利用双SLD光源提高OCT纵向分辨率的理论研究

提高光学相干层析成像(OpticalCoherenceTomography:OCT)系统纵向分辨率的关键是选取合适的光源,本文将双SLD光源代替传统OCT系统中的单个SLD光源,通过理论分析和计算机仿真,表明双SLD光源能有效提高OCT系统纵向分辨率。     

LASIK术后高阶像差对视觉质量影响的研究进展

随着屈光手术的发展,过去人们所追求的单纯裸眼视力的提高逐渐被追求视觉质量的提高所代替。LASIK术后患者低阶像差减小,高阶像差进一步增加,虽然裸眼视力提高,但是对比敏感度下降,尤其是暗环境下和有眩光时视觉质量不能达到理想效果,因为高阶像差是影响视网膜成像的重要因素,对比敏感度是评价视网膜成像质量好坏的重要指标之一,所以探讨不同成分高阶像差以及它们之间适当组合对视觉质量的影响和LASIK术后各频段对比敏感度的变化,研究各项高阶像差与对比敏感度之间的关系可以为临床外科屈光医生提供一定的理论指导,进而解决LASIK术后的眩光、星形放射、暗视力差等问题。本文通过概括LASIK术后高阶像差和对比敏感度的变化,对它们之间关系的研究现状和进展作一综述。     

基于自适应光学的视网膜单细胞光学相干层析成像技术

介绍了一种基于CCD相机的并行光学相干层析成像技术,将所建立的层析成像系统和自适应光学视网膜相机结合。利用一维光学相干层析系统对人眼视网膜进行追踪并控制相干门在视网膜内的位置,利用基于CCD相机的二维光学相干层析成像系统记录视网膜的干涉图像。用眼模型和牛眼视网膜组织对系统进行了测试,通过将4幅干涉图像的获取时间控制在7 ms以内来减少视网膜运动对成像的影响;系统的轴向点扩展函数和灵敏度分别达到10 μm和76 dB。实验结果表明,所建立的基于自适应光学的视网膜光学相干层析成像系统的空间分辨率和灵敏度远远高于其它基于自适应光学的视网膜成像技术。     

一种低成本、高性价比的穿戴式扩散光学断层人脑成像系统

现有扩散光学断层成像(diffuse optical tomography,DOT)系统常采用高档光探测器和放大器,令系统成本居高不下、性价比较低.本文旨在使用全新技术降低系统成本、增加成像深度,研发一套可实用于人脑成像的新型扩散光学断层成像系统.为此采用了成本较低的新型光探测器和一款自主设计研制的光电二极管前置放大器.相较于实验室原有DOT系统,新系统整体成本节约了40%以上.其次,设计了一款具有弹性并可适应多种不规则待测物(subject)外形的无光纤穿戴式脑-机接口(brain computer interface,BCI)装置.本文首次将手持式3D激光扫描仪应用于待测物外形结构和光源-探测器位置信息的精确获取.最后综合应用上述技术装备于人脑形状仿体成像实验中,新系统的目标成像深度提升至35 mm.验证结果说明本系统已具备了实际人脑功能成像能力.     

光学相干层析成像技术用于裸鼠皮肤霉菌感染研究

利用中心波长为850 nm的宽带光源SLD实现了纵向分辨率为8μm的光学相干层析成像系统。系统采用傅里叶域光学延迟线实现了深度扫描速度为160 mm/s,成像深度为3 mm。获得了裸鼠皮肤霉菌感染部位和健康皮肤的光学相干层析(optical coherence tom ography,OCT)图像,皮肤病变前后的内部结构信息清晰可见。     

420～750 nm超连续谱光源和532 nm激光致兔视网膜损伤修复

超连续谱(SC)光源是一种宽光谱、高亮度、眼睛危害大的新光源,有关它致视网膜损伤研究却未见报道。为了观察SC光源致视网膜损伤特点和修复过程,试验将波长420～750 nm的SC光源与532 nm激光进行比较,采用两者平行光入射,在0. 1 s照射时间,3 mm角膜光斑直径条件下,用略高于视网膜损伤阈值的功率照射青紫蓝灰兔视网膜;通过检眼镜和HE染色观察视网膜照后4 h,1、3、7、14 d损伤修复过程。SC光源和532 nm激光致视网膜的损伤在检眼镜下为灰色小圆斑。照后4 h出现视网膜外核层固缩深染,感光细胞外节与视网膜色素上皮层(RPE)粘连;随后RPE层色素增生、损伤的外核层细胞丢失,损伤进行性加重; 3 d后色素细胞开始向外核层和内核层迁移,胶质细胞填充损伤区域。由此可见,波长420～750 nm的SC光源主要损伤视网膜外核层和RPE层,后期色素颗粒和胶质细胞填充损伤区域。其视网膜损伤特点和修复过程与532 nm激光类似。     

