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Lung Cancer Imaging with Fluorescence Endoscopy
Published in Mary-Ann Mycek, Brian W. Pogue, Handbook of Biomedical Fluorescence, 2003
Georges Wagnières, Annette McWilliams, Stephen Lam
Most endogenous fluorophores are associated with the structural matrix of tissues or are involved in cellular metabolic processes [30]. The most important of the former are collagen and elastin, the structure of which is the result of cross-linking between fluorescing amino acids. Fluorophores involved in cellular metabolism include reduced nicotinamide adenine dinucleotide (NADH) and flavins. Other fluorophores include the aromatic amino acids (e.g., tryptophan, tyrosine, phenylalanine), various porphyrins, and lipopigments (e.g., ceroids, lipofuscin), which are the end-products of lipid metabolism. In addition, red porphyrin fluorescence, probably due to bacteria, may be significant in certain sites and/or lesions.
Preparation and evaluation of a nanoemulsion containing cordycepin and its protective effect on skin
Published in Journal of Dispersion Science and Technology, 2023
Hucheng Zhang, Lina Deng, Jun Yang, Guowei Yang, Haitao Fan, Yiqi Yin, Shuai Luo, Shuangshi Li, Linying Liu, Ming Yang
Reactive oxygen species (ROS) are highly reactive oxygen-containing free radicals. Ordinarily, the concentrations of ROS are sufficiently low that they do not damage cells. Some ROS have physiological functions such as in cell signaling, metabolism, survival, and apoptosis. However, when physical and chemical factors in the environment induce high concentrations of ROS that exceed the scavenging capacity of cells, a state of oxidative stress ensues. For example, after ultraviolet irradiation, a large amount of oxygen-containing free radicals produced by the skin will damage the DNA, protein, lipid and other substances and form water-insoluble lipofuscin, which will lead to age spots and warts. Complex antioxidant enzyme defense systems exist, such as superoxide dismutase (SOD), Catalase (CAT), and glutathione (GSH), to avoid this peroxidation damage. The reaction mechanism is as follows: SOD converts superoxide anion (O2–) into hydrogen peroxide (H2O2), which is then converted into water by CAT; GSH is transformed into oxidized GSSH under the action of glutathione oxidase (GSH PX), which reduces peroxides and limits damage to cells.
Bioimaging of metals in environmental toxicological studies: Linking localization and functionality
Published in Critical Reviews in Environmental Science and Technology, 2022
Identification of metal ions in biological systems should certainly be linked with their functionality in organisms, and there is a real need to develop various biosensors capable of detecting the functions of other molecules in organisms. There are various commercially available probes for cellular localization and function (e.g., lysosome trackers, mitochondria trackers, pH, membrane potentials, RNA, among many others). The applications of AIE, which emit fluorescence when molecules are aggregated, are particularly powerful for the visualization of various cellular structures, functions, and movements. There is also a variety of bioprobes available for the investigation of subcellular structures and processes of cells based on the AIEgens. These AIEgens have shown their biocompatibility and photostability as compared to many commercially available bioprobes which have aggregation-caused quenching (ACQ) efforts and are unstable. Song et al. (2021) recently summarized the different AIEgens available for the imaging of various subcellular structures such as nuclei, membranes, lipid droplets, endoplasmic reticulum (ER), mitochondria, lysosomes, and cytoplasm. Of particular importance for metals are a few organelles such as mitochondria (targeted metal toxic site) and lysosomes (targeted metal detoxification site). Lipid droplets may be important for metal handling and the formation of lipofuscin. ER is an important site for protein and lipid synthesis, and Golgi bodies are important in protein transport. Fluorescence imaging allows the visualization of these subcellular structures as well as the processes associated with them. Table 4 summarizes some of these AIEgens that may be potentially used for environmental toxicological studies of metals. It should be noted that this field is expanding rapidly, and it is a matter whether they are assessible for use by toxicologists.