Differential ligand regulation of PlexB signaling in motor neuron axon guidance in Drosophila

Plexins (Plexs) are a large family of phylogenetically conserved guidance receptors that bind specifically to semaphorins (Semas), another large family of guidance molecules. In the Drosophila embryonic central nervous system (CNS), the secreted semaphorins Sema-2a and Sema-2b both act as ligands for PlexB, but mediate mutually independent and opposite functions (repulsive and attractive guidance, respectively). PlexB is also known to regulate motor axon guidance in the embryonic peripheral nervous system (PNS). However, it is unclear whether the mechanisms of ligand regulation of PlexB seen in the CNS are similar or the same as those that exist in PNS motor axon guidance. Here, we find that two distinct modes of ligand regulation underlie differential roles of PlexB in PNS motor axon pathfinding during embryonic development. Epistasis analyses in the intersegmental nerve b (ISNb) pathway suggest that PlexB serves as a receptor for both Sema-2a and Sema-2b and integrates their mutually dependent but opposite guidance functions. Furthermore, we present evidence that PlexB mediates not only Sema-2a/2b-dependent guidance functions, but also Sema-2a/2b-independent target recognition in establishing the segmental nerve a (SNa) motor axon pathway. These results demonstrate that a single guidance receptor can elicit diverse effects on the establishment of neuronal connectivity via regulation of its ligands themselves.     

Prevention of treatable infectious diseases: A game-theoretic approach

We model outcomes of voluntary prevention using an imperfect vaccine, which confers protection only to a fraction of vaccinees for a limited duration. Our mathematical model combines a single-player game for the individual-level decision to get vaccinated, and a compartmental model for the epidemic dynamics. Mathematical analysis yields a characterization for the effective vaccination coverage, as a function of the relative cost of prevention versus treatment; note that cost may involve monetary as well as non-monetary aspects. Three behaviors are possible. First, the relative cost may be too high, so individuals do not get vaccinated. Second, the relative cost may be moderate, such that some individuals get vaccinated and voluntary vaccination alleviates the epidemic. In this case, the vaccination coverage grows steadily with decreasing relative cost of vaccination versus treatment. Unlike previous studies, we find a third case where relative cost is sufficiently low so epidemics may be averted through the use of prevention, even for an imperfect vaccine. However, we also found that disease elimination is only temporary—as no equilibrium exists for the individual strategy in this third case—and, with increasing perceived cost of vaccination versus treatment, the situation may be reversed toward the epidemic edge, where the effective reproductive number is 1. Thus, maintaining relative cost sufficiently low will be the main challenge to maintain disease elimination. Furthermore, our model offers insight on vaccine parameters, which are otherwise difficult to estimate. We apply our findings to the epidemiology of measles.     

飞蛾藤属植物的多指标含量测定及化学模式识别研究

目的 建立HPLC测定飞蛾藤属植物多指标含量的方法，为飞蛾藤属植物的质量控制提供参考。方法 采用Agilent 5 TC-C₁₈色谱柱(250 mm×4.6 mm，5 μm)，流动相乙腈-0.1%磷酸梯度洗脱，体积流量1.0 mL·min^-1，柱温25 ℃，检测波长345 nm；并结合聚类分析、主成分分析及偏最小二乘判别分析评价飞蛾藤属植物中9种成分的差异。结果 9种成分在各自范围内线性关系良好(r>0.999 0)，精密度、稳定性及重复性试验结果的RSD均<3.00%，平均加样回收率为97.29%~103.21%。聚类分析、主成分分析及偏最小二乘判别分析结果显示，16批飞蛾藤属植物可明显分开，组内样品有很强的相似性，而组间样品差异较大。通过PLS-DA中变量重要性投影分析发现4个差异性指标成分，分别为绿原酸、异绿原酸A、N-反式-阿魏酰酪胺和东莨菪内酯。结论 建立了简便、精密的飞蛾藤属植物多指标含量测定方法，且通过统计方法证明绿原酸、异绿原酸A、N-反式-阿魏酰酪胺和东莨菪内酯为飞蛾藤属植物质量差异性评价的指标成分，为飞蛾藤属植物的区分及质量控制提供参考。     

Alobar holoprosencephaly with cyclopia – Autopsy-based observations from one medical center

Holoprosencephaly, a major congenital malformation of the brain, consists in a complete or partial failure of the prosencephalon to divide into separate hemispheres. Alobar holoprosencephaly with cyclopia was analyzed on the basis of autopsy reports performed for hospitals admitting patients from the Lublin Region in Eastern Poland in the period of 20 years (1981–2000). The malformation was found in seven newborns – five girls, one boy and one child with sex not established due to agenesia of the genital organs, all autopsied in the years 1990–1999. According to clinical data, none of the mothers (age 24–39 years) was exposed to any prescribed or over-the-counter (OTC) drugs during pregnancy, but one was exposed to paints in early pregnancy. The proboscis was present in four of seven cases. Six of seven children displayed additional congenital malformations. In two cases intrapancreatic accessory spleen suggesting trisomy 13 was found. Alobar holoprosencephaly with cyclopia is a rare lethal congenital anomaly frequently accompanied by other malformations and characterized by large variations in incidence.     