光学相干层析成像技术在内窥镜中的应用

光学相干层析成像(optical coherence tomography,OCT)技术是继X射线成像、核磁共振成像、超声成像等之后的一种新型的成像技术,其可光纤化的特点使得它易于医用电子内窥镜相结合。OCT内窥镜技术可实现对人体内部器官的高速率、高分辨率、无损伤、实时成像。主要介绍了OCT技术的种类、基本原理以及包括探测深度和纵向分辨率等的参数;简述了OCT内窥镜的发展历史以及最新成果,重点分析了光源对OCT内窥镜的影响。总结了OCT内窥镜的主要应用。     

红外成像技术在生命科学中的应用

红外成像技术是利用物体自身各部分对红外热辐射的差异把红外辐射图像转换为可视图像的技术.对红外成像技术历史进行了简单介绍,对远红外成像技术在生命科学包括医学、植物、动物及农业中的应用进行了综述,并对红外成像技术在生命科学中的应用作了展望.     

基于不同光源的无标记显微成像技术

目的:随着对微观世界探索的不断深入,人们对显微成像系统的性能,如成像效率、成像质量以及三维成像等均提出了越来越高的要求。方法:近年来,在显微成像领域涌现出一批代表性的技术如定量相位成像技术、太赫兹成像技术以及结构光超分辨成像技术等,此类技术凭借无损伤、无侵入、无电离辐射、可实时、可定量等优势,在医学诊断、无损检测和安全检查等方面有着广泛应用。结论:本文根据光源的不同对显微成像技术进行了分类,首先对高相干激光、低相干光、太赫兹波以及结构光作为光源的四类无标记成像技术进行了简要介绍,并阐明了成像的基本原理,然后对这几类技术进行了特征分析。最后探讨了显微成像技术的发展趋势。     

用侧向光源进行前列腺光声扫描成像的研究（英文）

光声成像技术是近年来兴起的前列腺早期检测与成像的新技术。前列腺组织的结构特征需要一种无创的且光穿透深度足够大的光声激发方式。本文设计了一种可用于经由尿道对前列腺光辐照的侧向光源,并结合直肠处长焦区聚焦式超声换能器的光声探测展开了前列腺仿体的光声扫描成像。结果表明,侧向光源有利于单侧吸收体的定位和成像,具有较好的成像范围和深度,结合侧向光源的旋转可实现全方位成像。因此该侧向光源有望成为早期前列腺肿瘤光声成像技术中一种新型的光源结构,具有重要意义。     

Characterizing the Human Cone Photoreceptor Mosaic via Dynamic Photopigment Densitometry

Densitometry is a powerful tool for the biophysical assessment of the retina. Until recently, this was restricted to bulk spatial scales in living humans. The application of adaptive optics (AO) to the conventional fundus camera and scanning laser ophthalmoscope (SLO) has begun to translate these studies to cellular scales. Here, we employ an AOSLO to perform dynamic photopigment densitometry in order to characterize the optical properties and spectral types of the human cone photoreceptor mosaic. Cone-resolved estimates of optical density and photosensitivity agree well with bulk estimates, although show smaller variability than previously reported. Photopigment kinetics of individual cones derived from their selective bleaching allowed efficient mapping of cone sub-types in human retina. Estimated uncertainty in identifying a cone as long vs middle wavelength was less than 5%, and the total time taken per subject ranged from 3–9 hours. Short wavelength cones were delineated in every subject with high fidelity. The lack of a third cone-type was confirmed in a protanopic subject. In one color normal subject, cone assignments showed 91% correspondence against a previously reported cone-typing method from more than a decade ago. Combined with cone-targeted stimulation, this brings us closer in studying the visual percept arising from a specific cone type and its implication for color vision circuitry.     

