Cerebellar transcranial direct current stimulation modulates verbal working memory.

BACKGROUND: Neuroimaging studies show cerebellar activations in a wide range of cognitive tasks and patients with cerebellar lesions often present cognitive deficits suggesting a cerebellar role in higher-order cognition. OBJECTIVE: We used cathodal transcranial direct current stimulation (tDCS), known to inhibit neuronal excitability, over the cerebellum to investigate if cathodal tDCS impairs verbal working memory, an important higher-order cognitive faculty. METHOD: We tested verbal working memory as measured by forward and backward digit spans in 40 healthy young participants before and after applying cathodal tDCS (2 mA, stimulation duration 25 min) to the right cerebellum using a randomized, sham-controlled, double-blind, cross-over design. In addition, we tested the effect of cerebellar tDCS on word reading, finger tapping and a visually cued sensorimotor task. RESULTS: In line with lower digit spans in patients with cerebellar lesions, cerebellar tDCS reduced forward digit spans and blocked the practice dependent increase in backward digit spans. No effects of tDCS on word reading, finger tapping or the visually cued sensorimotor task were found. CONCLUSION: Our results support the view that the cerebellum contributes to verbal working memory as measured by forward and backward digit spans. Moreover, the induction of reversible "virtual cerebellar lesions" in healthy individuals by means of tDCS may improve our understanding of the mechanistic basis of verbal working memory deficits in patients with cerebellar lesions.

Transcranial direct current stimulation for the treatment of focal hand dystonia.

The treatment of writer's cramp, a task-specific focal hand dystonia, needs new approaches. A deficiency of inhibition in the motor cortex might cause writer's cramp. Transcranial direct current stimulation modulates cortical excitability and may provide a therapeutic alternative. In this randomized, double-blind, sham-controlled study, we investigated the efficacy of cathodal stimulation of the contralateral motor cortex in 3 sessions in 1 week. Assessment over a 2-week period included clinical scales, subjective ratings, kinematic handwriting analysis, and neurophysiological evaluation. Twelve patients with unilateral dystonic writer's cramp were investigated; 6 received transcranial direct current and 6 sham stimulation. Cathodal transcranial direct current stimulation had no favorable effects on clinical scales and failed to restore normal handwriting kinematics and cortical inhibition. Subjective worsening remained unexplained, leading to premature study termination. Repeated sessions of cathodal transcranial direct current stimulation of the motor cortex yielded no favorable results supporting a therapeutic potential in writer's cramp.

Transcranial Direct Current Stimulation for the Treatment of Chronic Tinnitus: A Randomized Controlled Study.

BACKGROUND: Tinnitus is an often disabling condition for which there is no effective therapy. Current research suggests that tinnitus may develop due to maladaptive plastic changes and altered activity in the auditory and prefrontal cortex. Transcranial direct current stimulation (tDCS) modulates brain activity and has been shown to transiently suppress tinnitus in trials. OBJECTIVE: To investigate the efficacy and safety of tDCS in the treatment of chronic subjective tinnitus. METHODS: In a randomized, parallel, double-blind, sham-controlled study, the efficacy and safety of cathodal tDCS to the auditory cortex with anode over the prefrontal cortex was investigated in five sessions over five consecutive days. Tinnitus was assessed after the last session on day 5, and at follow-up visits 1 and 3 months post stimulation using the Tinnitus Handicap Inventory (THI, primary outcome measure), Subjective Tinnitus Severity Scale, Hospital Anxiety and Depression scale, Visual Analogue Scale, and Clinical Global Impression scale. RESULTS: 42 patients were investigated, 21 received tDCS and 21 sham stimulation. There were no beneficial effects of tDCS on tinnitus as assessed by primary and secondary outcome measures. Effect size assessed with Cohen's d amounted to 0.08 (95% CI: -0.52 to 0.69) at 1 month and 0.18 (95% CI: -0.43 to 0.78) at 3 months for the THI. CONCLUSION: tDCS of the auditory and prefrontal cortices is safe, but does not improve tinnitus. Different tDCS protocols might be beneficial.

