Effect of cisplatin and ACTH4-9 on neural transport in cisplatin induced neurotoxicity.

Cisplatin causes a dose limiting peripheral neuropathy, however, the biological mechanism by which this occurs is unknown. Murine N1E.115 neuroblastoma cells and neural crest derived pigment cells have similar transport mechanisms to human neural cells and were used to study the effect of cisplatin on cellular transport. Cisplatin reduced both the number and velocity of organelles moving in the anterograde and retrograde direction, compared to control cells. Cisplatin induced inhibition of transport was prevented by the simultaneous administration of ACTH4-9. This analog alone had no effect on N1E.115 organelle, or erythrophore granule, movement. In both N1E.115 and pigment cells cisplatin inhibited transport within 1 h of exposure to the drug. The degree of inhibition did not increase insignificantly if pigment cells were incubated in cisplatin for 48 h compared to acute exposure. Microtubules in both pigment cells and N1E.115 neurites retained their structural integrity suggesting that factors other than changes in gross microtubule morphology are responsible for cisplatin neurotoxicity. Cisplatin reduces N1E.115 neurite growth after 48 h incubation but this can be prevented by simultaneous use of ACTH4-9. This study demonstrates for the first time that cisplatin and ACTH4-9 affect fast axonal transport by specific mechanisms which appear related to their observed neurotoxic and neuroprotective roles, respectively.

Paraoxon toxicity is not potentiated by prior reduction in blood acetylcholinesterase.

The role of blood acetylcholinesterase in moderating the effects of organophosphate challenge in rats was tested. Adult male rats (n = 42) were injected (iv) either with monoclonal antibodies (MAb) to rat acetylcholinesterase (EC 3.1.1.7; AChE) or normal mouse IgG (controls). Two days later, the rats were injected (sc) with either a mild (0.17 mg/kg) or moderate dosage (0.34 mg/kg) of paraoxon or with vehicle. Neurological integrity was assessed by a functional observational battery followed by motor activity, 3 to 4 hr after dosing. Blood, brain, and diaphragm tissues were then collected for determination of AChE activity. MAb treatment reduced whole blood and plasma AChE activity by 32 and 90%, respectively, but did not affect neurobehavioral parameters or the AChE activity of brain or diaphragm. The paraoxon challenge produced dose-related neurobehavioral changes and inhibition of brain and diaphragm AChE activity to the same extent in IgG- and MAb-treated rats. Thus, significant loss in blood AChE alone produced no detectable neurobehavioral deficits and did not alter the subsequent responses to paraoxon challenge.

Tubulomembranous lesions in p-bromophenylacetylurea neuropathy reflect local stasis of fast axonal transport: evidence from electron microscopic autoradiography.

The source of the membranous materials that accumulate in distal axons of rats intoxicated with p-bromophenylacetylurea (BPAU) was studied by electron microscopy. 35S-Methionine was injected into the ventral horn of the spinal cord at 2, 14, and 35 days after injection of BPAU. Three days later, samples of the deep peroneal nerves were obtained, and autoradiographs of thin cross sections were prepared. Organellar accumulations were absent from vehicle-treated control nerves and rare in the clinically latent period after administration of BPAU. In later stages of neuropathy, approximately 20% of the myelinated axons in any specific section were swollen and packed with tubules, membranes, and mitochondria. Numerous silver grains were located over the accumulated organelles, and the coincidence was statistically significant. The results indicate a sporadic local stasis of fast-transported proteins and provide a plausible explanation for axonal damage in BPAU neuropathy.

Catecholamine binding by adrenal medullary protein can interfere with a sensitive radioenzymatic assay for norepinephrine.

Norepinephrine (NE) binds extensively to protein that copurifies with phenylethanolamine-N-methyltransferase (PNMT) prepared from bovine adrenal medulla. This binding interferes with a NE assay that employs PNMT to catalyze the transfer of a tritiated methyl group from S-adenosyl-L-methionine to the amine group of NE. It was discovered that the protein binding of endogenous NE is reversed by dialysis at pH 6.0. Preparations of PNMT intended for use in radioenzymatic assays should involve one or more purification steps at pH 6.0.

Acrylamide neuropathy in the rat: effects on energy metabolism in sciatic nerve.

