A combined robotic and cognitive training for locomotor rehabilitation: evidences of cerebral functional reorganization in two chronic traumatic brain injured patients.

It has been demonstrated that automated locomotor training can improve walking capabilities in spinal cord-injured subjects but its effectiveness on brain damaged patients has not been well established. A possible explanation of the discordant results on the efficacy of robotic training in patients with cerebral lesions could be that these patients, besides stimulation of physiological motor patterns through passive leg movements, also need to train the cognitive aspects of motor control. Indeed, another way to stimulate cerebral motor areas in paretic patients is to use the cognitive function of motor imagery. A promising possibility is thus to combine sensorimotor training with the use of motor imagery. The aim of this paper is to assess changes in brain activations after a combined sensorimotor and cognitive training for gait rehabilitation. The protocol consisted of the integrated use of a robotic gait orthosis prototype with locomotor imagery tasks. Assessment was conducted on two patients with chronic traumatic brain injury and major gait impairments, using functional magnetic resonance imaging. Physiatric functional scales were used to assess clinical outcomes. Results showed greater activation post-training in the sensorimotor and supplementary motor cortices, as well as enhanced functional connectivity within the motor network. Improvements in balance and, to a lesser extent, in gait outcomes were also found.

The m.12316G>A mutation in the mitochondrial tRNA Leu(CUN) gene is associated with mitochondrial myopathy and respiratory impairment.

Mitochondrial disorders are often associated with mutations in mitochondrial tRNA. Independent observation of the same molecular defect in unrelated subjects is a generally required proof of pathogenicity. A sporadic case of chronic external ophthalmoplegia (cPEO) with ragged red fibres (RRFs) has been previously related to an m.12316G>A substitution in tRNA(Leu(CUN)). Sequencing muscle-derived mtDNA, we found the m.12316G>A substitution in an adult woman with mitochondrial myopathy and respiratory impairment. Her muscle biopsy presented several cytochrome c oxidase-negative (COX-) fibres, and RRFs as signs of mitochondrial proliferation. Restriction-fragment length polymorphism (RFLP) analysis of the mutation in isolated muscle fibres showed a threshold of at least 60% of mutated mtDNA to determine a COX deficiency phenotype. This second report of the m.12316G>A mutation in a sporadic patient consolidates its pathogenic nature and provides further elements for genetic counselling.

Mitochondrial DNA G8363A mutation in the tRNA Lys gene: clinical, biochemical and pathological study.

The G8363A is a very rare mtDNA tRNA(Lys) gene mutation that has been associated to MERRF-like syndrome, cardiomyopathy or Leigh syndrome. Here, we describe the clinical and molecular features of a new large multigenerational family and we review the literature of cases with this mutation. In our family seven members presented a heterogeneous mitochondrial disease phenotype, from MERRF-like syndrome to isolated psychiatric disorder, associated with the G8363A mutation. The two probands are dizygotic twin sisters affected by mental retardation, neural deafness, myopathy, myoclonic epilepsy and ataxia. Twins' muscle biopsies showed a severe cytochrome c oxidase (COX) deficiency and ragged-red fibers. Their mitochondrial respiratory chain was defective in complexes I and IV in muscle. A severe reduction in complex IV activity was also observed in fibroblasts and myoblasts. Molecular analysis showed a G8363A transition in the mtDNA tRNA(Lys) gene. The mutation was almost homoplasmic (>90%) in muscle and blood of the twins and heteroplasmic (55+/-8%) in blood sample from affected maternal relatives. Based on our family data and the meta-analysis of the literature, we confirm that mutational load directly correlates with severity of the disease (severe vs mild/moderate phenotype; P=0.00168) and with disease onset (P<0.00001). However the presence of several exceptions and overlaps among patients with different clinical severity limits the clinical usefulness of this observation. Although the pathogenicity of the G8363A mutation is well established, counselling is a difficult task for clinicians because of the large phenotypical variability. Our study contributes further data on the clinical spectrum and its relation with the level of G8363A tRNA(Lys) mtDNA mutation.

Inclusion body myopathy and frontotemporal dementia caused by a novel VCP mutation.

Hereditary inclusion body myopathy (IBM) with Paget's disease of the bone (PDB) and frontotemporal dementia (FTD) is a rare autosomal dominant disease caused by mutations in the valosin-containing protein (VCP) gene. We report a novel heterozygous VCP gene mutation (R159C) in a 69-year-old Italian patient presenting with slowly progressive muscle weakness of the distal upper and proximal lower limbs since the age of 50 years, 18 years later FTD supervened. No dementia or myopathies were revealed in the family history covering two generations. Degenerative changes and rimmed vacuoles together with VCP- and ubiquitin-positive cytoplasmic and nuclear aggregates were observed at the muscle biopsy. Several elements support the pathogenic role of the R159C VCP gene mutation: the occurrence at the same codon of a different, previously identified pathogenic mutation within a VCP gene mutational hot-spot, the histopathological and biochemical evidence of muscle VCP accumulation and the combined clinical presentation of IBM and FTD. These findings suggest VCP gene investigation even in apparently sporadic cases.

