Computational fluid dynamics endpoints for assessment of adenotonsillectomy outcome in obese children with obstructive sleep apnea syndrome

Background

Improvements in obstructive sleep apnea syndrome (OSAS) severity may be associated with improved pharyngeal fluid mechanics following adenotonsillectomy (AT). The study objective is to use image-based computational fluid dynamics (CFD) to model changes in pharyngeal pressures after AT, in obese children with OSAS and adenotonsillar hypertrophy.

Methods

Three-dimensional models of the upper airway from nares to trachea, before and after AT, were derived from magnetic resonance images obtained during wakefulness, in a cohort of 10 obese children with OSAS. Velocity, pressure, and turbulence fields during peak tidal inspiratory flow were computed using commercial software. CFD endpoints were correlated with polysomnography endpoints before and after AT using Spearman?s rank correlation (r_s).

Results

Apnea hypopnea index (AHI) decreases after AT was strongly correlated with reduction in maximum pressure drop (dP_TAmax) in the region where tonsils and adenoid constrict the pharynx (r_s=0.78, P=0.011), and with decrease of the ratio of dP_TAmax to flow rate (r_s=0.82, P=0.006). Correlations of AHI decrease to anatomy, negative pressure in the overlap region (including nasal flow resistance), or pressure drop through the entire pharynx, were not significant. In a subgroup of subjects with more than 10% improvement in AHI, correlations between flow variables and AHI decrease were stronger than in all subjects.

Conclusions

The correlation between change in dP_TAmax and improved AHI suggests that dP_TAmax may be a useful index for internal airway loading due to anatomical narrowing, and may be better correlated with AHI than direct airway anatomic measurements.     

X-ray absorption and phase contrast imaging to study the interplay between plant roots and soil structure

Plant performance is, at least partly, linked to the location of roots with respect to soil structure features and the micro-environment surrounding roots. Measurements of root distributions from intact samples, using optical microscopy and field tracings have been partially successful but are imprecise and labour-intensive. Theoretically, X-ray computed micro-tomography represents an ideal solution for non-invasive imaging of plant roots and soil structure. However, before it becomes fast enough and affordable or easily accessible, there is still a need for a diagnostic tool to investigate root/soil interplay. Here, a method for detection of undisturbed plant roots and their immediate physical environment is presented. X-ray absorption and phase contrast imaging are combined to produce projection images of soil sections from which root distributions and soil structure can be analyzed. The clarity of roots on the X-ray film is sufficient to allow manual tracing on an acetate sheet fixed over the film. In its current version, the method suffers limitations mainly related to (i) the degree of subjectivity associated with manual tracing and (ii) the difficulty of separating live and dead roots. The method represents a simple and relatively inexpensive way to detect and quantify roots from intact samples and has scope for further improvements. In this paper, the main steps of the method, sampling, image acquisition and image processing are documented. The potential use of the method in an agronomic perspective is illustrated using surface and sub-surface soil samples from a controlled wheat trial. Quantitative characterization of root attributes, e.g. radius, length density, branching intensity and the complex interplay between roots and soil structure, is presented and discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

活细胞内5-羟色胺可见荧光的多光子激发成像

应用多光子激发激光扫描显微镜对5-羟色胺（5-hydroxytryptamine, 5-HT）孵育的大鼠粘膜型肥大细胞进行自发荧光成像,首次观察到了活细胞内5-HT相关的可见荧光,并对其产生机理进行了初步探讨.实现了对活细胞内5-HT空间分布的高分辨成像,为研究活组织或细胞内5-HT的空间分布和含量与细胞功能状态的关系提供了新的实验方法.     

超声技术在抑郁症诊疗中的作用研究及应用进展

超声波作为一种机械振动波,兼具波动效应、力学效应和热效应.这3种效应在临床中均有较大应用价值,可用于疾病的成像诊断、辅助给药、调控以及热消融治疗等.超声技术所具有的非侵入性、穿透力强、空间分辨率高等特性,使其在神经系统疾病的诊断和治疗中具有广泛的应用前景.而抑郁症作为一种常见的精神疾病,其诊断和治疗都面临很大的困难.因此,大量学者将超声技术应用于抑郁症诊疗.本文主要从超声成像、超声定点给药、超声调控、超声诱导抑郁几个方面总结近十年来超声技术在抑郁症中的应用,以期为研究抑郁症发病机制及诊疗提供一定的参考和帮助.     

