Showing papers on "Nervous system published in 1975"

Substance p: localization in the central nervous system and in some primary sensory neurons

Abstract: Antibodies to substance P with a high titer have been produced and used in immunohistochemical studies on the peripheral and central nervous system of the rat and the cat. Evidence was obtained for the localization of substance P in a certain population of primary sensory neurons, probably small nerve cells with unmyelinated processes. Substance P or a peptide similar to it was also observed in cell bodies in the medial habenula and in probable nerve terminals in many brain areas. The results give morphological support for a transmitter (or modulator) role of substance P in the nervous system.

The nerve ring of the nematode Caenorhabditis elegans: Sensory input and motor output

Abstract: The general organization and structure of the nerve ring, the main mass of central nervous system neuropil, in the small soil nematode Caenorhabditis elegans is described. The nerve ring receives sensory input from the anterior tip of the animal by means of six nerve bundles, all nerve fibers of which have centrally located cell bodies. The anterior sensory structures are classically divided into two types, papillary and amphidial, and are assumed responsible for mechano- and chemoreception, respectively. Papillary fibers enter directly into the nerve ring, whereas amphidial fibers enter the ventral ganglion, a posterior extension of the nerve ring, in a circuitous manner which is not discussed in detail. Of those papillary fibers which project into the nerve ring neuropil, 22 end in easily characterized sensory structures whereas 14 terminate distally near sensory organs but have no function which can be deduced on the basis of comparative morphology. After entering the ring the fibers maintain their identity and do not anastamose with one another. Cell bodies of each papillary sensory neuron have been mapped around the nerve ring. The cephalic musculature is shown to consist of 32 muscle cells which form four longitudinal submedial groups of eight muscles each. Innervation of this musculature occurs wholly within the CNS by means of processes of the muscle cells which are sent centrally. The anterior 16 cephalic muscle cells are innervated by the ring only, in well delimited regions termed muscle plates. The posterior 16 are dually innervated by means of processes sent both to the nerve ring plates and to their nearest medial longtitudinal nerve cord. The nerve ring neuropil is characterized as having fibers containing one of four morphologically distinct vesicle types. Gap junction contacts are observed within the main neuropil involving one of these fiber types and within the muscle plate regions among muscle processes, which do not contain vesicles. An evolutionarily primitive sensory-motor synapse within the nerve ring is described from an identified sensory neuron onto an identified cephalic muscle cell process. Comparisons are made with the nervous system of Ascaris lumbricoides, the only other nematode to be extensively studied, to illustrate the conservativeness of the nemic nervous system.

Immunocytochemical localization of substance P in mammalian intestine.

Abstract: In mammalian intestine immunoreactive Substance P is localized not only in the plexuses of Auerbach and Meissner, as could be anticipated, but also in a number of basally situated, often basigranular, endocrine cells which have been identified tentatively as enterochromaffin. The presence of a neurohormone in cells of this type confirms their close association with the nervous system, noted by Masson (1924), and suggests that their postulated origin from the nervous system (Danisch, 1924) may well be correct.

Tetanus toxin: Direct evidence for retrograde intraaxonal transport

Abstract: The neurotoxin tetanospasmin causes tetanus when it reaches the central nervous system. In this autoradiographic study, 125-I-labeled tetanospasmin was injected into the leg muscles of rodents, and the nerves supplying these muscles were crushed. The labeled toxin accumulated within axons on the distal side of the crush. This study provides direct evidence for retrograde axonal transport of a macromolecular toxin that acts at synapses in the central nervous system.

Metabolism of amino acids and ammonia in rat brain cortex slices in vitro: a possible role of ammonia in brain function

