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1.
Living mysticetes (baleen whales) and odontocetes (toothed whales) differ significantly in auditory function in that toothed whales are sensitive to high‐frequency and ultrasonic sound vibrations and mysticetes to low‐frequency and infrasonic noises. Our knowledge of the evolution and phylogeny of cetaceans, and mysticetes in particular, is at a point at which we can explore morphological and physiological changes within the baleen whale inner ear. Traditional comparative anatomy and landmark‐based 3D‐geometric morphometric analyses were performed to investigate the anatomical diversity of the inner ears of extinct and extant mysticetes in comparison with other cetaceans. Principal component analyses (PCAs) show that the cochlear morphospace of odontocetes is tangential to that of mysticetes, but odontocetes are completely separated from mysticetes when semicircular canal landmarks are combined with the cochlear data. The cochlea of the archaeocete Zygorhiza kochii and early diverging extinct mysticetes plot within the morphospace of crown mysticetes, suggesting that mysticetes possess ancestral cochlear morphology and physiology. The PCA results indicate variation among mysticete species, although no major patterns are recovered to suggest separate hearing or locomotor regimes. Phylogenetic signal was detected for several clades, including crown Cetacea and crown Mysticeti, with the most clades expressing phylogenetic signal in the semicircular canal dataset. Brownian motion could not be excluded as an explanation for the signal, except for analyses combining cochlea and semicircular canal datasets for Balaenopteridae. J. Morphol. 277:1599–1615, 2016. © 2016 Wiley Periodicals, Inc.  相似文献   
2.
Biochemical detection of inborn errors of creatine metabolism or transport relies on the analysis of three main metabolites in biological fluids: guanidinoacetate (GAA), creatine (CT) and creatinine (CTN). Unspecific clinical presentation of the diseases might be the cause that only few patients have been diagnosed so far. We describe a LC–MS/MS method allowing fast and reliable diagnosis by simultaneous quantification of GAA, CT and CTN in urine, plasma and cerebrospinal fluid (CSF) and established reference values for each material.  相似文献   
3.
PurposeAccurate determination of the bifurcation angle and correlation with plaque buildup may lead to the prediction of coronary artery disease (CAD). This work evaluates two techniques to measure bifurcation angles in 3D space using coronary computed tomography angiography (CCTA).Materials and MethodsNine phantoms were fabricated with different bifurcation angles ranging from 55.3° to 134.5°. General X-ray and CCTA were employed to acquire 2D and 3D images of the bifurcation phantoms, respectively. Multiplanar reformation (MPR) and volume rendering technique (VRT) were used to measure the bifurcation angle between the left anterior descending (LAD) and left circumflex arteries (LCx). The measured angles were compared with the true values to determine the accuracy of each measurement technique. Inter-observer variability was evaluated. The two techniques were further applied on 50 clinical CCTA cases to verify its clinical value.ResultsIn the phantom setting, the mean absolute differences calculated between the true and measured angles by MPR and VRT were 2.4° ± 2.2° and 3.8° ± 2.9°, respectively. Strong correlation was found between the true and measured bifurcation angles. Furthermore, no significant differences were found between the bifurcation angles measured using either technique. In clinical settings, large difference of 12.0° ± 10.6° was found between the two techniques.ConclusionIn the phantom setting, both techniques demonstrated a significant correlation to the true bifurcation angle. Despite the lack of agreement of the two techniques in the clinical context, our findings in phantoms suggest that MPR should be preferred to VRT for the measurement of coronary bifurcation angle by CCTA.  相似文献   
4.
目的:观察有或无CT脑灌注"点征"自发性脑内出血(sICH)患者的临床疗效。方法:以本院2013年5月~2015年5月就诊的100例s ICH,均接受基线CT脑灌注检查,依据是否有"点征"将患者分为观察组(有"点征")与对照组(无"点征"),24内行CT平扫复查,比较两组影像学结果及临床结果。并通过Logistic多因素分析影响s ICH患者预后不良(死亡)危险因素。结果:观察组24h内CT平扫复查血肿增长6 mL以上、血肿增长相对值33%及以上比率均明显高于对照组(P0.05);观察组血肿进展发生率、3个月内死亡率分别为63.04%、36.96%,显著高于对照组的14.81%、7.41%(P0.05)。Logistic回归分析发现sICH患者预后不良独立危险因素包括基线血肿体积、"点征"。结论:有或无CT脑灌注"点征"自发性脑内出血患者血肿进展、预后不同,基线血肿体积、"点征"为sICH患者预后不良的独立危险因素。  相似文献   
5.