Using unmanned aerial vehicle‐based multispectral,RGB and thermal imagery for phenotyping of forest genetic trials: A case study in Pinus halepensis

The assessment of genetic differentiation in functional traits is fundamental towards understanding the adaptive characteristics of forest species. While traditional phenotyping techniques are costly and time‐consuming, remote sensing data derived from cameras mounted on unmanned aerial vehicles (UAVs) provide potentially valid high‐throughput information for assessing morphophysiological differences among tree populations. In this work, we test for genetic variation in vegetation indices (VIs) and canopy temperature among populations of Pinus halepensis as proxies for canopy architecture, leaf area, photosynthetic pigments, photosynthetic efficiency and water use. The interpopulation associations between vegetation properties and above‐ground growth (stem volume) were also assessed. Three flights (July 2016, November 2016 and May 2017) were performed in a genetic trial consisting of 56 populations covering a large part of the species range. Multispectral (visible and near infrared wavelengths), RGB (red, green, blue) and thermal images were used to estimate canopy temperature and vegetation cover (VC) and derive several VIs. Differences among populations emerged consistently across flights for VC and VIs related to leaf area, indicating genetic divergence in crown architecture. Population differences in indices related to photosynthetic pigments emerged only in May 2017 and were probably related to a contrasting phenology of needle development. Conversely, the low population differentiation for the same indices in July 2016 and November 2016 suggested weak interpopulation variation in the photosynthetic machinery of mature needles of P. halepensis. Population differences in canopy temperature found in July 2016 were indicative of variation in stomatal regulation under drought stress. Stem volume correlated with indices related to leaf area (positively) and with canopy temperature (negatively), indicating a strong influence of canopy properties and stomatal conductance on above‐ground growth at the population level. Specifically, a combination of VIs and canopy temperature accounted for about 60% of population variability in stem volume of adult trees. This is the first study to propose UAV remote sensing as an effective tool for screening genetic variation in morphophysiological traits of adult forest trees.     

Whole‐brain microcirculation detection after ischemic stroke based on swept‐source optical coherence tomography

The occurrence and development of ischemic stroke are closely related to cerebral blood flow. Real‐time monitoring of cerebral perfusion level is very useful for understanding the mechanisms of the disease. A wide field of view (FOV) is conducive to capturing lesions and observing the progression of the disease. In this paper, we attempt to monitor the whole‐brain microcirculation in middle cerebral artery occlusion (MCAO) rats over time using a wide FOV swept‐source OCT (SS‐OCT) system. A constrained image registration algorithm is used to remove motion artifacts that are prone to occur in a wide FOV angiography. During ischemia, cerebral perfusion levels in the left and right hemispheres, as well as in the whole brain were quantified and compared. Changes in the shape and location of blood vessels were also recorded. The results showed that the trend in cerebral perfusion levels of both hemispheres was highly consistent during MCAO, and the position of the blood vessels varied over time. This work will provide new insights of ischemic stroke and is helpful to assess the effectiveness of potential treatment strategies.      

Human erythrocyte flickering: temperature,ATP concentration,water transport,and cell aging,plus a computer simulation

