Catalytic dehydrogenative cross-coupling: forming carbon-carbon bonds by oxidizing two carbon-hydrogen bonds

The interaction of light within tissue has been used to recognize disease since the mid-1800s. The recent developments of small light sources, detectors, and fiber optic probes provide opportunities to quantitatively measure these interactions, which yield information for diagnosis at the biochemical, structural, or (patho)physiological level within intact tissues. However, because of the strong scattering properties of tissues, the reemitted optical signal is often influenced by changes in biochemistry (as detected by these spectroscopic approaches) and by physiological and pathophysiological changes in tissue scattering. One challenge of biomedical optics is to uncouple the signals influenced by biochemistry, which themselves provide specificity for identifying diseased states, from those influenced by tissue scattering, which are typically unspecific to a pathology. In this review, we describe optical interactions pursued for biomedical applications (fluorescence, fluorescence lifetime, phosphorescence, and Raman from cells, cultures, and tissues) and then provide a descriptive framework for light interaction based upon tissue absorption and scattering properties. Finally, we review important endogenous and exogenous biological chromophores and describe current work to employ these signals for detection and diagnosis of disease.

Quantitative optical spectroscopy for tissue diagnosis

The nucleosome, which is the primary building block of chromatin, is not a static structure: It can adopt alternative conformations. Changes in solution conditions or changes in histone acetylation state cause nucleosomes and nucleosomal arrays to behave with altered biophysical properties. Distinct subpopulations of nucleosomes isolated from cells have chromatographic properties and nuclease sensitivity different from those of bulk nucleosomes. Recently, proteins that were initially identified as necessary for transcriptional regulation have been shown to alter nucleosomal structure. These proteins are found in three types of multiprotein complexes that can acetylate nucleosomes, deacetylate nucleosomes, or alter nucleosome structure in an ATP-dependent manner. The direct modification of nucleosome structure by these complexes is likely to play a central role in appropriate regulation of eukaryotic genes.

Alteration of Nucleosome Structure as a Mechanism of Transcriptional Regulation

Structure Elucidation of a Senescence Cross-Link from Human Extracellular Matrix: Implication of Pentoses in the Aging Process *

Age-related nuclear cataract-oxidation is the key.

Isolation and characterization of a fluorescent material in bovine achilles tendon collagen

The structure of pyridinoline, a collagen crosslink

Collagen types in normal and prematurely ruptured amniotic membranes

Evidence for natural existence of pyridinoline crosslink in collagen.

Crosslink of Collagen in Hypertrophic Scar

Daisaburo Fujimoto

Papers

Isolation and characterization of a fluorescent material in bovine achilles tendon collagen

The structure of pyridinoline, a collagen crosslink

Collagen types in normal and prematurely ruptured amniotic membranes

Evidence for natural existence of pyridinoline crosslink in collagen.

Crosslink of Collagen in Hypertrophic Scar