Heterozygous P0 knockout mice develop a peripheral neuropathy that resembles chronic inflammatory demyelinating polyneuropathy (CIDP)

Demyelinating peripheral neuropathies are clinically divided into inherited and acquired types. Inherited demyelinating neuropathies are caused by mutations in genes expressed by myelinating Schwann cells, whereas acquired ones, including chronic inflammatory demyelinating polyneuropathy (CIDP), are probably caused by autoimmune mechanisms. We find that heterozygous P0 knockout (P0+/-) mice develop a neuropathy that resembles CIDP. By one year of age, P0+/- mice develop severe, asymmetric slowing of motor nerves, with temporal dispersion or conduction block, which are features of acquired demyelinating neuropathies including CIDP. Moreover, morphological analysis of affected nerves reveals severe and selective demyelination of motor fibers, focal regions of demyelination, and inflammatory cells. These data suggest that immune-mediated mechanisms may contribute to the pathogenesis of the neuropathy in P0+/- mice.

Prominent proptosis in childhood thyroid eye disease

BACKGROUND

Orbital signs and symptoms occur in approximately one half of children with Graves disease, but the symptoms are usually minor and limited to the eyelids. Prominent proptosis is uncommon in children with this disorder.

METHODS

Review of eight children with prominent proptosis associated with thyroid eye disease. Four patients were treated at the Children's Hospital of Philadelphia, the other four at the Columbia Presbyterian Medical Center.

RESULTS

At initial presentation, children ranged in age from 3 to 16 years. There were five girls and three boys. Seven of eight children had hyperthyroidism at ophthalmic presentation. Four patients had restrictive myopathy, and all of the seven patients who underwent neuroimaging had extraocular muscle enlargement. Five patients were treated with lubrication. Two underwent orbital fat decompression. One patient had thyroid eye disease and myasthenia gravis.

CONCLUSIONS

Proptosis in childhood thyroid eye disease usually is associated with a hyperthyroid state. The proptosis may be dramatic, but corneal exposure and restrictive myopathy are seen in only some of the patients. Neuroimaging shows enlarged extraocular muscles. Most children with this complication can be treated conservatively with topical lubrication, but orbital fat decompression may be considered in patients with more advanced conditions.

Developmental profile in a patient with monosomy 10q and dup(17p) associated with a peripheral neuropathy

We report on a patient with dup(17p) and monosomy (10q) resulting from a familial translocation. Manifestations typical of both syndromes were present. The overall development of this patient was better by comparison with similar reported cases of either anomaly. Our evaluation detected severe gross motor delay and signs of a demyelinating peripheral neuropathy. This patient is trisomic for the region of 17p which includes the peripheral myelin protein-22 (PMP-22) gene, known to be duplicated in Charcot-Marie-Tooth neuropathy type 1A (CMT1A). Our analysis in this patient suggests that trisomy for the PMP-22 gene led to the demyelinating neuropathy and contributed to his severe motor developmental delay.

Neurologic manifestations in children with Lyme disease

OBJECTIVE

Lyme disease (LD) is a tick-borne spirochetal infection with a wide range of neurologic and non-neurologic manifestations. The clinical diversity of LD and limitations in serologic diagnosis often make it difficult to document the diagnosis of neuroborreliosis with certainty.

METHODS

We reviewed clinical manifestations in 97 seropositive children with particular attention to neurologic manifestations. Diagnostic criteria used in other case surveys were applied to determine how often a definitive diagnosis of neuroborreliosis could be made in children.

RESULTS

Of 69 children who met criteria for LD, 32% (22) had new neurologic signs, 73% (16) of which were accounted for by facial palsy and aseptic meningitis. Five of those with neurologic findings also had erythema migrans (EM), and one had both EM and arthritis. Among those with neurologic involvement, boys outnumbered girls two to one. Neurologic abnormalities resolved spontaneously in five children before their serologic results were known.

CONCLUSION

In our series, only 27% of children with neurologic abnormalities due to LD had a history of EM or arthritis. Seropositivity commonly constituted the primary basis for diagnosis of LD. Despite its nonspecificity, seropositivity for LD in children with neurologic symptoms usually signifies active neuroborreliosis.

Paternal transmission of congenital myotonic dystrophy

The congenital form of myotonic dystrophy is reported to be almost exclusively, if not exclusively, maternally transmitted. We present a case of congenital myotonic dystrophy which was inherited from a mildly affected father. This family illustrates that the congenital form of myotonic dystrophy can occur without intrauterine or other maternal factors related to the disease. The possibility of paternal transmission of the congenital form of myotonic dystrophy could be considered when counselling myotonic dystrophy patients and their families.