In recent years the study of root phenotypic plasticity in response to sub-optimal environmental factors and the genetic control of these responses have received renewed attention. As a path to increased productivity, in particular for low fertility soils, several applied research projects worldwide target the improvement of crop root traits both in plant breeding and biotechnology contexts. To assist these tasks and address the challenge of optimizing root growth and architecture for enhanced mineral resource use, the development of realistic simulation models is of great importance. We review this research field from a modeling perspective focusing particularly on nutrient acquisition strategies for crop production on low nitrogen and low phosphorous soils. Soil heterogeneity and the dynamics of nutrient availability in the soil pose a challenging environment in which plants have to forage efficiently for nutrients in order to maintain their internal nutrient homeostasis throughout their life cycle. Mathematical models assist in understanding plant growth strategies and associated root phenes that have potential to be tested and introduced in physiological breeding programs. At the same time, we stress that it is necessary to carefully consider model assumptions and development from a whole plant-resource allocation perspective and to introduce or refine modules simulating explicitly root growth and architecture dynamics through ontogeny with reference to key factors that constrain root growth. In this view it is important to understand negative feedbacks such as plant–plant competition. We conclude by briefly touching on available and developing technologies for quantitative root phenotyping from lab to field, from quantification of partial root profiles in the field to 3D reconstruction of whole root systems. Finally, we discuss how these approaches can and should be tightly linked to modeling to explore the root phenome.  相似文献   
6.
张子为  胡云  李爱梅  徐郁  黄洪  郭万华 《生物磁学》2009,(19):3707-3709,3731
目的:通过PET/CT检查观察脂肪肝患者肝脏及其他组织对18F脱氧葡萄糖(18F-FDG)摄入变化,探讨脂肪肝与糖脂代谢的相关性。方法:36例做PET/CT的健康和2型糖尿病男性患者,分为对照组(n=18例);脂肪肝组(n=9例);糖尿病脂肪肝组(n=9例)。常规测血糖、血脂及肝肾功能。PET/CT测肝脏CT值和肝脏、肾皮质,骨骼肌组织18F-FDG的最大标准摄入值(SUVmax)及平均标准摄入值(SUVmean)。结果:1.糖尿病脂肪肝组的TG显著高于单纯脂肪肝组和正常对照组,P=0.0003,0.0000。单纯脂肪肝组的TG亦显著高于正常对照组,P=0.028。2.糖尿病脂肪肝组的肝脏18F-FDG的SUVmean和SUVmax显著高于正常对照组的SUVmean和SUVmax,P=0.0054,0.0133。单纯脂肪肝组的肝脏SUVmean和SUVmax亦高于正常对照组,但比较无统计学差异。脑皮质、肾皮质和骨骼肌组织的18F-FDG的SUVmean和SUVmax三组间比较无显著性差异。3.Spearman相关性分析发现FBG与TG显著正相关(r=0.59919,P=0.0004);FBG和TG与肝脏的CT值显著负相关(r=-0.55625,P=0.0004;r=-0.45739,P=0.0097)。结论:脂肪肝与空腹血糖和甘油三酯升高显著相关。脂肪肝及2型糖尿病脂肪肝患者肝脏对葡萄糖摄取增高。  相似文献   
7.
