FUNCTIONAL STUDIES OF CULTURED BRAIN TISSUES AS RELATED TO "DEMYELINATIVE DISORDERS"

Intrathecal immune reset in multiple sclerosis: exploring a new concept

Multiple sclerosis impairment is mainly driven by the progressive phase, whose pathology remains elusive. No drug has yet been able to halt this phase so therapeutic management remains challenging. It was recently demonstrated that late disability correlates with the spreading of cortical subpial lesions, and tertiary lymphoid organs (TLO) were identified in close apposition with these lesions. TLO are of crucial importance since they are able to mount a complete local immune response, as observed in the intrathecal compartment from the moment MS is diagnosed (i.e. oligoclonal bands). This article examines the consequences of this intrathecal response: giving a worst clinical prognostic value and bearing arguments for possible direct brain toxicity, intrathecal secretion should be targeted by drugs abating both B-lymphocytes and plasma cells. Another consequence is that intrathecal secretion has value as a surrogate marker of the persistence of an ongoing intrathecal immune reaction after treatment. Although it is still unsure which mechanism or byproduct secreted by TLO triggers cortical lesions, we propose to target TLO components as a new therapeutic avenue in progressive MS. Whereas it was long considered that the inability of therapies to penetrate the blood-brain-barrier was a crucial obstacle, our proposed strategy will take advantage of the properties of the BBB to safely reset the intrathecal immune system in order to halt the slow axonal burning underlying secondary MS. We review the literature in support of the rationale for treating MS with intrathecal drugs dedicated to clearing the local immune response. Since many targets are involved, achieving this goal may require a combination of monoclonal antibodies targeting each cell sub-type. Hope might be rekindled with a one-shot intrathecal multi-drug treatment in progressive MS.

"Mystic" transient recurrent nerve palsy after thyroid surgery

BACKGROUND

The mechanism of transient recurrent laryngeal nerve (RLN) palsy remains unclear.

METHODS

Samples were harvested from the RLN adjacent thyroid capsule and perineural fascia during 223 lobectomies and 89 RLNs from cadavers were used for histologic and immunohistologic evaluation. Intraoperative chromoendoscopic features of the RLN were compared with postoperative ear, nose, and throat examinations.

RESULTS

Those nerves that macroscopically seem to be single-branched (35 of 89 = 39.3%), microscopically consist of multiple fascicles in most of the cases (23 of 35 = 65.7%), resembling a plexus more than a single cord. Chronic lymphocytic infiltration of the thyroid capsule adjacent to the RLN was present in 29% (65 of 223) of the cases. The perineural fascia showed lymphocytic (18 of 223 = 8.1%) or granulocytic (7 of 223 = 3.1%) infiltration.

CONCLUSIONS

The origin of transient RLN palsy is multifactorial: plexus shaped microscopic nerve structure with or without branches, frame-like adventitial tissue, variable epineurium, inflammatory changes that involve not only the thyroid capsule but the perineural fascia, resultant nerve edema, and diffuse microhemorrhages by injury of fragile capillaries.

Bladder dysfunction in multiple sclerosis

Multiple sclerosis (MS) is a relatively common disease of young adults. Patients with MS can have a wide range of symptoms and may develop significant disability. The cause of MS is unknown, but immunological mechanisms are important. In MS, the pathological features include prominent demyelination and inflammation, but there is also evidence of neurodegeneration. Bladder symptoms are common in MS. The bladder is under neural control, and bladder disturbance is usually attributed to demyelination or loss of axons from the neural pathways, particularly those in the spinal cord, that control the bladder. However, as with other symptoms in MS, the presence of bladder disturbance does not always correlate well with MRI lesions. We speculate that other possible causes of bladder dysfunction in MS might include the effects of circulating toxic factors. Urgency of micturition is prominent in MS, and better understanding of the receptors involved in bladder sensation suggests possible treatment strategies through inhibiting these receptors.

Sodium channels and multiple sclerosis: roles in symptom production, damage and therapy

Our understanding of the potential role of sodium channels in multiple sclerosis (MS) has grown substantially in recent years. The channels have long had a recognized role in the symptomatology of the disease, but now also have suspected roles in causing permanent axonal destruction, and a potential role in modulating the intensity of immune activity. Sodium channels might also provide an avenue to achieve axonal and neuronal protection in MS, thereby impeding the otherwise relentless advance of permanent neurological deficit. The symptoms of MS are largely determined by the conduction properties of axons and these, in turn, are largely determined by sodium channels. The number, subtype and distribution of the sodium channels are all important, together with the way that channel function is modified by local factors, such as those resulting from inflammation (eg, nitric oxide). Suspicion is growing that sodium channels may also contribute to the axonal degeneration primarily responsible for permanent neurological deficits. The proposed mechanism involves intra-axonal sodium accumulation which promotes reverse action of the sodium/calcium exchanger and thereby a lethal rise in intra-axonal calcium. Partial blockade of sodium channels protects axons from degeneration in experimental models of MS, and therapy based on this approach is currently under investigation in clinical trials. Some recent findings suggest that such systemic inhibition of sodium channels may also promote axonal protection by suppressing inflammation within the brain.

