Congenital Horner's syndrome does not alter Lisch nodule formation.

A 21-year-old woman with neurofibromatosis type 1 (NF-1) had a unilateral congenital Horner's syndrome with resultant hypopigmentation of the affected iris. Lisch nodules, which are melanocytic hamartomas, were similar in number, size, and pigmentation in both eyes. The present findings suggest that the formation of Lisch nodules is not influenced by the presence or absence of sympathetic innervation of the iris.

Nerve growth factor receptors on dissociated neurofibroma Schwann-like cells.

Neurofibromatosis is a disorder which predominantly involves cellular elements of peripheral neural sheaths. Little is known about the regulation of differentiation and proliferation of cells comprising neurofibromas. Because nerve growth factor-like activity may be present in neurofibromas and the cells comprising neurofibromas are neural crest derivatives, we have investigated whether nerve growth factor (NGF) receptors are present on cells from dissociated dermal neurofibromas. Using 125I-NGF to measure binding to cultured cells in suspension and for autoradiography, we identified a population of cells having characteristics of Schwann cells which exhibited saturable 125I-NGF binding. This binding is characteristic of the "fast" (low affinity) NGF receptor, having a Kd of approximately 1 nM and a Bmax of at least 120 fmol/10(6) cells. Less than 20% of the bound 125I-NGF (5 ng/ml) is not displaced when transferred to 0 degrees C by an excess of unlabeled NGF (10 micrograms/ml) and is therefore bound to either "slow" (high affinity) sites or is rapidly internalized. NGF receptors with characteristics of fast sites have recently been reported on Schwann-like cells from chick dorsal root ganglia [Zimmerman, A., and Sutter, A. Beta nerve growth factor (beta NGF) receptors on glial cells. Cell-cell interaction between neurones and Schwann cells in culture of chick sensory ganglia. EMBO J., 2: 879-885, 1983]. The identification of NGF receptors on both fetal chick dorsal root ganglia and neurofibroma Schwann-like cells suggests that NGF may have a role in the regulation of Schwann cell function in both normal development and in neurofibromatosis.

Schwann-like cells cultured from human dermal neurofibromas. Immunohistological identification and response to Schwann cell mitogens.

Primary cultures prepared from dermal and plexiform neurofibromas contain Schwann-like cells and fibroblast-like cells. SLC are elongated and bipolar or multipolar. By indirect immunofluorescence light microscopy, living SLC bind antibodies against laminin and against nerve growth factor receptor to their surface, but not antibodies against fibronectin. In these respects, cultured SLC are indistinguishable from cultured human adult Schwann cells. FLC are flat and pleomorphic. By indirect immunofluorescence light microscopy, living FLC bind antibodies against fibronectin but not against laminin or NGFR. In these respects, cultured FLC are indistinguishable from cultured human adult endoneurial fibroblasts. Considerable purification of viable SLC from SLC/FLC mixed cultures can be achieved by flow cytofluorometry using a monoclonal anti-NGFR antibody. Tritiated thymidine radioautography indicated that mitosis of SLC in mixed SLC/FLC cultures prepared from dermal neurofibromas is infrequent in MEM with 10% calf serum, more frequent in RPMI 1640 medium with 15% fetal calf serum. Central nervous system axolemmal fragments (rat or human) elicited a greater than 10-fold SLC proliferative response in mixed SLC/FLC cultures from three of seven dermal neurofibromas (from six patients with neurofibromatosis), but had no effect on SLC mitosis in cultures from the other four dermal neurofibromas. SLC mitosis was inhibited by concentrations of cyclic adenosine 3',5'-monophosphate analogues known to stimulate proliferation of normal rat Schwann cells. Glial growth factor partially purified from bovine pituitaries stimulated SLC mitosis both in SLC/FLC mixed cultures and in cultures of purified SLC. The studies we have described indicate that neurofibroma SLC can be cultured, unequivocally identified in culture by morphological and immunohistological criteria, purified, and stimulated to proliferate by several Schwann cell mitogens. Further quantitative comparisons of the baseline and mitogen-stimulated rates of proliferation of SLC and age-matched control human Schwann cells are needed, however, to determine which of the two alternate pathogenetic mechanisms for formation of neurofibromas mentioned in the introduction is correct.

Neurofibromatosis. A review of the clinical problem.

NF is a relatively common genetic disorder which predisposes to a variety of clinical manifestations involving multiple body systems. NF poses important questions to researchers involved with developmental neurobiology, nerve regeneration and growth, the mechanism of malignant degeneration, and the use of molecular techniques to identify genetic disorders. It is hoped that this conference will bring together researchers who have developed new techniques in these areas and will encourage them to apply these techniques to the problem of NF.

Tissue culture studies of neurofibromatosis: effects of axolemmal fragments and cyclic adenosine 3',5'-monophosphate analogues on proliferation of Schwann-like and fibroblast-like neurofibroma cells.

