Neurological functional recovery after thymosin beta4 treatment in mice with experimental auto encephalomyelitis.

In the present study, we hypothesized that thymosin beta 4 (Tbeta4) is a potential therapy of multiple sclerosis (MS). To test this hypothesis, SJL/J mice (n=21) were subjected to experimental autoimmune encephalomyelitis (EAE), an animal model of MS. EAE mice were treated with saline or Tbeta4 (6 mg/kg, n=10) every 3 days starting on the day of myelin proteolipid protein (PLP) immunization for total five doses. Neurological function, inflammatory infiltration, oligodendrocyte progenitor cells (OPCs) and mature oligodendrocytes were measured in the brain of EAE mice. Double immunohistochemical staining was used to detect proliferation and differentiation of OPCs. Tbeta4 was used to treat N20.1 cells (premature oligodendrocyte cell line) in vitro, and proliferation of N20.1 cells was measured by bromodeoxyuridine (BrdU) immunostaining. Tbeta4 treatment improved functional recovery after EAE. Inflammatory infiltrates were significantly reduced in the Tbeta4 treatment group compared to the saline groups (3.6+/-0.3/slide vs 5+/-0.5/slide, P<0.05). NG2(+) OPCs (447.7+/-41.9 vs 195.2+/-31/mm(2) in subventricular zone (SVZ), 75.1+/-4.7 vs 41.7+/-3.2/mm(2) in white matter), CNPase(+) mature oligodendrocytes (267.5+/-10.3 vs 141.4+/-22.9/mm(2)), BrdU(+) with NG2(+) OPCs (32.9+/-3.7 vs 17.9+/-3.6/mm(2)), BrdU(+) with CNPase(+) mature oligodendrocytes (18.2+/-1.7 vs 10.7+/-2.2/mm(2)) were significantly increased in the Tbeta4 treated mice compared to those of saline controls (P<0.05). These data indicate that Tbeta4 treatment improved functional recovery after EAE, possibly, via reducing inflammatory infiltrates, and stimulating oligodendrogenesis.

Polyradiculopathy in sarcoidosis.

We present three new and 14 retrospective cases of polyradiculopathy in sarcoidosis. Of these, 71% had weakness and 59% areflexia of the lower extremities, and 35% had sphincter dysfunction. Cases often were associated with central nervous system sarcoidosis. All cases involved thoracolumbar or lumbosacral roots, except a single case of cervical polyradiculopathy. Of 14 treated patients, nine improved with corticosteroids, laminectomy, or both. Polyradiculopathy complicating sarcoidosis: (1) is uncommon; (2) primarily involves thoracic and lumbar roots; (3) may arise from contiguous, hematogenous, or gravitational nerve root sleeve seeding; (4) may be asymptomatic; and (5) may improve with corticosteroids. Differential diagnosis of weakness in patients with sarcoidosis should include nerve root involvement from the primary process by direct sarcoid involvement.

Central pontine myelinolysis and pontine lesions after rapid correction of hyponatremia: a prospective magnetic resonance imaging study.

The rate at which profound hyponatremia should be corrected is the focus of a recent clinical debate. We prospectively studied neurological outcomes with serial magnetic resonance imaging in 13 hyponatremic subjects with serum sodium concentrations of less than 115 mmol/L (mean initial serum sodium concentration, 103.7; range, 93-113 mmol/L). All subjects were corrected to mildly hyponatremic levels at 24 hours and ultimately underwent an increase in serum sodium concentration of 25 mmol/L without development of hypernatremia. Magnetic resonance imaging revealed the development of pontine lesions in 3 patients. The correction rate of hyponatremia over the first 24 hours was significantly faster in patients with pontine lesions (mean +/- SD, 1.25 +/- 0.4 mmol/(L . hr) versus 0.74 +/- 0.3 mmol/(L . hr); p less than 0.05). Initial sodium concentration was also significantly lower in the pontine lesion group (97.3 +/- 6.7 vs 105.6 +/- 5.2 mmol/L, p less than 0.05). We conclude that the correction rate of hyponatremia plays a significant role in the pathogenesis of pontine lesions in individuals with profound hyponatremia who undergo large increases in sodium concentration as a result of severe initial hyponatremia.

Central pontine myelinolysis after rapid correction of hyponatremia: a magnetic resonance imaging study.

We describe a patient with severe hyponatremia (serum sodium 94 mmol/L) who developed encephalopathy and decorticate posturing after a 29 mmol/L rise in serum sodium concentration during the first 24 hours of correction. High-resolution computed tomography of the pons was normal during the first, second, and twelfth weeks of the illness. Subsequent magnetic resonance imaging revealed a pontine lesion consistent with central pontine myelinolysis.

Oligodendrocyte development and the natural history of multiple sclerosis. A new hypothesis for the pathogenesis of the disease.

The cause of multiple sclerosis (MS) is not known. This article presents a review of recent studies concerned with the development of oligodendrocytes and suggests that the primary lesion in MS could be related to damage to oligodendroglial progenitor cells. Loss of the capacity to generate oligodendrocytes could alter the course of normal development such that insufficient cells are produced to support growth and replace cells lost through attrition, and as a result, regions of demyelination appear. The site and extent of the primary loss of oligodendroglial precursors would then predetermine the time of onset, site, and severity of the neurologic manifestations of MS. It is suggested that MS is a single, continuous process and that clinical, pathologic, and immunologic findings may be understood as the consequences of the acquired inability to generate sufficient oligodendrocytes to maintain myelin.