The pathophysiology of multiple sclerosis: the mechanisms underlying the production of symptoms and the natural history of the disease

The pathophysiology of multiple sclerosis is reviewed, with emphasis on the axonal conduction properties underlying the production of symptoms, and the course of the disease. The major cause of the negative symptoms during relapses (e.g. paralysis, blindness and numbness) is conduction block, caused largely by demyelination and inflammation, and possibly by defects in synaptic transmission and putative circulating blocking factors. Recovery from symptoms during remissions is due mainly to the restoration of axonal function, either by remyelination, the resolution of inflammation, or the restoration of conduction to axons which persist in the demyelinated state. Conduction in the latter axons shows a number of deficits, particularly with regard to the conduction of trains of impulses and these contribute to weakness and sensory problems. The mechanisms underlying the sensitivity of symptoms to changes in body temperature (Uhthoff's phenomenon) are discussed. The origin of 'positive' symptoms, such as tingling sensations, are described, including the generation of ectopic trains and bursts of impulses, ephaptic interactions between axons and/or neurons, the triggering of additional, spurious impulses by the transmission of normal impulses, the mechanosensitivity of axons underlying movement-induced sensations (e.g. Lhermitte's phenomenon) and pain. The clinical course of the disease is discussed, together with its relationship to the evolution of lesions as revealed by magnetic resonance imaging and spectroscopy. The earliest detectable event in the development of most new lesions is a breakdown of the blood-brain barrier in association with inflammation. Inflammation resolves after approximately one month, at which time there is an improvement in the symptoms. Demyelination occurs during the inflammatory phase of the lesion. An important mechanism determining persistent neurological deficit is axonal degeneration, although persistent conduction block arising from the failure of repair mechanisms probably also contributes.

Axonal transection in the lesions of multiple sclerosis

BACKGROUND

Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system and is the most common cause of neurologic disability in young adults. Despite antiinflammatory or immunosuppressive therapy, most patients have progressive neurologic deterioration that may reflect axonal loss. We conducted pathological studies of brain tissues to define the changes in axons in patients with multiple sclerosis.

METHODS

Brain tissue was obtained at autopsy from 11 patients with multiple sclerosis and 4 subjects without brain disease. Fourteen active multiple-sclerosis lesions, 33 chronic active lesions, and samples of normal-appearing white matter were examined for demyelination, inflammation, and axonal pathologic changes by immunohistochemistry and confocal microscopy. Axonal transection, identified by the presence of terminal axonal ovoids, was detected in all 47 lesions and quantified in 18 lesions.

RESULTS

Transected axons were a consistent feature of the lesions of multiple sclerosis, and their frequency was related to the degree of inflammation within the lesion. The number of transected axons per cubic millimeter of tissue averaged 11,236 in active lesions, 3138 at the hypocellular edges of chronic active lesions, 875 in the hypocellular centers of chronic active lesions, and less than 1 in normal-appearing white matter from the control brains.

CONCLUSIONS

Transected axons are common in the lesions of multiple sclerosis, and axonal transection may be the pathologic correlate of the irreversible neurologic impairment in this disease.

Immunologically induced electrophysiological dysfunction: implications for inflammatory diseases of the CNS and PNS

During inflammation of the central or peripheral nervous system, a high number of immunologically active molecules, including bacterial or viral products as well as host-derived cytokines, are released. Patients suffering from inflammatory CNS or PNS diseases often develop transient symptoms with a rapid recovery, which obviously cannot be accounted for by immunologically induced tissue damage. These observations led to the hypothesis that immunologically active molecules can affect directly the electrophysiological functions of neurons and glial cells. Evidence for this hypothesis came from in vitro studies showing that cytokines, such as interleukins or tumor necrosis factors, arachidonic acid and its metabolites, interfere with electrophysiological properties of neurons or glial cells. These molecules affect ion currents, intracellular Ca2+ homeostasis, membrane potentials, and suppress or enhance the induction and maintenance of long-term potentiation. Similarly, virus proteins from human immunodeficiency virus type I were found to alter intracellular Ca2+ concentrations of neurons and astrocytes by modulating either transmitter receptors and channels or membrane transporters. Cerebrospinal fluid from MS patients contains factors which increase Na+ current inactivation and thereby reduce neuronal excitability. Immunoglobulins in sera of patients suffering from multifocal motor neuropathy and from acquired neuromyotonia interfere with nerve fibers, inducing alterations of conduction. Increased knowledge of these mechanisms will help to explain the pathogenesis of neurological symptoms and may provide a rationale for new therapeutic strategies.