Six dermal neurofibromas obtained from 5 patients with neurofibromatosis were dissociated and the cells were plated on polylysine-coated glass. Two principal cell types were observed in the cultures: elongated and bipolar Schwann-like cells (SLCs), and polymorphic flattened fibroblast-like cells (FLCs). Indirect immunofluorescence demonstrated that SLCs expressed surface laminin but not surface fibronectin; FLCs expressed surface fibronectin but were only weakly positive for surface laminin. Tritiated thymidine autoradiography demonstrated that cultured SLCs proliferated slowly (labeling index, 0.7 to 4.0%), whereas FLCs divided more rapidly (labeling index, 7.5 to 26.4%). Axolemmal fragments prepared from human or rat central nervous system specimens adhered to SLCs derived from each of the 6 neurofibromas, but not to FLCs. Axolemmal fragments induced a marked proliferative response of SLCs from 2 of the 6 neurofibromas but had no effect on proliferation of SLCs from the other 4 neurofibromas or FLCs from any of the 6 neurofibromas. In one patient from whom 2 neurofibromas were obtained, SLCs from one neurofibroma responded to axolemmal fragments, while SLCs from the other did not. Treatment of the cultures with 0.1 mM cyclic adenosine 3'5'-monophosphate (cAMP) analogue, 8-bromo cAMP, caused marked inhibition of proliferation of both SLCs and FLCs derived from all 6 neurofibromas. The same concentration of another cAMP analogue, dibutyryl cAMP, inhibited proliferation of SLCs but not of FLCs.

Autonomic neuropathy associated with autoimmune disease.

Mononeuropathy multiplex and mixed sensorimotor neuropathy are known complications of systemic vasculitis and related autoimmune disorders. Autonomic dysfunction is not generally considered a neurologic complication of these diseases. We report two patients who came to neurologic attention because of autonomic dysfunction and were then discovered to have autoimmune disease. Autonomic dysfunction may be the presenting sign of autoimmune disorders, which should be considered in the differential diagnosis of acquired autonomic disturbances.

Patterns of daytime sleepiness in narcoleptics and normals: a pupillometric study.

Pupil diameter was measured in light and dark conditions every half hour for 6.5-10 h in 3 normal controls and 3 narcoleptics. Mean pupillary diameter was significantly smaller in the narcoleptic group than in the normal group. Pupil activity was correlated with pupil diameter only in the dark condition in narcoleptics. Pupil diameter varied with a circa 90 min periodicity in the narcoleptics but not in the normal controls. These results indicate firstly, that one-time assessment of pupil size is insufficient; and secondly, that the appearance of these rhythms may be the result of a defect in arousal mechanisms of narcoleptics which usually play an inhibitory role.

Linkage analysis of neurofibromatosis (von Recklinghausen disease).

Linkage analysis of 28 genetic markers was undertaken in 108 subjects from 11 families with well-documented, classic, peripheral neurofibromatosis. Fifty-four persons were affected in one four-generation family, seven three-generation families, and three two-generation families. Lod scores were calculated using the standard LIPED programme for 49 combinations of theta male and theta female from 0.01 to 0.50. Lod scores excluded close linkage with 16 markers, including most tested on chromosome 1 and HLA on chromosome 6, and were inconclusive for 12 markers, including the secretor locus, closely linked to myotonic dystrophy. Analysis of five informative families resulted in a lod score of +2.2 for close linkage with GC on chromosome 4. However, the lod score for GC in the one additional informative family was negative, so that the final interpolated maximum was Z = 0.89 for theta male = 0.03, theta female = 0.28. Further studies are needed to evaluate this suggestion of linkage and possible genetic heterogeneity.

Ocular ergotamine tartrate toxicity during treatment of Vacor-induced orthostatic hypotension.

A 20-year-old woman developed severe orthostatic hypotension after attempting suicide by ingesting the rodenticide, Vacor. Oral ergotamine tartrate, 6 mg a day, was useful in treating the orthostatic hypotension. However, a bilateral toxic retinal vasculopathy, consisting of a severe generalized vasoconstriction and mild macular edema, occurred within three weeks. Additional findings were an extinguished electroretinogram and a reduced dark-adaptation retinal sensitivity; because we performed these two tests after instituting ergotamine therapy we do not know whether to attribute their abnormal results to Vacor toxicity, ergotamine toxicity, or a combination of the two.

Neurotransmitter analysis of dermal neurofibromas: implications for the pathogenesis and treatment of neurofibromatosis.

We examined 15 dermal neurofibromas from five adults with disseminated neurofibromatosis. All tumors contained axons that reacted for catecholamines and tyrosine hydroxylase on histochemical stains. Assay of tissue homogenates identified norepinephrine as the catecholamine. Assays for dopamine and choline acetyltransferase were negative. Some axonal components of dermal neurofibromas may originate in sympathetic adrenergic neurons. Most dermal neurofibromas do not contain neuronal cell bodies, and some of the axons may maintain functional connections with proximal sympathetic neuronal cell bodies. Sympathetic denervation may therefore affect the growth of these dermal neurofibromas.

The pupil in familial dysautonomia.

We performed infrared pupillography on 10 patients with familial dysautonomia. Pupillary constriction to light and accommodation was normal. There was no evidence for light-near dissociation, and tonic responses were not observed. Dilatation in darkness was normal. Ocular application of dilute pilocarpine produced miosis in all patients. Supersensitivity of the pupil to muscarinic agents in familial dysautonomia is unlikely to be explained by parasympathetic denervation. Possible explanations for this phenomenon include diminished lacrimation and corneal ulcerations.

Monoclonal antibodies against mouse nerve growth factor produced by somatic cell hybrids.

Spleen leukocytes from rats and mice immunized against mouse 2.5S nerve growth factor (NGF) and peripheral blood leukocytes from rabbits hyper-immunized against the same antigen were fused with the mouse plasmacytoma P3X63Ag8. Hybridomas were screened by immunological assays (micro-complement fixation test and solid phase radioimmunoassay) for production of antibodies that reacted with NGF. Significant variations were seen between culture fluids from different hybrid cells. In addition, most but not all hybridoma antibodies that reacted immunologically with NGF prevented neurite outgrowth from 8-day chick embryo sensory ganglia explants after binding to NGF. These results suggest that the hybridoma antibodies produced by the different clones react with different antigenic sites on the NGF molecule.