Electrically assisted ocular gene therapy.

Electrotransfer and iontophoresis are being developed as innovative non-viral gene delivery systems for the treatment of eye diseases. These two techniques rely on the use of electric current to allow for higher transfection yield of various ocular cell types in vivo. Short pulses of relatively high-intensity electric fields are used for electrotransfer delivery, whereas the iontophoresis technique is based on the application of low voltage electric current. The basic principles of these techniques and their potential therapeutic application for diseases of the anterior and posterior segments of the eye are reviewed. Iontophoresis has been found most efficient for the delivery of small nucleic acid fragments such as antisense oligonucleotides, siRNA, or ribozymes. Electrotransfer, on the other hand, is being developed for the delivery of oligonucleotides or custom designed plasmids. The wide range of strategies already validated and the potential for targeting specific types of cells confirm the promising early observations made using electrotransfer and iontophoresis. These two nonviral delivery systems are safe and can be used efficiently for targeted gene delivery to ocular tissues in vivo. At the present, their application for the treatment of ocular human diseases is nearing its final stages of adaptation and practical implementation at the bedside.

Comparison of Methods for Evaluation of the Bactericidal Activity of Copper-Sputtered Surfaces against Methicillin-Resistant Staphylococcus aureus.

Bacteria can survive on hospital textiles and surfaces, from which they can be disseminated, representing a source of health care-associated infections (HCAIs). Surfaces containing copper (Cu), which is known for its bactericidal properties, could be an efficient way to lower the burden of potential pathogens. The antimicrobial activity of Cu-sputtered polyester surfaces, obtained by direct-current magnetron sputtering (DCMS), against methicillin-resistant Staphylococcus aureus (MRSA) was tested. The Cu-polyester microstructure was characterized by high-resolution transmission electron microscopy to determine the microstructure of the Cu nanoparticles and by profilometry to assess the thickness of the layers. Sputtering at 300 mA for 160 s led to a Cu film thickness of 20 nm (100 Cu layers) containing 0.209% (wt/wt) polyester. The viability of MRSA strain ATCC 43300 on Cu-sputtered polyester was evaluated by four methods: (i) mechanical detachment, (ii) microcalorimetry, (iii) direct transfer onto plates, and (iv) stereomicroscopy. The low efficacy of mechanical detachment impeded bacterial viability estimations. Microcalorimetry provided only semiquantitative results. Direct transfer onto plates and stereomicroscopy seemed to be the most suitable methods to evaluate the bacterial inactivation potential of Cu-sputtered polyester surfaces, since they presented the least experimental bias. Cu-polyester samples sputtered for 160 s by DCMS were further tested against 10 clinical MRSA isolates and showed a high level of bactericidal activity, with a 4-log(10) reduction in the initial MRSA load (10(6) CFU) within 1 h. Cu-sputtered polyester surfaces might be of use to prevent the transmission of HCAI pathogens.

Non-pharmacological interventions for chronic pain in people with spinal cord injury.

