Diffusion tensor imaging reveals brain abnormality patterns in a patient with semantic dementia

BACKGROUND： Previous studies regarding primary progressive aphasia （PPA） have focused on progressive, non-fluent aphasia. Little information is available with regard to the use of diffusion tensor imaging compared with conventional magnetic resonance imaging for the detection of subtle structural abnormalities. OBJECTIVE： To investigate and localize brain abnormalities in a Chinese patient with semantic dementia. DESIGN, TIME AND SETTING： A concurrent, non-randomized, case-controlled, neuroimaging, clinical trial was performed at the Department of Radiology, West China Hospital of Sichuan University in March 2009. PARTICIPANTS： One 75-year-old male patient, who was diagnosed with semantic dementia, and 21 age- and gender-matched healthy volunteers were recruited for the study. METHODS： Diffusion tensor imaging was used to determine mean diffusion （MD） and fractional anisotropy （FA） in the brains of the patient and the 21 healthy subjects. Voxel-based analysis of MD and FA values was performed using statistical parametric mapping. MAIN OUTCOME MEASURES： MD and FA value maps differences between patient and controls. RESULTS： MD was significantly increased in both cerebra, but was predominant on the left side and expanded to outside of the language-related region. Reduced MD was not detected in any of the brains. FA was shown to be decreased in the corpus callosum, but was increased in the basal ganglia. CONCLUSION： The present study provided clear in vivo magnetic imaging evidence of diffuse brain involvement in semantic dementia. Increases in MD were greater than in FA when brain diffusion alterations were detected, which suggested that MD could be a better marker of disease progression.

Repetitive transcranial magnetic stimulation of language function in patients with refractory epilepsy A preliminary functional magnetic resonance imaging study

To investigate whether repetitive transcranial magnetic stimulation （rTMS） can improve language function in patients with refractory epilepsy, three right-handed, refractory epilepsy patients who had complained of language dysfunction, were recruited. Over 1 month, 1-Hz rTMS treatment was performed every 3 days. A battery of language production and functional MRI were evaluated in the patients using a standard verb generation task both before and 1 month after rTMS treatment. Significant and lasting improvement in verb production was observed following rTMS treatment. Functional MRI results revealed that the left frontal lobes of two patients were more activated than they had been prior to therapy, and activation was primarily concentrated in the language-related areas. Results demonstrated that low frequency rTMS has potential to improve language function in patients with refractory epilepsy.

基于集成学习的高分辨率人口空间化模拟

高分辨率的人口空间化数据已成为重要决策中不可或缺的基础数据。文章旨在探索基于集成学习融合社会感知大数据和多源遥感数据进行人口空间化模拟的方法体系,选取浙江省为研究区,以腾讯位置大数据、兴趣点和遥感数据为数据源,使用神经网络、XGBoost和随机森林三种机器学习算法以及Stacking集成学习方法分别构建人口空间化模型并对比分析其模拟精度,获得2020年浙江省100 m分辨率的人口栅格数据。结果表明:①单个机器学习算法中,随机森林的模拟精度最高,Stacking集成学习策略具有良好泛化性能,有效缓解了单一模型的高值溢出现象,减少了模拟误差;②集成学习人口网格中浙江省人口高值集中于城市中心区域,峰值约为500人/网格,人口密度随城市中心距离增大逐级递减;③与WorldPop人口数据集相较,集成学习人口数据集在城市中心人口模拟、数据完整性等方面有显著优势。

The Ubiquitin E3 Ligase PUB17 Positively Regulates Immunity by Targeting a Negative Regulator, KH17, for Degradation