Ultrastructural organization of the ocelloide of Nematodinium. Phylogenetic aspect of the evolution of Warnowiidae Lindemann dinoflagellates photoreceptor (author's transl)

In this study, more details of the different parts of the "ocelloide" of Nematodinium are given. The "hyalosome" which has a radial symmetry is made of endoplasmic reticulum, except the mitochondrial layer. There is only one constrictor ring and only a beginning of the periocellar gallery. The basal sheet on which the crystalline lens lies is a local differentiation of the cortical layer which is observed on the ceiling of the ocellar camera. This camera is related to the intercingular sulcus. There is also an ocellar fiber. The "melanosome" which is made of a double membrane and of many couples of thylakoids is flattened dorso-ventrally. The structure of the retina is similar to that observed in the other Warnowiidae. The pigmented ring is rather well developed and is in continuity with the upper part of the retina. Owing to the simpler organization of its ocelloide, Nematodinium is situated before the genera Warnowia and Erythropsidinium in the evolutionary series.     

Interpretation of anatomic correlates of outer retinal bands in optical coherence tomography

By providing the sectioning capability to differentiate individual retinal layers, optical coherence tomography (OCT) is revolutionizing eye disease diagnosis and treatment evaluation. A better understanding of the hyper- and hypo-reflective bands in retinal OCT is essential for accurate interpretation of clinical outcomes. In this article, we summarize the interpretations of clinical OCT and adaptive optics (AO) OCT (AO-OCT) of the outer retina in the human eye, and briefly review OCT investigation of the outer retina in animal models. Quantitative analysis of outer retinal OCT bands is compared to established parameters of retinal histology. The literature review and comparative analysis support that both inner/outer segment (IS/OS) junction and IS ellipsoid zone nonexclusively contribute to the second band; and OS, OS tips, and retinal pigment epithelium apical processes contribute to the third band in conventional OCT. In contrast, AO-OCT might predominantly detect the IS/OS junction and OS tip signals at the second and third bands due to its improved sectioning capability and possible AO effect on the sensitivities for recording ballistic and diffusive photons from different regions of the outer retina.     

Multimode Optical Fiber Surface Plasmon Resonance Signal Processing Based on the Fourier Series Fitting

Multimode optical fiber is widely used because of its large core size, strong light-gathering ability, and remote on-line sensing ability in various environments. Due to the mode coupling and polarization loss, the signal curve obtained has wide full width at half-maximum (FWHM) and small peak value. Therefore, efficient methods to calculate the resonant wavelength are required. This paper presents a method to process the surface plasmon resonance curve (SPR) based on the Fourier series fitting. The calculated resonant wavelength is obtained with one-dimensional extremum-search method. Experiment results show the proposed method can accurately calculate the resonant wavelength of high concentration solution. Additionally, the method has higher sensitivity and is unaffected by the light source fluctuation. This method has potential value in processing the SPR signal of the multimode optical fiber.     

The structure of the stemloop D subdomain of coxsackievirus B3 cloverleaf RNA and its interaction with the proteinase 3C

Stemloop D (SLD) of the 5' cloverleaf RNA is the cognate ligand of the coxsackievirus B3 (CVB3) 3C proteinase (3Cpro). Both are indispensable components of the viral replication initiation complex. SLD is a structurally autonomous subunit of the 5' cloverleaf. The SLD structure was solved by NMR spectroscopy to an rms deviation of 0.66 A (all heavy atoms). SLD contains a novel triple pyrimidine mismatch motif with a central Watson-Crick type C:U pair. SLD is capped by an apical uCACGg tetraloop adopting a structure highly similar to stable cUNCGg tetraloops. Binding of CVB3 3Cpro induces changes in NMR spectra for nucleotides adjacent to the triple pyrimidine mismatch and of the tetraloop implying them as sites of specific SLD:3Cpro interaction. The binding of 3Cpro to SLD requires the integrity of those structural elements, strongly suggesting that 3Cpro recognizes a structural motif instead of a specific sequence.     

The molecular basis for inhibition of sulindac and its metabolites towards human aldose reductase

Sulindac (SLD) exhibits both the highest inhibitory activity towards human aldose reductase (AR) among popular non-steroidal anti-inflammatory drugs and clear beneficial clinical effects on Type 2 diabetes. However, the molecular basis for these properties is unclear. Here, we report that SLD and its pharmacologically active/inactive metabolites, SLD sulfide and SLD sulfone, are equally effective as un-competitive inhibitors of AR in vitro. Crystallographic analysis reveals that π-π stacking favored by the distinct scaffold of SLDs is pivotal to their high AR inhibitory activities. These results also suggest that SLD sulfone could be a potent lead compound for AR inhibition in vivo.     

