Optimal stimulation frequency for vibrational optical coherence elastography

Vibrational optical coherence elastography (OCE) is a promising tool for extracting the mechanical property of soft tissue. Purpose of this study is focusing on settling the optimal frequency range for vibrational OCE with evenly distributed stress filed. A finite element model of 2% agar phantom was built by ANSYS with a vibration stimulation frequency range from 200 to 3000 Hz. Practical experiments were carried out for cross‐validation with the same frequencies and sample. Lateral and horizontal stress filed distributions under different frequencies were mathematically evaluated by coefficient of variance and degree of linearity. Results from simulation and practical experiment cross‐validated each other and 1000 Hz was set as the maximum ideal frequency for vibrational OCE, while the minimum frequency is set by theoretical calculation with a result of 250 Hz. An ex vivo biological sample was utilised to testify performance of vibrational OCE with excitation frequencies in and out of concluded optimal range, which showed that stiffness was better mapped out in optimal frequency range.     

EST分子标记开发及在比较基因组学中的应用

数量迅速增加的EST(expressed sequence tags)为分子标记的开发提供了宝贵的资源。与来自于基因组DNA开发的传统标记相比,以EST为基础的分子标记是一种新型分子标记,具有其显著的优势,如开发简便、信息量高和通用性好等,在多方面都有重要的利用价值。本文详细地介绍了目前基于EST开发的5类分子标记以及基于生物信息学方法的开发策略,这些标记包括EST-PCR、EST-SSR、EST-SNP、EST-RFLP和EST-AFLP。此外,对这些标记在比较基因组学研究中的应用进行了评述,包括比较作图、遗传多样性评价及系统发育研究等。     

Bone morphogenetic protein-7 (BMP-7) mediates ischemic preconditioning-induced ischemic tolerance via attenuating apoptosis in rat brain

A mild cerebral ischemic insult, also known as ischemic preconditioning (IPC), confers transient tolerance to a subsequent ischemic challenge in the brain. This study was conducted to investigate whether bone morphogenetic protein-7 (BMP-7) is involved in neuroprotection elicited by IPC in a rat model of ischemia. Ischemic tolerance was induced in rats by IPC (15 min middle cerebral artery occlusion, MCAO) at 48 h before lethal ischemia (2 h MCAO). The present data showed that IPC increased BMP-7 mRNA and protein expression after 24 h reperfusion following ischemia in the brain. In rats of ischemia, IPC-induced reduction of cerebral infarct volume and improvement of neuronal morphology were attenuated when BMP-7 was inhibited either by antagonist noggin or short interfering RNA (siRNA) pre-treatment. Besides, cerebral IPC-induced up-regulation of B-cell lymphoma 2 (Bcl-2) and down-regulation of cleaved caspase-3 at 24 h after ischemia/reperfusion (I/R) injury were reversed via inhibition of BMP-7. These findings indicate that BMP-7 mediates IPC-induced tolerance to cerebral I/R, probably through inhibition of apoptosis.     

邻苯二甲酸对萝卜种子萌发、幼苗叶片膜脂过氧化及渗透调节物质的影响

华北地区是我国玉米的主产区,玉米秸秆还田不仅可有效改善土壤理化性状、提高土壤生物有效性,还会在腐解过程中释放出目前公认的化感物质——酚酸类物质,邻苯二甲酸是玉米秸秆腐解液中的主要酚酸类物质。从玉米秸秆还田过程中主要腐解产物(邻苯二甲酸)对蔬菜作物的化感效应角度进行了研究,为量化秸秆还田量及构建粮-菜轮作制度探寻化感效应依据。试验以萝卜为蔬菜材料,通过配置4个浓度(0.05、0.5、1.0、2.0 mmol/L)的邻苯二甲酸溶液,模拟玉米秸秆还田条件,以清水为对照,研究主要腐解产物邻苯二甲酸对萝卜种子萌发、幼苗生长、膜脂过氧化作用及渗透调节物质的影响。结果表明:(1)萝卜不同生育期对邻苯二甲酸化感效应的响应程度不同。在0.05-1 mmol/L浓度范围内,邻苯二甲酸处理促进了萝卜种子萌发,但随着处理浓度的增大,促进作用减弱;浓度达到2 mmol/L时对萝卜种子萌发具有抑制效果。(2)邻苯二甲酸0.05mmol/L处理,促进了萝卜幼苗干鲜物质积累,幼苗根系生长,其中根系长度和根系表面积分别比对照提高42.03%、38.36%,显著高于清水对照;植株体内超氧化物歧化酶(Superoxide dismutase, SOD)活性增大,过氧化物酶(Peroxidase, POD)、过氧化氢酶(Catalase, CAT)活性降低,膜脂过氧化产物丙二醛(Malonaldehyde, MDA)含量与对照无显著差异。(3)当邻苯二甲酸浓度超过0.5 mmol/L时,萝卜幼苗脂质过氧化伤害加剧,体内MDA含量急剧增加,代谢与生理功能出现紊乱,正常生长及干鲜物质积累受到显著抑制。邻苯二甲酸浓度达到2 mmol/L时,叶片数较对照降低了36.51%;根系长度、根系表面积及根尖数降幅分别为64.46%、40.20%、41.28%。(4)对于渗透调节物质的影响,邻苯二甲酸处理促进了萝卜幼苗叶片可溶性糖含量的增加,但随着处理浓度的升高其促进作用逐渐减弱;可溶性蛋白含量随着邻苯二甲酸处理浓度的升高表现出逐渐减少的趋势,分别较对照降低了12.82%、14.88%、21.58%、24.73%。因此,华北地区实施玉米-萝卜轮作模式,从化感效应角度研究玉米秸秆量化还田,应将土壤中邻苯二甲酸浓度控制在0.5 mmol/L范围以内,以防止邻苯二甲酸浓度过高对萝卜幼苗生长的抑制作用。     

Total HIV/AIDS Expenditures in Dehong Prefecture,Yunnan Province in 2010: The First Systematic Evaluation of Both Health and Non-Health Related HIV/AIDS Expenditures in China

Objective

We assessed HIV/AIDS expenditures in Dehong Prefecture, Yunnan Province, one of the highest prevalence regions in China, and describe funding sources and spending for different categories of HIV-related interventions and at-risk populations.