Abstract: — (1) The sum of the values of total (tissue + medium) amino acid-N of glutamate, glutamine, γ-aminobutyrate, and aspartate (referred to as the glutamate system) and of ammonia-N of incubated rat brain cortex slices is approximately constant under a variety of metabolic conditions (presence or absence of glucose or of oxygen or in the presence of metabolic inhibitors such as aminooxyacetate, malonate, methionine sulfoximine, fluoroacetate, ouabain, 2:4 dinitrophenol, or Amytal). Fluctuations in the value of one constituent are compensated by fluctuations in the values of other constituents. The same applies to infant rat brain cortex slices and to rat brain synaptosome preparations. It is suggested that the constancy of the glutamate-ammonia system implies a coupling of neurons and glia in such a manner that glutamate released from the neurons during excitation is taken up by the glia and there converted to glutamine. The glutamine is returned to the neurons where it is hydrolysed to glutamate and ammonia. The glia, on this view, exercise an important buffering effect on the extracellular content of the excitatory amino acid, glutamate, and possibly on that of other functionally active amino acids emanating from the neurons. (2) The magnitude of the glutamate-ammonia system in the infant rat brain cortex is about 43% of that in the adult. It is suggested that, with maturity, the development of the glutamate-ammonia system is linked with the development of the citric acid cycle of operations. (3) The ammonia in the system is tightly linked to the activity of the ATP-controlled glutamine synthetase. (4) Proteolytic ammonia and amino acids are formed, during the incubation, to values that seem to be independent of a wide variety of metabolic conditions. The total value is approximately 10 μmol/g in the first h of incubation. (5) As the ammonium ion is necessary for the return of glutamate to the neuron in the form of glutamine, it is inferred that the ion plays a functional role in the nervous system by helping to maintain the steady state of glutamate in the neuron.

Behavioral Correlates and Firing Repertoires of Neurons in the Dorsal Hippocampal Formation and Septum of Unrestrained Rats

Abstract: The experiments reported here are among the simplest experiments one might do on the nervous system. We simply record action potentials from a single neuron in the dorsal hippocampal formation and septum in an unrestrained rat and study the correlation between the firing of the neuron and the behavior of a rat. However, there is no reason to believe that this approach is going to be valuable. If one were to record from a single element in a computer and try to correlate voltages at this element with either the input or the output of the computer, one would, in general, not learn much of use, except perhaps about the input and output devices. Clearly, the firing of some neurons in the brain has something to do with overt behavior or with information coming into the brain, especially for those neurons within a few synapses of a receptor or effector. Equally clearly, there are some things going on in the brain which do not have a simple relation to overt behavior or inputs to brain. The hippocampus is many synapses away from sensory or motor neurons, so simple relations cannot be expected.

Direct effects of ethanol on the nervous system.

Abstract: Neurophysiological, neurochemical and behavioral studies of the effects of ethanol on the nervous system have so far failed to identify specific, direct, primary mechnisms of action that may account for the typical pattern of alcohol intoxication in vivo. Electroencephalogram and evoked response studies indicate biphasic effects in the intact subject, which may correlate better with the level of arousal than with a specific drug action. Effects on spinal reflexes are also biphasic, probably representing the net result of direct influence on resting membrane potential, primary afferent depolarization, and neurotransmitter release. With the exception of its inhibitory effect on release of oxytocin, vasopressin and possibly other hypothalamic peptides, ethanol does not appear notably different in its spectrum of effects from a wide range of other hypnotics, anesthetics and minor tranquilizers. Interpretation of the findings is complicated by the fact that functional alteration of any given neuronal system by ethanol in vivo may reflect a) direct local action of ethanol on the cells under study, b) change in the input to those cells because of an action elsewhere in the nervous system, c) effects of ethanol metabolites, or d) indirect consequences of decreased blood flow, oxygen or metabolite supply, hormonal action, or hypothermia, due to disturbances of homeostasis in the whole body as a result of deep intoxication. To date, attempts to circmvent b, c and d by the study of brain tissue in vitro have shown consistent effects of ethanol only at concentrations well above those that are meaningful in vivo. Relatively specific patterns of action of different drugs in vivo may prove to be largely dependent on their customary rates and routes of administration, and on summation of minor differences in the dose-response curves with different types of neuron, even though the basic types of molecular action may be essentially similar.

Capillary innervation in the mammalian central nervous system: an electron microscopic demonstration.

Abstract: Capillaries in the cat hypothalamus receive axon terminals which are comparable to neurovascular junctions in cerebral and systemic arteries and arterioles. The innervation of capillaries in the central nervous system may be derived from central neurons, in contrast to cerebral arterial vessels, which are supplied by the peripheral autonomic nervous system.