Conduction properties of central demyelinated and remyelinated axons, and their relation to symptom production in demyelinating disorders

The conduction properties of central demyelinated and remyelinated axons are discussed, and related to the expression of symptoms in central demyelinating disease. The mechanisms underlying the block and restoration of conduction in segmentally demyelinated axons are described, together with the range of deficits expressed by the conducting axons. These abnormalities are related to clinical relapses and remissions, and to the phenomena of weakness, fatigue, the temperature sensitivity of symptoms, and the generation of 'positive' symptoms (e.g. Uhthoff's and Lhermitte's symptoms). The potential role of circulating 'blocking factors' in the symptomatology of central demyelinating disease is examined, and some approaches are advanced for the symptomatic therapy of such diseases.

Preliminary studies of cytokine-induced functional effects on the visual pathways in the rabbit

Epidural visual evoked potentials (VEP) were used to study the role of cytokines in the induction of pathophysiologic changes associated with inflammation in the central nervous system (CNS) of the rabbit. In normal rabbits, intraocular injection of human recombinant interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF) increased the peak latency of the cortical VEP by more than 2 ms within 3 h of injection; equal volume injections of control substances had no effect. Alterations in conduction induced by IFN-gamma and TNF reversed within 24 h and could be reinduced by reinjection. Intraocular injection of recombinant human interleukin-1 beta (IL-1) induced a more progressive delay in conduction that peaked 24 h after intraocular challenge and reversed over the ensuing 48 h. Pathologic examination of the tissues indicated that the primary effect of these cytokines is on the vasculature and induces changes associated with inflammation. The results suggest that the acute reversible effects of cytokines on CNS function are associated with vascular events; further they support the sensitivity of the 'rabbit eye model' for studies on the pathophysiologic effect of inflammatory mediators on the CNS in vivo.

Electrophysiological analysis of factors involved in the primary demyelinating diseases: the rabbit eye model system

This study explores the longitudinal assessment of visual evoked potentials (VEPs) in the rabbit as a method for defining factors underlying functional and structural changes associated with optic neuritis and the inflammatory demyelinating diseases. In rabbits with experimental autoimmune encephalomyelitis (EAE) induced by sensitization with guinea pig spinal cord myelin, injection of lymphokines into the posterior chamber of one eye (monocular challenge) produces an early inflammatory response in the retina and optic nerve, and an alteration in the VEP, all limited to the injected eye and its projections. The earliest changes in the timing and distribution of the cortical VEP occur within hours of ocular challenge and precede histopathological evidence of structural demyelination at the light microscope level. Prechallenge assessment allows the induced monocular prechiasmal effects to be distinguished from the more diffuse electrophysiological findings associated with EAE (i.e. those due to sensitization alone). In sensitized/challenged animals there is a clear correspondence between electrophysiological and morphological measures of dysfunction at the time points sampled. These results suggest that this model system afford an excellent opportunity to examine the precise structural correlates of the early functional changes associated with the onset of inflammatory demyelination within the CNS. Furthermore, the stability of the system provides the capacity to monitor alterations over the complete course of inflammation, demyelination and remyelination, induced by experimental manipulations.

Unusual findings in Creutzfeldt-Jakob disease. Case report

We present a definite case of Creutzfeldt-Jakob disease (CJD) with visual evoked response (VER) and CSF oligoclonal band abnormalities and discuss the neurobiological significance and diagnostic value of these findings.

The role of myo-inositol in multiple sclerosis

Myo-inositol was given orally to nine multiple sclerosis patients and nine healthy control subjects. Pattern reversal evoked potential testing was used to assess its effect. The principal positive wave increased in amplitude, duration and area in a dose-dependent manner in the multiple sclerosis group compared with controls. Cerebrospinal fluid concentrations of myo-inositol in multiple sclerosis and controls were similar. The significance of these observations is discussed in relation to recent discoveries in inositol phospholipid function.

