of the responses of three highly significant factors assayed by factorial design. The factors studied were caprylic acid concentration, plasma pH and temperature, and their response was assessed in terms of filtration speed, residual albumin, total protein content and turbidity. The results evidenced that the three variables are involved in the precipitation process. Moreover, the factors displayed significant interactions, indicating that their levels distinctly affect the optimization procedure. The best combination was 3% caprylic acid, 37 C and plasma pH 4.9; under these conditions, all immunoglobulins and only 0.1% albumin remained in the supernatant, in a very fast and simple procedure. After formulation, the antivenom obtained by this procedure presented full lethality neutralizing activity and absence of protein aggregates.

- by Carolina Perdomenico
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- Pharmaceutical Chemistry, Factorial Design, Regression Analysis, Temperature

Among fungal toxins causing organ damage in the human body, amatoxins and orellanine remain exceptional. Amatoxins, a group of bicyclic octapeptides occurring in some Amanita, Galerina and Lepiota species, induce deficient protein synthesis resulting in cell death, but might also exert toxicity through inducing apoptosis. Target organs are intestinal mucosa, liver and kidneys. Poisoning will result in dehydration and electrolyte derangement, liver necrosis and possibly kidney damage. In established poisoning the mainstay of treatment is optimum symptomatic and supportive care. No specific treatment is available, but some pharmaceuticals, like silibinin, benzylpenicillin and acetylcysteine, might have a role in limiting the extent of hepatic damage. Orellanine is a nephrotoxic bipyridine N-oxide found in some Cortinarius species. Its mechanism of action is not fully understood, but it has been shown to inhibit protein synthesis and to generate free oxygen radicals. As early symptoms often are lacking or vague, poisoning may initially be overlooked or misinterpreted and the patients usually present with established renal damage. Supportive care is the only therapeutic option. Tricholoma equestre might contain a myotoxin and repeated ingestion may cause significant rhabdomyolysis. Ingestion of Amanita smithiana and A. proxima has been reported to result in kidney damage. Gyromitrin, a toxic compound that is converted to hydrazines in the stomach, occurs in some Gyromitra species. It is mainly neurotoxic, but may also induce moderate hepatic damage and haemolysis. q

- by Hans-Åke Persson
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- Kidney diseases, Protein synthesis, Intestinal Mucosa, Human Body

Four thousand and seventy eight cases of snakebite, occurring between January and December 2000, were analysed for clinical and epidemiological features. Cases of about 379 had features of envenoming and 81 died. All the victims with systemic envenoming had neurotoxicity. No case with coagulopathy was recorded. Snakebite was more frequent between the ages of 10 and 40 years (76%) and in males (73%). The majority (80%) of the snakebites were observed during the monsoon. Seventy percent of the bites with clinical features of envenoming occurred between 1400 and 2200 h. Five thousand eight hundred and fifty nine vials of polyvalent antisnake venom were used. Case fatality rate varied in the ten centres surveyed. It was as low as 3% in some to as high as 58% in others. Overall death rate among all snakebite cases was 2%. q

- by Sanjib Sharma
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- Nepal, Adolescent, Child, Infant

Accumulation of ciguatoxins (CTXs) in tropical reef fish tissues during their life is responsible of the most prevalent human seafood intoxication in the South Pacific called Ciguatera Fish Poisoning (CFP). It has been assumed for a long time that CTXs are transferred and accumulated along the trophic food chain, and consequently that smaller individuals within a given fish species are safer to eat than larger ones. However, the relationship between toxicity and fish size has been studied for a limited number of species only and the conclusions are often contradictory. The toxicity of 856 fishes from 59 different species sampled in six islands in French Polynesia between 2003 and 2011 was assessed by Receptor Binding Assay. Among them, 45 species Â island and 32 families Â island for which the number of individuals was !6 allowed testing the relationship between toxicity and size. Except for six specimens of Lutjanus bohar caught in Fakarava (P < 0.01; R 2 ¼ 0.854), the 44 remaining species Â island showed no significant increase of CTXs concentration with fish total length (TL). Moreover, the proportion of toxic individuals decreased significantly for Epinephelus polyphekadion from Fakarava (n ¼ 24; P < 0.05) and Kyphosus cinerascens from Raivavae (n ¼ 29; P < 0.05), while no significant variation was detected for the other 43 species Â island. At the family level, only three positive and three negative relationships between size and CTXs concentration were observed among the 32 family Â island analyzed. No relationship between the proportion of toxic fish within a family and the relative total length of individuals were observed. The lack of relationship between toxicity and size observed for most of the species and families from the six islands suggests that fish size cannot be used as an efficient predictor of fish toxicity in French Polynesia. These results highlight the need for improving our knowledge about metabolic processes which may play a role in CTXs bio-accumulation and depuration among the different trophic levels of fishes.

- by Hélène Taiana Darius
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- Polynesia, FISH, Fishes, Trophic Level

The acute poisoning of chronic renal patients during hemodialysis sessions in 1996 in Caruaru City (Pernambuco State, Brazil) stimulated an intensive search for the cause of this severe complication. This search culminated in the identification of microcystins (MC), hepatotoxic cyclic heptapeptides produced by cyanobacteria, as the causative agents. More than ten years later, additional research data provides us with a better understanding of the factors related to cyanobacterial bloom occurrence and production of MC in Brazil and other South American countries. The contamination of water bodies and formation of toxic blooms remains a very serious concern, especially in countries in which surface water is used as the main source for human consumption. The purpose of this review is to highlight the discoveries of the past 15 years that have brought South American researchers to their current level of understanding of toxic cyanobacteria species and that have contributed to their knowledge of factors related to MC production, mechanisms of action and consequences for human health and the environment.

