Cognitive inhibition tasks interfere with dual-task walking and increase prefrontal cortical activity more than working memory tasks in young and older adults

BackgroundPrior work suggests there may be greater reliance on executive function for walking in older people. The pre-frontal cortex (PFC), which controls aspects of executive function, is known to be active during dual-task walking (DTW). However, there is debate on how PFC activity during DTW is impacted by ageing and the requirements of the cognitive task.Research questionFunctional near infrared spectroscopy, was used to investigate how PFC activity during walking was affected by (i) healthy ageing; and (ii) dual-tasks that utilise inhibition or working memory aspects of executive function.MethodsYoung (n = 26, 16 females, mean 20.9 years) and older (n = 26, 16 females, mean 70.3 years) adults performed five conditions: normal walking; Reciting Alternate Letters of the alphabet (RAL, requiring cognitive inhibition and working memory) during standing and walking; and serial subtraction by threes (SS3, requiring working memory alone) during standing and walking. Walking speed, cognitive performance, the PFC haemodynamic response, and fear of falling ratings were analysed using linear mixed-effects modelling.ResultsCompared to quiet standing, PFC activity increased during normal walking for older adults but decreased for young adults (p < 0.01). Across both groups, fear of falling contributed to higher PFC activity levels when walking (p < 0.01). PFC activity increased during DTW, and this increase was greater when performing RAL compared to the SS3 task (p < 0.01). Although the rate of correct responses was higher for RAL, walking speed reduced more with RAL than SS3 in the young group (p = 0.01), and the rate of correct responses reduced more when walking with RAL than SS3 in the older group (p < 0.01).SignificanceOlder adults have increased levels of PFC activation during walking compared to younger adults and fear of falling is a cofounding factor. The interference between gait and a concurrent cognitive task is higher when the cognitive task requires inhibition.     

The necessity of using two parameters to describe isotonic shortening velocity of muscle tissues: the effect of various interventions upon initial shortening velocity (vi) and curvature (b)

Summary In skinned skeletal muscle fibers and skinned preparations of myocardium or smooth muscle, for all conditions studied, the length traces during isotonic shortening are always found to be significantly curved. It is demonstrated that the observed curvature is not simply due to inhomogeneities on the sarcomere level in striated muscle, damaged ends of the preparations, double overlap and collision of filaments, or depletion of MgATP during the period of isotonic shortening. It is shown that the velocity of shortening can be described by an exponential function: v=v_i exp (-b[SL_i-SL]) with SL_i: sarcomere length at the start of the release; SL: sarcomere length during isotonic shortening. Thus, instantaneous shortening velocity (v) is determined by two parameters: v_i, the initial shortening velocity for SL=SL_i, and b, a constant characterizing the decrease in velocity during isotonic shortening. Factors which affect isotonic shortening can do this by affecting v_i, or by changing b, or both. Therefore, when analysing the effects of interventions which affect instantaneous shortening velocity, these two possibilities have to be distinguished. Since curvature of the length traces might be caused by noncrossbridge components, only v_i, the initial speed of shortening, is a parameter which directly reflects kinetics of the cross-bridge cycle while instantaneous speed of shortening might also be affected by noncrossbridge factors.Analysing isotonic shortening in terms of v_i and b, the effects of ionic strength, free Ca⁺⁺ concentration, MgATP/MgADP ratio and temperature on unloaded isotonic shortening have been studied. For the conditions used, it can be shown that ionic strength and free Ca⁺⁺ concentration only affect b without significant effect on v_i, whereas MgATP/MgADP ratio and temperature affect both v_i and b. This means that of these factors only MgATP/MgADP ratio and temperature affect the crossbridge kinetics which determine the maximum speed of shortening while ionic strength and free Ca⁺⁺ concentration have no such effect within the experimental error.Dedicated to Prof. R. Jacob on the occasion of his 60th birthday.Supported by the Deutsche Forschungsgemeinschaft: Br 849/1-1.     

Caspase-6 activity predicts lower episodic memory ability in aged individuals

Caspase-6 (Casp6), a cysteinyl protease that induces axonal degeneration, is activated early in Alzheimer Disease (AD) brains. To determine whether Casp6 activation is responsible for early cognitive impairment, we investigated the abundance of Casp6 activity, paired helical filament–1 (PHF-1) phosphorylated Tau and amyloid beta peptide (Aβ) pathology by immunohistochemistry in the hippocampal formation of aged non–cognitively impaired (NCI) individuals. Casp6 activity was restricted to the entorhinal cortex (ERC) and CA1 regions of the hippocampus. Pathology scores were then correlated with cognitive scores obtained within 1 year of death. Regression analyses revealed that ERC and CA1 Casp6 activity were the main contributor to lower episodic memory performance, whereas ERC PHF-1 pathology predicted lower semantic and working memory performance. Aβ did not correlate with any of the cognitive tests. Because Casp6 activity and PHF-1 pathology are intimately associated with AD pathology and memory decline is an early event in AD, we conclude that Casp6 activity and PHF-1 immunoreactivity in ERC identifies aged individuals at risk for developing AD.     

