Botulinum toxin injection for post‐stroke spasticity

Introduction: The aim of this study was to evaluate test feasibility, validity, and reproducibility of the rate of force development scaling factor (RFD‐SF) for the hip muscles. Methods: Feasibility was assessed as the testing compliance, validity as the ability to compute the RFD‐SF from a linear regression, and reproducibility with a test–retest design in 20 healthy subjects. Reliability and agreement (reproducibility) were evaluated using intraclass correlation coefficient (ICC_3,1) and percent standard error of measurement (SEM), respectively. Results: The RFD‐SF testing protocol was completed successfully by all subjects, although the analysis had to be modified for hip rotators. Reliability was high (ICC_3,1 > 0.70) for all muscles except hip abductors (ICC_3,1 = 0.69) and internal rotators (ICC_3,1 = 0.58). Agreement was high for all muscles (SEM < 10%). Conclusions: Hip adductor, flexor, and external rotator RFD‐SF can be evaluated with confidence, provided the analysis is modified for external rotators, whereas hip abductor and internal rotator RFD‐SF assessment is not recommended. Muscle Nerve 50: 932–938, 2014     

Intracellular distribution of differentially phosphorylated dual‐specificity tyrosine phosphorylation‐regulated kinase 1A (DYRK1A)

The gene encoding dual‐specificity tyrosine phosphorylation‐regulated kinase 1A (DYRK1A) is located within the Down syndrome (DS) critical region of chromosome 21. DYRK1A interacts with a plethora of substrates in the cytosol, cytoskeleton, and nucleus. Its overexpression is a contributing factor to the developmental alterations and age‐associated pathology observed in DS. We hypothesized that the intracellular distribution of DYRK1A and cell‐compartment‐specific functions are associated with DYRK1A posttranslational modifications. Fractionation showed that, in both human and mouse brain, almost 80% of DYRK1A was associated with the cytoskeleton, and the remaining DYRK1A was present in the cytosolic and nuclear fractions. Coimmunoprecipitation revealed that DYRK1A in the brain cytoskeleton fraction forms complexes with filamentous actin, neurofilaments, and tubulin. Two‐dimensional gel analysis of the fractions revealed DYRK1A with distinct isoelectric points: 5.5–6.5 in the nucleus, 7.2–8.2 in the cytoskeleton, and 8.7 in the cytosol. Phosphate‐affinity gel electrophoresis demonstrated several bands of DYRK1A with different mobility shifts for nuclear, cytoskeletal, and cytosolic DYRK1A, indicating modification by phosphorylation. Mass spectrometry analysis disclosed one phosphorylated site in the cytosolic DYRK1A and multiple phosphorylated residues in the cytoskeletal DYRK1A, including two not previously described. This study supports the hypothesis that intracellular distribution and compartment‐specific functions of DYRK1A may depend on its phosphorylation pattern. © 2013 Wiley Periodicals, Inc.     

When the brain expects pain: common neural responses to pain anticipation are related to clinical pain and distress in fibromyalgia and osteoarthritis

Supraspinal processes in humans can have a top‐down enhancing effect on nociceptive processing in the brain and spinal cord. Studies have begun to suggest that such influences occur in conditions such as fibromyalgia (FM), but it is not clear whether this is unique to FM pain or common to other forms of chronic pain, such as that associated with osteoarthritis (OA). We assessed top‐down processes by measuring anticipation‐evoked potentials and their estimated sources, just prior (< 500 ms) to laser heat pain stimulation, in 16 patients with FM, 16 patients with OA and 15 healthy participants, by using whole‐brain statistical parametric mapping. Clinical pain and psychological coping factors (pain catastrophizing, anxiety, and depression) were well matched between the patient groups, such that these did not confound our comparisons between FM and OA patients. For the same level of heat pain, insula activity was significantly higher in FM patients than in the other two groups during anticipation, and correlated with the intensity and extent of reported clinical pain. However, the same anticipatory insula activity also correlated with OA pain, and with the number of tender points across the two patient groups, suggesting common central mechanisms of tenderness. Activation in the dorsolateral prefrontal cortex was reduced during anticipation in both patient groups, and was related to less effective psychological coping. Our findings suggest common neural correlates of pain and tenderness in FM and OA that are enhanced in FM but not unique to this condition.     

Region‐specific impairments in striatal synaptic transmission and impaired instrumental learning in a mouse model of Angelman syndrome

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by mental retardation and impaired speech. Because patients with this disorder often exhibit motor tremor and stereotypical behaviors, which are associated with basal ganglia pathology, we hypothesized that AS is accompanied by abnormal functioning of the striatum, the input nucleus of the basal ganglia. Using mutant mice with maternal deficiency of AS E6‐AP ubiquitin protein ligase Ube3a (Ube3a^m?/p+), we assessed the effects of Ube3a deficiency on instrumental conditioning, a striatum‐dependent task. We used whole‐cell patch‐clamp recording to measure glutamatergic transmission in the dorsomedial striatum (DMS) and dorsolateral striatum (DLS). Ube3a^m?/p+ mice were severely impaired in initial acquisition of lever pressing. Whereas the lever pressing of wild‐type controls was reduced by outcome devaluation and instrumental contingency reversal, the performance of Ube3a^m?/p+ mice were more habitual, impervious to changes in outcome value and action–outcome contingency. In the DMS, but not the DLS, Ube3a^m?/p+ mice showed reduced amplitude and frequency of miniature excitatory postsynaptic currents. These results show for the first time a selective deficit in instrumental conditioning in the Ube3a deficient mouse model, and suggest a specific impairment in glutmatergic transmission in the associative corticostriatal circuit in AS.     