BACKGROUND: Chronic pain is frequent in persons living with spinal cord injury (SCI). Conventionally, the pain is treated pharmacologically, yet long-term pain medication is often refractory and associated with side effects. Non-pharmacological interventions are frequently advocated, although the benefit and harm profiles of these treatments are not well established, in part because of methodological weaknesses of available studies. OBJECTIVES: To critically appraise and synthesise available research evidence on the effects of non-pharmacological interventions for the treatment of chronic neuropathic and nociceptive pain in people living with SCI. SEARCH METHODS: The search was run on the 1st March 2011. We searched the Cochrane Injuries Group's Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), four other databases and clinical trials registers. In addition, we manually searched the proceedings of three major scientific conferences on SCI. We updated this search in November 2014 but these results have not yet been incorporated. SELECTION CRITERIA: Randomised controlled trials of any intervention not involving intake of medication or other active substances to treat chronic pain in people with SCI. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed risk of bias in the included studies. The primary outcome was any measure of pain intensity or pain relief. Secondary outcomes included adverse events, anxiety, depression and quality of life. When possible, meta-analyses were performed to calculate standardised mean differences for each type of intervention. MAIN RESULTS: We identified 16 trials involving a total of 616 participants. Eight different types of interventions were studied. Eight trials investigated the effects of electrical brain stimulation (transcranial direct current stimulation (tDCS) and cranial electrotherapy stimulation (CES); five trials) or repetitive transcranial magnetic stimulation (rTMS; three trials). Interventions in the remaining studies included exercise programmes (three trials); acupuncture (two trials); self-hypnosis (one trial); transcutaneous electrical nerve stimulation (TENS) (one trial); and a cognitive behavioural programme (one trial). None of the included trials were considered to have low overall risk of bias. Twelve studies had high overall risk of bias, and in four studies risk of bias was unclear. The overall quality of the included studies was weak. Their validity was impaired by methodological weaknesses such as inappropriate choice of control groups. An additional search in November 2014 identified more recent studies that will be included in an update of this review.For tDCS the pooled mean difference between intervention and control groups in pain scores on an 11-point visual analogue scale (VAS) (0-10) was a reduction of -1.90 units (95% confidence interval (CI) -3.48 to -0.33; P value 0.02) in the short term and of -1.87 (95% CI -3.30 to -0.45; P value 0.01) in the mid term. Exercise programmes led to mean reductions in chronic shoulder pain of -1.9 score points for the Short Form (SF)-36 item for pain experience (95% CI -3.4 to -0.4; P value 0.01) and -2.8 pain VAS units (95% CI -3.77 to -1.83; P value < 0.00001); this represented the largest observed treatment effects in the included studies. Trials using rTMS, CES, acupuncture, self-hypnosis, TENS or a cognitive behavioural programme provided no evidence that these interventions reduce chronic pain. Ten trials examined study endpoints other than pain, including anxiety, depression and quality of life, but available data were too scarce for firm conclusions to be drawn. In four trials no side effects were reported with study interventions. Five trials reported transient mild side effects. Overall, a paucity of evidence was found on any serious or long-lasting side effects of the interventions. AUTHORS' CONCLUSIONS: Evidence is insufficient to suggest that non-pharmacological treatments are effective in reducing chronic pain in people living with SCI. The benefits and harms of commonly used non-pharmacological pain treatments should be investigated in randomised controlled trials with adequate sample size and study methodology.

A new method for geoelectrical investigations underwater

A new electrical method is proposed for determining the apparent resistivity of multi-earth layers located underwater. The method is based on direct current geoelectric sounding principles. A layered earth model is used to simulate the stratigraphic target. The measurement array is of pole-pole type; it is located underwater and is orientated vertically. This particular electrode configuration is very useful when conventional electrical methods cannot be used, especially if the water depth becomes very important. The calculated apparent resistivity shows a substantial quality increase in the measured signal caused by the underwater targets, from which little or no response is measured using conventional surface electrode methods. In practice, however, different factors such as water stratification, underwater streams or meteorological conditions complicate the interpretation of the field results. A case study is presented, where field surveys carried out on Lake Geneva were interpreted using the calculated apparent resistivity master-curves.

Ca(2+) signaling by T-type Ca(2+) channels in neurons.

Among the major families of voltage-gated Ca(2+) channels, the low-voltage-activated channels formed by the Ca(v)3 subunits, referred to as T-type Ca(2+) channels, have recently gained increased interest in terms of the intracellular Ca(2+) signals generated upon their activation. Here, we provide an overview of recent reports documenting that T-type Ca(2+) channels act as an important Ca(2+) source in a wide range of neuronal cell types. The work is focused on T-type Ca(2+) channels in neurons, but refers to non-neuronal cells in cases where exemplary functions for Ca(2+) entering through T-type Ca(2+) channels have been described. Notably, Ca(2+) influx through T-type Ca(2+) channels is the predominant Ca(2+) source in several neuronal cell types and carries out specific signaling roles. We also emphasize that Ca(2+) signaling through T-type Ca(2+) channels occurs often in select subcellular compartments, is mediated through strategically co-localized targets, and is exploited for unique physiological functions.

