High-throughput screening yields several small-molecule inhibitors of repeat-associated non-AUG translation.

Repeat-associated non-AUG (RAN) translation is a noncanonical translation initiation event that occurs at nucleotide-repeat expansion mutations that are associated with several neurodegenerative diseases, including fragile X-associated tremor ataxia syndrome (FXTAS), ALS, and frontotemporal dementia (FTD). Translation of expanded repeats produces toxic proteins that accumulate in human brains and contribute to disease pathogenesis. Consequently, RAN translation constitutes a potentially important therapeutic target for managing multiple neurodegenerative disorders. Here, we adapted a previously developed RAN translation assay to a high-throughput format to screen 3,253 bioactive compounds for inhibition of RAN translation of expanded CGG repeats associated with FXTAS. We identified five diverse small molecules that dose-dependently inhibited CGG RAN translation, while relatively sparing canonical translation. All five compounds also inhibited RAN translation of expanded GGGGCC repeats associated with ALS and FTD. Using CD and native gel analyses, we found evidence that three of these compounds, BIX01294, CP-31398, and propidium iodide, bind directly to the repeat RNAs. These findings provide proof-of-principle supporting the development of selective small-molecule RAN translation inhibitors that act across multiple disease-causing repeats.

Prepulse inhibition in patients with fragile X-associated tremor ataxia syndrome.

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late onset neurodegenerative disorder that affects carriers of the fragile X premutation, typically after age 50. Common symptoms include intention tremor, ataxia, neuropathy, autonomic dysfunction, cognitive decline, and dementia. The objectives of this study were to determine if patients with FXTAS have altered prepulse inhibition (PPI; a measure of sensorimotor gating), and to study possible correlations between PPI, molecular status, and cognitive performance. A passive acoustic PPI paradigm was applied in 163 subjects; 121 carriers of the fragile X premutation, and 42 healthy controls. There were significant differences in PPI between premutation carriers with FXTAS and controls at PPI 60 ms, and at 120 ms. This effect was more prominent in the male FXTAS patients. There was a tendency to an impaired PPI in female premutation carriers at the 120 ms condition. There was a significant correlation between the PPI deficit and a higher CGG repeat number. The results show an impairment in sensorimotor gating processes in male carriers of the fragile X premutation, which is more prominent in patients with FXTAS.

A new familial disease of saccadic oscillations and limb tremor provides clues to mechanisms of common tremor disorders.

Tremor disorders pose fundamental questions about disease mechanisms, and challenges to successful neurotherapeutics: What causes motor circuits to oscillate in disorders in which the central nervous system otherwise seems normal? How does inheritance 'determine' the clinical phenotype in familial tremor disorders? Here, we address these questions. Analogies between the neural circuits controlling rapid eye movements (saccades) and those controlling limb movements allow us to translate the interpretations from the saccadic systems to the limb movement system. Moreover, the relatively well understood neurophysiology of the ocular motor system offers a unique opportunity to test specific hypotheses about normal and abnormal motor control of both eye and limb movements. We describe a new familial disorder--'micro-saccadic oscillations and limb tremor (microSOLT)'--in a mother and daughter who had tiny saccadic oscillations of the eyes and tremor of the hands. This unique oscillatory movement disorder resembles other common tremor disorders (such as essential tremor) that occur in patients who have an otherwise normally functioning central nervous system. We hypothesize that microSOLT is caused by an inherited abnormality that results in abnormal membrane properties causing reduced external inhibition in the premotor neurons that generate the high-frequency discharge (burst) for saccades and for ballistic limb movements. To test this hypothesis, we recorded hand tremor and eye movements in two patients with microSOLT and particularly during natural circumstances when inhibition of the premotor saccadic burst neurons is removed (e.g. eye closure). We then simulated a conductance-based model for the premotor commands which included excitatory and reciprocally inhibitory burst neurons. The structure of this physiologically realistic model was based upon known cell types and anatomical connections in the brainstem (for saccades) and the thalamus (for limb movements). The physiological phenomenon of post-inhibitory rebound in premotor burst neurons makes the circuit inherently unstable and prone to oscillate unless prevented by external inhibition. Indeed, with simulated reduction of external inhibition (in this case glycinergic), saccadic oscillations and limb tremor were reproduced. Our results suggest that a single-inherited deficit can alter membrane properties, which impairs inhibition in an inherently unstable neural circuit causing the eye and limb oscillations in microSOLT. This concept has broad implications for understanding the mechanism and designing rationale pharmacotherapy for abnormal oscillations and may be applicable to other common disorders in which there are no structural abnormalities in the brain such as essential tremor.

Characterization of the spontaneous and gripping-induced immobility episodes on taiep rats.