Ubiquitination is a post-translational modification that regulates many processes in plants.Several ubiquitin E3 ligases act as either positive or negative regulators of immunity by promoting the degradation of different substrates.StPUB17 is an E3 ligase that has previously been shown to positively regulate immunity to bacteria,fungi and oomycetes,including the late blight pathogen Phytophthora infestans.Silencing of StPUB17 promotes pathogen colonization and attenuates Cf4/avr4 cell death.Using yeast-2-hybrid and co-immunoprecipitation we identified the putative K-homology(KH)RNA-binding protein(RBP),StKH17,as a candidate substrate for degradation by StPUB17.StKH17 acts as a negative regulator of immunity that promotes P.infestans infection and suppresses specific immune pathways.A KH RBP domain mutant of StKH17(StKH17GDDG)is no longer able to negatively regulate immunity,indicating that RNA binding is likely required for StKH17 function.As StPUB17 is a known target of the ubiquitin E3 ligase,StPOB1,we reveal an additional step in an E3 ligase regulatory cascade that controls plant defense.

Index of microcirculatory resistance: state-of-the-art and potential applications in computational simulation of coronary artery disease

The dysfunction of coronary microcirculation is an important cause of coronary artery disease(CAD).The index of microcirculatory resistance(IMR)is a quantitative evaluation of coronary microcirculatory function,which provides a significant reference for the prediction,diagnosis,treatment,and prognosis of CAD.IMR also plays a key role in investigating the interaction between epicardial and microcirculatory dysfunctions,and is closely associated with coronary hemodynamic parameters such as flow rate,distal coronary pressure,and aortic pressure,which have been widely applied in computational studies of CAD.However,there is currently a lack of consensus across studies on the normal and pathological ranges of IMR.The relationships between IMR and coronary hemodynamic parameters have not been accurately quantified,which limits the application of IMR in computational CAD studies.In this paper,we discuss the research gaps between IMR and its potential applications in the computational simulation of CAD.Computational simulation based on the combination of IMR and other hemodynamic parameters is a promising technology to improve the diagnosis and guide clinical trials of CAD.

Changes of cortical bone pores structure and their effects on mechanical properties in tail-suspended rats

Cortical bone is the main mechanical bearing structure of bone,and the mechanical properties of materials are not only related to bone mineral density,but also largely depend on its pores microstructure which affected by blood vessels.However,the change of pores structure in cortical bone under microgravity was still unclear.In this study,in order to clear the changes of pore structure with cortical vascular pores and its effect on bone mechanical properties,rat tail-suspension was used to simulate microgravity and the changes of the microstructure in rat tibia cortices were investigated by high-resolution micro-CT(3μm)while the bone mechanical properties were measured via three point bending test.The results showed the bone mineral density of cortical bone didn't change in tail-suspended rats.However,the pore structure of cortical bone in tail-suspended rats changed significantly,the proportion of pores greater than 15μm(cortical vascular pores)increased while that less than 15μm decreased.The mechanical properties of bone(such as maximum load and maximum stress)in tail-suspended rats deteriorated.And the volume ratio of pore vessels(vessel volume/tissue volume)was negatively correlated with the mechanical properties.In conclusion,the increase of cortical vascular pores in rats caused by the simulated microgravity contributes to the decrease of mechanical properties.

Drag Effects of Solute and Second Phase Distributions on the Grain Growth Kinetics of Pre-Extruded Mg-6Zn Alloy

In order to control the grain size during hot forming,grain growth behavior of a pre-extruded Mg-6Zn magnesium alloy and its correlation with solute and second phase distribution were investigated.Isothermal annealing was conducted on a Gleeble-1500 thermo-mechanical simulator.The mean grain size Dg of each annealed specimen was measured by the quantitative metallography technique.The grain growth kinetics of the Mg-6Zn alloy annealed at 473-623 K was obtained as Dg^4- Dg0^4=2.25 ×10^11 exp（-95450）by the least square linear regression method.The deviation of grain growth exponent n = 4 from the theoretical value of 2 may be attributed to the presence of solute zinc and second phases which will retard the boundary migration.Microscopic observations show that the non-uniform distribution of grain size for samples pre-extruded or annealed at low temperatures is closely related to the non-uniform distribution of fine and dispersed second phases but not to the non-uniform distribution of solute zinc.This indicates that second phase pinning effect plays an important role in microstructure refinement.