生长阶段及环境因子对东海原甲藻氨基酸氧化酶活性的影响

以中国沿海典型赤潮藻东海原甲藻为实验材料, 研究了不同生长阶段以及温度、光照和氮源对其氨基酸氧化酶活性的影响。结果表明, 在缺氮条件下东海原甲藻显示较高的氨基酸氧化酶活性。在15-30℃温度范围均检测出氨基酸氧化酶活性, 较低温度下(15-20℃)的氨基酸氧化酶活性显著高于高温处理组(25-30℃)(p<0.05), 其中20℃时的酶活最高。在50-100 μmol/(m²·s)的光强下, 氨基酸氧化酶活性较高(0.38-0.47 fmol/(h·cell)), 而在2 μmol/(m²·s)的低光强下, 虽然酶活受到显著抑制, 但仍达到0.28 fmol/(h·cell)。氮源组成对氨基酸氧化酶活性具有显著影响, 以丙氨酸为唯一氮源时的酶活最高(0.44 fmol/(h·cell)), NH₄⁺+丙氨酸为氮源时的酶活最低(0.22 fmol/(h·cell))。研究显示, 光照、温度和氮源是东海原甲藻氨基酸氧化酶活性的关键调控因子。东海原甲藻不仅能够有效利用游离氨基酸, 而且适应较广的温度和较低的光照条件, 这可能是东海原甲藻赤潮形成和持续的重要原因。     

Characterisation of the SUMO-like domains of Schizosaccharomyces pombe Rad60

The S. pombe Rad60 protein is required for the repair of DNA double strand breaks, recovery from replication arrest, and is essential for cell viability. It has two SUMO-like domains (SLDs) at its C-terminus, an SXS motif and three sequences that have been proposed to be SUMO-binding motifs (SBMs). SMB1 is located in the middle of the protein, SBM2 is in SLD1 and SBM3 is at the C-terminus of SLD2. We have probed the functions of the two SUMO-like domains, SLD1 and SLD2, and the putative SBMs. SLD1 is essential for viability, while SLD2 is not. rad60-SLD2Δ cells are sensitive to DNA damaging agents and hydroxyurea. Neither ubiquitin nor SUMO can replace SLD1 or SLD2. Cells in which either SBM1 or SBM2 has been mutated are viable and are wild type for response to MMS and HU. In contrast mutation of SBM3 results in significant sensitivity to MMS and HU. These results indicate that the lethality resulting from deletion of SLD1 is not due to loss of SBM2, but that mutation of SBM3 produces a more severe phenotype than does deletion of SLD2. Using chemical denaturation studies, FPLC and dynamic light scattering we show this is likely due to the destabilisation of SLD2. Thus we propose that the region corresponding to the putative SBM3 forms part of the hydrophobic core of SLD2 and is not a SUMO-interacting motif. Over-expression of Hus5, which is the SUMO conjugating enzyme and known to interact with Rad60, does not rescue rad60-SLD2Δ, implying that as well as having a role in the sumoylation process as previously described, Rad60 has a Hus5-independent function.     

A multipixel diffuse correlation spectroscopy system based on a single photon avalanche diode array

The autocorrelation of laser speckles from coherent near infrared light is used for noninvasive estimates of relative changes in blood perfusion in techniques such as laser Doppler flowmetry (LDF) and diffuse correlation spectroscopy (DCS). In this study, a 2D array of single photon avalanche diodes (SPADs) was used to combine the strengths of multiple detectors in LDF with high light sensitivity in DCS. The system was tested on milk phantoms with varying detector fiber diameter (200 and 600 μm), source‐detector fiber separation (4.6‐10.2 mm), fiber‐SPAD distance (2.5‐36.5 mm), contiguous measurement time per repetition for the autocorrelation (1‐33 ms) and temperature (15.6‐46.7°C). An in vivo blood occlusion test was also performed. The multipixel approach improved signal‐to‐noise ratio (SNR) and, in our setup, the use of a multimode detector fiber was beneficial for SNR. In conclusion, the multipixel system works, but improvements and further studies regarding, for example, the data acquisition and optimal settings are still needed.