Electrical stimulation in the nervous system: the current status of electrical stimulation of the nervous system for relief of pain

Abstract: The publication in 1965 of ti~e gate theory of pain perception by Melzack and Wall reawakened interest in the therapy of chronic pain and has led to a resurgence of interest in the use of electrical stimulation of the afferent nervous system for pain relief 19. Prior to the popularization of the gate theory, interest in pain as a treatable condition was limited to a few centers, and the techniques available for the control of pain were small in number. Drug therapy is only partially effective and carries serious side effects. Nerve blocks are effective in certain condition= ~ut d~ have limitations and side effects. Major procedures available for pain relief require destruction of some part of the nervous system with consequent loss of function. The gate theory appears to offer a way in which non-destru~;tive intervention into the nervous system might provide pain control without atten6ant loss of neurological function zT. P In addition to this increased interest in the use of electrical stimulation, tottake advantage of the therapeutic principles suggested by this gate theory, an increased empbasis on neurophysiological research in pain has occurred. Out of this io.creased interest new therapeutic techniques have evolved. At the present time several forms of electrical stimulation of the:afferent nervous system have proven ability to relieve pain. Other techniques of stimulation are of value in the diagnostic sense, and several forms of electrical stimulatior, of the central nervous system can still be considered investigative. Electrical stimulation has been employed with the application of the electrode externally on the skin or orifice lining. Peripheral nerves have been stimulated by 3mall electrodes applied on the skin, over key sites along the course, or by electrodes inserted through the skin for temporz.ry or

Comparative studies of purinergic nerves.

Abstract: Purinergic nerves supply the gastrointestinal tract of vertebrates, including fish, amphibians, reptiles and birds, as well as mammals. Their cell bodies are located in Auerbach's plexus and their axons extend in an anal direction before innervating mainly the circular muscle coat. In the stomach they are controlled by preganglionic cholinergic fibres of parasympathetic origin. They are involved in “receptive relaxation” of the stomach, “descending inhibition” in peristalsis and reflex relaxation of oesophageal and internal anal sphincters. The terminal varicosities of purinergic nerves are characterised by a predominance of “large opaque vesicles,” which can be distinguished from the “large granular vesicles” found in small numbers in both adrenergic and cholinergic nerves. Stimulation of purinergic nerves with single pulses produces hyperpolarisations of up to 25 mV (inhibitory junction potentials) in smooth muscle cells. These potentials are unaffected by atropine, adrenergic neuron blocking agents or sympathetic denervation, but are abolished by tetrodotoxin. The “rebound contraction” which characteristically follows cessation of purinergic nerve stimulation is probably due to prostaglandin. Evidence that ATP is the transmitter released from purinergic nerves includes: (1) synthesis and storage of ATP in nerves; (2) release of ATP from the nerves when they are stimulated; (3) exogenously applied ATP mimicking the action of nerve-released transmitter, both producing a specific increase in K+ conductance; (4) the presence of Mg-activated ATPase, 5′-nucleotidase and adenosine deaminase, enzymes which inactivate ATP; (5) drugs (including quinidine, some 2-substituted imidazolines, 2-2′pyridylisatogen and dipyridamole) which produce similar blocking or potentiating effects on the response to exogenously applied ATP and nerve stimulation. Speculations are made about the evolution and development of the nervous system, including the possibility that purinergic nerves are a primitive nerve type.

Manter and Gatz's Essentials of Clinical Neuroanatomy and Neurophysiology

Abstract: Section 1: Basic Principles 1. Introduction to the Nervous System 2. Physiology of Nerve Cells Section 2: Peripheral Nervous System 3. Fibers of the Spinal Nerves 4. Spinal Reflexes and Muscle Tone 5. Autonomic Nervous System Section 3: Ascending and Descending Pathways 6. Pain and Temperature 7. Proprioception, Touch, and Tactile Discrimination 8. Motor Pathways 9. Lesions of the Peripheral Nerves, Spinal Nerve Roots, and Spinal Cord Section 4: Brain Stem and Cerebellum 10. Organization of the Brain Stem and Cranial Nerves 11. Cranial Nerves of the Medulla 12. Cranial Nerves of the Pons and Midbrain 13. Lesions of the Brain Stem 14. Hearing 15. Vestibular System 16. Cerebellum Section 5: Forebrain 17. Basal Ganglia 18. Vision 19. Optic Reflexes and Eye Movements 20. Cerebral Cortex and Thalamocortical Connections 21. Limbic System 22. Olfaction 23. Chemical Neuroanatomy Section 6: Circulation of Blood and Cerebrospinal Fluid 24. Cerebral Arteries Supplying the Forebrain 25. Cerebrospinal Fluid Section 7: Approaches to Patients with Neurologic Symptoms 26. Clinical Evaluation of Neurologic Disorders 27. Neurologic Diagnostic Tests Suggested Readings

Histofluorescent localization of serotonin and dopamine in the nervous system and gill of Mytilus edulis (Bivalvia).

