Assessment of coronary flow reserve in nuclear cardiology

The coronary flow reserve is a quantitative parameter defined by the ratio maximal myocardial blood flow to rest myocardial blood flow, which allows to give functional information on the whole coronary arterial tree, integrating both epicardial arteries and microcirculatory. The coronary flow reserve is a powerful tool to guide therapy and to assess prognosis. Exploratory tools, initially limited to experimental invasive techniques, have evolved over the last 10 years, allowing to envisage its use in daily clinical practice. This article reviews the pathophysiology of the coronary flow reserve and the various invasive and non-invasive exploration tools available to practitioners, integrating them into clinical practice.     

输尿管镜钬激光碎石术后残留结石的危险因素分析

目的：分析与输尿管镜钬激光碎石术后致使结石残留相关的临床危险因素。方法：选取我院214例接受输尿管镜钬激光碎石术的输尿管结石患者进行回顾性分析,对14个特征性临床因素与结石残留的关系应用单因素方差分析进行评价,对存在相关性的临床因素再应用计算机COX比例风险模型进行多因素分析。结果：全组患者结石残留率为42．52％（91／214）。单因素方差分析：ESWL史、惠侧肾功能、结石位置、结石最大径、击碎后最大径、术后第1日输液量、术后第1日尿量、术后下床时间、术后解痉利尿药使用与术后结石残留相关（P值均〈0．05）;经过COX比例风险模型检测,患侧肾功能、结石位置、击碎后最大径、是结石残留的危险因素（P〈0．05）,而术后第1日尿量及术后解痉利尿药使用是结石残留的保护因素（P〈0．05）。结论：患侧肾功能不良、结石位于上段、击碎后直径仍大易导致残留结石,而术后第1天尿量较多且适当应用解痉利尿药能减少残留结石。     

Testing for Homogeneity in Meta‐Analysis I. The One‐Parameter Case: Standardized Mean Difference

Summary Meta‐analysis seeks to combine the results of several experiments in order to improve the accuracy of decisions. It is common to use a test for homogeneity to determine if the results of the several experiments are sufficiently similar to warrant their combination into an overall result. Cochran’s Q statistic is frequently used for this homogeneity test. It is often assumed that Q follows a chi‐square distribution under the null hypothesis of homogeneity, but it has long been known that this asymptotic distribution for Q is not accurate for moderate sample sizes. Here, we present an expansion for the mean of Q under the null hypothesis that is valid when the effect and the weight for each study depend on a single parameter, but for which neither normality nor independence of the effect and weight estimators is needed. This expansion represents an order O(1/n) correction to the usual chi‐square moment in the one‐parameter case. We apply the result to the homogeneity test for meta‐analyses in which the effects are measured by the standardized mean difference (Cohen’s d‐statistic). In this situation, we recommend approximating the null distribution of Q by a chi‐square distribution with fractional degrees of freedom that are estimated from the data using our expansion for the mean of Q. The resulting homogeneity test is substantially more accurate than the currently used test. We provide a program available at the Paper Information link at the Biometrics website http://www.biometrics.tibs.org for making the necessary calculations.     

分数阶微分方程边值问题正解的唯一性

分数阶微分方程在生物科学和其他领域发挥着重要作用.考虑来类分数阶微分方程边值问题正解的这来性,得到的结证不仅可以保证正解的存在这来,而且可以用于构造迭代序列来逼近这个解.     

β-Lapachone activity in synergy with conventional antimicrobials against methicillin resistant Staphylococcus aureus strains

The aim of this study was to evaluate the antimicrobial activity of lapachol, α-lapachone, β-lapachone and six antimicrobials (ampicillin, amoxicillin/clavulanic acid, cefoxitin, gentamicin, ciprofloxacin and meropenem) against twelve strains of Staphylococcus aureus from which resistance phenotypes were previously determined by the disk diffusion method. Five S. aureus strains (LFBM 01, LFBM 26, LFBM 28, LFBM 31 and LFBM 33) showed resistance to all antimicrobial agents tested and were selected for the study of the interaction between β-lapachone and antimicrobial agents, busing checkerboard method. The criteria used to evaluate the synergistic activity were defined by the Fractional Inhibitory Concentration Index (FICI). Among the naphthoquinones, β-lapachone was the most effective against S. aureus strains. FICI values ranged from 0.07 to 0.5, suggesting a synergistic interaction against multidrug resistant S. aureus (MRSA) strains. An additive effect was observed with the combination β-lapachone/ciprofloxacin against the LFBM 33 strain. The combination of β-lapachone with cefoxitin showed no added benefit against LFBM 31 and LFBM 33 strains. This study demonstrated that, in general, β-lapachone combined with beta lactams antimicrobials, fluoroquinolones and carbapenems acts synergistically inhibiting MRSA strains.     

