Mammals mechanism

Suarez, S. (1998). The oviductal sperm reservoir in mammals Mechanisms of formation. Biol. Reprod. 58 1105-1107. 

Mode of Action. All of the insecticidal carbamates are cholinergic, and poisoned insects and mammals exhibit violent convulsions and other neuromuscular disturbances. The insecticides are strong carbamylating inhibitors of acetylcholinesterase and may also have a direct action on the acetylcholine receptors because of their pronounced stmctural resemblance to acetylcholine. The overall mechanism for carbamate interaction with acetylcholinesterase is analogous to the normal three-step hydrolysis of acetylcholine however, is much slower than with the acetylated enzyme. 

The mammalian and avian immune systems function similarly both incorporate humoral and cell-mediated cytotoxic mechanisms, " and are thought to share a 160m year old relationship with the reptilian immune system. The immune system of mammals shows sexual dimorphism " a greater immune response is normally observed in females, which has been attributed to differences in steroid hormone concentration. In the toad Bufo regularis, sexual dimorphism of the immune system is also apparent. ... 

Fatty acids with odd numbers of carbon atoms are rare in mammals, but fairly common in plants and marine organisms. Humans and animals whose diets include these food sources metabolize odd-carbon fatty acids via the /3-oxida-tion pathway. The final product of /3-oxidation in this case is the 3-carbon pro-pionyl-CoA instead of acetyl-CoA. Three specialized enzymes then carry out the reactions that convert propionyl-CoA to succinyl-CoA, a TCA cycle intermediate. (Because propionyl-CoA is a degradation product of methionine, valine, and isoleucine, this sequence of reactions is also important in amino acid catabolism, as we shall see in Chapter 26.) The pathway involves an initial carboxylation at the a-carbon of propionyl-CoA to produce D-methylmalonyl-CoA (Figure 24.19). The reaction is catalyzed by a biotin-dependent enzyme, propionyl-CoA carboxylase. The mechanism involves ATP-driven carboxylation of biotin at Nj, followed by nucleophilic attack by the a-carbanion of propi-onyl-CoA in a stereo-specific manner. 

Additional roles traditionally recognised for white adipose tissue include thermal insulation (as in the blubber of sea mammals) and mechanical protection to internal organs. However, in recent years it has become apparent that the function of white adipose tissue is much more extensive. This follows from the discovery that it is a major endocrine organ, secreting a diverse... 

The mechanism of fluoroacetate toxicity in mammals has been extensively examined and was originally thought to involve simply initial synthesis of fluorocitrate that inhibits aconitase and thereby the functioning of the TCA cycle (Peters 1952). Walsh (1982) has... 

Cavalier E, E Rogan (1998) Mechanisms of tumor initiation by polycyclic aromatic hydrocarbons in mammals. Handbook Environ Chem 3J 82-117. 

This confirms the tacit hypothesis which states that the effect of a toxic substance on an organism is of the same nature whatever the animal (provided they are all mammals) and the means of penetration. Yet the effective intensity, ie toxic dose, is obviously influenced by the means of penetration since the different mechanisms of penetration make it more or less difficult for the toxic substance to enter the organism. 

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