Anatomical Parameters of tDCS to Modulate the Motor System after Stroke: A Review

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method to modulate the local field potential in neural tissue and consequently, cortical excitability. As tDCS is relatively portable, affordable, and accessible, the applications of tDCS to probe brain-behavior connections have rapidly increased in the last 10 years. One of the most promising applications is the use of tDCS to modulate excitability in the motor cortex after stroke and promote motor recovery. However, the results of clinical studies implementing tDCS to modulate motor excitability have been highly variable, with some studies demonstrating that as many as 50% or more of patients fail to show a response to stimulation. Much effort has therefore been dedicated to understand the sources of variability affecting tDCS efficacy. Possible suspects include the placement of the electrodes, task parameters during stimulation, dosing (current amplitude, duration of stimulation, frequency of stimulation), individual states (e.g., anxiety, motivation, attention), and more. In this review, we first briefly review potential sources of variability specific to stroke motor recovery following tDCS. We then examine how the anatomical variability in tDCS placement [e.g., neural target(s) and montages employed] may alter the neuromodulatory effects that tDCS exerts on the post-stroke motor system.

[Analysis of clinical pathway in changing and disabling neurological diseases]

Neurological diseases are characterized by the complexity of care and by a constant and changing disability. More and more frequently, their impact on the clinical pathway remains unknown. Seven postgraduate rehabilitation students (Master coordination du handicap, université Pierre-et-Marie-Curie, Paris) reconstructed the clinical pathway of 123 patients with various neurological diseases: multiple sclerosis, Alzheimer disease, amyotrophic lateral sclerosis, spinal trauma, Parkinson disease and brain tumors. There was a significant correlation between disease duration and the number of specialists involved in care, the number of prescribed drugs and the number of short-term hospitalizations; there was no correlation with age. This result suggests that with time an increasing number of complications related to the initial neurological disease developed. Hospitalization in rehabilitation units was highly correlated with the degree of disability and also with the help received by the patients during the course of their disease. This result suggests that these hospitalizations were a direct consequence of burn out among relatives. General practitioners (GP) were highly involved only during the initial part of the pathway, and their involvement rapidly declined thereafter, suggesting a probable relation with the specificities and the complexity of care for neurological diseases which induces a progressive transfer of responsibilities from the GP to the hospital. Social care was always incomplete and occurred too late during the course of the disease. The feeling by the patients that their care pathway was chaotic was highly correlated with the quality of the information given to the patient at the time of the announcement of their disease. This study confirms that cares for neurological diseases is highly specific and that expert centers and coordination networks are in a key position to ensure an efficient care pathway.

Dual-tDCS Enhances Online Motor Skill Learning and Long-Term Retention in Chronic Stroke Patients

BACKGROUND

Since motor learning is a key component for stroke recovery, enhancing motor skill learning is a crucial challenge for neurorehabilitation. Transcranial direct current stimulation (tDCS) is a promising approach for improving motor learning. The aim of this trial was to test the hypothesis that dual-tDCS applied bilaterally over the primary motor cortices (M1) improves online motor skill learning with the paretic hand and its long-term retention.

METHODS

Eighteen chronic stroke patients participated in a randomized, cross-over, placebo-controlled, double bind trial. During separate sessions, dual-tDCS or sham dual-tDCS was applied over 30 min while stroke patients learned a complex visuomotor skill with the paretic hand: using a computer mouse to move a pointer along a complex circuit as quickly and accurately as possible. A learning index involving the evolution of the speed/accuracy trade-off was calculated. Performance of the motor skill was measured at baseline, after intervention and 1 week later.

RESULTS

After sham dual-tDCS, eight patients showed performance worsening. In contrast, dual-tDCS enhanced the amount and speed of online motor skill learning compared to sham (p < 0.001) in all patients; this superiority was maintained throughout the hour following. The speed/accuracy trade-off was shifted more consistently after dual-tDCS (n = 10) than after sham (n = 3). More importantly, 1 week later, online enhancement under dual-tDCS had translated into superior long-term retention (+44%) compared to sham (+4%). The improvement generalized to a new untrained circuit and to digital dexterity.