- by Ernani Pinto
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- Water, Brazil, Environmental Monitoring, Aquatic Ecosystem

The seas and oceans around Australia harbour numerous venomous jellyfish. Chironex fleckeri, the box jellyfish, is the most lethal causing rapid cardiorespiratory depression and although its venom has been characterised, its toxins remain to be identified. A moderately effective antivenom exists which is also partially effective against another chirodropid, Chiropsalmus sp. Numerous carybdeids, some unidentified, cause less severe illness, including Carybdea rastoni whose toxins CrTX-A and CrTX-B are large proteins. Carukia barnesi, another small carybdeid is one cause of the 'Irukandji' syndrome which includes delayed pain from severe muscle cramping, vomiting, anxiety, restlessness, sweating and prostration, and occasionally severe hypertension and acute cardiac failure. The syndrome is in part caused by release of catecholamines but the cause of heart failure is undefined. The venom contains a sodium channel modulator. Two species of Physalia are present and although one ...

- by James Tibballs
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- Epidemiology, Australia, Treatment, Adolescent
- by Jorge Galarce
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- Argentina, Snake venoms, Yield, Snakes

Toads have a pair of parotoid macroglands behind the eyes that secrete poison used in passive defence against predators. These macroglands are composed of juxtaposed alveoli, each one bearing a syncytial gland, all connected to the exterior by ducts. When the parotoids are bitten, the poison is expelled on the predator oral mucosa in the form of jets, causing several pharmacological actions. After poison release, the empty secretory syncytia immediately collapse in the interior of their respective alveoli and gradually start refilling. After parotoid manual compression, simulating a predator's bite, we studied, by means of morphological methods, the replacement of the poison inside the alveoli. The results showed that after compression, a considerable number of alveoli remained intact. In the alveoli that were effectively affected the recovery occurs in different levels, from total to punctual and often restrict to some areas of the syncytia. The severely affected alveoli seem not recover their original functional state. The fact that only a part of the parotoid alveoli is compressed during an attack seems to be crucial for toad survival, since the amphibian, after being bitten by a predator, do not lose all its poison stock, remaining protected in case of new attacks.

- by Mizue Egami
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- Brazil, Bufonidae, Toxicon

Lectins are carbohydrate binding (glyco)proteins which are ubiquitous in nature. In plants, they are distributed in various families and hence ingested daily in appreciable amounts by both humans and animals. One of the most nutritionally important features of plant lectins is their ability to survive digestion by the gastrointestinal tract of consumers. This allows the lectins to bind to membrane glycosyl groups of the cells lining the digestive tract. As a result of this interaction a series of harmful local and systemic reactions are triggered placing this class of molecules as antinutritive and/or toxic substances. Locally, they can affect the turnover and loss of gut epithelial cells, damage the luminal membranes of the epithelium, interfere with nutrient digestion and absorption, stimulate shifts in the bacterial flora and modulate the immune state of the digestive tract. Systemically, they can disrupt lipid, carbohydrate and protein metabolism, promote enlargement and/or atrophy of key internal organs and tissues and alter the hormonal and immunological status. At high intakes, lectins can seriously threaten the growth and health of consuming animals. They are also detrimental to numerous insect pests of crop plants although less is presently known about their insecticidal mechanisms of action. This current review surveys the recent knowledge on the antinutritional/toxic effects of plant lectins on higher animals and insects. q

- by José Oliveira
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- International organizations, Insecticides, Cell line, Intestinal Mucosa

Honey badgers (Mellivora capensis) prey upon and survive bites from venomous snakes (Family: Elapidae), but the molecular basis of their venom resistance is unknown. The muscular nicotinic cholinergic receptor (nAChR), targeted by snake a-neurotoxins, has evolved in some venom-resistant mammals to no longer bind these toxins. Through phylogenetic analysis of mammalian nAChR sequences, we show that honey badgers, hedgehogs, and pigs have independently acquired functionally equivalent amino acid replacements in the toxin-binding site of this receptor. These convergent amino acid changes impede toxin binding by introducing a positively charged amino acid in place of an uncharged aromatic residue. In venom-resistant mongooses, different replacements at these same sites are glycosylated, which is thought to disrupt binding through steric effects. Thus, it appears that resistance to snake venom aneurotoxin has evolved at least four times among mammals through two distinct biochemical mechanisms operating at the same sites on the same receptor.

- by Danielle Drabeck
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- Convergent Evolution, Toxicon
- by Prasanna Lakshmi
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- RNA, RNA polymerase, Liver, Chromatin

Before the introduction of the first Australian antivenom was the era of the self-styled 'snakemen' and their diverse snakebite remedies. Many received multiple bites from highly dangerous snakes, some of which were deliberately taken to either prove a certain treatment or liven up their show. The mortality rate among these handlers and showmen was high. Production of the first effective Australian antivenom, the tiger snake antivenom, in 1930, began the scientific approach to treating snakebite and opened new frontiers for professional and amateur snake people. Collecting venoms in the development and early production of antivenoms was carried out by a number of professional herpetologists often with little or no reward and in some instances at the ultimate cost of their lives. This paper reviews the most important of those late nineteenth and twentieth century snakemen and their contributions to venom research, antivenom production and current toxinological knowledge. r

- by Peter Mirtschin
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- Death, Production, Toxicology, Australia