分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Wen, Wen
Liu, Tingting
Zhang, Ting
Sun, Xinghuai
Wen, Wen
Sun, Xinghuai
Wen, Wen
Sun, Xinghuai
Zhang, Peng
He, Sheng
Gao, Jian
Sun, Xinghuai
He, Sheng
摘要： PURPOSE. This study investigated a novel motion-on-color paradigm to functionally isolate the magnocellular pathway and evaluate its diagnostic value in preperimetric glaucoma patients. METHODS. Thirty patients with preperimetric primary open-angle glaucoma and 30 controls participated in this study. They were tested in both the foveal and peripheral locations. Contrast sensitivity was assessed for the direction discrimination of a moving luminance-modulated grating presented on top of a red/green isoluminant grating. The moving test grating was designed to target the magnocellular pathway, while the background red/green isoluminant grating was designed to saturate the parvocellular pathway. The luminance-modulated grating was presented at spatial frequency of 0.5 cyc/deg, moving horizontally at four temporal frequencies (3 Hz, 8 Hz, 15 Hz, 25 Hz). Participants were asked to indicate the direction of motion for the luminance grating. As a comparison condition, frequency-doubling stimuli were also presented in the periphery and participants were asked to detect the occurrence of the frequency-doubled pattern. Two-way repeated-measures analysis of variance was performed with temporal frequency modulations as within-subject factor and group as between-subject factor, while contrast sensitivity was the dependent variable. Receiver operating characteristic (ROC) analysis was used to characterize diagnostic performance of the new procedure in comparison with the frequency-doubling tests for preperimetric glaucoma. RESULTS. The contrast sensitivity function in both the fovea and the periphery showed an inverted "V" shape with highest sensitivity in the intermediate temporal frequencies, consistent with physiological properties of the magnocellular pathway. At the fovea, compared to the control group, the sensitivity for the glaucoma patients was slightly but not significantly reduced (P > 0.05), and there was no significant interaction between groups and temporal frequency (P > 0.05). In the periphery, patients' sensitivity was significantly lower (P < 0.001) than that of normal participants, especially in high temporal frequencies, as supported by a statistically significant interaction between groups and temporal frequency (P < 0.001). The areas under ROC curves (AUROC) obtained for the motion-on-color paradigm in the periphery were 0.957 (25 Hz), 0.870 (15 Hz), 0.758 (8 Hz), and 0.561 (3 Hz) and were 0.761 for the traditional frequency-doubling test. CONCLUSIONS. The motion-on-color paradigm revealed a loss of contrast sensitivity in the peripheral visual field in preperimetric glaucoma. When applied with stimuli at high temporal frequency, the new paradigm had higher diagnostic sensitivity and specificity than the traditional frequency-doubling test. The findings also support the viewpoint that selective evaluation of magnocellular pathway function could facilitate the earlier detection of functional defects in glaucoma before visual field defects by standard perimetry.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Men, Dong
Zhou, Juan
Zhang, Zhi-Ping
Cui, Zong-Qiang
Deng, Jiao-Yu
Wang, Dian-Bing
Zhang, Xian-En
Men, Dong
Zhang, Ting-Ting
Hou, Li-Wei
Shi, Yuan-Yuan
Zhang, Jin-Li
摘要： The self-assembly of nanoparticles into larger superstructures is a powerful strategy to develop novel functional nanomaterials, as these superstructures display collective properties that are different to those displayed by individual nanoparticles or bulk samples. However, there are increasing bottlenecks in terms of size control and multifunctionalization of nanoparticle assemblies. In this study, we developed a self-assembly strategy for construction of multifunctional nanoparticle assemblies of tunable size, through rational regulation of the number of self-assembling interaction sites on each nanoparticle. As proof-of-principle, a size-controlled enzyme nanocomposite (ENC) was constructed by self-assembly of streptavidin-labeled horseradish peroxidase (SA-HRP) and autobiotinylated ferritin nanoparticles (bFNP). Our ENC integrates a large number of enzyme molecules, together with a streptavidin-coated surface, allowing for a drastic increase in enzymatic signal when the SA is bound to a biotinylated target molecule. As result, a 10000-fold increase in sensitivity over conventional enzyme-linked immunosorbent assays (ELISA) methods was achieved in a cardiac troponin immunoassay. Our method presented here should provide a feasible approach for constructing elaborate multifunctional superstructures of tunable size useful for a broad range of biomedical applications.
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