CONCLUSION

A single-session of dual-tDCS, applied while stroke patients trained with the paretic hand significantly enhanced online motor skill learning both quantitatively and qualitatively, leading to successful long-term retention and generalization. The combination of motor skill learning and dual-tDCS is promising for improving post-stroke neurorehabilitation.

Screening of mutations in genes that predispose to hereditary paragangliomas and pheochromocytomas

Thirty per cent of the paragangliomas and pheochromocytomas reported are hereditary. Mutations in SDHB, SDHC, SDHD, and more recently SDHAF2 and TMEM127 genes have been described in these hereditary tumors. We looked for mutations in these 5 genes in a series of 269 patients with paragangliomas and/or pheochromocytomas. The SDHB, SDHC, and SDHD genes were analyzed in a series of 269 unrelated index patients with paragangliomas and/or pheochromocytomas using dHPLC screening of point mutations followed by direct sequencing and Multiplex PCR Liquid Chromatography to detect large rearrangements confirmed by quantitative PCR. In a second phase, we adapted Multiplex PCR Liquid Chromatography to the SDHAF2 and TMEM127 genes. This method and direct sequencing were applied to 230 patients without the SDHB, C, D mutations. Of the 269 patients, 44 carried a mutation (16.3%). Thirty-seven different mutations were identified: 18 in SDHB (including 2 large deletions), 8 in SDHD, 6 in SDHC, 5 in TMEM127, and no mutations in SDHAF2. Thirteen mutations have not been published so far. An exhaustive study of the different genes is needed to make possible a familial genetic diagnosis in paraganglioma and pheochromocytoma hereditary syndromes. Although mutations in SDHC and TMEM127 are less frequent than mutations in SDHB and SDHD, they also have less evident clinical feature indicators. Analyzing SDHAF2 must be restricted to familial extra-adrenal paragangliomas. Multiplex PCR Liquid Chromatography is a sensitive, fast, and inexpensive method for screening large rearrangements, which are infrequent in these syndromes.

The role of public health inspectors in maintaining housing in northern and rural communities: recommendations to support public health practice

OBJECTIVE

Although there is much evidence about the effects of particular housing conditions on health, less is known about the practices of public health inspectors (PHIs) in relation to minimizing or eliminating potential housing health risks. The purpose of this qualitative study was to illuminate the practices of PHIs in relation to types of biological and physical housing risks.

METHOD

This study used photo vignettes to focus on PHIs' perceptions, options, and resultant interventions with regards to typical housing risks encountered by PHIs in northeastern Ontario. The vignettes represented two general categories of potential housing risks: biological exposures, and physical characteristics of housing. During a semi-structured interview, 34 PHI participants viewed the vignettes, assessed the housing hazard depicted in each, and described the most appropriate intervention. Traditional content analysis methods were used.

RESULTS

The assessment of the physical housing hazards was fairly consistent among the PHIs. There seemed to be more variation in their assessment of risk associated with biological factors. Variation in responses was often explained by their different interpretations of the scope of the provincial legislation as well as local public health unit policies and practices.

CONCLUSION

This study demonstrated that PHIs' assessment and responses to potential physical housing hazards were influenced by an interplay between variables related to residents, local service partners, organizational culture, and policy. The recommendations for action also range from specific public health unit protocol to broader research and policy advocacy initiatives. Collectively, the recommendations focus on strategies for optimizing the role of PHIs in reducing housing health risks in mid-size urban or rural areas.

Residual Stresses in Ultrathin Metal Sublayers Within Au/Ni Multilayers

Metallic Multilayers (MLs) have attracted a considerable interest during these last years because of their unusual properties. In small periods ML's (a few nm) the high density of interfaces give rise to structures very far from equilibrium. Au/Ni multilayers have been grown in the (111) orientation by M.B.E. on Si(100) via a Cu(100) buffer layer. Two different parameters have been studied: the Au:Ni ratio at constant (4 nm) superperiod and the superperiod at constant (1:1) Au:Ni ratio. The full strain state of Au and of Ni has been determined via x-ray diffraction measurements. The high lattice parameter misfit beween Au and Ni (14%) implies that all the layers are partially relaxed. Residual strains as high as several % are encountered. The residual strain in the Au layers is clearly correlated with their thickness. A residual stress as high as 3.9 GPa is determined in the thinner layers.