Methods

2010 HIV/AIDS expenditures in Dehong Prefecture were evaluated based on UNAIDS’ National AIDS Spending Assessment methodology.

Results

Nearly 93% of total expenditures for HIV/AIDS was contributed by public sources. Of total expenditures, 52.7% was allocated to treatment and care, 24.5% to program management and administration and 19.8% to prevention. Spending on treatment and care was primarily allocated to the treatment of opportunistic infections. Most (40.4%) prevention spending was concentrated on most-at-risk populations, injection drug users (IDUs), sex workers, and men who have sex with men (MSM), with 5.5% allocated to voluntary counseling and testing. Prevention funding allocated for MSM, partners of people living with HIV and prisoners and other confined populations was low compared to the disproportionate burden of HIV/AIDS in these populations. Overall, people living with HIV accounted for 57.57% of total expenditures, while most-at-risk populations accounted for only 7.99%.

Conclusions

Our study demonstrated the applicability of NASA for tracking and assessing HIV expenditure in the context of China, it proved to be a useful tool in understanding national HIV/AIDS response from financial aspect, and to assess the extent to which HIV expenditure matches epidemic patterns. Limited funding for primary prevention and prevention for MSM, prisoners and partners of people living with HIV, signal that resource allocation to these key areas must be strengthened. Comprehensive analyses of regional and national funding strategies are needed to inform more equitable, effective and cost-effective HIV/AIDS resource allocation.     

人精子特异性乳酸脱氢酶结构和功能的计算生物学分析

精子特异性乳酸脱氢酶（lactate dehydrogenase,LDH）,又称乳酸脱氢酶C4（lactate dehydrogenase C4,LDH-C4）,特异性地存在于哺乳动物发育成熟的睾丸组织中,与精子的生成、代谢、获能等有密切关系. 根据GenBank数据库中人LDH-C4氨基酸序列（P07864）,利用PROSITE数据库预测人LDH-C4的功能基序|利用Clustalw2、TreeView1.6.6进行LDH-C4进化树的构建|利用I-TASSER软件预测人LDH-C4的二、三、四级结构以及功能位点. 结果表明：在190~196位有1个LDH活性位点,该位点为脊椎动物各亚型乳酸脱氢酶共有的催化位点,为进化中的1个保守序列|从进化树来看,LDHC和LDHB的亲缘关系比较近|人LDH-C4与小鼠LDH-C4的二级、三级结构具有很高的相似性|LDH-4属乳酸脱氢酶 苹果酸脱氢酶（LDH-MDH）超家族中的LDH-(cd05293）家族的成员,属于NAD依赖性酶,拥有LDH-1家族具备的基本结构特点. 以上结果为研究LDH-C4基因突变对其功能的影响打下基础.     

基于光谱技术的产前检测方法研究进展

优生优育是我们重要的国策。自二胎政策颁布以来,高龄产妇数量呈现明显上升的趋势,先天性畸形儿的发生几率变大。传统的产前检测方法存在较高流产风险、灵敏度低、耗时等问题,探寻一种无损快捷、经济灵敏的产前检测方法至关重要。本文首先介绍了常见的胎儿出生缺陷及当前临床常见的产前检测方法的优缺点,重点综述了光谱技术的特点及其在产前检测中的应用。其中包括光谱核型、实时荧光定量PCR、SNP等位基因位点分析等利用荧光光谱分析方法和拉曼光谱在产前检测中的应用情况。特别阐述了表面增强拉曼光谱SERS在生物检测中的优势,最后总结并展望了SERS光谱在产前检测的应用。     

Magnetic Field–Suppressed Lithium Dendrite Growth for Stable Lithium‐Metal Batteries

Lithium metal is the most attractive anode material due to its extremely high specific capacity, minimum potential, and low density. However, uncontrollable growth of lithium dendrite results in severe safety and cycling stability concerns, which hinders the application in next generation secondary batteries. In this paper, a new and facile method imposing a magnetic field to lithium metal anodes is proposed. That is, the lithium ions suffering Lorentz force due to the electromagnetic fields are put into spiral motion causing magnetohydrodynamics (MHD) effect. This MHD effect can effectively promote mass transfer and uniform distribution of lithium ions to suppress the dendrite growth as well as obtain uniform and compact lithium deposition. The results show that the lithium metal electrodes within the magnetic field exhibit excellent cycling and rate performance in a symmetrical battery. Additionally, full batteries using limited lithium metal as anodes and commercial LiFePO₄ as cathodes show improved performance within the magnetic field. In summary, a new and facile strategy of suppressing lithium dendrites using the MHD effect by imposing a magnetic field is proposed, which may be generalized to other advanced alkali metal batteries.