Abstract: Monoamine localization was accomplished in Mytilus edulis by the use of histofluorescence. Intracellular stores of dopamine and serotonin were found to be synthesized in the proper neuron and transported down the axon to the terminal varicosities.Most of the cells in the cortex of the cerebral and visceral ganglia were non-fluorescent. Of the fluorescent cells, serotonin predominated in the cerebral ganglion and dopamine predominated in the visceral ganglion. There was a net flow of serotonin in the cerebro-visceral connective from the cerebral to the visceral ganglion and a net flow of dopamine in the opposite direction.Serotonin fluorescence was localized in intracellular granules in neurons and blood cells. Dopamine fluorescence was distributed homogenously in neurons and in the supporting rod of the gill. The visceral ganglion supplies the gill with nerve fibers of both types.Exogenously supplied serotonin and dopamine were taken up by both kinds of nerve cells and by some other tissues. Endogenous st...

Observations on the interactions of Schwann cells and astrocytes following X-irradiation of neonatal rat spinal cord.

Abstract: Myelination was inhibited in the spinal cord of three day-old rats with 2000 rads of X-irradiation Myelination subsequently occurred as a result of caudal migration of oligodendrocytes and extensive invasion of the cord by Schwann cells Although oligodendrocytes were present in areas containing Schwann cells, astrocytes were absent The presence of Schwann cells in the neuropil of the spinal cord did not stimulate production of basement membrane by astrocytes, so no new glial limiting membrane was formed Evidence is presented which suggests that if astrocytes do not form a glial limiting membrane when opposed by large numbers of Schwann cells they are destroyed by the invading cells It is suggested that the glial limiting membrane normally inhibits entry of Schwann cells into the central nervous system; if this is destroyed and not reconstituted, Schwann cells can migrate freely into the neuropil

Short-axon cells in the olfactory bulb: dendrodendritic synaptic interactions.

Abstract: 1. In the rabbit olfactory bulb, analysis has been carried out of extracellular unitary responses in the glomerular layer to olfactory nerve volleys. 2. Units in the glomerular layer responded to single volleys with single, double, triple or longer repetitive spike discharges. The shortest initial latencies are consistent with monosynaptic excitation from the olfactory nerves; longer latencies may reflect longer nerve pathways or polysynaptic connexions in the glomerular layer. 3. Like mitral and tufted cells, some glomerular layer units gave evidence of activation by discrete nerve bundles. This correlates with recent anatomical evidence for projections of discrete olfactory nerve bundles to the glomeruli. 4. Facilitation of glomerular layer units took the form of lower spike thresholds and shorter latencies, when testing with paired olfactory nerve volleys of weak strength at relatively short intervals (less than 40 msec). Supression took the form of raised thresholds, longer latencies and briefer repetitive discharges; this was particularly evident with strong volleys at long testing intervals. 5. The early period of facilitation and later period of suppression did not correlate with the recovery cycle of the olfactory nerves; the nerves had an absolute refractory period of approximately 3 msec, relative refractory period of 15-30 msec, and a small supernormal period of several hundred msec or more. 6. The evidence that the facilitation and suppression are mediated by dendrodendritic pathways through the periglomerular short-axon cells is discussed in relation to recent electronmicroscopical studies. The results have implications for similar pathways through short-axon cell dendrites in other parts of the nervous system.

New cell surface antigens in rat defined by tumors of the nervous system.

Abstract: Tumors of the central and peripheral nervous system were induced in rats with ethylnitrosourea. Many of these tumors were transplanted in syngeneic recipients, and several cell lines were derived from them. An antiserum raised against one such cell line in C3H mice defined two cell surface antigens in cytotoxicity tests. One, the common antigen, was present on rat brain and embryonic tissues and was present in large amounts on most tumors or cell lines from the nervous system. Fibroblastic cell lines had smaller amounts of this antigen, which also could be detected by immunofluorescence. The other, restricted antigen was not detected on normal or other, restricted antigen was not detected on normal or embryonic tissues. It was present on six tumors from the nervous system, on one glial cell line, and on a Schwann-cell line RN22. In addition, it was present on four out of eleven cloned cell lines isolated from rat tumors at the Salk Institute. Two of the positive clonal lines had been shown to have properties unique to neuronal cells. The restricted antigen was therefore expressed on the cell surface of some, but not all, glial, Schwann, and neuronal neoplastic cells.

Biochemically differentiated mouse glial lines carrying a nervous system specific cell surface antigen (NS-1).