Growth And Structure Of Nanometric Iron Oxide Films

Nanometric films of iron oxides (Fe3O4, α and γ Fe2O3) of high crystalline order and purity are epitaxially grown on α-A12O3(0001) by atomic oxygen assisted MBE. A complete characterization of the films structure has been performed by in situ LEED and RHEED, and ex situ GIXRD using synchrotron radiation. The films grown at room temperature and post annealed at 400°C and 700°C (po2=10−6 Torr) are respectively metastable γ-Fe2O3 (111) and α-Fe2O3 (0001). For a substrate temperature of 450°C during growth, Fe3O4 (111) is directly obtained. GIXRD shows an in-plane expansion of the films, which decreases with thickness (0.8 and 0.2% for film thickness of 20 and 80 Å, respectively).

Double lethal coconut crab (Birgus latro L.) poisoning

We report a double lethal coconut crab Birgus latro L. poisoning in New Caledonia. Both patients died after showing gastro-intestinal symptoms, major bradycardia with marked low blood pressure, and finally asystolia. Both had significative hyperkaliemia, suggesting a digitaline-like substance intoxication. Traditional knowledge in the Loyalty Islands relates coconut crab toxicity to the consumption of the Cerbera manghas fruit by the crustacean. Elsewhere previous descriptions of human poisoning with the kernel of fruits of trees belonging to the genus Cerbera, known to contain cardiotoxic cardenolides, appear to be very similar to our cases. Cardenolides assays were performed on patient's serum samples, fruit kernel and on the crustacean guts, which lead us to suppose these two fatal cases were the result of a neriifolin intoxication, this toxin having been transmitted through the coconut crab.

Pneumopathie avec bactériémie à Yersinia enterocolitica chez un patient diabétique porteur de l'antigène HLA-B27

INTRODUCTION

We report a new case of pneumonia and bacteremia due to Yersinia enterocolitica (YE) in a diabetic patient with HLA-B27 positive spondylarthritis.

OBSERVATION

A 75-year-old man was admitted for a pneumonia. He was suffering from HLA-B27 positive spondylarthritis and stable diabetes mellitus. Amoxicillin with clavulanic acid was ineffective. Two blood and stool cultures were positive for YE. There was no evidence of septic metastases, immunodepression and iron overload. Outcome was uneventful after 21 days of ofloxacin.

CONCLUSION

YE pneumonia is rare. In this patient, diabetes mellitus and spondylarthritis with HLA-B27 may have played a role in the infection but their imputability remain questionable.

15N-Nitrate signature in low-order streams: effects of land cover and agricultural practices

Many studies have shown that intensive agricultural practices significantly increase the nitrogen concentration of stream surface waters, but it remains difficult to identify, quantify, and differentiate between terrestrial and in-stream sources or sinks of nitrogen, and rates of transformation. In this study we used the delta15N-NO3 signature in a watershed dominated by agriculture as an integrating marker to trace (1) the effects of the land cover and agricultural practices on stream-water N concentration in the upstream area of the hydrographic network, (2) influence of the in-stream processes on the NO3-N loads at the reach scale (100 m and 1000 m long), and (3) changes in delta15N-NO3 signature with increasing stream order (from first to third order). This study suggests that land cover and fertilization practices were the major determinants of delta15N-NO3 signature in first-order streams. NO3-N loads and delta15N-NO3 signature increased with fertilization intensity. Small changes in delta15N-NO3 signature and minor inputs of groundwater were observed along both types of reaches, suggesting the NO3-N load was slightly influenced by in-stream processes. The variability of NO3-N concentrations and delta15N signature decreased with increasing stream order, and the delta15N signature was positively correlated with watershed areas devoted to crops, supporting a dominant effect of agriculture compared to the effect of in-stream N processing. Consequently, land cover and fertilization practices are integrated in the natural isotopic signal at the third-order stream scale. The GIS analysis of the land cover coupled with natural-abundance isotope signature (delta15N) represents a potential tool to evaluate the effects of agricultural practices in rural catchments and the consequences of future changes in management policies at the regional scale.

