Todd Alter

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Journals/Publications

• Wang, L., Chapman, J., Palmer, R. A., Alter, T. M., Hooper, B. A., van Ramm, O., & Mizaikoff, B. (2006). Classification of atherosclerotic rabbit aorta samples with an infrared attenuated total reflection catheter and multivariate data analysis. Applied spectroscopy, 60(10), 1121-6.
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  The strongly overlapping infrared absorption features of atherosclerotic and normal rabbit aorta samples as governed by their water, lipid, and protein content render the direct evaluation of molecular characteristics obtained from infrared (IR) spectroscopic measurements challenging for classification. We have successfully applied multivariate data analysis and classification techniques based on partial least squares regression (PLS), linear discriminant analysis (LDA), and principal component regression (PCR) to IR spectroscopic data obtained by using a recently developed infrared attenuated total reflectance (IR-ATR) catheter prototype for future in vivo diagnostic applications. Training data were collected ex vivo from atherosclerotic and normal rabbit aorta samples. The successful classification results on atherosclerotic and normal aorta samples utilizing the developed data evaluation routines reveals the potential of spectroscopy combined with multivariate classification strategies for the identification of normal and atherosclerotic aorta tissue for in vitro and, in the future, in vivo applications.
• Hooper, B. A., Maheshwari, A., Curry, A. C., & Alter, T. M. (2003). Catheter for diagnosis and therapy with infrared evanescent waves. Applied optics, 42(16), 3205-14.
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  We have developed an optical delivery device (catheter) capable of transmitting broadband infrared light (IR wavelengths from 2 to 10 microm) for both diagnostic and therapeutic applications. The catheter is 1.68 mm in outer diameter and 1 m in length. It consists of two hollow glass waveguides coupled to a high-refractive-index optic tip. The IR light interacts with the tissue at the optic-tissue interface to measure the spectral signatures and perform therapy on the tissue at this interface. Fourier-transform IR spectrophotometer light is used to obtain the spectral signatures, and an IR free-electron laser (FEL) is used to study the therapeutic interaction of evanescent waves with the tissue. We present our catheter design; preliminary IR spectroscopy of aorta, blood, fatty tissue, and muscle; and IR FEL therapy on atheroslerotic aorta.
• Alexis, N. E., Hu, S. C., Zeman, K., Alter, T., & Bennett, W. D. (2001). Induced sputum derives from the central airways: confirmation using a radiolabeled aerosol bolus delivery technique. American journal of respiratory and critical care medicine, 164(10 Pt 1), 1964-70.
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  Indirect evidence suggests that induced sputum derives from the surfaces of the bronchial airways. To confirm this experimentally, we employed a radiolabeled aerosol bolus delivery technique that preferentially deposits aerosol in the central airways in humans. We hypothesized that there would be significantly more radioactivity recovered in an induced sputum sample, and greater airways clearance of radiolabeled particles, immediately after a central versus peripheral airways deposition. Ten healthy volunteers underwent radiolabeled aerosol deposition ((99m)Tc sulfur colloid particles) to the central and peripheral airways on separate occasions followed immediately by induced sputum or no sputum (control), while seated in front of a gamma camera. Radioactivity was measured in the selected sputum sample, processed cell pellet, and supernatant fraction. Significantly more radioactivity was present in all portions of the sputum sample after central versus peripheral airways deposition (i.e., selected sample: 15,607 counts +/- 2,985 versus 943 counts +/- 298, p = 0.001). Clearance from the whole lung was significantly greater 40 min after central versus peripheral airways deposition (48 +/- 3% versus 5 +/- 1%, p = 0.0001). Compared with control, induced sputum greatly enhanced clearance after central deposition (48 +/- 3% versus 11 +/- 6%, p = 0.0001), but not after peripheral deposition (5 +/- 1% versus 3 +/- 0.8%). These results provide direct evidence that induced sputum derives from the central airways with little or no contribution from the peripheral airways.