Nerve-tissue

Lecithin—is a substance first obtained from the yolk of hens eggs, and subsequently found to exist in brain-tissue, particular jr the gray substance, nerve-tissue, semen, blood-corpuscles, blood-serum, milk, bile, and other animal tissues and fluids. 

As obtained from brain-tissue lecithin is a colorless or faintly yellowish, imperfectly crystalline solid, or sometimes of a waxy consistency. It is very hygroscopic. It does not dissolve in HaO, in which, however, it swells up and forms a mass like starch-paste. It dissolves in alcohol or ether, very sparingly in the cold, hut readily under the influence of heat. It dissolves in chloroform and in benzene. Lecithin is very prone to decomposition, particularly at slightly elevated temperatures. Its chlorid combines with PtCh to form an insoluble yellowish chloroplatinate. 

When an alcoholic solution of lecithin is brought into contact-with hot solution of barium hydroxid it yields barium glycerophosphate, barium stearate, and cholin (see p. 276). This decomposition indicates the constitution of lecithin and its relations to the fats. Glycerophosphoric acid is phosphoric acid in which an atom of hydrogen has been replaced by the univalent i-emalnder CHaOH- CHOH—CHa—left by the removal of OH from, glycerol  

In lecithin the remaining oxhydryl groups of the glycerol remainder are removed by union with the basic hydrogen of two molecules of stearic acid, and one of the two remaining basic hydrogen atoms of the phosphoric acid is displaced by cholin. It is obvious that the number of lecithins is not limited to one, but that many may exist, and probably do, into whose composition any one, or any combination of two, of the acids of the same series as stearic acid may enter, s (CH,), 

Nerve-tissue, wliich is exceedingly complex in its chemical com-position, and whose, chemistry is still in a most rudimentary condition, seems to contain similar constituents in its different parts, which differ, however, materially in their quantitative composition. 

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Ca waves in systems [ike Xenopus laevis oocytes and pancreatic (3 cells fall into this category Electrochemical waves in cardiac and nerve tissue have this origin and the appearance and/or breakup of spiral wave patterns in excitable media are believed to be responsible for various types of arrhythmias in the heart [39, 40]. Figure C3.6.9 shows an excitable spiral wave in dog epicardial muscle [41]. 

Cerebrosides are found in the brain and in the myelin sheath of nerve tissue The structure of the cerebroside phrenosine is... 

This correlates narcotic potency, a gas s solubiUty in nerve tissue Hpids which can be approximated by its solubiUty in light oils such as oHve oil. 

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. 

Peripheral nervous system Nerve tissues lying outside the brain and spinal cord, functions include the transmittal of sensory information such as touch, heat, cold, and pain, and the motor impulses for limb movement. 

Nerven-, nerve, neuro-. -entzundung,/. neuri. tis. -faser,/. nerve fiber, -gewebe, n. nerve tissue, -kitt, m. (Anat.) neuroglia, -kunde, -lehre, /. neurology, -masse, /. = Nerven-stoff, -reiz, m. nervous stimulus, -stoff, m. nerve substance, neural substance, -system, -werk, n. nervous system, -zelle, /. nerve cell. 

Sphingomyelins are the second major group of phospholipids. These compounds have sphingosine or a related dihydroxyamine as their backbone and are particularly abundant in brain and nerve tissue, where they are a major constituent of the coating around nerve fibers. 

LDL is the major carrier of cholesterol to the periphery and supplies the cholesterol essential for the integrity of nerve tissue, steroid hormone synthesis, and cell membranes. The association between elevated plasma cholesterol carried in LDL and the risk of coronary heart disease has been well established. LDL is also sometimes called the bad cholesterol. 

GLYCOLIPIDS (GLYCOSPHINGOLIPIDS) ARE IMPORTANT IN NERVE TISSUES IN THE CELL MEMBRANE... 

Tumors may arise from epithelial, connective (i.e., muscle, bone, and cartilage), lymphoid, and nerve tissue. The suffix-oma is... 

Rapid-acting neurotoxin that binds to sodium channels in nerve tissue leading to an increase in the release of neurotransmitters. It is a solid obtained from the venom of the Brazilian scorpion Tityus serrulatus. 

The database for acute-duration inhalation exposure was insufficient to derive an MRL for this duration. Only one study was identified describing neurological effects for this duration, in which histopathology on nerve tissue was not performed (De Martino et al. 1987). 

Hopf2 concludes that although insect nerve tissues produce substances that simulate acetylcholine and a cholinesterase which is inhibited by organo-phosphorus insecticides, these substances (in locusts at any rate) are not antagonized by atropine. Furthermore, tubocurarine does not poison insects, although it is active in warm-blooded animals and affects the neuromuscular junctions (see pp. 36, 37). In short, different physiological mechanisms appear to be at work in insects. In particular, it seems that acetylcholine, when injected into a variety of insects, has no marked toxic action. It seems then that, in some... 

Phenol can have beneficial effects when used for medical reasons. It is an antiseptic (kills germs) when applied to the skin in small amounts and may have antiseptic properties when gargled as a mouthwash. It is an anesthetic (relieves pain) and is a component of certain sore-throat lozenges and throat sprays or gargles. Small amounts of phenol in water have been injected into nerve tissue to lessen pain associated with certain nerve disorders. Phenol destroys the outer layers of skin if allowed to remain in contact with skin, and small amounts of... 

As with almost all lawn chemicals, the long-term human effects of exposure to 2,4-D remain entirely unclear. Laboratory animal studies have shown that the chemical can migrate into nerve tissues and accumulate in the brain, with resulting behavioral changes in test rats. Whether the chemical is a potential... 

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