Laser has been widely employed in Cardiovascular diseases. Since 1980's we have investigated laser works as follows: 1) Transmyocardial revascularization (TMR) by CO₂ laser, 2) Laser vascular anastomosis, 3) Laser angioplasty (Argon, Nd-YAG). Based on excellent experimental studies laser was applied for 225 patients with intermittent claudication and chest pain.
They consisted of TMR in one case, vascular anastomosis in 111 cases, and laser angioplasty in 113 cases including intraoperative coronary angioplasty of 10 cases.₂ The patient with TMR is still alive more than 11 years. Good results in vascular anastomosis and laser angioplasty could be apparently obtained. An availability of laser in cardiovascular diseases could be clearly confirmed through these experimental and clinical studies.

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CO₂ and Nd: YAG lasers have been used in head and neck surgery for the past twenty years, KTP laser recently as well. Laser surgery in head and neck area was reviewed and the results of laser treatment were presented based on our experience. Laser surgery was performed for 204 cases of allergic rhinitis at our out-patient clinic. The therapy was effective in 91% of cases for nasal obstruction and 87% for nasal symptoms overall. Sixty-eight cases of glottic carcinoma were treated with laser surgery. The 5-year suvival rate was 100% for T1 and 80% for T2 cases. Glottis T1 can be treated by laser surgery alone. Laser surgery followed by external radiotherapy for glottis T2 improves the voice conservation rate. Seventeen patients with subglottic and/or tracheal stenosis were treated with laser surgery. Sixteen patients required emergency endotracheal laser surgery and satisfactory results were achieved in twelve cases. Six of seven patients with stenosis due to malignant tumor could be treated satisfactorily, although long term follow-up confirmed recurrence of tumor.

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The US governmental policy on science & technology is aiming to be strategic for economic stability and the following five targets are included.
1) Maintenance of leadership on scientific knowledge. 2) Enforcement of linkage between basic researches and national targets. 3) Promotion on investments for basic sciences. 4) Training on excellent scientists towards 21 century. 5) Enhancement on American peoples' understanding for sciences.
The characteristics of research & development in medical fields in Canada are indicated as the two targets-one is network for research core facilities and partnership between universities and industries.
Recently, the Japanese government are interest to construct“Highly Estimated Research System”which included the plans on increase of research funds and improvement of research conditions of researchers and research circumstances.
Finally, the requirements to promote on research on laser medicine and the establishment of“the International Research & Development Center of Laser Medicine”was discussed.

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Current status of Free electron laser (FEL) technology and application are presented. A representative FEL technology is FREE ELECTRON LASER RESEARCH INSTITUTE, Inc. FEL facility will serve the several application and be a promising instrument for medical use. FEL is quite effective for bio/medical application as an infrared tunable radiation source, of which examples are the surface reforming of tooth and the introduction gene into cell.

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TULIP was performed in 11 patients with Benign Prostatic Hypertrophy (BPH). Every TULIP was done under spinal (saddle block) anesthesia. Each procedure during TULIP was according to the TULIP instruments maker's instruction using Nd: YAG laser with 40W.
Complications during or after TULIP was negligible.
Four of 5 patients with complete urinary retention have maintained good condition with AUA symptom score of 7±1.6 over 2 years since TULIP. One patient who suffered from cerebral infarction during follow-up period still goes without large residual urine but with AUA symptom score of 26.
Other 6 patients have shown improvements on AUA symptom score from 23.8±3.5 to 14. 5±6.0 on 1~2 months after TULIP.
According to our clinical experience, it is concluded that TULIP is a safe and reliable treatment for BPH.

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Prostatic surgery using contact irradiation method with Nd: YAG laser was performed in 71 patients with symptomatic BPH in Nihon University Hospital. This therapy in this mode is similar to standard TUR-P, because of creating a large cavity by vaporization in the prostatic urethra. The results of preoperative examinations in the 71 cases were as follows; International Prostate Symptom Score (IPSS) ranged from 12-32 (av. 21) points, and maximal flow rate (Qmax) ranged from 0.4-19.5 (av. 6. 53) ml/sec. The results of postoperative examinations were as follows; 6-week postoperative IPSS and Qmax were 2-26 (av. 10. 2) points and 2.9-29 (av. 13. 3) ml/sec., respectively. Improvements of these subjective and objective urinary conditions were maintained for over one year. Prostatic surgery using contact irradiation method with Nd: YAG laser was equal or slightly inferior to standard TURP in usefulness but less invasive than standard TURP.

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Laser prostatectomy by contact-dragging irradiation using Ultraline^TM, side-firing laser fiber, and Nd: YAG laser was performed in 121 patients with BPH between August 1993 and July 1996. The total irradiation energy ranged from 18,147 to 365,185 (mean: 129,179) joules. The operation time ranged from 17 to 175 (mean: 77.8) minutes. It required 5.5 days on average until the patients became catheter-free after operation. As postoperative complications, urethral stricture occurred in 13 patients, epididymitis in 8, and postoperative hemorrhage in 1. Formation of cavity in the prostatic urethra by means of vaporization during operation improved dysuria early after operation and reduced a prostate volume by 31.1% through sloughing of coagulation layer within several weeks after operation, enabling maintenance of a good urination status over 2 years after operation. Since total irradiation energy was large (3,539 J/ml prostate) in the present method, transurethral ultrasonography (TUUS) was employed to ensure safe operation and to evaluate the results of operation. The present operation enabled channeling similar to that achieved by conventional TUR-P and complete removal of the transition zone of the prostate of 30ml or small. Postoperative complications, however, frequently occurred considered to be due to elongated operation time, thus it was considered to be the limit of vaporization method using Nd: YAG laser at present.

