Monte Carlo simulation method and diffusion approximation method are proposed to examine the time decay constants of indocyanine green, the so called plasma disappearance rate from the liver. The decay constants were estimated using an optically homogeneous turbid slab as a tissue model. Simulation results showed the diffusion approximation to be more stable than the Monte Carlo simulation. The calculated decay constants in a turbid media based on the diffusion approximation produced lower numbers compared to the constants in a clear media. This result fitted well with the reported clinical data.

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We studied experimentally photodynamic therapy (PDT) effects using SMT-F mammary carcinoma on mice. PDT with Photofrin II (DHE, 5mg/kg) and argon dye laser (ADL, 630nm) induced 5-10mm tumor necrosis in depth, depending on power density and energy density. Clinically, we applied PDT in February 1996 to a locally recurrent breast cancer patient. She was a 73 years old female and had previously been treated by several modalities including standard radical mastectomy in 1988. PDT condition employed was DHE (2mg/kg i. v. 48 hours before illumination) and excimer dye laser irradiation (EDL, 630nm, 8mJ/pulse, 40Hz, 134J/cm2). Tumor nodules were newly detected beyond laser-irradiated area 3 and half months after PDT. However, no tumor regrowth was observed at PDT-treated area for 1 year and 10 months till patient died of wide-spread breast cancer in October 1997. In applying PDT to a recurrent breast cancer, there are several problems : 1) no established laser condition, 2) no good diagnostic modality evaluating tumor depth at superficial regions, 3) no insurance coverage for superficial neoplasm PDT, 4) long period light guarding for Photofrin-PDT, and 5) no good method to evaluate clinical PDT effects in an early period.

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A photodynamic therapy (PDT)-resistant variant of the P388 murine leukemia cell line was isolated by repeated PDT with mono-L-aspartyl chlorin e6 (NPe 6) in vitro to the 0.1% survival level, followed by twelve regrowth cycles. The resistant variant was 1.38-fold more resistant to PDT with NPe 6 (10-15 μg/ml). However, more than 20 μg/ml, there was no difference between cells. The PDT-12 cells had less uptake of NPe 6 after 2h incubation than P388. We examined cross-resistance to adriamycin and the partitioning behavior determinant of the aqueous biphasic system. There was no difference in cytotoxicity and the uptake of adriamycin (ADM) between parental and PDT-12 cells. Partitioning behavior of parental cells and PDT-12 cells was compared. The latter has an inherently higher degree of membrane hydrophobicity. NPe 6 is comparatively hydrophilic, but the P388/ADR cells had reduced accumulation of the drug by extrusion by P-glycoprotein rather than membrane hydrophobicity. Furthermore, NPe 6-PDT cytotoxicity depended on accumulation into cells. Therefore, the PDT-12 cells acquired a hydrophobic membrane by repeating NPe 6-PDT twelve times. The PDT-12 cells were not cross-resistant to adriamycin. NPe 6 penetration into PDT-12cells was prevented by membrane hydrophobicity.

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[in Japanese]

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Optical coherence tomography (OCT) is a new technology for performing high resolution cross sectional imaging. OCT is analogous to ultrasound imaging, except that it uses light instead of sound. OCT can provide cross sectional images of tissue structure on the micron scale in situ and in real time. Using OCT in combination with catheters and endoscopes enables high resolution intraluminal imaging of organs. OCT functions as a type of optical biopsy and is a powerful imaging technology for medical diagnostics because unlike conventional histopathology which requires removal of a tissue specimen and processing for microscopic examination, OCT can provide images of tissue in situ and in real time. OCT can be used where standard excisional biopsy is hazardous or impossible, to reduce sampling errors associated with excisional biopsy, and to guide interventional procedures. In this paper, we review OCT technology and describe its potential medical applications.

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Objective: To introduce an office or bedside method of evaluating both the motor and sensory components of swallowing called Flexible Endoscopic Evaluation of Swallowing with Sensory Testing (FEESST). FEESST combines the established endoscopic evaluation of swallowing with a technique that determines laryngopharyngeal sensory discrimination thresholds by endoscopically delivering air pulse stimuli to the mucosa innervated by the superior laryngeal nerve.
Methods: Endoscopic assessment of laryngopharyngeal sensory capacity followed by endoscopic visualization of deglutition was prospectively performed 148 times on 133 patients with dysphagia over an 8 month period. The patients had a variety of underlying diagnoses, with stroke and chronic neurological disease predominating (n=94). Subsequent to sensory testing, a complete dysphagia evaluation was conducted. Various food and liquid consistencies were dyed green and attention was paid to their management throughout the pharyngeal stage of swallowing. Evidence of latent swallow initiation, pharyngeal pooling and/or residue, laryngeal penetration, laryngeal aspiration and / or reflux was noted. Recommendations for therapeutic intervention were based upon information obtained during the FEESST and involved dietary and behavioral modifications, prevention of oral alimentation and/or referral to other related specialists.
Results: All patients successfully completed the examination. In 111 of the evaluations (75%), severe (>6.0mm Hg air pulse pressure) unilateral or bilateral LP sensory deficits were found. With puree consistencies, 47% of evaluations with severe deficits compared to 11% of evaluations with either normal sensitivity or moderate (4.0-6.0mm Hg air pulse pressure) sensory deficits displayed aspiration (p<.001, chi-squared test). With puree consistencies, 69% of evaluations with severe deficits compared to 24% with normal or moderate deficits displayed laryngeal penetration (p<.001, chi-squared test).
Conclusion: FEESST allows the clinician to obtain a comprehensive sensorimotor assessment of swallowing that is performed as the initial swallowing evaluation for the patient with dysphagia.

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