Biological activity of region 65-102 of the myelin basic protein

Region 65-102 of the myelin basic protein (MBP) houses a number of antigenic determinants known to induce delayed-type hypersensitivity, experimental allergic encephalomyelitis (EAE), suppressor cell function, and antibodies. In this report we describe the biological activity of synthetic peptides S53, S55, and S49 with sequence homology to region 69-84 of the rat, guinea pig, and bovine MBP. Peptide S53-A, defined by residues 75-84 of the guinea pig (SQRSQDEN) and of the rat (SQRTQDEN) MBP induced clinical signs of disease in Lewis rats. These included weight loss, flaccid tail, "muscle wasting," and hind-leg weakness. Histological examination of brain, spinal cord, and sciatic nerve sections of diseased rats revealed the complete absence of focal and perivascular lymphocytic infiltrates characteristics of demyelinating EAE lesions. Elongation of peptide S53 by three or six residues to residue sequences naturally found at its N-terminal end gave rise to peptides S55S (PQKSQRSQDEN) and S49S (GSLPQKSQRSDQDEN), respectively. Lewis rats challenged with either S55S or S49S developed classical clinical and histological signs of EAE. Severe hind-leg paralysis was accompanied by incontinence and sometimes death. Injected in the form of carrier-free peptide, S53 was a meager B cell immunogen. S53 conjugated with methylated-bovine serum albumin was also a potent immunogen and produced clinical signs of disease without CNS pathology. By comparison, carrier-free S55S and S49S were potent immunogens giving rise to antibodies that cross reacted completely and competitively with S55S but considerably less so with S53. The results show that the sequence of S53 defines an epitope responsible for the formation of anti-S53 antibodies. Elongation of the S53 sequence at its N-terminal end generated an additional epitope which induced cell-mediated immunity responsible for the concomitant development of pathological signs of EAE. It may be concluded that the induction of classical signs of EAE requires specific and defined sequences capable of expressing both B cell and T cell functions.

Comparison of in vitro demyelination and cytotoxicity of humoral factors in multiple sclerosis and other neurological diseases

The distribution and nature of serum factors causing in vitro demyelination and glial lysis were investigated in multiple sclerosis (MS), other neurological diseases (OND), ill control and control groups. MS sera were unique in affecting only CNS myelin and glia whereas stroke and Guillain-Barré syndrome (GBS) sera brought changes to both CNS and PNS tissue. Through both visual scoring of myelin damage and the quantitative measurement of radiolabel release from cerebellar cultures, it was evident that the MS and OND groups have similar myelino- and cytotoxic effects. This may reflect MS and OND sera sharing similar humoral factors. 74% MS, 68% OND and 22% of control scores were above a score threshold designed to exclude culture handling trauma effects. When classified by their current disease state MS patients with severe and mild disease yielded higher in vitro scores than did those with moderate disease who comprised an older age group. No other clinical features of MS patients gave any association with in vitro serum effects. The rare demonstration of bound Fab IgG in cultures after MS serum tests indicates that immune mechanisms are unlikely to make a large contribution to serum-induced demyelination and cellular change in vitro.

Immunological study of the rat hypothalamic ventromedial nucleus

Specific anti-sera were prepared by injecting the homogenates of rat ventromedial nucleus (VMH) and caudate nucleus (Cd) into the rabbit. Anti-VMH serum, after absorption of common components in rat normal serum and anti-Cd serum, reacted specifically to the rat VMH with only one precipitation line. Anti-VMH serum was successfully applied to 80 VMH neurons by electrophoresis through 5 barreled micropipettes. Fresh anti-VMH serum caused an irreversible response (increase and subsequent sudden cessation of firing) in 8 of the 25 VMH neurons tested. Anti-VMH serum reversibly inhibited 32 of 80 VMH neurons and 13 of these were also tested with glucose. Discharge rates of 12 of the 13 neurons increased by glucose. Most of these neurons were not affected by anti-Cd serum or normal rabbit serum. Results of these immunological and electrophysiological studies suggest the existence of specific membrane receptor binding sites on the glucoreceptor neurons in the VMH. These sites afford one route for producing the excitatory effect that glucose has on VMH neurons.

Immune responses to myelin antigens in multiple sclerosis

Multiple sclerosis is considered to be a putative immunopathologic disease and there has been considerable effort over the years to prove an autoimmune etiology for it. To date, the evidence is all indirect and there is no proof of either antibody and/or cell-mediated hypersensitivity to any single identifiable CNS constituent whether a constituent of normal CNS or specific to the CNS of MS patients.

Immunoglobulin-deficient rats fail to develop experimental allergic encephalomyelitis

Lewis rats were treated from day of birth with a rabbit anti-rat IgM antiserum. As adults these animals were found to have no detectable serum IgM and greatly reduced levels of IgG. They failed to respond to the B-cell mitogen LPS, or to make antibodies to sheep red blood cells (SRBC) or myelin basic protein (BP). These B-lymphocyte and immunoglobulin-deficient rats failed to develop clinical or histological evidence of EAE when sensitized with either whole spinal cord or purified BP. That some T-cell functions of these suppressed animals were not altered was seen by their ability to respond normally to PHA and to reject tissue allografts. The results would suggest that B-cell function (immunoglobulin-antibody production) is essential for the induction of EAE.

