A kinematic and computational study of leech crawling: Support for a CPG based on travelling waves of excitation.

Many well characterized central pattern generators (CPGs) underlie behaviors (e.g., swimming, flight, heartbeat) that require regular rhythmicity and strict phase relationships. Here, we examine the organization of a CPG for leech crawling, a behavior whose success depends more on its flexibility than on its precise coordination. We examined the organization of this CPG by first characterizing the kinematics of crawling steps in normal and surgically manipulated animals, then by exploring its features in a simple neuronal model. The behavioral observations revealed the following. (1) Intersegmental coordination varied considerably with step duration, whereas the rates of elongation and contraction within individual segments were relatively constant. (2) Steps were generated in the absence of both head and tail brains, implying that midbody ganglia contain a CPG for step production. (3) Removal of sensory feedback did not affect step coordination or timing. (4) Imposed stretch greatly lengthened transitions between elongation and contraction, indicating that sensory pathways feed back onto the CPG. A simple model reproduced essential features of the observed kinematics. This model consisted of an oscillator that initiates propagating segmental waves of activity in excitatory neuronal chains, along with a parallel descending projection; together, these pathways could produce the observed intersegmental lags, coordination between phases, and step duration. We suggest that the proposed model is well suited to be modified on a step-by-step basis and that crawling may differ substantially from other described CPGs, such as that for swimming in segmented animals, where individual segments produce oscillations that are strongly phase-locked to one another

BILATERAL RENAL ARTERY STENOSIS IN A HYPERTENSIVE LUPUS PATIENT WITHOUT RENAL DYSFUNCTION: A CASE REPORT

Systemic lupus erythematosus (SLE) is associated with a high prevalence of atherosclero-sis and an enhanced cardiovascular mortality. In adult subjects, several studies have shown the coexistence of SLE and renal artery stenosis, most of them with unilateral in-volvement or with renal dysfunction. We observed a 62-year-old man with SLE and a 10-year history of moderate-to-severe hy-pertension who was admitted to our hospital because of uncontrolled blood pressure val-ues (152/95 mmHg), despite drug therapy. No signs of renal impairment were evident. After an initial physical examination, which presented a periumbilical bruit, a renal ultra-sound was performed with evidence of bilateral renal artery stenosis. An angio-MR study also confirmed the diagnosis and showed a double renal artery on the right side. Many different factors can contribute to the bilateral renal artery stenosis in this patient. Chronic inflammatory state associated to SLE, metabolic alterations with dyslipidemia and steroid therapy may all be involved in the development of the renal atherosclerotic le-sions

An economic evaluation of Alexander Technique lessons or acupuncture sessions for patients with chronic neck pain : A randomized trial (ATLAS)

OBJECTIVES: To assess the cost-effectiveness of acupuncture and usual care, and Alexander Technique lessons and usual care, compared with usual GP care alone for chronic neck pain patients. METHODS: An economic evaluation was undertaken alongside the ATLAS trial, taking both NHS and wider societal viewpoints. Participants were offered up to twelve acupuncture sessions or twenty Alexander lessons (equivalent overall contact time). Costs were in pounds sterling. Effectiveness was measured using the generic EQ-5D to calculate quality adjusted life years (QALYs), as well as using a specific neck pain measure-the Northwick Park Neck Pain Questionnaire (NPQ). RESULTS: In the base case analysis, incremental QALY gains were 0.032 and 0.025 in the acupuncture and Alexander groups, respectively, in comparison to usual GP care, indicating moderate health benefits for both interventions. Incremental costs were £451 for acupuncture and £667 for Alexander, mainly driven by intervention costs. Acupuncture was likely to be cost-effective (ICER = £18,767/QALY bootstrapped 95% CI £4,426 to £74,562) and was robust to most sensitivity analyses. Alexander lessons were not cost-effective at the lower NICE threshold of £20,000/QALY (£25,101/QALY bootstrapped 95% CI -£150,208 to £248,697) but may be at £30,000/QALY, however, there was considerable statistical uncertainty in all tested scenarios. CONCLUSIONS: In comparison with usual care, acupuncture is likely to be cost-effective for chronic neck pain, whereas, largely due to higher intervention costs, Alexander lessons are unlikely to be cost-effective. However, there were high levels of missing data and further research is needed to assess the long-term cost-effectiveness of these interventions

In politics, caricatures can become facts, and that is bad for everyone

The distortion of facts is nothing new to politics and election campaigns. But, with the rise of the internet and 24-hour news cycle, rumors and conspiracy theories can now spread easier than ever through social networks to reach potential voters. Michael Cacciatore and co-authors look at two examples from the 2008 presidential election campaign to better understand how unsubstantiated rumors can become facts in voters’ minds. They find that values, including political ideology and evangelical Christian status, were primarily responsible for propelling misperceptions about President Barack Obama’s faith, while media use played a more important role in driving the misperception that Sarah Palin, and not Saturday Night Live’s Tina Fey, was responsible for the “I can see Russia from my house” quote. The latter finding lends some credibility to the so-called “lamestream media” effect often espoused by prominent Republican figures

Reductions in co-contraction following neuromuscular re-education in people with knee osteoarthritis