Energy metabolism was examined in rat sciatic nerve before and after induction of neuropathy by treatment with acrylamide monomer. The in vivo activities of two glycolytic enzymes, glyceraldehyde-3-phosphate dehydrogenase and nerve-specific enolase, were resistant to acrylamide. The levels of adenosine 5'-triphosphate and creatine phosphate were also unaffected by acrylamide after either short-term or long-term treatment. The turnover of high-energy phosphate was somewhat reduced in the nerves of severely intoxicated animals. These findings cast doubt on the hypothesis that acrylamide neuropathy begins with an attack on the means of generating metabolic energy, although the eventual failure of one or more energy-consuming processes in peripheral nerve remains likely.

Evolution of butyrylcholinesterase in higher primates: an immunochemical study.

Serum butyrylcholinesterase (BuChE; EC 3.1.1.8) of man and the higher primates was tested enzymatically and immunochemically, with the aid of monoclonal antibodies (McAb) developed against the enzyme isolated from human blood. Enzyme activities showed great differences across species and among individuals, but all samples tested were dibucaine-sensitive. One McAb showed similar affinities for BuChE of each species, but another showed marked differences in affinity, preferring species in the order: man greater than chimpanzee = pygmy chimpanzee greater than gorilla much greater than orangutan greater than gibbon. We conclude that at least one epitope of BuChE underwent progressive modification during the later stages of primate evolution.

Not 'indifference to pain' but varieties of hereditary sensory and autonomic neuropathy.

Three children, from different kinships, with generalized insensitivity to pain, showed unusual manifestations of congenital, presumably inherited, sensory and autonomic neuropathy. The first child appeared to have a syndrome resembling those previously described as congenital indifference to pain, congenital universal loss of pain sensation from infancy without other apparent neurological deficit. Unlike most types of hereditary sensory and autonomic neuropathies (types I, II, III), but like type IV, she had normal sensory nerve action potentials. Abnormalities of sudomotor function and of somatosensory evoked potentials were demonstrated. A severe decrease in the number of sural nerve A delta fibres and a small reduction in C fibres were demonstrated morphometrically. An abnormality of C fibres was confirmed by a marked reduction in nerve dopamine-beta-hydroxylase activity. The plasma and CSF concentrations of beta endorphins, substance P and several other neuropeptides and hormones were normal. Unequivocal evidence of a neuropathic lesion is provided by this patient; her disorder may be identified as the fifth type of hereditary sensory and autonomic neuropathy. The second patient had a congenital pansensory neuropathy and progressive retinitis pigmentosa. Whether the disorder is inherited and, if so, whether the retinitis pigmentosa results from the same or from a second genetic abnormality, is unclear. The third case has, in addition to what is usually seen in hereditary sensory and autonomic neuropathy, type II, an unusually severe kinaesthetic difficulty in oral food handling. The sural nerves of the second and third patients had fibre composition characteristic of hereditary sensory and autonomic neuropathy, type II, few or no myelinated fibres and reduced numbers of unmyelinated fibres.

Acute panautonomic neuropathy.

Two patients with acute panautonomic neuropathy had severe impairment of sympathetic and parasympathetic function of acute onset. Autonomic tests suggesting a postganglionic lesion and direct evidence of loss of unmyelinated and small myelinated fibers on nerve biopsy were found in Patient 1. There was a selective loss of small myelinated and unmyelinated nerve fibers; C potential was absent in the in vitro compound action potential; dopamine-beta-hydroxylase activity was unmeasurable. No definite abnormalities were found on the nerve biopsy of Patient 2. The acute panautonomic neuropathies appear to comprise a spectrum of somatic and autonomic involvement.

Abnormalities of axonal transport: are they a cause of peripheral nerve disease?

Applications of pulse-labeling techniques to the study of axonal transport have provided new insights into certain types of peripheral nerve disease. In normal neurons, many of the newly synthesized proteins that are rapidly transported to distal parts of the cell eventually undergo a process of "turnaround," after which they are carried back to the cell bodies for degradation. This turnaround is selectively impaired in rat nerves early in the course of streptozotocin-induced diabetes and of experimental neuropathies induced by exposure to acrylamide, zinc pyridinethione, or p-bromophenylacetylurea. In the neuropathy of p-bromo-phenylacetylurea, depression of turnaround precedes the clinical signs of neurologic dysfunction, is later proportional to the severity of the disability, and may account for the characteristic accumulation of debris in preterminal axons.

