Fiber-based polarization-sensitive Mueller-matrix optical coherence tomography with continuous source polarization modulation

A novel fiber-based Mueller-matrix optical coherence tomography system is demonstrated for acquiring polarization images of biological tissues in vivo. The system features a single broadband source, a rapid scanning optical delay line, and an electro-optical polarization modulator that modulates the polarization states of the source light continuously. A frame of a 200 by 1515 pixel 2D image can be acquired in half a second. The Jones matrix of a sample is calculated from two frequency components--the A-scan carrier frequency component and the beat frequency component between the modulation frequency and the carrier frequency. For samples having negligible diattenuation, the Jones matrix can be calculated from a single measurement of either the horizontal or the vertical interference signal. The system was first validated by imaging standard polarization elements and then applied to imaging biological samples

Characterization of the polarization properties of biological tissues with fiber-based Mueller-matrix optical coherence tomography

A fast scanning fiber-based system of Mueller-matrix optical coherence tomography was built to characterize the polarization properties of biological tissues with high spatial resolution. A polarization modulator with its fast-axis oriented at 45° in the source arm of the Michelson interferometer, driven by a sinusoidal wave, was used to continuously modulate the incident polarization states of both the sample and the reference arms. Two detection channels were used to detect the horizontal and vertical polarization components of the interference signals, which were used to calculate the roundtrip Jones matrix of the sample. The roundtrip polarization parameters of the sample were calculated from the measured Jones matrix. The system was successfully tested for both standard optical polarization elements and various types of biological samples

Characterization of the polarization properties of biological tissues with fiber-based Mueller-matrix optical coherence tomography

A fast scanning fiber-based system of Mueller-matrix optical coherence tomography was built to characterize the polarization properties of biological tissues with high spatial resolution. A polarization modulator with its fast-axis oriented at 45° in the source arm of the Michelson interferometer, driven by a sinusoidal wave, was used to continuously modulate the incident polarization states of both the sample and the reference arms. Two detection channels were used to detect the horizontal and vertical polarization components of the interference signals, which were used to calculate the roundtrip Jones matrix of the sample. The roundtrip polarization parameters of the sample were calculated from the measured Jones matrix. The system was successfully tested for both standard optical polarization elements and various types of biological samples

The Extracellular Matrix and Blood Vessel Formation: Not Just a Scaffold

The extracellular matrix plays a number of important roles, among them providing structural support and information to cellular structures such as blood vessels imbedded within it. As more complex organisms have evolved, the matrix ability to direct signalling towards the vasculature and remodel in response to signalling from the vasculature has assumed progressively greater importance. This review will focus on the molecules of the extracellular matrix, specifically relating to vessel formation and their ability to signal to the surrounding cells to initiate or terminate processes involved in blood vessel formation

Proteins on the catwalk: modelling the structural domains of the CCN family of proteins

The CCN family of proteins (CCN1, CCN2, CCN3, CCN4, CCN5 and CCN6) are multifunctional mosaic proteins that play keys roles in crucial areas of physiology such as angiogenesis, skeletal development tumourigenesis, cell proliferation, adhesion and survival. This expansive repertoire of functions comes through a modular structure of 4 discrete domains that act both independently and in concert. How these interactions with ligands and with neighbouring domains lead to the biological effects is still to be explored but the molecular structure of the domains is likely to play an important role in this. In this review we have highlighted some of the key features of the individual domains of CCN family of proteins based on their biological effects using a homology modelling approach