Immunospecific inhibition of nerve conduction by T lymphocytes reactive to basic protein of myelin

Experimental autoimmune encephalomyelitis (EAE) induced by immunization to the basic protein of central nervous system myelin (BP) is a paralytic disease in which T lymphocytes attack the individual's own central nervous system. As the target is in white matter, EAE has been considered an experimental model of some aspects of human disease such as multiple sclerosis. To investigate whether autoimmune T lymphocytes could produce paralysis, we studied the effects on the electrophysiology of isolated nerves produced by T-lymphocyte lines reactive specifically to BP or other antigens. We now report that propagation of action potentials evoked by electrical stimulation was blocked by incubating optic nerves with specific anti-BP T cells. This blockade could be reversed for up to two hours by removing the anti-BP line cells from the optic nerve. The anti-BP line cells had no effect on conduction along allogeneic optic nerves or syngeneic peripheral nerves. This indicates that disruption of the function of myelin in neuroimmunological disease may result from an immunologically specific interaction between autoimmune T lymphocytes and myelin antigens.

Cancer and depression: cancer presenting with depressive illness: an autoimmune disease?

It is proposed that some cases of depressive illness in cancer patients may be caused by immunological interference with the activity of serotinin, one of the neurotransmitters thought to be implicated in depression. This interference could be mediated in two ways. Antibody induced against a protein released from cancer cells could, on the basis of cross-reactivity with CNS tissue, bind to receptors for serotonin and block them. Such primary antibodies could stimulate the production of anti-idiotypic antibodies, which would act as an alternative receptor for serotonin and reduce its synaptic availability.

Antibrain antibodies in multiple sclerosis. Relation to clinical variables

IgG antibrain antibodies (ABA) of several specificities can be demonstrated in multiple sclerosis (MS) with the complement fixation technique. This technique seems to discriminate between IgG specifically and non-specifically bound to CNS preparations. Complement-fixing ABA were titrated in paired serum and CSF samples from 87 patients with clinically definite MS, 15 patients with probable MS, 29 patients with other neurological diseases, and 13 "healthy" controls. In addition, sera from 55 non-MS patients were tested. In 40% of the sera and 88% of the CSF samples from patients with clinically definite MS, ABA reacting with human brain homogenate were demonstrated. The corresponding figures for probable MS were 21% and 73%, and for the controls 11% and 6%. Two of 9 sera from patients with the Guillain-Barré syndrome were strongly positive. There was a tendency for higher CSF ABA titres in younger MS patients and in those with an earlier onset of disease. ABA titres in serum and CSF were both correlated with a more malignant course. Irrespective of the mechanism of induction of ABA in MS--an excessive immunogenic stimulation and/or a defective immunoregulation--they are potentially pathogenic in several ways, e.g. (1) by direct antibody action. (2) by interaction with complement, (3) by antibody-dependent K-cell-mediated cytotoxicity, and (4) by interaction with phagocytic cells. Of several correlations among the routine CSF variables in MS, the finding of more pronounced abnormalities in male patients was notable.

Experimental allergic encephalitis; treatment with drugs which alter CNS serotonin levels

Lennon and Carnegie have proposed that the clinical symptomatology of experimental allergic encephalitis (EAE), an acute autoimmune demyelinating disease, may be due, at least in part, to an immune response directed against CNS serotonin receptors. To test this hypothesis we treated strain 13 guinea pigs, which had been immunized with guinea pig basic protein (GPBP) in complete Freund's adjuvant (CFA), with drugs known to affect central nervous system (CNS) serotonin levels. These drugs included imipramine hydrochloride, tryptophan and carbidopa which increase CNS serotonin and reserpine which decreases it. Five experiments were conducted in which all immunized animals treated with saline only died, as expected, as did all animals treated with reserpine which died even more quickly. A significant proportion of animals treated with the other three drugs, alone or in combination, survived or lived longer than controls. We conclude that survival of animals with EAE is enhanced by treatment with these drugs. We suggest that further evaluation of a possible blockade in serotonin transmission in EAE and multiple sclerosis (MS) is warrented, since, if such a blockade were demonstrated, it is possible that these drugs may have potential for therapeutic efficacy in patients with MS.

Hind-limb motor ability in Lewis rats during the onset and recovery phases of experimental autoimmune encephalomyelitis

Hind-limb motor function in adult female Lewis rats with experimental autoimmune encephalomyelitis (EAE) was investigated using an objective behavioral measurement of motor ability. Rats were pretrained to avoid falling from the external surface of a power-driven running wheel. The performance of EAE-group rats on the wheel was then compared with that of saline and adjuvant controls immediately prior to the onset of clinical signs of EAE, and within 3 days of apparent recovery from EAE. Results indicate no apparent hind-limb motor deficit in the absence of overt clinical signs of EAE, despite histological evidence of severe inflammatory lesions persisting in the central nervous system (CNS) at the time of the post-recovery test. The remarkably transient nature of motor impairment is discussed within the context of a continuing search for the underlying cause(s) of clinical signs of EAE.

