视觉诱发电位与优势眼

目的:研究正常儿童优势眼视觉诱发电位特征。方法:对47名正常儿童进行全视野刺激多导视觉诱发电位研究。结果:优势眼视觉诱发电位以0_z电极为代表,P_(100)潜伏期较非优势眼缩短(P<0.01),而N_(75)—P_(100)峰峰值较非优势眼增大(P<0.05)。结论:中枢神经系统存在偏利现象,这种偏利现象可能与控制视神经髓鞘优先形成的某种遗传机制有关,或是中枢神经系统突触的局部构造、突触效能的差异。     

Microscale Transport and Sorting by Kinesin Molecular Motors

As biomolecular detection systems shrink in size, there is an increasing demand for systems that transport and position materials at micron- and nanoscale dimensions. Our goal is to combine cellular transport machinery-kinesin molecular motors and microtubules-with integrated optoelectronics into a hybrid biological/engineered microdevice that will bind, transport, and detect specific proteins, DNA/RNA molecules, viruses, or cells. For microscale transport, 1.5 microm deep channels were created with SU-8 photoresist on glass, kinesin motors adsorbed to the bottom of the channels, and the channel walls used to bend and redirect microtubules moving over the immobilized motors. Novel channel geometries were investigated as a means to redirect and sort microtubules moving in these channels. We show that DC and AC electric fields are sufficient to transport microtubules in solution, establishing an approach for redirecting microtubules moving in channels. Finally, we inverted the geometry to demonstrate that kinesins can transport gold nanowires along surface immobilized microtubules, providing a model for nanoscale directed assembly.     

Potent inhibition of SARS-associated coronavirus (SCOV) infection and replication by type I interferons (IFN-alpha/beta) but not by type II interferon (IFN-gamma).

We sought to investigate the anti-severe acute respiratory syndrome (SARS)-associated coronavirus (SCoV) activities of type I (alpha and beta) and type II (gamma) interferons (IFN) in vitro. Type I IFNs protected cells from cytopathic effects (CPE) induced by SCoV, and inhibited viral genomic RNA replication in FRhk-4 cells (measured by quantitative RT-PCR) in a dose-dependent manner. Intracellular viral RNA copies were reduced 50% by IFN-alpha at a concentration of 25 U/ml and by IFN-beta at a concentration of 14 U/ml. IFN-gamma had fewer effects on inhibition of viral infection and replication. The type I IFN receptor signaling pathway in host cells is mainly involved in the inhibition of SCoV infection and replication. Type I IFNs could be used as potential agents for anti-SARS treatment.     

Improved DOP-PCR-based representational whole-genome amplification using quantitative real-time PCR.

In many cases, only a minute amount of partially degraded genomic DNA can be extracted from archived clinical samples. Diverse whole-genome amplification methods are applied to provide sufficient amount of DNA for comparative genome hybridization, single-nucleotide polymorphism, and microsatellite analyses. In these applications, the reliability of the amplification techniques is particularly important. In PCR-based approaches, the plateau effect can seriously alter the original relative copy number of certain chromosomal regions. To eliminate this distorting effect, we improved the standard degenerate oligonucleotide-primed PCR (DOP-PCR) technique by following the amplification status with quantitative real-time PCR (QRT-PCR). With real-time detection of the products, we could eliminate DNA overamplification. Probes were prepared from 10 different tumor samples: primary and metastatic melanoma tissues, epidermoid and bronchioloalveolar lung carcinomas, 2 renal cell carcinomas, 2 colorectal carcinomas, and a Conn and Cushing adenoma. Probes were generated by using nonamplified and amplified genomic DNA with DOP-PCR and DOP-PCR combined with QRT-PCR. To demonstrate the reliability of the QRT-PCR based amplification protocol, altogether 152 relative copy number changes of 44 regions were determined. There was 85.6% concordance in copy number alterations between the QRT-PCR protocol and the nonamplified samples, whereas this value was only 63.8% for the traditional DOP-PCR. Our results demonstrate that our protocol preserves the original copy number of different chromosomal regions in amplified genomic DNA than standard DOP-PCR techniques more accurately.     