Dual regulation of clock gene Per2 expression in discrete brain areas by the circadian pacemaker and methamphetamine‐induced oscillator in rats

Behavioral rhythms induced by methamphetamine (MAP) treatment in rats are independent of the circadian pacemaker in the suprachiasmatic nucleus (SCN). To know the site and mechanism of an underlying oscillation (MAP‐induced oscillator; MAO), extra‐SCN circadian rhythms in the discrete brain areas were examined in rats with and without the SCN. To fix the phase of MAO, MAP was supplied in drinking water at a restricted time of day for 14 days (R‐MAP) and subsequently given ad libitum (ad‐MAP). Plain water was given to the controls at the same restricted time (R‐Water). Clock gene Per2 expression was measured by a bioluminescence reporter in cultured brain tissues. In SCN‐intact rats, MAO was induced by R‐MAP and behavioral rhythms were phase‐delayed from the restricted time under ad‐MAP with relative coordination. Circadian Per2 rhythms in R‐MAP rats were not affected in the SCN but were slightly phase‐advanced in the olfactory bulb (OB), caudate–putamen (CPU) and substantia nigra (SN) as compared with R‐Water rats. Following SCN lesion, R‐MAP‐induced MAO phase‐shifted more slowly and did not show a sign of relative coordination. In these rats, circadian Per2 rhythms were significantly phase‐shifted in the OB and SN as compared with SCN‐intact rats. These findings indicate that MAO was induced by MAP given at a restricted time of day in association with phase‐shifts of the extra‐SCN circadian oscillators in the brain dopaminergic areas. The findings also suggest that these extra‐SCN oscillators are the components of MAO and receive dual regulation by MAO and the SCN circadian pacemaker.     

Estradiol regulates responsiveness of the dorsal premammillary nucleus of the hypothalamus and affects fear‐ and anxiety‐like behaviors in female rats

Research suggests a causal link between estrogens and mood. Here, we began by examining the effects of estradiol (E₂) on rat innate and conditioned defensive behaviors in response to cat odor. Second, we utilized whole‐cell patch clamp electrophysiological techniques to assess noradrenergic effects on neurons within the dorsal premammillary nucleus of the hypothalamus (PMd), a nucleus implicated in fear reactivity, and their regulation by E₂. Our results show that E₂ increased general arousal and modified innate defensive reactivity to cat odor. When ovariectomized females treated with E₂ as opposed to oil were exposed to cat odor, they showed elevations in risk assessment and reductions in freezing, indicating a shift from passive to active coping. In addition, animals previously exposed to cat odor showed clear cue + context conditioning 24 h later. However, although E₂ persisted in its effects on general arousal in the conditioning task, its effects on fear disappeared. In the patch clamp experiments noradrenergic compounds that typically induce fear clearly excited PMd neurons, producing depolarizations and action potentials. E₂ treatment shifted some excitatory effects of noradrenergic agonists to inhibitory, possibly by differentially affecting α‐ and β‐adrenoreceptors. In summary, our results implicate E₂ in general arousal and fear reactivity, and suggest these may be governed by changes in noradrenergic responsivity in the PMd. These effects of E₂ may have ethological relevance, serving to promote mate seeking even in contexts of ambiguous threat and shed light on the involvement of estrogen in mood and its associated disorders.     

Subpicomolar diphenyleneiodonium inhibits microglial NADPH oxidase with high specificity and shows great potential as a therapeutic agent for neurodegenerative diseases

Activation of microglial NADPH oxidase (NOX2) plays a critical role in mediating neuroinflammation, which is closely linked with the pathogenesis of a variety of neurodegenerative diseases, including Parkinson's disease (PD). The inhibition of NOX2‐generated superoxide has become an effective strategy for developing disease‐modifying therapies for PD. However, the lack of specific and potent NOX2 inhibitors has hampered the progress of this approach. Diphenyleneiodonium (DPI) is a widely used, long‐acting NOX2 inhibitor. However, due to its non‐specificity for NOX2 and high cytotoxicity at standard doses (µM), DPI has been precluded from human studies. In this study, using ultra‐low doses of DPI, we aimed to: (1) investigate whether these problems could be circumvented and (2) determine whether ultra‐low doses of DPI were able to preserve its utility as a potent NOX2 inhibitor. We found that DPI at subpicomolar concentrations (10^?14 and 10^?13 M) displays no toxicity in primary midbrain neuron‐glia cultures. More importantly, we observed that subpicomolar DPI inhibited phorbol myristate acetate (PMA)‐induced activation of NOX2. The same concentrations of DPI did not inhibit the activities of a series of flavoprotein‐containing enzymes. Furthermore, potent neuroprotective efficacy was demonstrated in a post‐treatment study. When subpicomolar DPI was added to neuron‐glia cultures pretreated with lipopolysaccharide, 1‐methyl‐4‐phenylpyridinium or rotenone, it potently protected the dopaminergic neurons. In summary, DPI's unique combination of high specificity toward NOX2, low cytotoxicity and potent neuroprotective efficacy in post‐treatment regimens suggests that subpicomolar DPI may be an ideal candidate for further animal studies and potential clinical trials. GLIA 2014;62:2034–2043