Photodynamic efficacy of the pulsed laser and the continuous wave (CW) laser for excitation source of photodynamic therapy to the murine B-cell leukemia (BCL1-B20) was compared. In this investigation, we used 2, 4-bis (1-decyloxyethyl) -Ga (III) -1, 3, 5, 8, -tetramethylporphyrin-6, 7-dipropionyl diaspartic acid (ATX-70) as a photosensitizer. The cells ware counterstained for DNA with propidium iodide and analyzed by flow cytometry (FCM). BCL1-B20 cells were incubated with 10μg/ml of ATX-70 at 37°C for 60 min prior to exposure to either pulsed or CW laser light. After six hours irradiation of the CW laser light, a number of the control and the irradiated cells underwent apoptosis, while few apoptotic cells were observed after the pulsed laser irradiation under the same condition. In contrast, cells treated with 1μg/ml ATX-70 for 60 min and irradiated the pulsed laser light showed a high incidence of apoptosis after PDT, whereas there was a much lower incidence of apoptosis in the control cells or CW laser light irradiated one. An examination of extracted cellular DNA by gel electrophoresis showed the characteristic DNA ladder indicated that internucleosomal cleavage of DNA during apoptosis. During the course of the pulsed laser irradiation, the degree of DNA fragmentation had been significantly higher than the case applying the CW laser in PDT. These results, together with the other recent reports, are consistent with the hypothesis that the excessive sensitization can delay or prevent an apoptotic response for PDT. Findings in this work suggest that the pulsed laser light exhibits significant cytotoxicity in much lower concentration of photosensitizer compared with the CW laser light.

View full abstract

The clinical treatment with Nd-YAG laser was carried out on 140 cases in outpatients, during 1988 and 1997. They were treated with high power laser containing 44 leukoplakia, 23 haemangioma, 20 fibroma, 12 papilloma, 12 oral lichen planus, 5 malignant tumors and others.
The purpose of this study was to assess the clinical efficacy of Nd-YAG laser for oral and maxillofacial lesions.
The Nd-YAG laser surgery managed benign tumors, i. e., fibroma, papilloma, granuloma and haemangioma of which size was smaller than 30mm in diameter. However it wasn't able to manage for the case of which size was larger than them, and for some cases which were in the lip.
It showed a good control for leukoplakia within a definite period of time. However, 17 of 44 cases (38.6%) were recurred after laser surgery. Some cases in the site of tongue were changed malignancy, It suggested that we need special care for the cases on the tongue, because of their high malignant frequency. Therefore, we should carry out a biopsy before an operation.
Twelve of 16 cases (75%) with oral lichen planus were recurred, it suggested that the Nd-YAG laser wouldn't be able to manage them, and so we need to compare with the results which were treated with the other type of laser, or the other therapy.

View full abstract

A high power diode laser surgical system was developed by Applied Optronics Corporation (AOC) of the United States of America in 1996. With the features of compactness and lightweight, it further emits laser beam of the maximum output power of 60W with the wavelength of 980nm, and the transmission of the laser beam through flexible optical fibers is possible. This time we have applied this laser system over the living tissues, and performed the clinical evaluations at two facilities to confirm the efficiency and safety in its hemostatic, cutting, coagulating, vaporizing effects, etc. We have made endoscopic laser treatments and surgical laser operations in totally 64 cases, and excellent treatment results were obtained in all cases. We have observed no negative side-effects relating to the clinical evaluations and we have confirmed that this laser surgical system would be an efficient and safe medical device for the treatment and surgical operations through endoscopes and in the peritoneotomy.

View full abstract