Quantifying lipofuscin in retinal pigment epithelium in vivo by visible-light optical coherence tomography-based multimodal imaging.

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Lipofuscin in the retinal pigment epithelium (RPE) is the major source of fundus autofluorescence (FAF). A technical challenge to accurately quantify the FAF intensities, thus the lipofuscin concentration, is to compensate the light attenuation of RPE melanin. We developed the VIS-OCT-FAF technology to accomplish optical coherence tomography (OCT) and FAF simultaneously with a single broadband visible light source. We demonstrated that light attenuation by RPE melanin can be assessed and corrected using the depth-resolved OCT signals. FAF images from albino and pigmented rats showed that without compensation, FAF signals from pigmented rats are lower than that from albinos. After compensation, however, FAF signals from pigmented rats are higher. This finding is supported by measurements of lipofuscin fluorophore A2E in the RPE using liquid chromatography/mass spectrometry (LC/MS) showing that compensated FAF intensities correlate linearly with A2E contents. The present work represents an important step toward accurately assessing RPE lipofuscin concentrations by FAF.






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Nafar, Zahra, Rong Wen, Ziqiang Guan, Yiwen Li and Shuliang Jiao (2020). Quantifying lipofuscin in retinal pigment epithelium in vivo by visible-light optical coherence tomography-based multimodal imaging. Scientific reports, 10(1). p. 2942. 10.1038/s41598-020-59951-y Retrieved from https://hdl.handle.net/10161/20319.

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Ziqiang Guan

Research Professor in Biochemistry

We develop and apply mass spectrometry techniques to address biochemical and biomedical questions that are lipid-related. Research projects include:

1) Structural lipidomics

o   Develop and apply high resolution tandem mass spectrometry-based lipidomics for the discovery, structural elucidation and functional study of novel lipids.

2) Elucidation of novel pathways/enzymes of lipid biosynthesis and metabolism

o   Genetic, biochemical and MS approaches are employed to identify the substrates and pathways involved in lipid biosynthesis and metabolism

3) Identification of lipid biomarkers of genetic diseases and cancers

o    Provide molecular insights into the disease mechanisms, as well as to serve as the diagnostic and prognostic tools of diseases.

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