Neurotoxins

Bioremediation may also be an appropriate tool for dealing with chemical agents such as the mustards and organophosphate neurotoxins (66), but httie work on actual bioremediation has been pubUshed. 

Mode of Action. DDT and its analogues specifically affect the peripheral sense organs of insects and produce violent trains of afferent impulses that result in hyperactivity, convulsions, and paralysis. Death results from metaboHc exhaustion and the production of an endogenous neurotoxin. The very high lipophilic nature of these compounds faciUtates absorption through the insect cuticle and penetration to the nerve tissue. The specific site of action is thought to be the sodium channels of the axon, through inhibition of Ca " ATPase. 

Both the ease of use of this method for characterization of proteins and nucleic acids, and the abiHty to analyze many samples simultaneously for comparative purposes, have led to the prevalence of this technique. The drawbacks of a polyacrylamide matrix is that acrylamide is a neurotoxin, the reagents must be combined extremely carefiiUy, and the gels are not as pHable as most agarose gels. 

Tetrodotoxin is one of the most powerful non-protein neurotoxins known. It occurs in the liver and ovaries of the Japanese puffer fish, Sphoerides rubripes and S. phyreus, and its lethal effects have been known for centuries, although it was isolated in crystalline form... 

Fig.l. The more important metabolites of tryptorhan Degradation of the tryptophan accompanied with increasing in 10 times of kynurenine level in the case of renal failure. As the result of 3-hydroxy-kynurenine s ability of easy oxidize neurotoxin compounds form. 

Sensitive to toxins, in this case means that the assay presents no false negative results. Primary hepatocytes can elucidate hepatotoxins, and mouse neuroblastoma cells can elucidate sodium channel-blocking neurotoxins therefore these assays can be used to screen for the appropriate toxins. 

It is obvious from the provisional risk assessment values for microcystins, and, being of the same order of magnitude of mammalian toxicity, similar values may be calculated for the cyanobacterial neurotoxins, that sensitive detection methods are required to detect these low concentrations of toxins. Of the biological methods of detection discussed earlier, the mouse and invertebrate bioassays are not sensitive enough without concentration of water samples, in that they are only able to detect mg of microcystins per litre. Only the immunoassays (ng-/rg 1 and the protein phosphatase inhibition assays (ng O... 

HBr, AcOH, 70, 8 h, 45-50% yield. During the synthesis of L-2-amino-3-oxalylaminopropionic acid, a neurotoxin, cleavage with Na/NH3 or [C oHg ] Na gave a complex mixture of products. 

Investigation of immune recognition segments in presynapsis and postsynapsis neurotoxins (macrocyclic peptides) 98KPS22. 

Acrylamide is the most important and the simplest of the acrylic and methacrylic amides. Acrylamide is a colorless crystalline solid. The basic physical properties and solubilities of acrylamide are given in Table I. Acrylamide is a severe neurotoxin and is a cumulative toxicological hazard. 

Botulinum neurotoxins (A-G), tetanus toxin Synaptic peptides a) Synapto-brevin b) Syntaxin c) SNAP25 Zinc dependent endoprotease Cleavage of synaptic peptides Inhibition of transmitter release (tetanus, botulism)... 

Botulinum neurotoxins are widely used as therapeutic agents to cause reduction or paralysis of skeletal muscle contraction. They are used to treat cervical dystonia, which causes regional involuntary muscle spasms often associated with pain. Moreover, they are used in strabism, blepharospasm, hemifacial spasm, and... 

Bronchial Asthma. Figure 2 Mechanisms of bronchial hyperresponsiveness. Toxic products from eosinophils [cationic peptides, reactive oxygen species (ROS)] cause epithelial injury. Nerve endings become easily accessible to mediators from mast cells, eosinophils [eosinophil-derived neurotoxin (EDN)], and neutrophils, and to airborne toxicants such as S02. Activation of nerve endings stimulates effector cells like mucosal glands and airway smooth muscle either directly or by cholinergic reflexes. 

Clostridial neurotoxins are bacterial protein toxins that consist of a heavy and a light chain connected by a disulfide bond and non-covalent interactions. They... 

The light chains of the clostridial neurotoxins are metalloproteases with exclusive specificity for neuronal SNAREs. TeNT, BoNTs B,D,F, and G cleave synapto-brevin, BoNTs A and E SNAP-25, and BoNT/Cl syntaxin, and to a lesser extent also SNAP-25. Cleavage of any of the SNAREs causes complete and irreversible block of synaptic transmission. 

Dopaminergic neurotoxin that causes parkinsonism via lesion of nigrostriatal dopamine neurons in rat, mice, monkeys. Unlike the dopaminergic neurotoxin MPTP (N-methy 1-4-phenyl-1,2,3,6-tetrahydropyridine) it does not cross the blood-brain barrier. 

A synthetic neurotoxin that causes parkinsonism in human and nonhuman primates, mice, gold fish, and dogs. MPTP is inert but metabolized by MAO-B to the neurotoxin MPP+ (1,2-dihydropyridine ion). This neurotoxin causes depletion of dopamine and degeneration of nigrostriatal dopamine neurons similar to what is observed in Parkinson s disease. 

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