Cardiac calsequestrin (CASQ2) contributes to intracellular Ca2+ homeostasis by virtue of its low-affinity/high-capacity Ca2+ binding properties, maintains sarcoplasmic reticulum (SR) architecture and regulates excitation–contraction coupling, especially or exclusively upon β-adrenergic stimulation. Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disease associated with cardiac arrest in children or young adults. Recessive CPVT variants are due to mutations in the CASQ2 gene. Molecular and ultra-structural properties were studied in hearts of CASQ2R33Q/R33Q and of CASQ2−/− mice from post-natal day 2 to week 8. The drastic reduction of CASQ2-R33Q is an early developmental event and is accompanied by down-regulation of triadin and junctin, and morphological changes of jSR and of SR-transverse-tubule junctions. Although endoplasmic reticulum stress is activated, no signs of either apoptosis or autophagy are detected. The other model of recessive CPVT, the CASQ2−/− mouse, does not display the same adaptive pattern. Expression of CASQ2-R33Q influences molecular and ultra-structural heart development; post-natal, adaptive changes appear capable of ensuring until adulthood a new pathophysiological equilibrium.  相似文献   
8.
PurposeThe purpose of this study was to develop and validate a Monte Carlo (MC) simulation tool for patient dose assessment for a 320 detector-row CT scanner, based on the recommendations of International Commission on Radiological Protection (ICRP). Additionally, the simulation was applied on four clinical acquisition protocols, with and without automatic tube current modulation (TCM).MethodsThe MC simulation was based on EGS4 code and was developed specifically for a 320 detector-row cone-beam CT scanner. The ICRP adult reference phantoms were used as patient models. Dose measurements were performed free-in-air and also in four CTDI phantoms: 150 mm and 350 mm long CT head and CT body phantoms. The MC program was validated by comparing simulations results with these actual measurements acquired under the same conditions. The measurements agreed with the simulations across all conditions within 5%. Patient dose assessment was performed for four clinical axial acquisitions using the ICRP adult reference phantoms, one of them using TCM.ResultsThe results were nearly always lower than those obtained from other dose calculator tools or published in other studies, which were obtained using mathematical phantoms in different CT systems. For the protocol with TCM organ doses were reduced by between 28 and 36%, compared to the results obtained using a fixed mA value.ConclusionsThe developed simulation program provides a useful tool for assessing doses in a 320 detector-row cone-beam CT scanner using ICRP adult reference computational phantoms and is ready to be applied to more complex protocols.  相似文献   
9.
Bone-cement interface has been investigated under selected loading conditions, utilising experimental techniques such as in situ mechanical testing and digital image correlation (DIC). However, the role of bone type in the overall load transfer and mechanical behaviour of the bone-cement construct is yet to be fully quantified. Moreover, microdamage accumulation at the interface and in the cement mantle has only been assessed on the exterior surfaces of the samples, where no volumetric information could be obtained. In this study, some typical bone-cement interfaces, representative of different fixation scenarios for both hip and knee replacements, were constructed using mainly trabecular bone, a mixture of trabecular and cortical bone and mainly cortical bone, and tested under static and cyclic compression. Axial displacement and strain fields were obtained by means of digital volume correlation (DVC) and microdamage due to static compression was assessed using DVC and finite element (FE) analysis, where yielded volumes and strains (εzz) were evaluated. A significantly higher load was transferred into the cement region when mainly cortical bone was used to interdigitate with the cement, compared with the other two cases. In the former, progressive damage accumulation under cyclic loading was observed within both the bone-cement interdigitated and the cement regions, as evidenced by the initiation of microcracks associated with high residual strains (εzz_res).  相似文献   
10.
CT灌注成像(CT perfusion imaging,CTPI)作为一种功能成像技术可无创性评估靶目标的血流动力学情况。自1993年Mile等首次报道其在肝脏肿瘤的应用以来,随着工业技术的进步,软硬件的更新,既往CTPI存在的问题,诸如,辐射剂量过高,扫描协议缺乏标准化,呼吸运动伪影,结果可重复性问题,扫描范围较小等问题均得到了不同程度的改善,使其在肝脏肿瘤应用中表现出了巨大的潜力。众所周知,CTPI的出现弥补了传统形态学成像方式对肿瘤的早期诊断,预后评估,检测新型分子靶向药物疗效等的不足。本文总结了近年来肝CTPI技术在肝肿瘤应用现状、存在的问题及未来展望。  相似文献   
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