Toxins, cascading effects

A phytotoxin may require binding sites within a plant in order to affect it adversely (1, 14). In the case of maculosin, a host specific toxin, a very specific receptor site may exist in spotted knapweed. Such a site may be a protein that has a normal role in the maintenance of cellular function, but coincidentally serves as a phytotoxin receptor (li, 15). Binding of the toxin by the receptor may result in a disruption in the functional role of the protein or result in a cascade effect involving other proteins. Either effect could result in cellular death (1, 111. 

Some research has concluded that in certain patients a cascading effect occurs. Eosinophils cluster around the fungi in the respiratory tract and produce toxins to subdue the fungi. In sinusitis, these toxins also destroy the outer lining of the sinus tissue, clearing the way for a bacterial infection that causes inflammation and sinusitis. 

The jl, 8 and k receptors are coupled, via pertussis toxin-sensitive G proteins, to inhibition of adenylyl cyclase activity, activation of receptor-linked currents, and suppression of voltagegated Ca currents. The hyperpolarization of membrane potential by K -current activation and the limiting of Ca entry by suppression of Ca currents are tenable but unproven mechanisms for explaining opioid inhibition of neurotransmitter release and pain transmission. Opioid receptors couple to an array of second-messenger systems, including activation of MAP kinases and the phospholipase C (PLC)-mediated cascade. Prolonged exposure to opioids results in adaptations at multiple levels within these signaling cascades that may relate to effects such as tolerance, sensitization, and withdrawal... 

The sensitivity of the early ELISA methods (51) was in the same range as previous in vitro methods, but increased greatly with the incorporation of amplifier systems (58,64). Specificity has also improved with the preparation of antitoxins against highly purified toxins and use of monoclonal antibodies (64). The reports on the ELCA method describe meticulous preparation of high quality reagents and an exceptionally effective amplification which utilizes the Russell s viper venom factor X activator to initiate the clotting cascade (9,10). Its sensitivity appears to equal or exceed that of the mouse. 

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