Prévalence de l’hypertonie oculaire et du glaucome dans une population française non sélectionnée

AIMS

To measure intraocular pressure (IOP) in a large human sample and to assess the prevalence of glaucoma with elevated IOP and ocular hypertension (OHT) in this population.

METHODS

We measured IOP in 2,074 subjects (men: women: 1,384: 690). If the IOP was higher than 20 mmHg, a photograph of the optic disc was taken and the visual field was examined. The optic nerve head and the visual field were evaluated in 395 individuals.

RESULTS

In men aged 18-39 years, mean IOP was 15.5+/-3.1 mmHg and 16.4+/-3.5 mmHg after 60 years of age. In women, IOP reached 14.5+/-3.3 and 15.9+/-3.1 mmHg, respectively. IOP greater than 21 mmHg was found in 10.1% of males and 6.4% of females. The prevalence of OHT increased with age: from 5.3% to 15.5% in men and from 3% to 7.5% in women for the same age ranges. A diagnosis of glaucoma with elevated IOP was made in 2.2% of males and 3.0% of females. The prevalence of glaucoma increased with age from 0.8% to 5.7% in men and from 0.6% to 4.7% in women under 40 years and over 60 years of age, respectively.

DISCUSSION

This study confirms the increase in IOP with age and the role of aging in the prevalence of OHT and glaucoma with elevated IOP.

CONCLUSION

This transversal study shows the feasibility of intraocular hypertension and glaucoma screening and prevalence assessment in a nonselected large population in France.

A gene for an autosomal recessive lower motor neuron disease with childhood onset maps to 1p36

OBJECTIVE

To describe the clinical features of a novel variant of autosomal recessive lower motor neuron disease (LMND) with childhood onset and to map the disease-causing gene.

METHODS

The authors performed a clinical study in a large consanguineous African family. After linkage exclusion to SMN1 and SOD1 loci, they performed a genome-wide linkage analysis to map the underlying genetic defect.

RESULTS

This novel variant of LMND with childhood onset and autosomal recessive mode of inheritance is characterized by a progressive symmetric and generalized involvement of the musculature. Four of the five affected patients had muscle weakness since age 3, strongly worsening during childhood and leading to generalized tetraplegia in adulthood. Genetic analyses using homozygosity mapping strategy assigned this progressive generalized LMND locus to an interval of 3.9 cM (or 1.5 megabases) on chromosome 1p36, between loci D1S508 and D1S2633 (Z(max) = 3.79 at theta = 0.00 at locus D1S253). This region encloses 27 candidate genes.

CONCLUSION

Genetic mapping of a novel rare phenotype of lower motor neuron disease opens the way toward the identification of a new gene involved in motor neuron degeneration, located in the 1p36 chromosomal region.

Decreased SBPase activity alters growth and development in transgenic tobacco plants

The effects of reduced SBPase activity on growth and development were examined in a set of transgenic tobacco plants produced using an antisense construct driven by the ribulose bisphosphate carboxylase, small subunit promoter. Photosynthetic carbon assimilation rates and carbohydrate levels in source leaves were decreased in the antisense plants. Growth rate and total shoot biomass were reduced in the SBPase antisense plants, even in plants where SBPase activity was reduced by only 25%. Floral biomass also decreased in response to reductions in SBPase activity and the onset of flowering was delayed by 5-10 d. This is the first demonstration of a link between reproductive biomass and reductions in Calvin cycle enzyme activity using antisense plants. Furthermore, unexpected changes in the growth and development of the antisense plants were evident. Small reductions in SBPase activity (above 50% wild type) resulted in shorter plants with only a small decrease in stem biomass and specific leaf area. In contrast, plants with larger reductions in SBPase activity had an increase in specific leaf area and attained heights similar to that of the wild-type plants but with a much reduced stem biomass, largely due to a decrease in xylem tissue. This bi-modal response of growth to reductions in SBPase activity has similarities to changes in leaf and stem anatomy and morphology that accompany light acclimation.