Auditory electrophysiology: findings in multiple sclerosis

15 patients suffering from definite multiple sclerosis were studied by electrocochleography (ECochG) and brain stem electric responses (BSER), including objective analysis of the electrophysiological data. In 7 patients, both ECochG and BSER were performed, in 2 only ECochG and in 6 only BSER. Systematic deviations from normative values were found in all 9 patients tested by ECochG, but the deviations occurred only at 75 dB pe SPL or below. Despite normal or near-normal audiometric thresholds, the cochleae seemed to be involved. At click intensities of 95 dB pe SPL or higher, the BSER revealed a normal AP-V (Jewett) interval in all 13 patients tested. However, a deviant configuration of the BSER following the wave V complex was found in 6 of the 13 patients. The deviation is described as a dominant, relatively low-frequency component of the response. The discrepancies between these results and those reported in the literature indicate a strong need for applying methods that compensate for peripheral hearing dysfunctions and objective methods of analysis to identify and evaluate the various components of the evoked potentials.

Some recent advances in the clinical aspects of multiple sclerosis

Recent work on the clinical aspects of multiple sclerosis is reviewed with particular regard to symptomatology: New approaches to clinical symptoms and the identification of more subtle impairments are illustrated by recent studies of visual function in M.S. patients; pathophysiology: It is now widely appreciated that the dysfunction observed in patients is not determined solely by histologically demonstrable demyelination. The function of the demyelinated neuron is highly variable, being dependent upon factors which may change from day to day. Recent ideas about 'neuro-electric blocking factors' and other factors that may influence demyelinated neurons and hence symptoms are discussed; diagnosis: tests on C.S.F., electro-physiological and psychophysiological tests and computer tomography as aids to diagnosis and the controversy over 'specific' blood tests are reviewed; course and prognosis: Long term follow-up studies confirm that, in a significant proportion of cases, the course of M.S. may be benign and have identified some early prognostic indices;

TREATMENT

The results of trials of symptomatic (spinal cord stimulation) and would-be curative therapies (such as dietary supplementation with poly-unsaturated fatty acids and immunosuppression) are briefly discussed.

Glycine in the central nervous system in experimental allergic encephalomyelitis

The content of glycine, a possibly inhibitory neurotransmitter was studied in central nervous system of guinea pigs with experimental allergic encephalomyelitis (EAE). The glycine level was increased in spinal cord, but not in the brain of animals with EAE. The greatest increase in glycine concentration was in lumbosacral cord, and at the time of appearance of clinical signs of diseases. The results are discussed in terms of possible connection between the changes of glycine concentration and clinical signs of EAE.

Abnormal protein patterns in multiple sclerosis

Sera from patients with multiple sclerosis (MS) and those obtained from normal subjects are indistinguishable by regular 5% or 7% polyacrylamide gel electrophoresis. However, 11 out of 15 MS sera examined by gradient polyacrylamide gel electrophoresis showed three distinct protein bands. None of the sera obtained from 10 normal subjects showed the characteristic protein patterns when they were examined by gradient gel electrophoresis. Similar results were obtained with de-albumin serum samples or with serum proteins precipitable at 50% ammonium sulfate saturation. These three proteins have now been purified to homogeneity by preparative gradient gel electrophoresis. Molecular weights of these proteins were estimated from gradient gel electrophoresis as 398,000, 363,000 and 302,000 daltons, respectively.

Multiple sclerosis: demyelination and myelination inhibition of organotypic tissue cultures of the spinal cord by sera of patients with multiple sclerosis and other neurological diseases

Sera from 44 patients with Multiple Sclerosis, of three patients with neurological syndromes compatible with Multiple Sclerosis, of 34 patients suffering from other neurological diseases and of 25 pregnant healthy young women were tested for their demyelinating activity in myelinated tissue cultures. In order to leave the investigators unprejudiced, all sera were coded and intermixed with controls of rabbit EAE serum which had a potent demyelinating capacity. Demyelination was graded (from 0--4), heat lability at 56 degrees C (complement dependency?) was also tested with each serum. Only demyelination of a degree of 2 and more, which was abolished by heating to 56 degrees C, was counted as positive. Six of the 44 sera from MS patients (13.6%), 19 of 37 sera from neurological patients and none of the healthy young women demyelinated. Thus, serum demyelination of tissue cultures seems to be a nonspecific indicator of chronic disease of the nervous system and is of considerable general neurological interest, but does not indicate a demyelinating disease. Myelination inhibition was not observed with any of the human sera tested for it.