Electroencephalogram changes during inhalation with nitric oxide in the pediatric intensive care patient--a preliminary report.

OBJECTIVES: Although endogenous nitric oxide (NO) is an excitatory mediator in the central nervous system, inhaled NO is not considered to cause neurologic side effects because of its short half-life. This study was motivated by a recent case report about neurologic symptoms and our own observation of severe electroencephalogram (EEG) abnormalities during NO inhalation. DESIGN: Blind, retrospective analyses of EEGs which were registered before, during, and after NO inhalation. EEG was classified in a 5-point rating system by an independent electroencephalographer who was blinded to the patients' clinical histories. Comparisons were made with the previous evaluation documented at recording. Other EEG-influencing parameters such as oxygen saturation, hemodynamics, electrolytes, and pH were evaluated. SETTING: Pediatric intensive care unit of a tertiary care university children's hospital. PATIENTS: Eleven ventilated, long-term paralyzed, sedated children (1 mo to 14 yrs) who had EEG or clinical assessment before NO treatment and EEG during NO inhalation. They were divided into two groups according to the NO-indication (e.g., congenital heart defect, acute respiratory distress syndrome). MEASUREMENTS AND MAIN RESULTS: All 11 patients had an abnormal EEG during NO inhalation. EEG-controls without NO showed remarkable improvement. EEG abnormalities were background slowing, low voltage, suppression burst (n = 2), and sharp waves (n = 2) independent of patients' age, NO-indication, and other EEG-influencing parameters. CONCLUSIONS: These preliminary data suggest the occurrence of EEG-abnormalities after application of inhaled NO in critically ill children. We found no correlation with other potential EEG-influencing parameters, although clinical state, medication, or hypoxemia might contribute. Comprehensive, prospective, clinical assessment regarding a causal relationship between NO-inhalation and EEG-abnormalities and their clinical importance is needed.

Spinal cord stimulation treatment for angina pectoris: more than a placebo?

BACKGROUND: The effects of thoracolumbal spinal cord stimulation (SCS) are confined to restricted microcirculatory areas. This limitation is generally attributed to a predominantly segmental mode of action on the autonomic nervous system. The goal of this study was to determine whether SCS applied close to supraspinal autonomic centers would induce generalized hemodynamic changes that could explain its alleged antianginal properties. METHODS: Invasive hemodynamic tests were performed in 15 anesthetized Göttingen minipigs submitted to iterative cervical SCS of various duration and intensity. RESULTS: Hemodynamic changes exceeding 10% were observed in 59 of 68 SCS sessions (87%). Their extent and time to peak varied with SCS intensity. At 2, 5, and 10 V, significant (t test p < 0.05) peak changes occurred in cardiac output (+34%, +29%, and +28%, respectively), stroke volume (+19%, +16%, +15%), mean pressure (+9%, +27%, +40%), heart rate (+14%, +23%, +14%), systemic (-17%, NS, NS), and pulmonary vascular (25%, NS, NS) resistances. Strikingly, at 2 V, the increase in cardiac output (+34%) was higher than the synchronous rise in rate pressure product (+22%), indicating efficient cardiac work. At 10 V, however, the cardiac work was inefficient (rate pressure product + 53%/cardiac output + 28%). CONCLUSIONS: Low-voltage cervical neuromodulation reduces the postcharge and improves cardiac work efficiency. The resulting reduction in oxygen myocardial demand may account for decreased anginal pain.

Inferring the degree of incipient speciation in secondary contact zones of closely related lineages of Palearctic green toads (Bufo viridis subgroup).