Abstract: Six biochemically differentiated clonal lines have been established from a transplantable glioma (tg26) of the C57BL/6 inbred mouse strain. Antibodies have been previously raised against G26 tumor cells, which define a cell surface component(s), NS-1 (nervous system antigen-1), found exclusively in the nervous system. NS-1 concentrations approximate the levels of the original G26 tumor when the clonal lines are grown as clonal tumors in vivo, but are reduced when the cells are grown in vitro. NS-1 concentrations are further reduced in vitro upon incubation of the cells with 1 mM dibutyryl 3:5-cyclic AMP. H-2 histocompatibility antigen concentration, in contrast, is unaffected by dibutyryl cAMP. In addition to expressing NS-1, the neuroectodermal origin of these cell lines is further confirmed by their synthesis of the nervous system specific acidic protein S-100 and by the high specific activity of the enzyme 2:3-cyclic nucleotide 3-phosphohydrolase. In addition, they respond to catecholamines by the elevation of intracellular 3:5-cyclic AMP levels. Whereas expression of S-100 protein is high under in vitro conditions but negligible after one passage in vivo, 2:3-cyclic nucleotide 3-phosphohydrolase is not detectable in vitro but becomes detectable again in vivo. The two membrane-bound constituents, NS-1 and 2:3-cyclic nucleotide 3-phosphohydrolase, therefore seem to be subjected to different regulatory mechanisms from that of the soluble, intracellular S-100 protein.

Latent infection of the peripheral ANS with herpes simplex virus.

Abstract: IN both experimentally infected animals1,2 and in asymptomatic human subjects3,4 herpes simplex virus (HSV) can establish a latent infection in the sensory ganglia of the nervous system. It is probably the periodic reactivation of virus within these ganglia that gives rise to recurrent herpetic eruptions on epithelial surfaces innervated by the infected ganglia. The ganglia of the peripheral autonomic nervous system seem to share a common embryogenesis with sensory ganglia5. Although it has been shown that acute infection of autonomic ganglia with HSV6 and the related herpesvirus, pseudorabies virus7–9, can occur, it has not been established that the peripheral autonomic nervous system (ANS) can support a latent infection with these or other viruses. We report here a marine model of latent infection of the superior cervical ganglion (SCG) of the sympathetic division of the ANS.

Fundamentals of Neurophysiology

Abstract: 1 The Structure of the Nervous System- 11 The Nerve Cells- 12 Supporting and Nutritive Tissue- 13 The Nerves- 14 The Structure of the Spinal Cord- 2 Excitation of Nerve and Muscle- 21 Resting Potential- 22 Resting Potential and Na+ Influx- 23 The Sodium Pump- 24 The Action Potential- 25 Kinetics of Excitation- 26 Electrotonus and Stimulus- 27 Propagation of the Action Potential- 3 Synaptic Transmission- 31 The Neuromuscular Junction: Example of a Chemical Synapse- 32 The Quantal Nature of Chemical Transmission- 33 Central Excitatory Synapses- 34 Central Inhibitory Synapses- 35 The Transmitter Substances at Chemical Synapses- 4 The Physiology of Small Groups of Neurons Reflexes- 41 Typical Neuronal Circuits- 42 The Monosynaptic Reflex Arc- 43 Polysynaptic Motor Reflexes- 5 Muscles- 51 Contraction of the Muscle- 52 Dependence of Force Development on Fiber Length and Velocity of Shortening- 53 Excitation-Contraction Coupling- 54 Regulation of Muscle Contraction- 6 Motor Systems- 61 Spinal Motor Systems I: Roles of Muscle Spindles and Tendon Organs- 62 Spinal Motor Systems II: Polysynaptic Motor Reflexes the Flexor Reflex- 63 Functional Anatomy of Supraspinal Motor Centers- 64 Reflex Control of the Posture of the Body in Space- 65 Functions of the Basal Ganglia, Cerebellum and Motor Cortex- 7 Regulatory Functions of the Nervous System, as Exemplified by the Spinal Motor System- 71 The Stretch Reflex as a Length-Control System- 72 Static and Dynamic Properties of Control Systems- 8 The Autonomic Nervous System- 81 Functional Anatomy of the Peripheral Autonomic Nervous System- 82 Acetylcholine, Noradrenaline and Adrenaline- 83 Smooth Muscle: Myogenic Activity and Responses to Stretching, Acetylcholine, and Adrenaline- 84 Antagonistic Effects of Sympathetic and Parasympathetic Activity on Autonomic Effectors- 85 Central Nervous Regulation: Spinal Reflex Arc, Bladder Regulation- 86 Genital Reflexes- 87 Central Nervous Regulation: Arterial Blood Pressure, Regulation of Muscle Perfusion- 88 The Hypothalamus The Regulation of Body Temperature, Osmolality of the Extracellular Fluid, and the Endocrine Glands- 89 Integrative Functions of the Hypothalamus Limbic System- 9 Integrative Functions of the Central Nervous System- 91 Structure and General Physiology of the Cerebral Cortex the Electroencephalogram- 92 Waking, Sleeping, Dreaming- 93 Consciousness and Speech: Structural and Functional Prerequisites- 94 Learning and Memory- 95 The Frontal Lobes- 10 Suggested Readings- 11 Answer Key