Novel Twinkle (PEO1) gene mutations in mendelian progressive external ophthalmoplegia.

Multiple deletions of mitochondrial DNA (mtDNA) are associated with different mitochondrial disorders inherited as autosomal dominant and recessive traits. Causative mutations have been found in five genes, mainly involved in mtDNA replication and stability. They include POLG1, the gene encoding the catalytic subunit of mtDNA polymerase (pol gamma), POLG2 encoding its accessory subunit, ANT1 coding the adenine nucleotide translocator and PEO1 which codes for Twinkle, the mitochondrial helicase. Finally OPA1 missense mutations are involved in phenotypes presenting optic atrophy as a major feature.To define the relative contribution of POLG1, POLG2, ANT1 and PEO1 genes to the mtDNA multiple deletion syndromes, we analysed them in a cohort of 67 probands showing accumulation of multiple mtDNA deletions in muscle. The patients were predominantly affected with a mitochondrial myopathy with or without progressive external ophthalmoplegia (PEO). Genetic analysis revealed that 1) PEO1 has a major role in determining familial PEO, since it accounts for 26.8% of familial cases, followed by ANT1 (14.6%) and POLG1 (9.8%); 2) no mutations in any of the known genes were found in 53.7% of probands of this series. Six novel missense mutations contributing to the mutational load of PEO1 gene (p.R334P, p.W315S, p. S426N, p.W474S, p.F478I, p.E479K) were associated with an adult onset PEO phenotype.

Is M129V of PRNP gene associated with Alzheimer's disease? A case-control study and a meta-analysis.

The methionine/valine (M/V) polymorphism at codon 129 within the prion protein gene (PRNP) represents a known risk factor for Creutzfeldt-Jakob disease (CJD). Few authors reported also the effects of this polymorphism on the risk of Alzheimer's disease (AD), although with controversial results. To better clarify this issue, we performed a novel case-control study and a meta-analysis of published association studies between PRNP and AD. Our findings argue against PRNP as a susceptibility gene for developing AD in the Italian population but support the hypothesis that the V allele influences cognitive performances. The meta-analysis, revealed that Caucasian subjects homozygous at codon 129 had a 1.3-fold increased risk [95% CI: 1.0-1.6, p = 0.05] of developing AD compared to heterozygous individuals. We also observed that MM genotype and M allele represent a risk factor for AD, independently from the ethnic background, providing a significant but modest association between this polymorphism and AD.

Vascular endothelial growth factor gene variability is associated with increased risk for AD.

Converging evidence points to a pivotal role of vascular endothelial growth factor (VEGF) in neuronal protection and a lack of its activity in neurodegenerative disorders. To investigate this possible association, we screened the VEGF gene promoter for various well-known single-nucleotide polymorphisms in a series of 249 consecutively recruited Italian patients with sporadic Alzheimer's disease (AD). Genetic analysis indicated different distributions of two single-nucleotide polymorphisms in the AD population compared with healthy control subjects. In particular, the frequencies of -2578A/A and -1198C/T genotypes were significantly greater in AD patients than in control subjects (23.7 vs 14.7% and 2.8 vs 0%, respectively). The -2578A/A genotype was associated with an increased risk for disease, independently of apolipoprotein E genotype. The risk was significantly increased with respect to various VEGF genotype combinations. In contrast, no difference in serum VEGF levels was detected comparing 96 patients and 49 control subjects. These findings suggest that polymorphisms within the promoter region of the VEGF gene confer greater risk for AD, probably by reducing its neuroprotective effect, and confirm the biological role of VEGF in neurodegenerative processes.

Influence of the Glu298Asp polymorphism of NOS3 on age at onset and homocysteine levels in AD patients.

The distribution of the Glu298Asp polymorphism in NOS3 gene was determined in 405 Italian patients with "probable" Alzheimer's disease (AD) compared with 253 age-matched controls. Total plasma homocysteine (tHcy) levels were evaluated in 97 patients and 23 controls, and were correlated with the Glu298Asp genotype. A significantly increased frequency of the Glu/Glu genotype in late onset AD (LOAD) patients was found. tHcy levels were significantly increased in patients compared with controls and, notably, higher in LOAD than in early onset AD (EOAD). Stratifying by the Glu298Asp genotype, a trend toward an increase of tHcy was present in Glu/Glu homozygous. This wild type genotype seems to be associated with LOAD. tHcy levels are significantly increased in AD compared with controls and, moreover, higher in LOAD than in EOAD, possibly in correlation with the microvascular disease occurring with aging. Besides, a contribution of the Glu/Glu genotype in increasing tHcy levels has been observed.