On the physiology of cognitive decline in type 1 diabetes

ObjectivesType 1 diabetes mellitus (T1DM) may be associated with cognitive impairment and notably a decline in psychomotor speed, information processing speed and attention. The mechanism for this decline is uncertain. Previous studies by our group and others have demonstrated a decline in EEG-power and event-related potential amplitude in T1DM. The objectives of the present study were to explore whether 1) the association between event-related potential (N100) amplitude and psychomotor speed is different between T1DM and healthy subjects, and 2) the decline in N100 amplitude depends on duration of diabetes.MethodsPatients with T1DM (N = 204) and healthy control subjects (N = 358) were included in a cross-sectional study. Event-related brain potentials were recorded with auditory reaction tasks. Psychomotor speed was evaluated with the Grooved Pegboard test in a subset of the patients (N = 70) and the healthy control subjects (N = 89).ResultsPatients with T1DM had a decrease in the N100 amplitude that correlated with a decline in psychomotor speed, longer duration of diabetes and increasing age. In healthy controls, the N100 amplitude did not decrease with age and the association between psychomotor speed and N100 amplitude was absent.ConclusionThe association between psychomotor speed and N100 amplitude is likely to be a specific trait for T1DM since it was not found in healthy controls and was dependent on diabetes duration. Our findings indicate that the pathogenesis of cognitive decline in T1DM may involve a disease-related factor with a long-term influence on the N100 amplitude.     

From the Cover: Supercell tornadoes are much stronger and wider than damage-based ratings indicate

Tornadoes cause damage, injury, and death when intense winds impact structures. Quantifying the strength and extent of such winds is critical to characterizing tornado hazards. Ratings of intensity and size are based nearly entirely on postevent damage surveys [R. Edwards et al., Bull. Am. Meteorol. Soc. 94, 641–653 (2013)]. It has long been suspected that these suffer low bias [C. A. Doswell, D. W. Burgess, Mon. Weather Rev. 116, 495–501 (1988)]. Here, using mapping of low-level tornado winds in 120 tornadoes, we prove that supercell tornadoes are typically much stronger and wider than damage surveys indicate. Our results permit an accurate assessment of the distribution of tornado intensities and sizes and tornado wind hazards, based on actual wind-speed observations, and meaningful comparisons of the distribution of tornado intensities and sizes with theoretical predictions. We analyze data from Doppler On Wheels (DOW) radar measurements of 120 tornadoes at the time of peak measured intensity. In striking contrast to conventional damage-based climatologies, median tornado peak wind speeds are ∼60 m⋅s⁻¹, capable of causing significant, Enhanced Fujita Scale (EF)-2 to -3, damage, and 20% are capable of the most intense EF-4/EF-5 damage. National Weather Service (NWS) EF/wind speed ratings are 1.2 to 1.5 categories (∼20 m⋅s⁻¹) lower than DOW observations for tornadoes documented by both the NWS and DOWs. Median tornado diameter is 250 to 500 m, with 10 to 15% >1 km. Wind engineering tornado-hazard-model predictions and building wind resistance standards may require upward adjustment due to the increased wind-damage risk documented here.

Tornadoes cause direct harm to people, infrastructure, and communities (1). Quantifying tornado risk requires accurate knowledge of their wind speeds and the size of the areas at risk from these intense winds. However, since direct measurements of tornado winds are rare, tornado intensity and size are nearly always inferred indirectly from postevent damage surveys applying the Fujita (F) or Enhanced Fujita (EF) scales (2–5) to infer maximum wind speeds. Statistics concerning tornado frequency, intensity, and size are derived from these surveys. However, because most tornadoes do not damage well-engineered structures, from which the most intense wind speeds can be inferred, and many occur in primarily rural areas, damage-based tornado wind speed and size estimations are likely severely low biased (6–11). A limited climatology (12), using Doppler On Wheels (DOW) radar data (13–15), suggested that tornadoes may be larger and more intense than indicated by these surveys. In-situ observations of wind speeds reliably demonstrable to be inside the radius of maximum winds of tornadoes are very rare (16, 17) and inadequate for deriving a statistically meaningful climatology. It is no exaggeration to state that, until now, statistics concerning even the most basic characteristics of tornadoes, including intensity and size, could not be quantified with confidence.     

