Distal axonal degeneration

Delayed neuropathy characterized by distal axonal degeneration is a systemic health effect caused by some organophosphate pesticides and is not due to anticholinesterase inhibition. EPN is neurotoxic to atropine-protected hens, producing polyneuropathy progressing to paralysis and some deaths after ingestion of 5-10mgA g/day. There are no reports, however, of neurotoxicity from EPN in humans. ... 

Ohnishi A et ah Ethylene oxide induces central peripheral distal axonal degeneration of the lumbar primary neurones in rats. Br J Ind Med 2-311,-1,19, 1985... 

Some OFs react with a poorly characterized enzyme—"neurotoxlc esterase" (NTE)—of unknown function resident In CNS, PNS, and some ocher tissues and precipitate a delayed CNS-FNS distal axonal degeneration, which Is expressed clinically as a sensorimotor... 

The molecular and cellular events during Wallerian degeneration in the peripheral nervous system transform the damaged nerve into an environment that supports regeneration. First, the cut axon degenerates distal to the injury site and, within 18-48 hours, cytoskel-etal disintegration of axonal neurofilaments and microtubules occurs, which is due to proteases such as calpains... 

Handlers of methyl methacrylate cement have developed paresthesia of the fingers. Dental technicians who use bare hands to mold methyl methacrylate putty had significantly slower distal sensory conduction velocities from the digits, implicating mild axonal degeneration in the area of contact with methyl methacrylate. The toxic effect on the nervous tissues may be due to diffusion into the nerve cells causing lysis of the membrane lipids and destruction of the myelin sheath. 

Detailed studies of the PNS in animal models of toxic neuropathy reveal that in most instances the axonal degeneration initially involves only the distal end of the... 

In thiamin-deficient rats, electron microscopy of the sciatic and plantar nerves shows distally pronounced axonal degeneration, with an increase in the number of mitochondria and proliferation of vesicular elements of the endoplasmic reticulum. This is followed by disintegration of neurotubules and neurofilaments, and finally axonal shrinkage and myelin disruption (Pawlik etal., 1977). 

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