Background Both increased knee muscle co-contraction and alterations in central pain processing have been suggested to play a role in knee osteoarthritis pain. However, current interventions do not target either of these mechanisms. The Alexander Technique provides neuromuscular re-education and may also influence anticipation of pain. This study therefore sought to investigate the potential clinical effectiveness of the AT intervention in the management of knee osteoarthritis and also to identify a possible mechanism of action. Methods A cohort of 21 participants with confirmed knee osteoarthritis were given 20 lessons of instruction in the Alexander Technique. In addition to clinical outcomes EMG data, quantifying knee muscle co-contraction and EEG data, characterising brain activity during anticipation of pain, were collected. All data were compared between baseline and post-intervention time points with a further 15-month clinical follow up. In addition, biomechanical data were collected from a healthy control group and compared with the data from the osteoarthritis subjects. Results: Following AT instruction the mean WOMAC pain score reduced by 56% from 9.6 to 4.2 (P<0.01) and this reduction was maintained at 15 month follow up. There was a clear decrease in medial co-contraction at the end of the intervention, towards the levels observed in the healthy control group, both during a pre-contact phase of gait (p<0.05) and during early stance (p<0.01). However, no changes in pain-anticipatory brain activity were observed. Interestingly, decreases in WOMAC pain were associated with reductions in medial co-contraction during the pre-contact phase of gait. Conclusions: This is the first study to investigate the potential effectiveness of an intervention aimed at increasing awareness of muscle behaviour in the clinical management of knee osteoarthritis. These data suggest a complex relationship between muscle contraction, joint loading and pain and support the idea that excessive muscle co-contraction may be a maladaptive response in this patient group. Furthermore, these data provide evidence that, if the activation of certain muscles can be reduced during gait, this may lead to positive long-term clinical outcomes. This finding challenges clinical management models of knee osteoarthritis which focus primarily on muscle strengthening

Impairments in hearing and vision impact on mortality in older people: the AGES-Reykjavik Study.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.to examine the relationships between impairments in hearing and vision and mortality from all-causes and cardiovascular disease (CVD) among older people.population-based cohort study.the study population included 4,926 Icelandic individuals, aged ≥67 years, 43.4% male, who completed vision and hearing examinations between 2002 and 2006 in the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-RS) and were followed prospectively for mortality through 2009.participants were classified as having 'moderate or greater' degree of impairment for vision only (VI), hearing only (HI), and both vision and hearing (dual sensory impairment, DSI). Cox proportional hazard regression, with age as the time scale, was used to calculate hazard ratios (HR) associated with impairment and mortality due to all-causes and specifically CVD after a median follow-up of 5.3 years.the prevalence of HI, VI and DSI were 25.4, 9.2 and 7.0%, respectively. After adjusting for age, significantly (P < 0.01) increased mortality from all causes, and CVD was observed for HI and DSI, especially among men. After further adjustment for established mortality risk factors, people with HI remained at higher risk for CVD mortality [HR: 1.70 (1.27-2.27)], whereas people with DSI remained at higher risk of all-cause mortality [HR: 1.43 (1.11-1.85)] and CVD mortality [HR: 1.78 (1.18-2.69)]. Mortality rates were significantly higher in men with HI and DSI and were elevated, although not significantly, among women with HI.older men with HI or DSI had a greater risk of dying from any cause and particularly cardiovascular causes within a median 5-year follow-up. Women with hearing impairment had a non-significantly elevated risk. Vision impairment alone was not associated with increased mortality.National Institutes of Health, National Institute on Aging (NIA) N01-AG-12100 NIA Z01-AG007380 National Eye Institute (NEI) ZIAEY000401 National Institute on Deafness and Other Communication Disorders (NIDCD) Division of Scientific Programs/IAA Y2-DC-1004-02 Hjartavernd (Icelandic Heart Association) Althingi (Icelandic Parliament

Gamma radiation induces hydrogen absorption by copper in water

One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories.Peer reviewe

A systematic review of studies measuring and reporting hearing aid usage in older adults since 1999: a descriptive summary of measurement tools

Objective: A systematic review was conducted to identify and quality assess how studies published since 1999 have measured and reported the usage of hearing aids in older adults. The relationship between usage and other dimensions of hearing aid outcome, age and hearing loss are summarised. Data sources: Articles were identified through systematic searches in PubMed/MEDLINE, The University of Nottingham Online Catalogue, Web of Science and through reference checking. Study eligibility criteria: (1) participants aged fifty years or over with sensori-neural hearing loss, (2) provision of an air conduction hearing aid, (3) inclusion of hearing aid usage measure(s) and (4) published between 1999 and 2011. Results: Of the initial 1933 papers obtained from the searches, a total of 64 were found eligible for review and were quality assessed on six dimensions: study design, choice of outcome instruments, level of reporting (usage, age, and audiometry) and cross validation of usage measures. Five papers were rated as being of high quality (scoring 10–12), 35 papers were rated as being of moderate quality (scoring 7–9), 22 as low quality (scoring 4–6) and two as very low quality (scoring 0–2). Fifteen different methods were identified for assessing the usage of hearing aids. Conclusions: Generally, the usage data reviewed was not well specified. There was a lack of consistency and robustness in the way that usage of hearing aids was assessed and categorised. There is a need for more standardised level of reporting of hearing aid usage data to further understand the relationship between usage and hearing aid outcomes

Method to Measure Tone of Axial and Proximal Muscle

The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs1, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention