Depth-resolved blood oxygen saturation measurement by dual-wavelength photothermal (DWP) optical coherence tomography

Non-invasive depth-resolved measurement of hemoglobin oxygen saturation (SaO2) levels in discrete blood vessels may have implications for diagnosis and treatment of various pathologies. We introduce a novel Dual-Wavelength Photothermal (DWP) Optical Coherence Tomography (OCT) for non-invasive depth-resolved measurement of SaO2 levels in a blood vessel phantom. DWP OCT SaO2 is linearly correlated with blood-gas SaO2 measurements. We demonstrate 6.3% precision in SaO2 levels measured a phantom blood vessel using DWP-OCT with 800 and 765 nm excitation wavelengths. Sources of uncertainty in SaO2 levels measured with DWP-OCT are identified and characterized

Monoclonal antibody recognition of cholesterol monohydrate crystal faces

AbstractBackground: The immune system can elicit antibodies against a wide variety of antigens. We have proposed that crystal surfaces may also operate as antigens, binding specific antibodies. Here we exploit the crystal surfaces of cholesterol monohydrate to investigate antibody-surface recognition at the molecular level.Results: Four monoclonal antibodies were selected. Two specifically interact with cholesterol monohydrate crystals, and one with 1,4-dinitrobenzene crystals. The fourth interacts nonselectively with various solid substrates. The relative reactivities of the four antibodies to the different surfaces of cholesterol monohydrate and to other surfaces were compared. The nonspecific antibody adsorbs mainly at imperfections. Of the two specific antibodies, one shows a clear preference for one set of faces, relative to others, the second adsorbs selectively at one face of cholesterol monohydrate crystals.Conclusions: Monoclonal antibodies can be selected that specifically bind to the crystal surfaces of cholesterol monohydrate. The binding sites of such antibodies appear to recognize a number of molecular moieties, exposed at the surface in a specific structural organization. Different antibodies recognize different structural organizations with varying degrees of selectivity. Antibody-crystal surface interactions may serve as convenient models for studies aimed at an understanding of the molecular bases of antibody recognition