Neuronal properties of hybrid neuroblastoma X sympathetic ganglion cells.

Abstract: Clonal mouse neuroblastoma cells without tyrosine 3-monooxygenase [EC 1.14.16.2; tyrosine hydroxylase; L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating)] activity were fused with normal cells from embryonic mouse sympathetic ganglia. One of the 37 hybrid cell lines obtained possesses high tyrosine 3-monooxygenase activity and synthesizes dopamine. These cells also have excitable membranes and generate action potentials in response to electrical stimuli. Thus hybrid cells, generated by fusion of neuroblastoma cells with normal cells from the nervous system, can acquire neural properties not found with the parental neuroblastoma cells.

Demonstration of a nonadrenergic inhibitory nervous system in the trachea of the guinea pig

Abstract: A nonadrenergic inhibitory nervous system has been demonstrated in the guinea pig trachea. Electrical field stimulation of this system, in the presence of adrenergic and cholinergic blockade, resulted in relaxation of tracheal rings contracted by the mediators of immediate hypersensitivity or histamine. The relaxation was blocked by tetrodotoxin, which indicated that nerve stimulation was responsible for the relaxation. The gastrointestinal tract, which has a similar embryological origin to the respiratory tract, also has a nonadrenergic inhibitory system. In the gastrointestinal tract, this system is thought to be responsible for the relaxation phase of peristalsis, and absence of this system, in the colon and the rectum, is thought to be an explanation for the spastic bowel in Hirschsprung's disease. It is possible that an abnormality of the respiratory nonadrenergic inhibitory system may play a role in the pathogenesis of the hyperreactive airways in asthma. The airways, due to a lack of inhibition, may be either partially contracted or unable to relax, and thus appear hyperreactive to stimuli.

Cortical and Brain Stem Projections to the Spinal Cord of the American Opossum (Didelphis marsupialis virginiana); pp. 270–289

Abstract: The present report describes the results of experiment designed to study supraspinal systems in the American opossum by several techniques. The data indicate that although spinal fibers from the opossum motor-sensory cortex are small and limited in their distribution, those from the brain stem are comparable in their origin, course, caudal extent and distribution to those described for placental mammals. Such results support the use of the opossum as an experimental animal for nervous system research; but, furthermore, suggest that its marsupial embryology makes it an ideal model for experiments designed to elucidate the ontogeny of the nervous system.

Non-healing granuloma and the nervous system.

Abstract: Three cases of non-healing granuloma with neurological complications are described. One case suffered from Stewart's form of the disease and two from Wegener's variety. The literature is extensively reviewed and the incidence and manner of neurological involvement in 374 cases is discussed. We suggest a classification to indicate four forms of nervous system involvement. First, granulomatous lesions of the central nervous system. Second, vasculitis of the central nervous system. Third, vasculitis of the peripheral nervous system and fourth, infection of the central nervous system. Of all cases 21 per cent had some form of neurological complication. Wegener's type showed more frequent neurological involvement than Stewart's, 26.5 and 12 per cent respectively. Infection of the central nervous system was limited to cases of the Stewart variety.

Increased spontaneous transmitter release from presynaptic nerve terminal by methylmercuric chloride.

Abstract: IN recent years, several incidences of methylmercury pollution have been documented1,2, one of the most striking alterations induced by the compound being extensive damage to the nervous system. Experimental mercury poisoning has been produced in animals3,5, detailed morphological studies of which have shown that acute changes occur initially in the peripheral nerve fibres and thereafter in the central nerve cells3,4. Little is known, however, about functional changes in the nervous system, particularly in the initial stages of poisoning. This report describes one possible target site—the synaptic transmission in the sympathetic ganglia—for methylmercury poisoning. The study is also of interest, as a number of heavy metallic ions such as La3+, Co2+ and Mn2+ have recently been reported to have profound effects on neuromuscular transmission6–9.