Immune cross-reactivity in celiac disease: anti-gliadin antibodies bind to neuronal synapsin I.

Celiac disease is an immune-mediated disorder triggered by ingestion of wheat gliadin and related proteins in genetically susceptible individuals. In addition to the characteristic enteropathy, celiac disease is associated with various extraintestinal manifestations, including neurologic complications such as neuropathy, ataxia, seizures, and neurobehavioral changes. The cause of the neurologic manifestations is unknown, but autoimmunity resulting from molecular mimicry between gliadin and nervous system proteins has been proposed to play a role. In this study, we sought to investigate the immune reactivity of the anti-gliadin Ab response toward neural proteins. We characterized the binding of affinity-purified anti-gliadin Abs from immunized animals to brain proteins by one- and two-dimensional gel electrophoresis, immunoblotting, and peptide mass mapping. The major immunoreactive protein was identified as synapsin I. Anti-gliadin Abs from patients with celiac disease also bound to the protein. Such cross-reactivity may provide clues into the pathogenic mechanism of the neurologic deficits that are associated with gluten sensitivity.

Role of the olivo-cerebellar system in timing.

Timing has been proposed as a basic function of the cerebellar cortex (particularly the climbing fiber afferents and their sole source, the inferior olive) that explains the contribution of the cerebellum to both motor control and nonmotor cognitive functions. However, whether the olivo-cerebellar system mediates time perception without motor behavior remains controversial. We used event-related functional magnetic resonance imaging to dissociate the neural correlates of the perceptual from the motor aspects of timing. The results show activation of multiple areas within the cerebellar cortex during both perception and motor performance of temporal sequences. The results further show that the inferior olive was activated only when subjects perceived the temporal sequences without motor activity. This finding is most consistent with electrophysiological studies showing decreased responsiveness of the inferior olivary neurons to sensory input during expected, self-produced movement. Our results suggest that the primary role of the inferior olive and the climbing fiber system in timing is the encoding of temporal information independent of motor behavior.

Neurologic presentation of celiac disease.

Celiac disease (CD) long has been associated with neurologic and psychiatric disorders including cerebellar ataxia, peripheral neuropathy, epilepsy, dementia, and depression. Earlier reports mainly have documented the involvement of the nervous system as a complication of prediagnosed CD. However, more recent studies have emphasized that a wider spectrum of neurologic syndromes may be the presenting extraintestinal manifestation of gluten sensitivity with or without intestinal pathology. These include migraine, encephalopathy, chorea, brain stem dysfunction, myelopathy, mononeuritis multiplex, Guillain-Barre-like syndrome, and neuropathy with positive antiganglioside antibodies. The association between most neurologic syndromes described and gluten sensitivity remains to be confirmed by larger epidemiologic studies. It further has been suggested that gluten sensitivity (as evidenced by high antigliadin antibodies) is a common cause of neurologic syndromes (notably cerebellar ataxia) of otherwise unknown cause. Additional studies showed high prevalence of gluten sensitivity in genetic neurodegenerative disorders such as hereditary spinocerebellar ataxia and Huntington's disease. It remains unclear whether gluten sensitivity contributes to the pathogenesis of these disorders or whether it represents an epiphenomenon. Studies of gluten-free diet in patients with gluten sensitivity and neurologic syndromes have shown variable results. Diet trials also have been inconclusive in autism and schizophrenia, 2 diseases in which sensitivity to dietary gluten has been implicated. Further studies clearly are needed to assess the efficacy of gluten-free diet and to address the underlying mechanisms of nervous system pathology in gluten sensitivity.

The effect of levetiracetam on essential tremor.

The effect of a single dose of 1,000 mg of levetiracetam on essential tremor was investigated in 24 patients in a double-blind, placebo-controlled trial. There was a significant reduction of hand tremor for at least 2 hours as measured by accelerometry and functional tests.

Antigliadin antibodies in Huntington's disease.

The relevance of gluten sensitivity in sporadic and hereditary ataxia pathogenesis is unclear. The authors found high antigliadin antibody titers in 23 of 52 (44%) patients with Huntington's disease (HD), suggesting a previously unrecognized association between HD and gluten sensitivity. The results further question "gluten ataxia" as a distinct disease entity and raise the possibility that antigliadin antibodies in ataxia and other neurodegenerative diseases may be an epiphenomenon, the mechanisms of which remain to be investigated.

Constraint-induced therapy in stroke: magnetic-stimulation motor maps and cerebral activation.

Constraint-induced movement therapy (CI), a standardized intensive rehabilitation intervention, was given to patients a year or more following stroke. The goal was to determine if CI was more effective than a less-intensive control intervention in changing motor function and/or brain physiology and to gain insight into the mechanisms underlying this recovery process. Subjects were recruited and randomized more than 1 year after a single subcortical infarction. Clinical assessments performed before and after the intervention and at 6 months postintervention included the Wolf Motor Function Test (WMFT), the Motor Activity Log (MAL), and the Assessment of Motor and Process Skills (AMPS). Transcranial magnetic stimulation was used to map the motor cortex. Positron emission tomography was used to measure changes in motor task-related activation due to the intervention. MAL increased by 1.08 after CI therapy and decreased by 0.01 after control therapy. The difference between groups was significant (P < 0.001). Changes in WMFT and AMPS were not significantly different between groups. Cerebral activation during a motor task decreased significantly, and motor map size increased in the affected hemisphere motor cortex in CI patients but not in control patients. Both changes may reflect improved ability of upper motor neurons to produce movement.

Neural correlates of cross-modal binding.

Little is known about how the brain binds together signals from multiple sensory modalities to produce unified percepts of objects and events in the external world. Using event-related functional magnetic resonance imaging (fMRI) in humans, we measured transient brain responses to auditory/visual binding, as evidenced by a sound-induced change in visual motion perception. Identical auditory and visual stimuli were presented in all trials, but in some trials they were perceived to be bound together and in others they were perceived as unbound unimodal events. Cross-modal binding was associated with higher activity in multimodal areas, but lower activity in predominantly unimodal areas. This activation pattern suggests that a reciprocal and 'competitive' interaction between multimodal and unimodal areas underlies the perceptual interpretation of simultaneous signals from multiple sensory modalities.