Photodynamic therapy, PDT, has mainly been done using a laser system and a fluorescence dye which can be absorbed in a targeted cell culture or tumor. Establishing effective protocols of laser irradiation requires a knowledge of the local concentration of the dye in the target.
In this paper, Protoporphyrin IX that can be induced by δ-aminolevulenic acid (ALA) as the precurser of heme was used as the dye and the measurement of concentration of PPIX in cells was assessed in a cancer cell culture. The metabolic precursor ALA was included in the incubation media for 24 hours to induce cellular accumulation of PPIX for the purpose of PDT. The distributions of initial PPIX concentration, C_o in μg/ml, photobleaching light dose, H_b in J/cm², and photodtynamic dose, D_PDT which is defined as the number of photons absorbed by PPIX per g of cells, were measured on 124 individual cells using video fluorescence microscopy. The results showed that the H_b was normally distributed with a mean ± SD of 135 ± 56 J/cm² using 488 nm light. The C, and D_PDT were not normally distributed, with mean values (and ranges) of 6 (1-15) μg/ml and 5.2×10¹⁹(3×10¹⁸-2×10²⁰) photons absorbed by PPIX per g cells[ph/g], respectively. Individual PDT treatment of 131 cells via the microscope followed by 3-day incubation and assay for colony formation allowed specification of the D_PDT of individual cells destined for death of survival. The threshold D_PDT to achieve cell killing was not shrap, falling between 1×10¹⁸-30×10¹⁸ ph/g. In conclusion, a measurement system combined with an optical multichannel analyzer and a fluorescence microscope can be considered as a effective method for estimating PPIX concerntration in a cell.

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Holmium: YAG laser is a laser emitted from solid prepared by doping Holmium to YAG material. Its wavelength is in the near-infrared area at 2.08μm. It has the longest wavelength that can be transmitted by a quartz fiber. Characteristically having a large tissue absorption and less thermal injury around the site of irradiation, this new laser is being used not only for angioplasty and treatment of ureterostenosis but also for lithodialysis and ablation of bone tissue.
This time we studied the effects of Holmium: YAG laser irradiation on vital tissue macroscopiccaly and histopathologically. Additionally, we discuss its safety by comparing it with CO₂ laser and Nd: YAG laser, those are already in wide use clinically, in reference to literature. Much expectation is placed on further clinical application of Ho: YAG laser.

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Biomedical application of the fixation of a photosensitive reagent, tetrabrominated rhodamine (TBR), onto biological tissues model such as collagen gels was studied as a model for photolabeling tissues with medical reagents. Irradiation with an Ar ion laser caused photo-induced debromination and subsequent covalent linkage of TBR to collgen as a tissue model. In this paper, the quantum efficiency of laser induced photolabeling and how dimethylsulfoxide (DMSO) might enhance the efficiency of photolabeling are investigated. Video fluorescence assayed washed gels to measure the unbleached TBR affixed to a gel. A typical experiment used 20 μM TBR, a 4.5% collagen gel, and 1.7 W/cm² at 488 nm. Prolonged exposure caused 27% of the initial TBR to photolabel the collagen but the peak amount of unbleached affixed TBR occurred at 110s after 187 J/cm², and equaled 11% of the initial TBR. The quantum efficiency of photolabeling under these conditions was 2.3e-6±1.2e-6 (n=4 trials.) The inclusion of 25% DMSO in the gel increased the photolabeling efficiency 43% to 3.3e-6±1.5e-6 (n=4). A second experiment varied DIVISO levels in the gel but maintained a constant laser exposure of 100 J/cm². DMSO (10%) doubled the amount of affixed unbleached TBR, and 25% DMSO achieved a maximum 2.4-fold enhancement of photoolabeling. The results showed that laser induced photolabeling can be considered as a convenient method to determine the distribution of light in and on the biological tissue.

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The efficacy of photodynamic therapy using porphymer sodium for occlusion of corneal neovascularization has been evaluated experimentally. After the corneal neovascularization had been developed on albino rabbit eyes by a pellet mounting method, 2 mg/kg of porphymer sodium was administered intravenously. Argon green laser (514nm) was irradiated to the cornea with three varieties of energy at 24, 48, 72 and 95 hours after the administration, respectively. Slit-lamp examination, fluorescein angiography and light microscopic study were performed to observe whether the corneal new veesls were closed or not. With the exposure energy more than 38.2 J/cm², new vessels were occluded but surrounding normal tissues in the irradiation area such as the iris were severly damaged. Irradiation with exposure energy of 19.1 J./cm² during 24 and 72 hours after the administration of porphymer sodium was estimated more suitable to the treatment, because new vessel clusure was obtained with a mild damage of the surrounding normal tissue. Since new vessels were not closed in control groups which received laser irradiation without photosensitizer administration, it was supposed that the closure was not induced by thermal effect. The results of the present study suggested that photodynamic therapy using this photosensitizer was a new useful therapeutic agent for occlusion of ocular neovascularization.