陕西省某医院血液透析患者丙型肝炎病毒感染事件调查

通过个案流行病学调查、现场勘查和实验室检测,对一起医院内血液透析患者丙型肝炎（丙肝）病毒感染暴发事件进行调查分析,为医院内丙肝感染预防与控制提供借鉴。 本起丙肝病毒感染事件共涉及78例血液透析患者,确诊39例丙肝患者;现场勘查发现该医院血液透析室存在未对乙型肝炎、丙肝患者实行隔离透析,多人共用肝素注射器,部分透析器复用消毒程序不规范等问题,是导致本次暴发的主要原因。     

Microstructure,friction and corrosion resistance properties of a Ni–Co–Al2O3 composite coating

Ni–Co–Al₂O₃ composite coatings were prepared by pulsed electrodeposition and electrophoresis–electrodeposition on aluminum alloy. The content of Al₂O₃ particles of the Ni–Co–Al₂O₃ composite coating prepared by electrophoresis–electrodeposition was significantly higher than the composite coating prepared by pulsed electrodeposition. The composite coating prepared by electrophoresis–electrodeposition exhibited a better anti-wear performance than that prepared by pulsed electrodeposition. The morphology, composition and microstructure of the composite coatings were determined by means of X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The hardness and friction properties of the samples were tested on the microhardness tester and the friction and wear loss tester respectively.

Ni–Co–Al₂O₃ composite coatings were prepared by pulsed electrodeposition and electrophoresis–electrodeposition on aluminum alloy.     

伴有下斜肌功能亢进外斜V征眼外肌myogenin的研究

目的：：观察伴有下斜肌功能亢进的外斜V征患者下斜肌和内直肌中myogenin活性卫星细胞数量的变化,探讨伴有下斜肌功能亢进的外斜V征的可能发病原因。方法：将伴有下斜肌功能亢进外斜V征患者6例中切除的下斜肌及内直肌作为斜视组,行myogenin免疫组织化学染色,统计myogenin阳性染色的卫星细胞核数;角膜移植供体的下斜肌及内直肌(6例)作为对照组。结果：斜视组和对照组下斜肌中myogenin免疫染色阳性肌卫星细胞数占总细胞数比例分别为(22.7±7.03)%和(4.2±0.75)%,具有统计学差异(P<0.05)。斜视组和对照组内直肌中myogenin免疫染色阳性的肌卫星细胞数分别为(2.2±0.75)%和(4.5±1.05)%,具有统计学差异(P<0.05)。结论：首次报道伴有下斜肌功能亢进外斜V征患者眼外肌中表达 myogenin 免疫染色阳性肌卫星细胞的变化。myogenin可能是伴有下斜肌功能亢进外斜 V 征的致病因素。     

低中度近视EPI- LASIK术后视觉质量探讨

目的：：综合评价低中度近视机械法激光上皮下角膜磨镶术( EPI-LASIK)后视觉质量。方法：将行EPI-LASIK 术的60例120眼按等效屈光度( SE)分为两组：低度近视组(60眼),中度近视组(60眼)。测量术前和术后1 wk;1,6 mo的客观视力、像差、对比敏感度和眩光敏感度并进行比较。结果：术后两组裸眼视力( UCVA )均优于术前最佳矫正视力(UCVA)(P<0.05);两组术后6mo 总高阶像差值RMS比较有统计学差异( P<0.05)。两组术前及术后6mo高阶像差值比较均有统计学差异(P<0.05);术后1wk;1mo两组在五个频率上均有统计学差异(P<0.05);术后6 mo低度近视组恢复至术前水平,中度近视组在高频区(18.0c/d)和术前有统计学差异(P<0.05);术后1wk两组在3.0,6.0,12.0,18.0c/d频率上差异均有统计学差异(均P<0.05),术后1mo两组在12.0,18.0c/d频率上有统计学差异(均P<0.05),术后6mo两组均恢复至术前水平,比较均无明显差异。结论：低中度近视 EPI-LASEK 术后早期的视觉质量较差,中晚期有较好的视觉质量。     

腹型肥胖对炎性因子及代谢综合征的影响

目的腹型肥胖则是一系列代谢紊乱的始动因素,本研究的目的是研究腹型肥胖与体内炎性因子水平及代谢综合征(metabolic syndrome,MS)之间的关系,为儿童肥胖尤其是腹型肥胖的治疗提供一定理论依据。方法选取2011-2012年于西安交通大学第二附属医院儿科内分泌门诊就诊的单纯性肥胖儿童85例,根据腰围将其分为腹型肥胖组及非腹型肥胖组。测量研究对象的身高,体重,腰围及臀围;抽取空腹血并检测血脂,血糖以及超敏C反应蛋白(highsensitivity C-reactive protein,hs-CRP)及内脂素水平。结果腹型肥胖患儿体质指数(body mass index,BMI)、腰围、腰臀比均显著高于非腹型肥胖患儿(P均0.05);腹型肥胖组MS检出率显著高于非腹型肥胖组(P0.05);腹型肥胖患儿与非腹型肥胖患儿比较,高血压、高血糖、高TG血症、低HDL-C血症的患病人数在两组间差异均具有统计学意义(P0.05);腹型肥胖患儿血清中hs-CRP及内酯素的水平均显著高于非腹型肥胖组。结论腹型肥胖儿童比非腹型肥胖儿童更容易患MS,儿童腹部脂肪分布与甘油三酯及体内炎症因子增高关系较为密切。因此,应积极防治肥胖,尤其是腹型肥胖。