Images of human erythrocytes from a healthy donor were recorded under differential interference contrast (DIC) microscopy; they were acquired rapidly (~336 Hz) and the intensity of the centermost pixel of each cell was recorded for ~60 s (20,000 values). Various techniques were used to analyze the data, including detrended fluctuation analysis (DFA) and multiscale entropy (MSE); however, power spectrum analysis was deemed the most appropriate for metrifying and comparing results. This analysis was used to compare cells from young and old populations, and after perturbing normal conditions, with changes in temperature, adenosine triphosphate (ATP) concentration (using NaF, an inhibitor of glycolysis, and α-toxin, a pore-forming molecule used to permeabilize red cells to ATP), and water transport rates [using glycerol, and p-chloromercuriphenylsulfonic acid (pCMBS) to inhibit aquaporins, AQPs]. There were measurable differences in the membrane fluctuation characteristics in populations of young and old cells, but there was no significant change in the flickering time series on changing the temperature of an individual cell, by depleting it of ATP, or by competing with the minor water exchange pathway via AQP3 using glycerol. However, pCMBS, which inhibits AQP1, the major water exchange pathway, inhibited flickering in all cells, and yet it was restored by the membrane intercalating species dibutyl phthalate (DBP). We developed a computer model to simulate acquired displacement spectral time courses and to evaluate various methods of data analysis, and showed how the flexibility of the membrane, as defined in the model, affects the flickering time course.     

Receptor-specific targeting with complementary peptide nucleic acids conjugated to peptide analogs and radionuclides

Summary Genomic sequencing makes it possible to identify all the genes of an organism, now including Homo sapiens. Yet measurement of the expression of each gene of interest still presents a daunting prospect. Northern blots, RNase protection assays, as well as microarrays and related technologies permit measurement of gene expression in total RNA extracted from cultured cells or tissue samples. It would be most valuable, however, to quantitate gene expression noninvasively in living cells and tissues. Unfortunately, no reliable method has been available to measure levels of specific mRNAs in vivo. Peptide nucleic acids (PNAs) display superior ruggedness and hybridization properties as a diagnostic tool for gene expression, and could be used for this purpose. On the down side, they are negligibly internalized by normal or malignant cells in the absence of conjugated ligands. Nevertheless, we have observed that Tc-99m-peptides can delineate tumors, and PNA-peptides designed to bind to IGF-1 receptors on malignant cells are taken up specifically and concentrated in nuclei. We have postulated that antisense Tc-99m-PNA-peptides will be taken up by human cancer cells, will hybridize to complementary mRNA targets, and will permit scintigraphic imaging of oncogene mRNAs in human cancer xenografts in a mouse model. The oncogenes cyclin D1, ERBB2, c-MYC, K-RAS, and tumor suppressor p53 are being probed initially. These experiments provide a proof-of-principle for noninvasive detection of oncogene expression in living cells and tissues. This scintigraphic imaging technique should be applicable to any particular gene of interest in a cell or tissue type with characteristic receptors.     

Three-dimensional reconstruction of brain surface anatomy based on magnetic resonance imaging diffusion-weighted imaging: A new approach

Fifty normal noninfarct patients and 12 cases with infarcts of the cerebrum were examined with routine magnetic resonance imaging and echo-planar diffusion-weighted imaging. The diffusion-weighted three-dimensional images were reconstructed with volume-rendering processing on workstation. Precentral gyrus, post-central gyrus, superior parietal lobule, superior frontal gyrus, precentral sulcus, central sulcus, postcentral sulcus, intraparietal sulcus and superior frontal sulcus were best shown of all structures with an arbitrary score of 2.61–2.77. Supramarginal gyrus, middle frontal gyrus, inferior frontal gyrus and lateral sulcus were clearly shown in the majority of the cerebra with average scores of 2.0–2.49; angular gyrus, inferior frontal sulcus and superior temporal gyrus were not demonstrated satisfactorily and their average scores were 1.67–1.89. Middle temporal gyrus, inferior temporal gyrus, superior temporal sulcus and inferior temporal sulcus were difficult to identify, and thus had average scores of 0.87–1.26. Brain surface structures were better displayed in the older group of individuals than in the younger group. The structures in the 12 cases with acute or chronic cerebrum infarcts were also satisfactorily demonstrated with this new technique.     

鲜花的光学性质

本文采用反射光谱、荧光光谱、激发光谱研究了迎春花、紫红色芍药、大红月季和橙红月季的光生态。结果表明,不同的鲜花光生态有明显的差异,鲜花中的花青素和类胡萝卜素在紫外光、可见光的激发下发出荧光,使鲜花更加鲜艳靓丽。通过对鲜花光生态的讨论,揭示出阳光对花儿的影响与作用,为鲜花光生态膜的开发以及人工照明的应用提供一定的生态依据。