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This paper deals with the strategical synthesis method for fluorescent cancer diagnosis agents without phototoxicity.
Hetero-molecular dimers, combined with both the metalloporphyrins and porphyrins, were focused for fluoresent agents.
From the result of their dansyl-methionine test, biodistribution and fluorescence yield etc., Mn complex-free base are chosen.
One of them, HAT-D01, was found to be promising tumor fluorescent agent without phototoxicity.

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We synthesized and developed ¹¹¹In, ^99mTc labeled new tumor imaging agent, which consists of carrier (ATN-10, STA-R12) of the tumor imaging possessing both a nonradioactive manganese complex in the porphyrin ring and bifunctional chelating group (DTPA) attached to its side chain. Mammary cancer implanted with SHR rats, Lewis lung cancer implanted with BDF1 mice and colon 26 cancer implanted with CDF1 mice were used as animal tumor models for testing their capacity of tumor scintigraphic agents. The images of the threekinds of tumors were delineated more clearly by 99mTc-ATN-10, ^99mTc-STA-R12 than ⁶⁷Ga citrate.

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We have developed a Red/Green ratio fluorescence diagnostic system for the detection of malignant tumor using a new photosensitizer, NPe6 (ME2906), for endoscopic diagnosis of central type occult lung cancer.
Excimer dye laser (405nm) is used for excitation light.This system detects the red fluorescence (670nm) from ME2906 which is accumulated in malignant tumor and green auto-flurescence (530-570nm) which is decreased in malignant tumor compared that of to normal tissue.
The R/G ratio calculated by a computer system and the fluorescence image is displayed on the endoscopic image monitor.
Fluorescence images coinciding with the malignant tumor were obtained in animal models implanted with the Colon 26 tumor cell line and in clinical cases of lung Cancer.

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Photodynamic diagnosis of atherosclerotic plaques, which induced in the aorta of rabbits fed a cholesterol-rich diet for 20 weeks, has been available, Three main factors to diagnose atheroma were a newly developed photosensitizer of mono-L-aspartyl chlorin e6 (NPe6), a new laser equipment of tunable diode laser, and a new high resolution video monitoring sysytem.This article reviews new trends in photodynamic diagnosis for the atherosclerotic disease.

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Recently, fluorescence detection has been used in diagnosis of lung cancer. In highrisk patients, this method has been especially beneficial for localization of roentgenographically occult lung cancers. The excimer dye laser fluorescence image amalyzer system using Photofrin® as a photosensitizer has been tried for the early detection of lung cancer. With this system both a Photofrin®-specific fluorescence wavelength pat tern and endoscopic image can be seen simultaneously on the same monitor.
Photodynamic diagnosis (PDD) employing this system has performed in 23 cases of lung cancer including 8 cases of caicinoma in situ and 2 cases of vocal coad cancer. Fluorescence was recognized in all cases except one case, however, false positive results were also observed in 10 out of 23 cases with 2 mg/kg of Photofrin®. There are still some problems in this system including improvements widening the angle of divergence of the laser beam and standardization of fluorescence measurement, however, the possibility of photodiagnosis for lung cancer using this system is suggested.

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As the bacical experimentation pertaining to the principles of fluorescent broncoscopy, the wave length of autofluorescence, when excited through excitation light, was contrasted between the normal bronchial tissue and the cancerous tissue, The results were as follows. (1) Through ghe fluorescent microscope, strength of autofluorescence was increased, in the submucosal layer of the normal bronchial tissue, while it was decreased in the cancerous tissue, (2) Normal bronchial tissue and cancerous tissue being compared, autofluorescence was completely negative in the cancerous portion, while three peaks were observed in the renge of 500-510nm, 530-540nm, and 610-630nm in the normal bronchial tissue. (3) As for the principles of autofluorescence, the involvement of extracelluler stroma and endogeneous fluorophore (FAD) was strongly implied.

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Recentry several endoscopic fluorescence detection system have been created. Laser light was used for the excitation of autofluorescence, and sophisticated techniques also were necessary to amplify the fluorescence signal as well.
The authors tried to simplify the system with a conventional Xenon lamp excitation and image intensifier. Sensitivity of dysplasia increased in fluorescence endoscope compared with the white light.
In this paper, developed endoscope for cetection of tisue/mucosal autofluorescence is evaluated.

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