Nickel sensitivity: effects of prolonged oral intake of the element

25 nickel-sensitive females were given 10 mg NiSO4 in water in a single dose. 18 experienced generalized or localized flare-ups. 15 days later, 17 of the 25 patients were given gradually increasing daily doses of NiSO4 in water for 3 months. 14 ended the trial without flare-up, 3 had to stop because of intense worsening of cutaneous manifestations. A relationship does exist between the daily oral intake of nickel and its clinical manifestations, but it is not uniform and depends on the changing quantities and, above all, on the manner of intake. It would seem that a 10 mg NiSO4 oral challenge represents a sudden and large intake of the element to which the majority of sensitized subjects are not able to adapt. On the other hand, a gradual intake permits a majority of subjects to adapt to the element. We hypothesize that this behaviour is more likely due to intestinal adaptivity than to immunological tolerance.     

GABAergic inhibitory mechanisms for repetition-adaptivity in large-scale brain systems

Molecular mechanisms for systems level adaptivity of brain activation are largely unknown but a key role for active inhibition by gamma-aminobutyric acid (GABA) is plausible. We used functional magnetic resonance imaging to contrast the modulatory effects on brain adaptivity to task repetition and task difficulty of two GABAergic drugs, lorazepam and flumazenil. In a working memory paradigm, occipitotemporal regions clearly demonstrated attenuation of activation as a function of within-session task repetition or practice in data acquired following placebo, but this spatiotemporal pattern of repetition adaptivity was abolished by both lorazepam and flumazenil. However, in other brain systems flumazenil enhanced repetition adaptivity compared to placebo: in frontal cortex, flumzenil induced attenuation of signal related to task repetition and in hippocampus it exaggerated normal enhancement of signal with repetition. In contrast, there were no significant effects of either flumazenil or lorazepam on areas of frontal cortex which normally demonstrated significant neurocognitive load response or adaptivity to task difficulty. We argue that repetition adaptivity of large-scale brain systems is regulated by GABAergic inhibitory mechanisms and that expression of repetition adaptivity in a given brain system may show an "inverted-U" form of relationship with pharmacologically manipulable levels of GABAergic inhibitory tone.     

Patient-specific learning in real time for adaptive monitoring in critical care

Intensive care monitoring systems are typically developed from population data, but do not take into account the variability among individual patients’ characteristics. This study develops patient-specific alarm algorithms in real time. Classification tree and neural network learning were carried out in batch mode on individual patients’ vital sign numerics in successive intervals of incremental duration to generate binary classifiers of patient state and thus to determine when to issue an alarm. Results suggest that the performance of these classifiers follows the course of a learning curve. After 8 h of patient-specific training during each of 10 monitoring sessions, our neural networks reached average sensitivity, specificity, positive predictive value, and accuracy of 0.96, 0.99, 0.79, and 0.99, respectively. The classification trees achieved 0.84, 0.98, 0.72, and 0.98, respectively. Thus, patient-specific modeling in real time is not only feasible but also effective in generating alerts at the bedside.     

Computer Modeling of Red Blood Cell Rheology in the Microcirculation: A Brief Overview

One of the major functions of the cardiovascular system is to deliver blood to the microcirculation where exchange of mass and energy can take place. In the present article, we will provide an overview of the state-of-the-art computational methods for modeling of red blood cell (RBC) rheology and dynamics in the microcirculation. While significant progress has been made in simulation of single-file motion of deformable RBCs in capillaries and of diluted sheared suspensions of RBCs in infinite domains, detailed understanding of the mechanics of blood flow in intermediate diameter microvessels (8–1000μm) has presented formidable challenges. The difficulties are largely due to modeling the motion of multiple, interacting, highly deformable particles. The current computational tools consist mainly of three-dimensional (3D) boundary-integral methods for single RBC dynamics and deformation; and for rheology of large systems of droplets at large volume fractions using periodic boundary conditions and novel adaptive computational meshes. Further advances will result from combination of these tools to produce new algorithms capable of describing the motion and deformation of large systems of RBCs in microvessels at physiologically relevant volume fractions.     

血吸虫与宿主非适应性概述

血吸虫对宿主的特异性和宿主对血吸虫的相容性是宿主与血吸虫在长期进化过程中形成的, 其不仅与环境而且与两者的遗传等因素密切相关。本文从遗传学、 免疫学、 细胞生物学、 分子生物学、 生理学的角度对血吸虫与宿主的非适应性简要作一综述。     

纯滞后对象的观测补偿器控制方案

本文讨论了三种用于纯滞后过程的观测补偿器控制方案。第一种方案与Smith预估补偿方案进行了比较,表明它具有实施方便、对于对象模型参数的变化不灵敏以及稳定性较好等优点。第二种方案与前馈控制相类似,通过合适的观测补偿器参数的选择,可以完全补偿可测干扰的影响。第三种方案综合了前两种方案的优点,它不仅有良好的稳定性,而且有较强的适应能力。数字仿真的结果表明这类观测补偿器控制方案还可适用于对象是时变或者非线性的系统。