Reproductive isolation between lineages is expected to accumulate with divergence time, but the time taken to speciate may strongly vary between different groups of organisms. In anuran amphibians, laboratory crosses can still produce viable hybrid offspring >20 My after separation, but the speed of speciation in closely related anuran lineages under natural conditions is poorly studied. Palearctic green toads (Bufo viridis subgroup) offer an excellent system to address this question, comprising several lineages that arose at different times and form secondary contact zones. Using mitochondrial and nuclear markers, we previously demonstrated that in Sicily, B. siculus and B. balearicus developed advanced reproductive isolation after Plio-Pleistocene divergence (2.6 My, 3.3-1.9), with limited historic mtDNA introgression, scarce nuclear admixture, but low, if any, current gene flow. Here, we study genetic interactions between younger lineages of early Pleistocene divergence (1.9 My, 2.5-1.3) in northeastern Italy (B. balearicus, B. viridis). We find significantly more, asymmetric nuclear and wider, differential mtDNA introgression. The population structure seems to be molded by geographic distance and barriers (rivers), much more than by intrinsic genomic incompatibilities. These differences of hybridization between zones may be partly explained by differences in the duration of previous isolation. Scattered research on other anurans suggests that wide hybrid zones with strong introgression may develop when secondary contacts occur <2 My after divergence, whereas narrower zones with restricted gene flow form when divergence exceeds 3 My. Our study strengthens support for this rule of thumb by comparing lineages with different divergence times within the same radiation.

Prevalence of obesity and overweight and associated nutritional factors in a population-based Swiss sample: an opportunity to analyze the impact of three different European cultural roots.

PURPOSE: Obesity represents a growing public health concern worldwide. The latest data in Switzerland rely on self-reported body mass index (BMI), leading to underestimation of prevalence. We reassessed the prevalence of obesity and overweight in a sample of the Swiss population using measured BMI and waist circumference (WC) and explored the association with nutritional factors and living in different linguistic-cultural regions. METHODS: Data of 1,505 participants of a cross-sectional population-based survey in the three linguistic regions of Switzerland were analyzed. BMI and WC were measured, and a 24-h urine collection was performed to evaluate dietary sodium, potassium and protein intake. RESULTS: The prevalence of overweight, obesity and abdominal obesity was 32.2, 14.2 and 33.6 %, respectively. Significant differences were observed in the regional distribution, with a lower prevalence in the Italian-speaking population. Low educational level, current smoking, scarce physical activity and being migrant were associated with an higher prevalence of obesity. Sodium, potassium and protein intake increased significantly across BMI categories. CONCLUSIONS: Obesity and overweight affect almost half of the Swiss adolescents and adults, and the prevalence appears to increase. Using BMI and WC to define obesity led to different prevalences. Differences were furthermore observed across Swiss linguistic-cultural regions, despite a common socio-economic and governmental framework. We found a positive association between obesity and salt intake, with a potential deleterious synergistic effect on cardiovascular risk.

Endothelin-1-induced spreading depression in rats is associated with a microarea of selective neuronal necrosis.

Two different theories of migraine aura exist: In the vascular theory of Wolff, intracerebral vasoconstriction causes migraine aura via energy deficiency, whereas in the neuronal theory of Leão and Morison, spreading depression (SD) initiates the aura. Recently, it has been shown that the cerebrovascular constrictor endothelin-1 (ET-1) elicits SD when applied to the cortical surface, a finding that could provide a bridge between the vascular and the neuronal theories of migraine aura. Several arguments support the notion that ET-1-induced SD results from local vasoconstriction, but definite proof is missing. If ET-1 induces SD via vasoconstriction/ischemia, then neuronal damage is likely to occur, contrasting with the fact that SD in the otherwise normal cortex is not associated with any lesion. To test this hypothesis, we have performed a comprehensive histologic study of the effects of ET-1 when applied topically to the cerebral cortex of halothane-anesthetized rats. Our assessment included histologic stainings and immunohistochemistry for glial fibrillary acidic protein, heat shock protein 70, and transferase dUTP nick-end labeling assay. During ET-1 application, we recorded (i) subarachnoid direct current (DC) electroencephalogram, (ii) local cerebral blood flow by laser-Doppler flowmetry, and (iii) changes of oxyhemoglobin and deoxyhemoglobin by spectroscopy. At an ET-1 concentration of 1 muM, at which only 6 of 12 animals generated SD, a microarea with selective neuronal death was found only in those animals demonstrating SD. In another five selected animals, which had not shown SD in response to ET-1, SD was triggered at a second cranial window by KCl and propagated from there to the window exposed to ET-1. This treatment also resulted in a microarea of neuronal damage. In contrast, SD invading from outside did not induce neuronal damage in the absence of ET-1 (n = 4) or in the presence of ET-1 if ET-1 was coapplied with BQ-123, an ET(A) receptor antagonist (n = 4). In conclusion, SD in presence of ET-1 induced a microarea of selective neuronal necrosis no matter where the SD originated. This effect of ET-1 appears to be mediated by the ET(A) receptor.