Detection of quantitative trait loci affecting milk production traits on 10 chromosomes in Holstein cattle

Sons (n = 71 to 75) of each of six Holstein sires were genotyped at 69 microsatellite loci covering a total of 676 cM on chromosomes 3, 5, 9, 10, 13, 15, 17, 20, 23, and 26. Estimates of quantitative trait loci (QTL) effect and location were made using a least squares interval mapping approach based on daughter yield deviations of sons for 305 d milk, fat, and protein yield and fat and protein percentage. Thresholds for statistical significance of QTL effects were determined from interval mapping of 10,000 random permutations of the data across the bull sire families and within each sire family separately. Analyses combining data across sires indicated the presence of QTL affecting milk, fat, and protein yield on chromosomes 20 and 26 and a QTL affecting fat and protein percentage on chromosome 3. Analyses within each sire family separately indicated the presence of segregating QTL in at least one family on 7 of the 10 chromosomes. Statistically significant estimates of QTL effects on breeding value ranged from 438 to 658 kg of milk, from 17.4 to 24.9 kg of fat, 13.0 to 17.0 kg of protein, 0.04 to 0.17% fat, and 0.07 to 0.10% protein.

The epidermal growth factor receptor engages receptor interacting protein and nuclear factor-kappa B (NF-kappa B)-inducing kinase to activate NF-kappa B. Identification of a novel receptor-tyrosine kinase signalosome

The transcription factor nuclear factor-kappaB (NF-kappaB) is activated by a diverse number of stimuli including tumor necrosis factor-alpha, interleukin-1, UV irradiation, viruses, as well as receptor tyrosine kinases such as the epidermal growth factor receptor (EGFR). NF-kappaB activation by the tumor necrosis factor receptor (TNFR) involves the formation of a multiprotein complex termed a signalosome. Although previous studies have shown that the activated EGFR can induce NF-kappaB, the mechanism of this activation remains unknown. In this study, we identify components of the signalosome formed by the activated EGFR required to activate NF-kappaB and show that, although the activated EGFR uses mechanisms similar to the TNFR, it recruits a distinct signalosome. We show the EGFR forms a complex with a TNFR-interacting protein (RIP), which plays a key role in TNFR-induced NF-kappaB activation, but not with TRADD, an adaptor protein which serves to recruit RIP to the TNFR. Furthermore, we show that the EGFR associates with NF-kappaB-inducing kinase (NIK) and provide evidence suggesting multiprotein complex formation between the EGFR, RIP, and NIK. Using a dominant negative NIK mutant, we show that NIK activation is required for EGFR-mediated NF-kappaB induction. We also show that a S32/36 IkappaBalpha mutant blocks EGFR-induced NF-kappaB activation. Our studies also suggest that a high level of EGFR expression, a frequent occurrence in human tumors, is optimal for epidermal growth factor-induced NF-kappaB activation. Finally, although protein kinase B/Akt has been implicated in tumor necrosis factor and PDGF-induced NF-kappaB activation, our studies do not support a role for this protein in EGFR-induced NF-kappaB activation.

A specific interferon (IFN)-stimulated response element of the distal HLA-G promoter binds IFN-regulatory factor 1 and mediates enhancement of this nonclassical class I gene by IFN-beta

Type I interferons display a broad range of immunomodulatory functions. Interferon beta increases gene expression at the transcriptional level through binding of factors to the interferon-stimulated response element (ISRE) within the promoters of interferon-inducible genes, such as HLA class I. Despite mutation of the class I ISRE sequence within the nonclassical HLA-G class I gene promoter, we show that interferon beta enhances both transcription and cell surface expression of HLA-G in trophoblasts and amniotic and thymic epithelial cells that selectively express it in vivo. Deletion and mutagenesis analysis of a putative interferon-regulatory factor (IRF)-1 binding site within the HLA-G promoter show that HLA-G transactivation is mediated through an ISRE sequence 746 base pairs upstream from ATG, which is distinct from the interferon-responsive element described within proximal classical class I gene promoters. Electrophoretic mobility shift analysis and supershift analysis further demonstrate that interferon-responsive transcription factors, including IRF-1, specifically bind to the HLA-G ISRE. Our results provide evidence that IRF-1 binding to a functional ISRE within the HLA-G promoter mediates interferon beta-induced expression of the HLA-G gene. These observations are of general interest considering the implication of HLA-G in mechanisms of immune escape involved in fetal-maternal tolerance and other immune privilege situations.