A new era in palaeomicrobiology: prospects for ancient dental calculus as a long-term record of the human oral microbiome

The field of palaeomicrobiology is dramatically expanding thanks to recent advances in high-throughput biomolecular sequencing, which allows unprecedented access to the evolutionary history and ecology of human-associated and environmental microbes. Recently, human dental calculus has been shown to be an abundant, nearly ubiquitous, and long-term reservoir of the ancient oral microbiome, preserving not only microbial and host biomolecules but also dietary and environmental debris. Modern investigations of native human microbiota have demonstrated that the human microbiome plays a central role in health and chronic disease, raising questions about changes in microbial ecology, diversity and function through time. This paper explores the current state of ancient oral microbiome research and discusses successful applications, methodological challenges and future possibilities in elucidating the intimate evolutionary relationship between humans and their microbes.     

Quantifying Ca2+ Current and Permeability in ATP-gated P2X7 Receptors

ATP-gated P2X7 receptors are prominently expressed in inflammatory cells and play a key role in the immune response. A major consequence of receptor activation is the regulated influx of Ca²⁺ through the self-contained cation non-selective channel. Although the physiological importance of the resulting rise in intracellular Ca²⁺ is universally acknowledged, the biophysics of the Ca²⁺ flux responsible for the effects are poorly understood, largely because traditional methods of measuring Ca²⁺ permeability are difficult to apply to P2X7 receptors. Here we use an alternative approach, called dye-overload patch-clamp photometry, to quantify the agonist-gated Ca²⁺ flux of recombinant P2X7 receptors of dog, guinea pig, human, monkey, mouse, rat, and zebrafish. We find that the magnitude of the Ca²⁺ component of the ATP-gated current depends on the species of origin, the splice variant, and the concentration of the purinergic agonist. We also measured a significant contribution of Ca²⁺ to the agonist-gated current of the native P2X7Rs of mouse and human immune cells. Our results provide cross-species quantitative measures of the Ca²⁺ current of the P2X7 receptor for the first time, and suggest that the cytoplasmic N terminus plays a meaningful role in regulating the flow of Ca²⁺ through the channel.     

Macrophage ion currents are fit by a fractional model and therefore are a time series with memory

We studied macroscopic ion currents from macrophages and compared their patterns of behavior using classical and fractal analysis. Peak and steady state currents were measured respectively at the beginning and end of a voltage-clamp pulse. Hurst coefficients H and fractional dimensions were calculated for the current fluctuations (I _H ) during the intervening interval; these fluctuations are usually assumed to be white noise. We show that I _H is different from 0.5 and that the increments are stationary, indicating that the dynamic model has memory and that the intervening current fluctuations cannot be considered as white noise. I _H is less than 0.5, implying an antipersistent pattern. In addition, we show that the relation between inactivation and I _H versus voltage V fit an equation I _H (V) = f(V, α, m, d), where α is associated with fractional calculus and m and d are free parameters. Fitting by a fractional model confirms that the phenomenon has memory.     

Fractional cable equation models for anomalous electrodiffusion in nerve cells: infinite domain solutions

We introduce fractional Nernst-Planck equations and derive fractional cable equations as macroscopic models for electrodiffusion of ions in nerve cells when molecular diffusion is anomalous subdiffusion due to binding, crowding or trapping. The anomalous subdiffusion is modelled by replacing diffusion constants with time dependent operators parameterized by fractional order exponents. Solutions are obtained as functions of the scaling parameters for infinite cables and semi-infinite cables with instantaneous current injections. Voltage attenuation along dendrites in response to alpha function synaptic inputs is computed. Action potential firing rates are also derived based on simple integrate and fire versions of the models. Our results show that electrotonic properties and firing rates of nerve cells are altered by anomalous subdiffusion in these models. We have suggested electrophysiological experiments to calibrate and validate the models.