Brain energy consumption induced by electrical stimulation promotes systemic glucose uptake.

BACKGROUND: Controlled transcranial stimulation of the brain is part of clinical treatment strategies in neuropsychiatric diseases such as depression, stroke, or Parkinson's disease. Manipulating brain activity by transcranial stimulation, however, inevitably influences other control centers of various neuronal and neurohormonal feedback loops and therefore may concomitantly affect systemic metabolic regulation. Because hypothalamic adenosine triphosphate-sensitive potassium channels, which function as local energy sensors, are centrally involved in the regulation of glucose homeostasis, we tested whether transcranial direct current stimulation (tDCS) causes an excitation-induced transient neuronal energy depletion and thus influences systemic glucose homeostasis and related neuroendocrine mediators.METHODS: In a crossover design testing 15 healthy male volunteers, we increased neuronal excitation by anodal tDCS versus sham and examined cerebral energy consumption with (31)phosphorus magnetic resonance spectroscopy. Systemic glucose uptake was determined by euglycemic-hyperinsulinemic glucose clamp, and neurohormonal measurements comprised the parameters of the stress systems.RESULTS: We found that anodic tDCS-induced neuronal excitation causes an energetic depletion, as quantified by (31)phosphorus magnetic resonance spectroscopy. Moreover, tDCS-induced cerebral energy consumption promotes systemic glucose tolerance in a standardized euglycemic-hyperinsulinemic glucose clamp procedure and reduces neurohormonal stress axes activity.CONCLUSIONS: Our data demonstrate that transcranial brain stimulation not only evokes alterations in local neuronal processes but also clearly influences downstream metabolic systems regulated by the brain. The beneficial effects of tDCS on metabolic features may thus qualify brain stimulation as a promising nonpharmacologic therapy option for drug-induced or comorbid metabolic disturbances in various neuropsychiatric diseases.

Parkinson's disease.

In advanced Parkinson's disease (PD), the emergence of symptoms refractory to conventional therapy poses therapeutic challenges. The success of deep brain stimulation (DBS) and advances in the understanding of the pathophysiology of PD have raised interest in noninvasive brain stimulation as an alternative therapeutic tool. The rationale for its use draws from the concept that reversing abnormalities in brain activity and physiology thought to cause the clinical deficits may restore normal functioning. Currently the best evidence in support of this concept comes from DBS, which improves motor deficits, and modulates brain activity and motor cortex physiology, although whether a causal interaction exists remains largely undetermined. Most trials of noninvasive brain stimulation in PD have applied repetitive transcranial magnetic stimulation (rTMS), targeting the motor cortex. Current studies suggest a possible therapeutic potential for rTMS and transcranial direct current stimulation (tDCS), but clinical effects so far have been small and negligible with regard to functional independence and quality of life. Approaches to potentiate the efficacy of rTMS include increasing stimulation intensity and novel stimulation parameters that derive their rationale from studies on brain physiology. These novel parameters are intended to simulate normal firing patterns or to act on the hypothesized role of oscillatory activity in the motor cortex and basal ganglia with regard to motor control and its contribution to the pathogenesis of motor disorders. Noninvasive brain stimulation studies will enhance our understanding of PD pathophysiology and might provide further evidence for potential therapeutic applications.