Tissue culture studies of demyelinating disease: a critical review

Tissue culture studies of human and experimental demyelinating diseases have demonstrated that sera from patients with multiple sclerosis reversibly demyelinate central nervous system cultures. Similar changes are evoked by sera from animals with experimental allergic encephalomyelitis induced by inoculation with whole central nervous system tissue but not by encephalitogenic myelin basic protein. Sera and buffy coat or lymph node cells from humans with idiopathic polyneuritis and animals with experimental allergic neuritis demyelinate cultures of peripheral nervous system tissue. While these studies have contributed to speculations about pathogenetic mechanisms of demyelinating diseases, including the role of both circulating antibodies and delayed hypersensitivity factors, a number of important questions remain unanswered. Among these are the identity of the antigens that evoke antimyelin antibodies and the precise relationship of serum or cellular antimyelin factors to the pathogenesis or clinical course of the demyelinating diseases. Further studies with this technique may provide more complete information about the role of immunological events in induction of disease.

Peripheral nerve abnormality in multiple sclerosis

Biopsy specimens of sural nerve from 10 patients with multiple sclerosis (MS), of whom only 1 was severely disabled, were assessed by morphometric techniques and compared to nerves from age-matched controls. The frequency of abnormal teased fibers was increased in MS nerve, with many internodes showing at least a 50% reduction in myelin thickness. Myelinated nerve fiber densities were not significantly different in MS and control nerves. Regression analysis of axonal area on number of myelin lamellae indicated a generalized reduction of myelin lamellae in this disorder. It is suggested that peripheral myelin may be involved in multiple sclerosis.

Suppression of acute and chronic experimental allergic encephalomyelitis in Strain 13 guinea pigs. A clinical and pathological study

Adult inbred Strain 13 guinea pigs develop an acute, fatal form of experimental allergic encephalomyelitis (EAE) about 2 weeks after a single injection of isologous spinal cord in complete Freund's adjuvant (CFA), but similarly injected juveniles develop a delayed, rarely fatal chronic form. Thirty-seven sensitised adult Strain 13 animals were separated into 2 groups. One group was permitted to develop acute EAE. The other group was injected intramuscularly with 1 mg of guinea pig or bovine myelin basic protein (MBP) in incomplete Freund's adjuvant (IFA) on day 2, 7 or 10 post-inoculation (PI) followed by 0.2 mg in IFA every third day for a total of 10 doses. Animals in the unsuppressed group succumbed to acute EAE 13-16 days post-sensitisation. No animal in the suppressed group died during this period. Animals treated with MBP beginning 2 days PI showed no clinical signs, but mild clinical manifestations occurred in animals suppressed from days 7 and 10 PI. These signs remitted by 21 days post-sensitisation. One suppressed animal (out of 21) died during the fourth week postsensitisation. The other 20 suppressed animals appeared clinically normal towards the end of the course of MBP injections and remained so for the 6 months of study. Morphological examination revealed that CNS lesions occurred in all animals. In animals suppressed with MBP beginning on day 2 PI, lesions consisted only of a few meningeal inflammatory cells. Animals given MBP beginning on day 7 or 10 PI and sampled 1-2 weeks later, had lesions which could not be distinguished from those occurring in the non-suppressed acute EAE group. In time, the suppressed animals developed lesions which were typical of chronic EAE with remyelination as a predominant feature. Preliminary experiments on the suppression of chronic EAE in 5 juvenile Strain 13 guinea pigs have revealed that 3 MBP-injected animals failed to develop clinical disease over a 28-week period of study although lesions typical of chronic EAE were present. Simultaneously, 2 non-suppressed juvenile animals developed clinical signs by 12 weeks. These were associated with both acute inflammation and demyelination superimposed upon regions of chronic demyelinative activity.

In vivo test for myelinotoxicity of cerebrospinal fluid

A quantitative double blind procedure is described to test the myelinotoxicity of cerebrospinal fluid (SSF) by using optic nerves of Xenopus tadpoles as an in vivo model of a myelinated CNS tract. Only 0.5 ml of unconcentrated CSF is needed for a test and the result is known in 5 days. Groups of 8-10 Xenopus tadpoles received a subcutaneous injection of 12-13 muL of a coded CSF sample or of a saline control solution around the right optic nerve. After 48 h, whole mounts of the right optic nerves were prepared and the slides were randomized before using a differential-interference contrast microscope to count the myelin lesions. The myelinotoxicity of a CSF sample was considered positive (+) when it produced significantly higher (P less than 0.01) counts than the saline control. When P was less than 0.05, the counts were recorded as borderline (+/-) and it was negative (-) when P was greater than 0.05.

