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Phoneutria nigriventer (Labidognatha, Ctenidae) is a spider found in the warm regions of South America. Bites by this species cause intense local pain, autonomic dysfunction and paralysis. PhTx2, a neurotoxic fraction of the venom of this species, interferes with the physiology of sodium channel function. The present study describes the morphological changes in mouse phrenic nerve and diaphragm muscle...
The neutralization of botulinum toxin serotype A with polyclonal equine antitoxin was studied in isolated mouse hemidiaphragms and compared to the same action in live mice. The biological activity of the toxin in the isolated muscle could be markedly reduced with excess antitoxin, estimated as 3:1 molar ratios of IgG Ab:toxin or better. Toxin neutralization in vivo required higher ratios of Ab:toxin,...
Histopathological changes induced in mice by lyngbyatoxin A were studied in connection with the occurrence of the toxin in marine turtles implicated in human intoxication.Lyngbyatoxin A showed an i.p. lethal dose 250μg/kg in immature mice (3-week old) and most severely damaged capillaries of villi in the small intestine. Immature mice were more sensitive than matured ones and died of bleeding from...
Toxin-producing cyanobacteria pose a worldwide health threat to humans and animals due to their increasing presence in both drinking and recreational waters. Little work has, however, been done on a preventative therapy for anyone at risk of exposure to cyanobacterial toxins. The potential benefits of dietery supplementation of selenium, an antioxidant, to protect against the mouse liver injury induced...
Snake venoms are a very abundant source of nerve growth factors (NGF). NGFs of Elapidae showing 65% sequence homology with mouse or human NGF, while the Viperidae NGF shows N-glycosylation (Asn-21) typical of these mammalian NGFs. Snake NGF-induced neurite outgrowth (neurotropic activity) was measured in the past by using PC12 cell or dorsal root ganglion bioassays. The present study was aimed at...
Gambierol was isolated from Gambierdiscus toxicus, which causes ciguatera fish poisoning. The acute toxicological effects induced in mice by synthesized gambierol were studied. The lethal doses were about 80 μg/kg by i.p. and i.v., and 150 μg/kg by p.o. The main injury by this toxin was observed in the lung, and secondary in the heart, resulting in systemic congestion. Another toxic effect was seen...
The actions of botulinum neurotoxin (BoNT) were studied on evoked release of the neurotransmitter glycine in primary mouse spinal cord cells. 3 [H]-glycine was taken up by cells in physiological solution and released by depolarization with 56mM K + in the presence of 2mM Ca 2+ . Release of 3 [H]-glycine was found to be inhibited by BoNT serotypes A, B and E with similar...
Domoic acid (DA), an analog of the excitatory amino acid glutamate, is produced by the diatom genus Pseudo-nitzschia and acts as a neurotoxin in humans. During diatom blooms, DA can contaminate shellfish, as well as other filter feeding organisms, and can be transferred by ingestion to higher trophic levels, including marine mammals and humans. The prevalence of this algal toxin and its effects on...
In this paper, the reproductive toxicity of male mice treated with Microcystis aeruginosa cell extracts containing microcystins was examined. In contrast to the control group, male mice exposed intraperitoneally to 3.33 or 6.67μg microcystins/kg body weight for 14 days had decreased mean body weight, and the mean absolute weight of the testes and epididymides was decreased. However, the mean relative...
Microcystins produced by freshwater cyanobacteria are potent hepatotoxins and can cause animal intoxications and human illnesses. In the present study, the effects of microcystins on the embryonic development of Kunming mice were determined using cell extracts of Microcystis aeruginosa from the Nanwan reservoir, China. Forty-eight pregnant mice were divided into four groups of 12 mice. Pregnant mice...
Cylindrospermopsin (cyn) is a cyanobacterial toxin implicated in human and wildlife poisonings. We have completed studies investigating the potential of purified cyn to induce developmental toxicity in mammals. The teratology study involved intraperitoneal injections (8.0–128μgkg −1 ) on gestational days (GD) 8–12 with subsequent examination of term fetuses for viability, weight and morphological...
In the present study, a detailed activation time-course was examined for single chain native BoNT/E, enzymatically nicked in solution with trypsin. Through SDS-PAGE and Western blot analysis, the optimal nicking time was determined to be approximately 30min. At 30min, maximal di-chain BoNT/E and minimal secondary nicking (degradation) products were observed. The identity and integrity of the resulting...
Xeomin ® [Merz; 150kDa Botulinum type A toxin (BoNT/A)] and BOTOX ® [Allergan; 900kDa BoNT/A complex] were compared, to assess the degree of similarity between these products in terms of potency and antigenicity. Potency was evaluated in the Digit Abduction Score (DAS) mouse assay. Full-range dose–response profiles were achieved with 3 lots of each product, with similarity between...
Diarrhetic activity of pectenotoxin-6 (PTX6), a shellfish contaminant in Japanese scallops (Patinopecten yessoensis), was studied in vivo. Mice gavaged with 5mg/kg PTX6 did not show diarrhea or fluid secretion, and no prominent pathological changes were observed. There was no synergistic toxicity of PTX6 with okadaic acid (OA) or pectenotoxin-2 (PTX2) when toxins were given to mice by gavage. Synergistic...
Snake venom metalloproteinases (SVMPs) mainly distribute in Crotalid and Viperid snake venom and are classified into the Reprolysin subfamily of the M12 family of metalloproteinases. Previous function investigations have suggested that SVMPs are the key toxins involved in a variety of snake venom-induced pathogenesis including systemic injury, local damage, hemorrhage, edema, hypotension, hypovolemia,...
Botulinum neurotoxins induce a prolonged muscle paralysis by specifically blocking the release of neuronal transmitters from peripheral nerve junctions. The current method for assessing the potency of botulinum toxin and antitoxins is the mouse LD 50 assay. The mouse phrenic nerve–diaphragm assay is an in vitro assay that closely mimics in vivo respiratory paralysis. In this study, we have...
Bee stings are a health concern in the Americas, where fatal envenomings due to massive attacks by Africanized honeybees have been documented in the last decades. Most studies on the toxic effects of honeybee venom in experimental animals have been performed using the intravenous or intraperitoneal injection routes. The aim of this study was to develop a mouse model that would better resemble a massive...
Palytoxin (PlTX) is a marine toxin originally isolated from the zoantharians of the genus Palythoa. It is considered to be one of the most lethal marine toxins that block the Na + /K + -ATPase. This study was designed to investigate the acute effects of PlTX and ouabain, also an Na + /K + -ATPase blocker, on the mammalian peripheral nervous system using an ex vivo electrophysiological...
α-Amanitin, the main toxic substance from mushroom species (Amanita genus), blocks the activity of RNA polymerase II (Pol II) in mammalian cells causing inhibition of transcription and subsequent synthesis of structural and enzymatic proteins. It has been postulated that α-amanitin generates the increase of reactive oxygen species (ROS) concentration. The micronucleus (MN) test was used on an animal...
SylH3 and 24B11 are murine monoclonal antibodies directed against different epitopes on ricin toxin's binding (RTB) subunit that have been shown to passively protect mice against ricin challenge. Here we report that Fab fragments of SylH3 and 24B11 neutralize ricin in a cell based assay, and in a mouse challenge model as effectively as their respective full length parental IgGs. These data demonstrate...
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