Recurrent stroke associated with thymoma and anticardiolipin antibodies.

A 44-year-old woman developed recurrent thrombotic cerebral cortical infarctions. IgG and IgM anticardiolipin antibodies were found, as was a thymoma. To our knowledge, these antiphospholipid antibodies, which may inhibit prostacyclin formation and alter platelet function, have not been previously associated with this thymic neoplasm, an association we believe is not coincidental.

Pathologic findings in adrenoleukodystrophy heterozygotes.

Two women, heterozygous for X-linked adrenoleukodystrophy, contained striated adrenocortical cells without inflammation and central nervous system demyelinative lesions. Only one was symptomatic neurologically; neither exhibited hypoadrenalism. These findings further document the variability of adrenoleukodystrophy heterozygotes and provide evidence that the major pathologic differences between hemizygote and heterozygote are quantitative in nature.

Myasthenic globulin enhances the loss of acetylcholine receptor clusters.

Acetylcholine receptors are present in the sarcolemma of cultured skeletal muscle myotubes either as large clusters or in a diffuse distribution. Both the clustered and diffuse acetylcholine receptors are potentially removable from the membrane. Treatment of myotubes with globulin from patients with myasthenia gravis causes the loss of acetylcholine receptor clusters and the concomitant appearance of acetylcholine receptor microaggregates. The rate of acetylcholine receptor cluster loss is greater than the rate of acetylcholine receptor degradation, indicating that acetylcholine receptors are disrupted from clusters to form microaggregates before being removed from the plasma membrane.

Interaction of myasthenic immunoglobulins and cholinergic agonists on acetylcholine receptors of rat myotubes.

Acetylcholine receptor (AChR) antibodies from patients with myasthenia gravis (MG) impair neuromuscular transmission by altering the number of AChRs at the skeletal muscle motor endplate. Cholinergic agonists similarly impair transmission by altering the number and affinity of AChRs. The frequent clinical resistance ot anticholinesterase medication in patients with MG has raised the question of possible synergistic effects of these agents on regulation of AChRs and neuromuscular transmission. To investigate this question, rat myotube cultures were incubated with MG globulin and carbamylcholine (CMC) for 20 hours. The number of AChRs was assayed by 125I-alpha-bungarotoxin binding. Incubation of cultures with both MG globulins and CMC consistently produced greater reductions of AChRs than incubation with either substance alone. Cholinergic antagonists blocked the CMC effect but not the MG globulin effect. A muscarinic antagonist had no effect. The effects of short-term incubation with these substances on the affinity of AChR were assessed by the rate of 125I-alpha-bungarotoxin-AChR complex formation. CMC desensitized AChRs, but MG globulins did not alter the affinity of AChRs. Results with this in vitro model suggest that chronic anticholinesterase therapy in the presence of MG AChR antibodies may aggravate failure of neuromuscular transmission in MG.

The role of acetylcholine receptor antibodies in myasthenia gravis.

Myasthenia gravis is an autoimmune disease of man characterized by remitting and relapsing muscle fatigability. Although the etiology and pathogenesis are incompletely understood, the presence of circulating antibodies directed against the nicotinic acetylcholine (ACh) receptor in 80--90% of patients with myasthenia gravis and the identification of immune complexes at their neuromuscular junction have helped explain the altered neuromuscular transmission. The ACh receptor antibodies do not block access of ACh to the receptor, but do decrease the number of receptors by accelerating their degradation both in rat myotube cultures and in vivo models. In vitro these antibodies play a major role in myasthenia gravis. However, correlations of antibody titers with the clinical state following thymectomy or in neonatal myasthenia suggest that host factors may be equally important in determining whether the ACh receptor antibodies will result in clinical myasthenia.

Neonatal myasthenia gravis in the infant of a myasthenic mother in remission.

A 26-year-old woman was in spontaneous clinical remission from myasthenia gravis (MG) for six months, yet gave birth to a full-term infant with typical neonatal MG. It is believed that transplacental transfer of anti-acetylcholine (ACh) receptor antibodies is responsible for neonatal MG; therefore, neonatal MG represents an in vivo assay of the pathogenic potential of anti-ACh receptor antibodies in 2 human individuals. Anti-ACh receptor antibodies were present in both mother and infant (titers 12.3 X 10(-9) and 4.4 X 10(-9) moles per liter, respectively) at the time of birth, and both mother's and infant's sera accelerated the degradation of ACh receptors in myotube cultures. This case suggests that "host factors" unique to the individual appear to modify or even determine whether the presence of anti-ACh receptor antibodies will result in clinical myasthenia.

Acetylcholine receptor in myasthenia gravis: increased affinity for alpha-bungarotoxin.

Studies of the binding of 125 I-labeled alpha-bungarotoxin to myasthenic motor end-plates have been interpreted as showing a decrease in the number of acetylcholine (ACh) receptors at these end-plates. Equilibrium binding studies of 125 I-tagged alpha-bungarotoxin rather than to a decreased number of receoptors. Our results show increased rather than decreased affinity of myasthenic receptors for alpha-bungarotoxin and also suggest that the number of ACh receptors is indeed reduced. The presence of a change in binding affinity, in addition to the reduced number of ACh receptors, suggests the presence of membrane changes that may contribute to the pathogenesis of myasthenia gravis.