Prolonged effects of MK-801 in the cat during focal cerebral ischemia and recovery: survival, EEG activity and histopathology

Previously we reported an improvement in histological outcome in cats treated with MK-801 shortly after the induction of temporary middle cerebral artery occlusion, and examined after 2 h of ischemia followed by 4 h of reperfusion. This study investigates the prolonged effects of the same drug treatment. Focal cerebral ischemia was produced in 34 cats by temporary occlusion of the left middle cerebral artery for 2 h. Stroke severity was determined using the ratio of the EEG amplitude from the ipsilateral to that of the contralateral hemisphere. Thirty minutes after the onset of ischemia, cats were treated i.v. with either 1 mg/kg MK-801 or saline. Electrocortical activity of the animals who survived were followed for 6 days postocclusion at which point they were sacrificed for histopathological analysis. Twelve of the animals died during recovery, of which 4 were MK-801 treated, and 8 were saline controls. The EEG ratios in the non-surviving animals were more depressed than in the animals that survived, whereas the depression in the EEG amplitude in both the treated and the control surviving animals was equal. Among the survivors no reduction in infarct size with MK-801 treatment was observed. Thus treatment with MK-801 in the middle cerebral artery occlusion model in the cat leads to a significant increase in the rate of survival (P < 0.05), but no prolonged improvement in late histopathology, in contrast with acute histological findings using this model. MK-801 treatment may be shifting the stroke model towards the survival of animals with larger infarcts. Histological recovery during prolonged reperfusion may eliminate the early neuroprotective effects seen with MK-801 treatment.

Acute improvement in histological outcome by MK-801 following focal cerebral ischemia and reperfusion in the cat independent of blood flow changes

The present study reports on the acute effects of MK-801 on the histopathological outcome and blood flow changes during focal cerebral ischemia and reperfusion. In addition, acute changes in the EEG and blood pressure are also reported. In 16 halothane-anesthetized cats, the left middle cerebral artery (MCA) was occluded for 2 h followed by 4 h of reperfusion. Thirty minutes after the onset of ischemia, eight animals were treated with 1 mg/kg of MK-801, while eight animals received saline. Blood flow from the peripheral MCA territory was measured with H2 clearance. There was a comparable reduction in blood flow (down to 20% of control) in the ischemic gyri of the two groups followed by a partial recovery after recirculation. There was a similar decrease in the EEG amplitude over the ischemic central MCA territory in the treated and the untreated group. Treatment with MK-801 induced a burst suppression in the EEG and a transient drop (11.4 +/- 6.5 mm Hg) in the mean arterial pressure. The volume of early ischemic damage decreased by one-third in the MK-801-treated group compared to the untreated one, both in the total hemisphere (from 29 +/- 10 to 20 +/- 5%) and in the hemispheric cortex (range 36 +/- 8 to 24 +/- 13%). A major fraction of this improvement was localized to the middle and posterior parietal (mainly perifocal) regions of the MCA territory. These results show that in our model, MK-801 improves histopathological outcome despite the lack of apparent effect on the cortical blood flow, and an adverse effect on the systemic blood pressure. This is the first report that describes data on a reproducible model of reperfusion after temporary occlusion of the MCA in a cat, extending the findings of the Glasgow group, who observed similar neuroprotection in models of permanent MCA occlusion.

Combined therapy with MK-801 and nimodipine for protection of ischemic brain damage

Calcium ion can enter ischemic neurons through both receptor-operated and voltage-sensitive Ca2+ channels. To attenuate this Ca2+ entry and Ca2(+)-induced neuronal injury, we tried a combined treatment with the noncompetitive N-methyl-D-aspartate (NMDA) antagonist, MK-801, and the dihydropyridine calcium antagonist, nimodipine, in a cat middle cerebral artery occlusion (1 hour) and reperfusion (3 hours) model. We measured changes in cytosolic free calcium, nicotinamide adenine dinucleotide/reduced nicotinamide adenine dinucleotide redox state, and blood flow in the cat cortex using a newly developed fluorometric technique with indo-1, a fluorescent intracellular Ca2+ indicator. The combined treatment, starting 5 minutes into ischemia, was effective in reducing both Ca2+ entry and histologic damage and in enhancing recovery of the electroencephalogram following reperfusion. MK-801 alone was also effective, but to a lesser extent. These data suggest that the dual blockade of Ca2+ entry using MK-801 and nimodipine may be a useful tool for protection against ischemic brain damage.

Discrimination of relative spatial position

Subjects can accurately discriminate small changes in the relative position of features within a pattern. Simple patterns (intersected line segments) can undergo magnification and a variety of transformations without significantly affecting the discrimination thresholds. Features to be localized and compared need not be similar. We suggest that such relative position discriminations could support complex object identification.

Regional variation in cerebral perfusion during acute hypertension

Regional cerebral blood flow (rCBF) was measured in rats to define the autoregulatory response at different levels of hypertension. Mean arterial blood pressure (MABP) was raised with IV metaraminol. rCBF was measured using 14C-iodoantipyrine. Autoregulation was intact in normotensive animals and those with MABP of 152 to 158 mm Hg. At higher pressures, autoregulation was abnormal and heterogeneous. Hyperperfusion was most prominent in cerebellum, parietal gray matter, thalamus, striatum, and pons. These anatomic sites are recognized sites of hypertensive hemorrhage in humans.

31P NMR studies in Duchenne muscular dystrophy: age-related metabolic changes

To evaluate possible progressive metabolic changes in Duchenne muscular dystrophy, we used 31P nuclear magnetic resonance spectroscopy to measure high-energy phosphate compounds and phosphorylated diesters (PDE) in resting gastrocnemius muscle of 14 Duchenne patients and 10 normal boys. The patients had higher inorganic phosphate (Pi), intracellular pH, and PDE; and lower phosphocreatine (PCr) and PCr/Pi ratio; ATP was not significantly different. The patients showed significant age-related decreases in PCr and PCr/Pi, and increases in Pi and PDE, but ATP did not change. In normal boys, ATP increased with age, but PCr and Pi did not. These studies imply progressive metabolic deterioration in Duchenne dystrophy.