Structural and biochemical effects of essential fatty acid deficiency on peripheral nerve.

The effect of postweaning essential fatty acid (EFA) deficiency on the peripheral nerve was studied in groups of rats. At 325 days, the characteristic biochemical changes of EFA deficiency were present in isolated peripheral myelin, although to a lesser degree than reported in non-neural tissues. There was no significant difference between control and deficient groups in number or size distributions of myelinated fibers (MFs) in muscle and sensory nerves, in the incidence of teased fiber abnormalities, in rates of axonal transport of dopamine-beta-hydroxylase and acetylcholinesterase, or in conduction velocity and compound action potentials of peripheral nerve in vivo or in vitro. Four weeks after a standard sciatic crush injury, the median MF diameter in regenerated peroneal nerves was significantly smaller in EFA-deficient rats than in control rats, but this difference was no longer significant at 18 weeks. At 18 weeks, EFA-deficient and control regenerated nerves showed similar myelin periodicity and relationship of axonal area to number of myelin lamellae. We conclude that acquired EFA deficiency in the rat leads to biochemically abnormal peripheral myelin, but that this state is unaccompanied by clinical, physiological, or morphological evidence of neuropathy.

Multiple endocrine neoplasia, type 2b: phenotype recognition; neurological features and their pathological basis.

Sixteen patients affected with multiple endocrine neoplasia, type 2b (MEN 2b), were evaluated by clinical, neurological, nerve conduction and electromyographic, and postmortem examinations. Eight of the 11 patients examined clinically had symptoms: 5, neurogenic constipation; 1, failing vision due to hypertrophied corneal nerves; 1, neuromuscular symptoms and pes cavus; and 1, facial disfigurement. Expression of the dominantly inherited MEN 2b gene is more variable than previously known. When neuromuscular findings are present alone, the features may be those of peroneal muscular atrophy. Because 10 of the 11 patients had sufficiently full expression of the dominantly inherited gene--"Marfanlike" body build, full and fleshy lips, whitish yellow nodules (neuromas) on the tip and edges of the tongue, pes cavus, or peroneal muscular atrophy--the presence of MEN 2b was recognized and a search for the usually associated medullary thyroid carcinoma was instigated. In addition to the recognized involvement of autonomic nerves, we have confirmed that somatic motor and senory neurons may be involved. Findings at postmortem evaluation indicate that symptoms can be attributed to neuroma formation: a characteristic adventitious plaque of tissue composed of hyperplastic, interlacing bands of Schwann cells and myelinated fibers overlay the posterior columns of the spinal cord.

Lead neuropathy. 1) Morphometry, nerve conduction, and choline acetyltransferase transport: new finding of endoneurial edema associated with segmental demyelination.

Morphometric and pathologic studies along the length of the peripheral nervous system were obtained in groups of rats fed 4% lead carbonate for 3 and 6 months and in match-fed controls. The number and diameter histograms of L6 cytons of spinal ganglia and of myelinated fibers of proximal and distal portions of peroneal and sural nerve were not significantly different from the control groups. On the other hand, segmental demyelination occurred approximately as frequently in proximal as in distal parts of nerves. At 3 months approximately 1/3 of teased myelinated fibers showed changes of segmental demyelination (Condition C), or of remyelination after segmental demyelination (Condition F) or of both segmental demyelination and of remyelination (Condition D), while at 6 months more than 4/5ths of fibers showed these changes. As expected, regression lines of axonal area on number of lamellae of myelin, were less steep in nerves of rats fed on lead for 6 months as compared to controls. Axonal transport of choline acetyltransferase in lead neuropathy did not differ from that in control rats. As expected from the studies of others, conduction velocity of myelinated fibers of caudal nerve were low. A new finding was the often quite striking increase of transverse fascicular area of peripheral nerves. This was due to edema which appeared to develop at about the time of onset os segmental demyelination. Although the edema may be an epiphenomenon, it could be an important observation bearing on the development of lead neuropathy. It would be important to know next whether or not the blood nerve barrier is altered in lead neuropathy.