PubMed · 12014340
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Mike Smith. 2002. Got ears?. https://pubmed.ncbi.nlm.nih.gov/12014340/
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Theoretical and experimental aspects of two-dimensional (2D) biomedical photoacoustic imaging have been investigated. A 2D Fourier-transform-based reconstruction algorithm that is significantly faster and produces fewer artifacts than simple radial backprojection methods is described. The image-reconstruction time for a 208 x 482 pixel image is approximately 1 s. For the practical implementation of 2D photoacoustic imaging, a rectangular detector geometry was used to obtain an anisotropic detection sensitivity in order to reject out-of-plane signals, thereby permitting a tomographic image slice to be reconstructed. This approach was investigated by the numerical modeling of the broadband directional response of a rectangular detector and imaging of various spatially calibrated absorbing targets immersed in a turbid phantom. The experimental setup was based on a Q-switched Nd:YAG excitation laser source and a mechanically line-scanned Fabry-Perot polymer-film ultrasound sensor. For a 800 microm x 200 microm rectangular detector, the reconstructed image slice thickness was 0.8 mm up to a vertical distance of z = 3.5 mm from the detector, increasing thereafter to 2 mm at z = 10 mm. Horizontal and vertical spatial resolutions within the reconstructed slice were approximately 200 and 60 microm, respectively.
STUDY OBJECTIVES: The positional dependency of obstructive sleep apnea (OSA) is well known, but objective evidence for the positional effect on snoring is lacking. The aim of this study is to elucidate the effect of body position on snoring, and that of sleep stage as well. DESIGN: Retrospective analysis of the effects of body position and sleep stage on snoring in nonapneic snorers (snorer group) and OSA patients (apneic group). SETTING: A sleep laboratory in a national hospital in Japan. PATIENTS: Seventy-two patients who complained of habitual snoring and underwent overnight polysomnography. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: In the lateral position, most subjects in the snorer group showed decreased snoring both in time (p = 0.0004) and intensity (p = 0.0003), but subjects in the apneic group showed variable changes. In the apneic group, the positional dependency of snoring (the ratio of lateral value to supine value) was correlated with supine apnea-hypopnea index (AHI), that is, OSA patients with higher supine AHI tended to show increased snoring in the lateral position. AS to the effect of sleep stage, snoring was increased in deeper non-rapid eye movement sleep and decreased in rapid eye movement sleep in a given position. CONCLUSIONS: This study demonstrated that the positional dependency is different between nonapneic snorers and OSA patients. Most of the nonapneic snorers snore less in the lateral position than in the supine position in contrast to OSA patients who often fail to decrease snoring even in the lateral position.
The aim of this work was to measure and compare the binding constants of antibody immunoglobulin G (IgG) to bacterial cell wall proteins, streptococcal protein G and Staphylococcus aureus protein A, using an acoustic wave sensor. Devices, which used shear-horizontal acoustic waves propagating in a waveguide configuration at 108 and 155 MHz, were employed in the detection of apparent IgG binding constants at the solid-liquid interface in the range of 6.7-667 nM IgG. Real-time data during IgG-protein G and IgG-protein A binding yielded apparent association constants of 3.29 x 10(4) and 8.02 x 10(3) M(-1) s(-1) leading to equilibrium constants of 1.13 x 10(8) and 2.90 x 10(7) M(-1), respectively. The measured apparent rate constants are consistent with literature reports of higher affinity of protein G for IgG. Furthermore, protein binding through the Fc region of IgG is suggested to occur below 333 nM, while different mechanisms are suggested to occur above 333 nM. For the first time, nonequilibrium studies of IgG-protein G and A binding at a solid-liquid interface has yielded valuable quantitative kinetic information about binding mechanisms. The promise of this detection method is shown by providing quick determination of binding constants with low sample volumes.