桑杏颗粒治疗小儿风热挟痰证型咳嗽的疗效研究

目的：比较中药复方桑杏颗粒与急支糖浆治疗小儿咳嗽（风热挟痰证）的疗效,探讨复方桑杏颗粒治疗小儿咳嗽的临床应用前景。方法选择某市医院就诊的符合条件的患儿60例,随机分为两组,治疗组（30例）口服桑杏颗粒剂,对照组（30例）口服急支糖浆口服液,两组均以7天为一疗程,观察比较两组的疗效。结果治疗组咳嗽、咯痰症状、肺部听诊体征及胸片改善上均优于对照组。桑杏颗粒治疗小儿咳嗽的效果优于对照组,与急支糖浆相比,其需要治疗人数（NNT）为5人。结论桑杏颗粒剂治疗小儿急性支气管炎疗效显著,临床上值得推广应用。     

Heat Losses Caused by the Temporary Influence of Wind in Timber Frame Walls Insulated with Fibrous Materials

The paper presents the results of research concerning three fiber materials—mineral wool, hemp fiber and wood wool—as loose-fill thermal insulation materials. The analysis used the material parameters determined in previous works conducted by the authors, such as thermal conductivity and air permeability in relation to bulk density. These materials exhibit open porosity; thus, convection is an essential phenomenon in the heat transfer process. The paper aimed at conducting thermal simulations of various frame wall variants which were filled with the above-mentioned insulation materials. The simulations were performed with the Control Volume Method using the Delphin 5.8 software. The studies accounted for the effect of wind pressure and the time of its influence on a wall insulated by means of fiber material with a thickness of 150 as well as 250 mm. The simulation enabled us to obtain such data as maximal R-value reduction and time to return to equilibrium after filtration for the analyzed materials. The study proved that heat transfer in these insulations strongly depends on the bulk density, thickness of the insulation and wind pressure. The decrease in R is reduced as the density increases. This results from the decreased air permeability characterizing the material. Wind washing causes lower R reduction than air filtration in all models. The greater the thickness, the longer it takes for the models to return to the equilibrium state following air filtration (and wind washing). This period is comparable for air filtration and wind washing. Hemp fibers were characterized with the strongest susceptibility to air filtration; in the case of wood wool, it was also high, but lower than for hemp fibers, while mineral wool was characterized with the lowest.     

汪悦教授运用风药治疗痹证经验探析

[目的]总结探讨汪悦教授运用风药治疗痹证的临床经验。[方法]从痹证病因病机、风药功效、选药思路、配伍原则等方面介绍汪师经验,并附验案一则佐证。[结果]针对风邪、湿邪在痹证产生过程中的重要作用,汪师临证常根据邪气偏盛、病位证候等不同,并结合现代药理研究选用不同的风药进行治疗,以达到散风邪、燥湿邪、行气血、止痹痛的效果。遣方用药时常将风药与祛湿药、化瘀药、补血药、养阴药、温阳药等配伍使用,每获良效。所举验案患者患有脊柱关节炎,属于中医"骨痹"范畴,辨证属正虚邪实、肾阳不足、风湿痹阻,治拟温阳益肾、祛风胜湿、通络止痛,以阳和汤加减治疗,其中包括麻黄、独活等多味风药,收效甚佳。[结论]汪师灵活运用风药配伍组方以治疗痹证,疗效显著,值得进一步研究和探讨。     

张锡纯从脑论治痿证特色探析

[目的]探讨张锡纯从脑论治痿证的思路与特色。[方法]从中医文献整理、研究的角度,对张锡纯所著《医学衷中参西录》中从脑病角度论治痿证的相关论述、医案、具体药方进行系统分析,归纳和总结其痿证论治思路和特色。[结果]张锡纯汇通中西,以“肢体痿废”一症立论,结合现代医学对脑病的认识,创造性地提出脑贫血、脑充血两种病因均可导致肢体痿废,在此基础上以传统医学宗气不足、精髓不充、脏腑气血大热的观点诠释二者病机,立益气引血、镇肝熄风大法,创干颓汤、镇肝熄风汤、建瓴汤等,大大扩展了痿证的治疗思路。[结论]张锡纯衷中参西,从脑病角度论治痿证,对痿证理论的继承和发展作出重要贡献,于今日临床启发尤多。