Neuroelectric blocking factors in human and animal sera evaluated using the isolated frog spinal cord

The effects of sera from guinea-pigs with experimental allergic encephalomyelitis (EAE) and multiple sclerosis (MS) patients were evaluated and compared with the activity of control sera using the isolated frog spinal cord. Ventral root responses (VRR) were recorded during supramaximal ipsilateral dorsal root stimulation in the presence and absence of 25% serum. In control experiments with normal human and guinea-pig sera we observed a consistent, reversible increase in VRR averaging 20% and 17% respectively, and in no case was any significant decrease produced. In contrast, sera from EAE guinea-pigs 12 to 19 days after injection produced an equally rapid, reversible decrease in VRR. The decrease averaged 36% and was highly significant (P less than 0.0001) relative to controls. Similarly, sera from MS patients on the average decreased the VRR by 26%, and this again was significant compared with controls (P less than 10(-6).

Complement-fixing antibrain antibodies in multiple sclerosis. Comparison of their occurrence in cerebrospinal fluid and serum

Cerebrospinal fluid (CSF) and serum samples from 40 multiple sclerosis (MS) patients and 48 control patients were examined by a microcomplement fixation test for the presence of antibodies against saline extracts of human brain. When tested with an IgG content standardized in 100 mg per 100 ml, 13 of the MS CSF and one of the corresponding MS sera were positive, whereas none of the control specimens were positive. The antibody was shown to be highly organ specific when tested against extracts of myocard, spleen, kidney and peripheral nerve. Chromatographic experiments showed the antibody to belong to the IgG class. It was concluded that the antibody was probably synthesized intrathecally in 12 and extrathecally in one MS patient.

Subclinical optic neuropathy in multiple sclerosis. How early VER components reflect axon loss and conduction defects in optic pathways

The pathological effect of multiple sclerosis in the visual pathways consists of axonal demyelination and axonal loss. These two consequences of the disease, even in its subclinical stages, are reflected in changes in the initial component of the visual evoked response (VER) affecting its latency, configuration, or both. These abnormal early components of the VER were recorded in 25 patients with multiple sclerosis, only 10 of whom had any indication of visual involvement that could be documented historically or by conventional ophthalmic investigation.

Anti-synaptic antibody in allergic encephalomyelitis. I. Neurophysiological studies, in guinea pigs, on the exposed cerebral cortex and peripheral nerves, following immunological challenges with myelin and synaptosomes

The potential evoked at the surface of the cerebral cortex of a guinea pig, by stimulation of the contralateral forepaw, usually consists of an initial double positive wave whose waveform remains unchanged during rapid stimulation. In a guinea pig with experimental allergic encephalomyelitis (EAE) the response is attenuated at low frequencies of stimulation. Observations were also made on animals with experimental allergic neuritis (AEN). These animals showed a peripheral specificity for decreased conduction velocity, but have normal cortical evoked responses. Histological studies were undertaken in parallel with the electrophysiological studies and the concordance and discordance between the two is discussed. We conclude that there is no evident correlation between the severity of the electrophysiological effects and the histological lesions. An attempt was also made to induce an immunological challenge in guinea pigs, in the same way that EAE and EAN is produced, by the injection of synaptosomes. No clinical signs or alterations in the histology or electrophysiology of the animals were seen. A discussion is included on the elucidation of the site of action of EAE by discriminating between the direct effects on myelin and synapses and by the indirect effects of myelin damage on synapses. No firm conclusion is reached and the matter is left for further analysis in the subsequent paper. Finally, the neurophysiological alterations, demonstrated in the EAE and EAN situations, are discussed in terms of a humoral factor possibly acting on the myelin sheath and indirectly affecting synaptic function. This matter is further discussed in the subsequent paper.

Anti-synaptic antibody in allergic encephalomyelitis. II. The synapse-blocking effects in tissue culture of demyelinating sera from experimental allergic encephalomyelitis

It has been suggested that demyelination cannot account for all of the observed clinical symptoms of multiple sclerosis (MS), in particular the rapidity of onset and remission of the disease, and attention has been focussed on the role of the synapse in 'demyelinating diseases'. In the present paper we have attempted to resolve the fundamental question of the site of action of a demyelinating disease, experimental allergic encephalomyelitis (EAE), by the use of cultures of neonatal rat cerebellum. Electrophysiological and morphological development in these cultures run hand-in-hand, and in the first few days in vitro there is a 4-5 day period when synapses are both seen ultrastructurally and known to be functioning but before the onset of myelination. The serum from guinea pigs with EAE was added to these cultures at different stages during their development and the morphological and electrophysiological effects observed. An abolitionary effect on the bioelectric activity of the culture was only observed when the serum was added to mature, myelinated cultures. Also the same active sera had no effect on synaptic activity before myelination had occurred. We conclude that the synaptic blocking effect occurs only when myelin is destroyed.