In 1989, we described a new autosomic-recessive myelin-mutant rat that develops a progressive motor syndrome characterized by tremor, ataxia, immobility episodes (IEs), epilepsy, and paralysis. taiep is the acronym of these symptoms. The rat developed a hypomyelination, followed by demyelination. At an age of 7-8 months, taiep rats developed IEs, characterized electroencephalographically by REM sleep-like cortical activity. In our study, we analyzed the ontogeny of gripping-induced IEs between 5 and 18 months, their dependence to light-dark changes, sexual dimorphism, and susceptibility to mild stress. Our results showed that IEs start at an age of 6.5 months, with a peak frequency between 8.5 and 9.5 months. IEs have two peaks, one in the morning (0800-1000 h) and a second peak in the middle of the night (2300-0100 h). Spontaneous IEs showed an even distribution with a mean of 3 IEs every 2 h. IEs are sexually dimorphic being more common in male rats. The IEs can be induced by gripping the rat by the tail or the thorax, but most of the IEs were produced by gripping the tail. Mild stress produced by i.p. injection of physiological saline significantly decreased IEs. These results suggested that IEs are dependent on several biological variables, which are caused by hypomyelination, followed by demyelization, which causes alterations in the brainstem and hypothalamic mechanisms responsible for the sleep-wake cycle regulation, producing emergence of REM sleep-like behavior during awake periods.

AlphaMUPA mice: a transgenic model for increased life span.

AlphaMUPA is a line of transgenic mice that, compared with their wild type (WT) counterparts, spontaneously eat less (approximately 20%) and live longer (average approximately 20%), thus resembling dietary-restricted (DR) mice. Here, we show that body temperature was significantly reduced in alphaMUPA compared with WT throughout a wide range of ages. Plasma corticosterone was significantly higher in young alphaMUPA compared to young WT; however, it significantly declined in aged alphaMUPA, but not in aged WT. In addition, age-associated thymus involution occurred in alphaMUPA as it did in WT. Thus alphaMUPA mice appear to largely resemble, but also to somewhat differ from diet-restricted animals. We also report on four new transgenic lines that, like alphaMUPA, produced in the brain the mRNA that encodes the extracellular protease urokinase (uPA); however, transgenic uPA expression was most extensive and widespread in the alphaMUPA brain, where it also occurred in the hypothalamus. AlphaMUPA was also the only line that ate less, but also showed another characteristic, high frequency leg muscle tremor seen only at unstable body states. We hypothesize that transgenic uPA in the brain could have caused the alphaMUPA phenotypic alterations. Thus alphaMUPA offers a unique transgenic model of inherently reduced eating to investigate the homeostatic state of delayed aging at the systemic and single-cell levels.

Therapeutic stereotactic procedures on the thalamus for motor movement disorders.

The value of functional neurosurgery in the treatment of motor movement disorders is emphasized. The two methods of stereotactic procedures, namely a destructive one with small lesions centered on specific targets, and a non-destructive one with chronically inserted electrodes connected with an also implanted programmable neuropacemaker are described in detail. The results in Parkinsonian tremor, essential tremor, tremor of multiple sclerosis, post-traumatic tremor and in other involuntary movement disorders are reported and demonstrate that stereotactic neurosurgical treatment of these conditions is a safe and efficacious method.

[Quantitative evaluation of the T- and B-systems of immunity in various hereditary diseases of the nervous system]. / Kolichestvennaia otsenka T- i B-sistem immuniteta pri nekotorykh nasledstvennykh zabolevaniiakh nervnoí sistemy.

In 37 patients with some hereditary diseases of the nervous system (deforming muscular dystonia, hepatocerebral dystrophy, essential tremor, etc.), as well as in 22 healthy subjects (donors), the percentage and the absolute content of the T- and B-lymphocytes in the blood were determined. Use was made of the reactions of spontaneous, active, and complementary rosette formation and determination of the B-cells from superficial immunoglobulins. In all the hereditary diseases listed a drop of the content of thymus-dependent lymphocytes and an increase of the capacity of lymphocytes for complementary rosette formation were revealed. The data obtained can be, probably, interpreted as evidences of a secondary immunodeficient state, possibly, caused by metabolic disturbances which are known to play an essential role in the pathogenesis of hereditary diseases of the nervous system.

Cerebral calcinosis with late onset encephalopathy. Unusual type of pseudo-pseudohypoparathyreoidism.

A family from Western Norway is described in which 5 out of 9 members in one generation developed a progressive encephalopathy in middle life. Massive, symmetrical calcifications located in basal ganglia, dentate nuclei and cerebral sulci of the brain were seen on roentgenograms of the skull. All affected members exhibited a clinical syndrome which included mental deterioration, extrapyramidal motor deficit, cerebellar ataxia and tremor. The biochemical investigation showed normal serum calcium and phosphorous and concentration of immunoreactive parathyroid hormone was normal. The Ellsworth-Howard test with exogenously administered parathyroid extract revealed a subnormal phosphorous diuresis while urinary excretion of cyclic AMP was normal. Thus, the defect appears to be an insufficient intracellular response to cyclic AMP. The late onset of symptoms is compatible with the slight disturbance in calcium-phosphorous metabolism we have demonstrated. The family probably represents an unusual type of pseudo-pseudohypoparathyroidism of which only one other family has been reported earlier. The investigations and pedigree analysis of the present kindred is suggestive of an autosomal recessive inheritance of the disorder.

Copper supplementation in quaking mutant mice: reduced tremors and increased brain copper.

Mice homozygous for the mutant gene quaking (qk) with a high frequency of axial tremors had a low concentration of copper in the brain. Supplementation during pregnancy and lactation with a high level of dietary copper greatly reduced the frequency of tremors and brought brain copper level to normal in the off-spring. It is suggested that qk affects copper metabolism.