Poisons and Toxins

Harmful substances are everywhere. In fact almost any compound can be harmful. Even water can be used to cause death if administered excessively, as illustrated by a hazing incident (in the Spring of 2(X)3) at an npstate New York college campus where a freshman was forced to drink an excessive amount of water and died. However, the cause of the death is not the toxicity of water but rather because the excessive presence of water dilutes salt (sodium chloride) in the blood, which causes a salt imbalance (hyponitremia). 

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Point source Poisons and toxins Polar coordinates Polar ice caps Poliomyelitis Pollen analysis Pollination Pollution Pollution control... 

Any substance that reduces the velocity of an enzyme caialyzed reaction can be considered to be an "inhibitor. The inhibition of enzyme activity is one of the major regulatory devices of living cells, and one of the most important diagnostic procedures of the enzymologisL Inhibition studies often tell us something about the specificity of an enzyme, the physical and chemical architecture of the active site, and the kinetic mechanism of the reaction. In OUT everyday life, enzyme inhibitors can be found masquerading as drugs, antibiotics, preservatives, poisons, and toxins. In this section we examine a few simple types of enzyme inhibitors. 

Clinical research activity (study of bacterial infectious diseases, viral or parasitic examination of poison and toxins). 

The liver Is the main detoxification organ in the body and therefore comes Into contact with nearly every poison and toxin that enters the body. These materials could occur in case of poisoning, drug overdose, acute hepatitis, and allergies. While no true artificial liver has been developed, and transplantation is rare and difficult, several approaches have been attempted to replace and/or assist the function of the liver. The most common method is hemoperfusion in which the blood is passed through a column or bed of some sorbent material which can remove the poisons. The sorbents that have been used include charcoal, ion-exchange resins, affinity chromatography resins, immobilized enzymes and hepatic material or pieces of liver enclosed in artificial cells (9, 52). 

Poisons can be divided into corrosive, irritants, systemic poison, and toxins. Most organic compounds fall into the last two categories. 

All sea snakes are poisonous and their venoms are extremely toxic. The LD q for crude sea snake venom can be as low as 0.10 fig/g mouse body weight (i). For purified toxin the LD q is even lower, suggesting the high toxicity of sea snake toxins and venoms. This toxicity is derived from the presence of potent neurotoxins. Compared to snake venoms of terrestrial origin, sea snake venoms have been studied less. Different enzymes reported to be present or absent are summarized in Table I. 

Allergenic plants causing skin eruption by contact include poison ivy (Rhus radicans L.), poison oak (Rhus toxicodendron L.), poison sumac (Rhus vernix L.), and stinging nettle (Urtica dioica L.). In the United States, poison ivy and poison oak cause nearly 2 million cases of skin poisoning and skin irritation annually, for a loss of 333,000 working days. In addition, these weeds cause 3.7 million days of restricted activity among those people who are susceptible to the toxins (1). 

Some dinoflagellates of the genus Alexandrium produce neurotoxic compounds known as paralytic shellfish poisoning (PSP) toxins. Because these toxins can contaminate filter-feeding shellfish they may threaten public health and create economic problems for fisheries. PSP-toxins include at least a dozen saxitoxins, neosaxitoxins, and gonyautoxins (Scheme 1). 

Poisoning and sometimes death from eating (unidentified) mushrooms is well known. In particular, Amanita sp. are particularly dangerous, with much emphasis on the death cap fungus , Amanita phalloides.24 The best known toxins are the amatoxins and phallotoxins, which are complex, bicyclic peptides. An unusual feature relates to sulfur a tryptophan (or substituted tryptophan) unit is linked to a cysteine sulfur at the carbon atom next to the NH group of the pyrrole ring, forming the unit, -CH2-S-C(NH)=C, e.g. in... 

Fortunately, of the vast number of mushroom species that exists, only a few produce secondary metabolites that cause fatal poisonings. If toxins causing benign symptoms, such as abdominal pain and diarrhea, hallucinations, or alcohol incompatibility, are disregarded, the most significant mushroom toxins are the extremely hazardous compounds of amatoxins, orellanine, and, to a lesser extent, methylhydrazine and its derivatives. Consequently, there is only a... 

Among fish we find some of the most potent toxins in animals. We dis-tinguish passivelj toxic fish from actively toxic fish. The former simply have toxins in their tissues, typically taken from some other source such as their diet. The latter produce the poison and have evolved apparatus to discharge, deliver, or inj ect the... 

Ichthyootoxic Fishes. Those fish that produce a poison which is generally restricted to the gonads of the fish. The musculature and other parts of the fish are usually edible. There is a definite relationship between gonadal activity and toxin production. Fishes in this group are mainly freshwater species, but a few marine species have been incriminated. 

Using paralytic shellfish toxins extracted from mass cultures of Bay of Fundy excavata, we have found the symptoms of poisoning and the time course of their appearance to be similar in Atlantic herring, American pollock, winter flounder, Atlantic salmon, and cod (10). 

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