Excitability changes in the sciatic nerve and triceps surae muscle after spinal cord injury in mice.

BACKGROUND: From the onset to the chronic phase of spinal cord injury (SCI), peripheral axons and muscles are subjected to abnormal states of activity. This starts with very intense spasms during the first instant of SCI, through a no activity flaccidity phase, to a chronic hyperactivity phase. It remains unclear how the nature of this sequence may affect the peripheral axons and muscles. METHODS: We set out to investigate the changes in excitability of the sciatic nerve and to characterize the properties of muscle contractility after contusive injury of the mouse thoracic spinal cord. RESULTS: The following changes were observed in animals after SCI: 1) The sciatic nerve compound action potential was of higher amplitudes and lower threshold, with the longer strength-duration time constant and faster conduction velocity; 2) The latency of the onset of muscle contraction of the triceps surae muscle was significantly shorter in animals with SCI; 3) The muscle twitches expressed slower rising and falling slopes, which were accompanied by prolonged contraction duration in SCI animals compared to controls. CONCLUSION: These findings suggest that in peripheral nerves SCI promotes hyperexcitability, which might contribute to mechanisms of spastic syndrome.

Quantifying established clinical assessment measures using 3D-movement analysis in individuals with Down syndrome.

PURPOSE: A movement protocol for quantifying functional limitation in people with Down syndrome (DS) during the execution of a series of range of motion (ROM) tasks has been developed as a new assessment approach, combining quantitative measures of movement analysis and functional mobility with clinically established qualitative motor skill assessments. METHODS: Fifteen subjects with DS and 11 subjects with typical development were evaluated using this movement protocol. RESULTS: The results revealed longer durations in execution across all tasks in the DS group and were most likely due to low muscular tone and poor coordination. A significant difference in ankle ROM was found in the DS group during leg-lifting, with a wide plantar-flexion demonstrated during the entire movement. This result may be associated with the typical strategy for foot contact that generally favours the toe. Significant differences were also found in the trunk ROM and in the knee ROM and may likely reflect an increase of agonist-antagonist co-contraction, a strategy that may modify stability and dynamic equilibrium. CONCLUSION: The combined quantitative/qualitative protocol is an important advancement in evaluating individuals with DS and should be integrated into a more comprehensive evaluation of dynamic gait and lower limb analysis.

A large scale study of the psychometric characteristics of the IBR Modified Overt Aggression Scale: findings and evidence for increased self-destructive behaviors in adult females with autism spectrum disorder.

The psychometric characteristics of the IBR Modified Overt Aggression Scale were studied in over 2,000 people with Intellectual Disability (ID). Reliability ranged from good to excellent. Aggression toward others and objects was highest in the youngest adults, in those in the moderate to severe range of ID, and in those with an autism spectrum diagnosis. Self-injury was highest in those in the severe to profound range of ID and in those with autism, particularly the females. Females with autism were also more likely to make the most self-deprecating statements. Our data suggest that adult females with autism are a unique group and support the notion that mood and anxiety disorders play a role in self-destructive behaviors in this population.

Increased amyloid beta protein levels in children and adolescents with Down syndrome.

BACKGROUND: Persons with Down syndrome (DS) (40 years and older) have neuropathological changes characteristic of Alzheimer disease (AD). Soluble forms of amyloid beta (Abeta) peptide generated from amyloid precursor protein (APP) end at C-terminal residues 40 and 42. The presence of the apolipoprotein E (ApoE) epsilon4 allele is a significant risk factor for the development of sporadic AD. Although preliminary studies have shown an association of plasma Abeta42 and ApoE epsilon4 allele in older persons with DS who have dementia, the relationship between plasma Abeta40 and Abeta42 levels and ApoE phenotypes in children with DS has not been examined. Inflammation might play a role in the growth of DS brains. Neopterin is an immune activation marker for the cell-mediated immune response. OBJECTIVE: To examine the levels of plasma Abeta40, Abeta42, and neopterin in children or adolescents with DS or controls. MATERIALS AND METHODS: Blood was collected from DS (N=35; 7+/-3.8 years old) and their siblings (N=34; 10+/-4.5). Plasma Abeta40 and Abeta42, and neopterin levels were quantitated by sandwich ELISA. RESULTS: Abeta40 and Abeta42 levels were higher in DS than controls. The ratio of Abeta42/Abeta40 was lower in DS than in controls. There were significant negative correlations between age and Abeta40 in DS and controls, and between age and Abeta42 levels in DS but not in controls. There was no association of Abeta40 or Abeta42 levels with Apo E in either group. Neopterin levels were higher in DS than controls, and the levels were not correlated with Abeta40 and Abeta42 levels in DS or controls. CONCLUSIONS: The over expression of APP gene in DS leads to increases in plasma Abeta40 and Abeta42 levels before plaque formation in DS brain. Higher neopterin concentrations in DS reflect inflammatory cell activation. Further studies are needed to determine whether DS children with lower plasma Abeta42/Abeta40 ratios are at increased risk of developing AD during aging than those with higher ratios.

The effects of pulsed auditory stimulation on various gait measurements in persons with Parkinson's Disease.

The purpose of this study was to examine the Functional Ambulation Performance Score (FAP; a quantitative gait measure) in persons with Parkinson's Disease (PD) using the auditory stimulation of a metronome (ASM). Participants (n = 16; 5F/11M; range 60--84 yrs.) had a primary diagnosis of PD and were all independent ambulators. Footfall data were collected while participants walked multiple times on an electronic walkway under the following conditions: 1) PRETEST: establishing baseline cadence, 2) ASM: metronome set to baseline cadence, 3) 10ASM: metronome set to 10% FAP scores increased between PRETEST and POSTTEST. PRE/POSTTEST comparisons also indicated decreases in cycle time and double support and increases in step length and step-extremity ratio (step length/leg length). The results confirm prior findings that auditory stimulation can be used to positively influence the gait of persons with PD and suggest beneficial effects of ASM as an adjunct to dopaminergic therapy to treat gait dysfunctions in PD.