Diagnosis of Kala-Azar by Nested PCR Based on Amplification of the Leishmania Mini-Exon Gene

To diagnose visceral leishmaniasis (kala-azar), we have developed a nested PCR method based on amplification of the mini-exon gene, which is unique and tandomly repeated in the Leishmania genome. Nested PCR was sufficiently sensitive for the detection of DNA in an amount equivalent to a single Leishmania parasite or less. We examined the usefulness of this PCR method using bone marrow aspirates and buffy coat cells collected from kala-azar patients who had or had not received chemotherapy in northwest China. We obtained PCR positivity for all of the parasitologically positive bone marrow samples from the patients. Some ambiguities with the primary PCR results were eliminated by the subsequent nested PCR. The buffy coat samples from 7 of 12 patients with splenomegaly were positive by the nested PCR, although only 2 of them were positive for parasites by culture. However, buffy coat samples from nine children, whose splenomegaly has been reduced and clinically cured by antimony treatment, were all negative. Thus, this nested PCR method represents a new tool for the diagnosis of kala-azar with patient blood samples instead of bone marrow or spleen aspirates obtained by more invasive procedures.     

乙醇对人绒毛孕酮分泌的影响

本工作利用灌流技术观察了四种不同浓度的乙醇(0.5％、1％、2.5％、5％)对妊娠早期人工流产新鲜胎盘绒毛分泌孕酮的影响。结果表明,乙醇具有促进孕酮分泌的作用,并存在剂量依赖的关系。提示乙醇可能破坏胎盘激素内分泌的平衡,从而影响胎儿的正常生长与发育。     

Stress analysis between implant prostheses with different moduli and surrounding bones北大核心

背景:应力遮挡效应会导致植入假体修复骨缺损手术失败,其主要原因是由于植入假体的弹性模量大于骨组织弹性模量。目的:分析植入假体弹性模量对应力分布的影响,寻求消除应力遮挡现象的方法。方法:通过CT扫描的方式获取实验犬与人体骨组织的模型,分别对其优化后进行梯度赋值,建立较为可靠的骨骼力学模型,并与植入假体组合后进行有限元仿真。首先,通过对比格犬骨骼模型和人体骨骼模型及其对应的植入假体进行有限元仿真,模拟了不同弹性模量对植入假体修复术后的应力和位移分布情况;其次,分析了较小弹性模量差仍会形成应力遮挡现象的原因,建立了骨骼模型及植入假体模型,确立了材料属性赋予方法;最后,验证了该模型及材料属性赋予方法的可行性,并通过随机选取受力点的方式,定量分析植入假体弹性模量与骨骼弹性模量之间的关系对应力遮挡形成的影响。结果与结论:通过梯度赋值法建立与骨骼力学性质更加接近的实验犬骨骼模型和人体骨骼模型,该方法重建的力学模型与真实骨骼的力学性质更为接近;通过有限元仿真力学测试证明,不同弹性模量植入假体对假体本身与周围骨骼间相对位移的影响较小;另外量化弹性模量对假体植入骨骼后对应力分布的影响,可为后续的相关研究提供帮助。     

额外小染色体与原发闭经(附4例报告)

我们发现4例原发闭经伴额外小染色体病例,其核型分别为;46,XX/47,XX mar;46,X,del(X)/47,X,del(X) mar;47,XX, mar;45,X/46,X, mar/46,X r.作者讨论了mar的发生率、起源、诊断、临床表现及产前诊断等问题.     

基于电刺激的外层型人工视网膜的研究进展

外层型视网膜假体采用了MEMS技术,通过植入到视网膜相应部位的电极来刺激神经节细胞,并且能够在大脑皮层视觉区域引起对应的特征电位反应,最终部分恢复生物体的视觉.这种外层型视网膜植入装置可分为眼外和眼内部分.后者功能相对重要,设计也较为复杂.它是由包含MPDA和微电极的刺激芯片及附属装置组成.本篇文章主体包括四部分:首先是视网膜假体的概况;其次是视网膜生理基础和视网膜假体理论的简介;在第三部分,为设计理念和MPDA的制造过程;最后,是对难题的讨论和未来发展的展望.