Chemical messages

Testa, B. Drugs as chemical messages molecular structure, biological context, and structure-activity relationships. Med. Chem. Res. 1997, 7, 340-365. 

T cells control these learned responses and decide which tools to use in the reaction. Sometimes they choose several different tools at once, and multiple reactions ensue, such as when a person becomes sensitized to penicillin and has not only anaphylaxis but hemolytic anemia and serum sickness. There are different types of T cells, and they communicate either directly with other cells or by chemical messages called cytokines. The pattern of cytokines released is one way T cells have of determining which kind of response will occur. They are broadly called Thl andTh2 responses, with Thl mostly responding to infections and Th2 often producing allergy or asthma. 

We need to point additionally to the evolution of special organs, glands, which have stored chemical message systems to help coordinate activities and are associated with nerves and the brain (Figure 8.6 and Table 8.3). Glands are advantageous in organisation as chemical substations connected to different remote parts of the... 

Rasmussen, L.E.L. and Greenwood, D.R. (2003) Frontalin A chemical message of musth in Asian elephants (Elephas maximus). Chem. Senses 28,433-446. 

We feel that we may have a tentative answer to the question of why smaller males, of lesser PA content, appear not to "lie" in the context of courtship. Could such males not masquerade as "desirable" by producing exaggerated levels of HD Perhaps their failure to do so is a reflection of the fact that they would be "found out" unless they also produced outsized spermatophores. Smaller males, even if able to convert extra PA into HD for inflation of their chemical message, may lack the extra nutrient needed for inflation of the spermatophore. By putting the male to the test by way of a second criterion after mating, the female has the means to check on liars. 

In addition to its structural role in bone, and in teeth, the calcium ion is a carrier of chemical messages. It influences secretion, contraction of muscle, cell division, growth, transcription, as well as other key physiological processes. 

In summary, receptors are proteins, membrane-bound or intracellular, that act as specific receivers for chemical messages aud iuitiate metabolic chauges iu cells aud orgaus. Specific aud poteut agouists aud autagouists at receptors comprise several classes of drugs useful iu humau mediciue. 

A subset of all odorants is pheromones, about which much more follows later. Basically, pheromones transmit chemical messages among members of the same species. Bombykol is a pheromone for the silkworm moth the scent of lilacs as perceived by a human being is not. Although the question of human pheromones is difficult, that for many mammals is not. The pheromones in mammals are not detected... 

Such additions to the chemical communication systems within the brain markedly increase the flexibility of chemical communication. Consequently, it is suggested that the term neurotransmitter should be restricted to an agent that transfers a chemical message between neurones within... 

A number of very important natural and synthetic biochemicals belong to the phenylethylamine family. Two of these compounds, dopamine and epinephrine (adrenaline), are neurotransmitters, substances that carry chemical messages through the nervous system of humans and other animals. A third phenylethylamine, tyrosine, is an essential amino acid. And a familiar phenylethylamine found in plants is mescaline, whose chemical name is 2-(3,4,5-trimethoxy-phenyl)ethylamine. The primary natural sources of mescaline are four varieties of cactus two peyote species (Lophophora wiUiamsii and Lophophora diffusa), the San Pedro cactus (Trichocereus pacha-noi), and the Peruvian Torch cactus (Trichocereus peruvianus). 

The proportions of the individual green odour components in the leaf odour constitute a chemical message which, when perceived, directs the motor patterns of this insect. The... 

A large number of proteins present in the outer surfaces of cells serve as receptors that receive chemical messages and other signals from outside the cell. The receptors, which are sometimes enzymes, respond by generating internal signals that control metabolism and cell growth. Such molecular signaling is another major area of contemporary biochemistry. 

Serotonin and melatonin are evidently involved in maintenance of the 24-h circadian rhythm of the body (see Section 13).792/792a Melatonin regulates the sexual cycle in photoperiodic animals and influences the onset of puberty.792-794 The serotonin content of the brain is influenced by the diet, being higher after a meal rich in carbohydrates. Serotonin may serve as a chemical message sent from one set of neurons to the rest of the brain, reporting on the nature of dietary intake.784 Melatonin, which can readily form free radicals, may function as part of the body s antioxidant system.795 796... 

Classically, it has been held that this neurotransmitter-receptor complex initiates a process that reconverts the chemical message back into an electrical impulse in the second nerve. This is certainly true for rapid-onset neurotransmitters and can explain the initial actions of some slow-onset neurotransmitters as well. However, it is now known that the postsynaptic neuron has a vast repertoire of responses beyond just whether it changes its membrane polarization to make it more or less likely to fire. Indeed, many important biochemical processes are triggered in the postsynaptic neuron by neurotransmitters occupying their receptors. Some of these begin within milliseconds, whereas others can take days to develop (Figs. 1 — 11 to 1 — 13). 

This reuptake pump takes an active part in the neurotransmission process, which begins with the firing of the presynaptic neuron and release of neurotransmitter (Fig. 2—23). The neurotransmitter diffuses across the synapse, binds its neurotransmitter receptors selectively, and triggers all the subsequent events that translate that chemical message into another neuronal impulse in the postsynaptic neuron, activate postsynaptic genes, and regulate various cellular functions in the target neuron. The neurotransmitter then diffuses off its receptor and can be destroyed by enzymes or transported back into the presynaptic neuron. 

Basch, P.F. (1990) Single sex schistosomes and chemical messages. Reply. Parasitology Today 6, 298. 

There are a few surprising medical uses among the alkali and alkaline earth metals. Lithium combined with chlorine has been used for decades to treat a form of depression called bipolar disorder. Scientists are not exactly sure how lithium affects depression, but they think it may somehow change chemical messages in the brain. Doctors use barium, one of the heaviest alkaline earth metals, to get a better look at the stomach and intestines. They give their patients a drink called barium sulfate that travels to the gut. Bariums 56 electrons absorb X-rays and light up the stomach and intestines to reveal ulcers and other problems. 

Schneider D. (1969) Insect olfaction deciphering system for chemical messages. Science 163, 1031-1037. 

Ferveur J. F., Cobb M. and Jallon J. M. (1989) Complex chemical messages in Drosophila. In Neurobiology of Sensory Systems, eds R. N. Singh and N. J. Strausfeld. Plenum Publishing Corporation. 

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