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42 patients suffered from benign prostatic hyperplasia were treated with laser assisted TUR-P. Their results were studied comparatively with 56 other patients belonging to a group treated with VLAP only. Compared with the VLAP mono-therapy group, the laser assisted TUR-P group showed significant improvement in every parameter both one month and three months post-operatively. Especially, the patients on the laser assisted TUR-P therapy were notably improved in MFR, in post-void residual urine and in estimated prostate weight, one month after treatment, proving this therapy to be faster and more radical. Their estimated bleedings were significantly less than those of the 30 patients composing a TUR-P mono-therapy group. They required no transfusion and noticed no other serious complications. The laser assisted TUR-P is an efficient therapy that combines VLAP with TUR-P, making full use of their advantages and having their disadvantages made up for by each other.

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The holmium laser is a unique laser that is useful not only for soft tissue but for hard tissue as well. We have reported on the treatment of urinary calculi with the holmium laser and on its application to the human prostate. In this paper we report on endoscopic laser therapy between June 1993 and July 1996. We performed holmium laser therapy in 118 patients between June 1993 and August 1996. Seventy three patients were undergone holmium laserlithotripsy and 45 patients laser prostatectomy.
In laserlithotripsy, the holmium laser can fragment all types of calculi, and as long as the tip of the laser fiber does not come into contact with tissue it is safe. There is less propulsion of the calculi during lithotripsy than with pulsed dye or alexandrite lasers. Prostatic therapy with the holmium laser was bloodless and the subjective and objective results were also favorable. The holmium laser appeared to offer a wide range of endoscopic applications in the treatment of a variety of urologic diseases.

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In the past several years, Q switched ruby lasers have been found to be effective in the treatment of deep dermal pigmented lesions of the skin, such as Ota's nevus, in addition to other superficial pigmented skin lesions, and at present various types of laser equipment are being clinically employed. Although the recently developed Q; switched ruby laser is expected to supersede the conventional normal- pulsed ruby laser, it takes long time to treat extensive cases because of the small radiation spot size of the Q switched lasers. And it needs several times of irradiation and it takes about from 1 year and half to 2 years to diminish the lesion. However, we have designed a new therapeutic protocol which involves the combined use of both Q-switched and conventional normal- pulsed lasers, exploiting the specific advantages of each type. This new protocol has made it possible to treat patients with Ota's nevus with a high degree of therapeutic effectiveness. We also evaluated the effectiveness of twice irradiation of the Q switched ruby laser to shorten the period for complete diminishing the lesion as well.

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Many biomedical applications of lasers have been developed. In many cases, however, selection of a particular laser has been based largely on availability, and treatment protocols have often been developed by an empirical approach. Selective photothermolysis (SP) has been proposed as a construct which may be useful in designing laser systems for biomedical applications, especially for the treatment of pigmentary dermatoses. In this study, a Q-switched ruby (QSR) laser, with a pulse of light sufficiently short and energetic enough to produce localized high temperatures in the targets, was employed for the treatment of these serious cosmetic problems. The QSR laser was used to deliver 6J/cm²pulses at a wavelength of 694 nm and with a pulse duration of 30 ns. In the clinical trial of QSR laser for treatment of more than 1000 patients with various kinds of pigmented skin lesions, the QSR laser was demonstrated to be useful for treatment of dermal melanocytosis and black, brown, and blue tattoos which showed no significant response to previous therapies. In the patients with basal pigmentation, however, patients with postinflammatory pigmentation or chloasma showed no response, although most patients with solar lentigo and all patients with mucosal pigmentation revealed a good response after only one laser treatment. In addition, cafe-au-lait macules respond variably to treatment with QSR laser. No hypertrophic or atrophic scarring was observed in any of the patients, although transient postinflammatory hyperpigmentation was noted for several months. In conclusion, SP using the QSR laser appears to be a safe and effective method for lightening or eliminating nevus of Ota and some other pigmented lesions.

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The helium-neon (He-Ne) laser has been studied as an important dermatological therapeutic instrument for wound healing, but the mechanism of this use at the cellular and molecular level is still unknown. Our study revealed: 1) He-Ne laser induces a significant increase in IL-1α and IL-8 production in He-Ne laser treated keratinocytes, 2) this stimulatory effect of He-Ne laser is dosedependent. IL-1α and/or IL-8 induce keratinocyte migration and proliferation. He-Ne laser has a potential dermatological application in the treatment of segmental-type vitiligo, a dysfunction of sympathetic nerves in the lesions. Using laser Doppler flowmetry, we confirmed a significant increase in the cutaneous blood flow of depigmented lesions. Clinical applications of He-Ne laser in segmental-type vitiligo are rewarded by obvious improvement, perhaps due to melanocyte growth factors release from both epidermis and nerve ending.

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Development of the flashlamp pulsed dye laser technology has allowed us to treat superficial vascular disorders very effectively without surgical operation or scar formation. Wavelength of the dye laser is 577nm, corresponding to one of the absorption peaks of oxyhemoglobin and its pulse duration is shorter than thermal relaxation time of the blood vessels. Therefore, it specifically destructs blood vessels without impairing surrounding tissues. Histological examinations revealed a selective destruction of ectatic blood vessels, and replacement by collagen fibers 2 weeks after the treatment. The numbers and diameters of blood vessels located from the skin surface to a depth of 600μm were significantly decreased after the treatment. However, tissues around blood vessels or those below 600μm from the skin surface remained almost intact. Applications to port-wine stains, strawberry mark, teleangiectasia and same other skin lesions has achieved. An excellent or good clinical improvement after single treatment in 242 of the 450 patients (53.8%) without scar formation. Pulsed dye laser is thus of great value for treatment of reddish skin lesion with vascular dilatation or hyperplasia.

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Extracorporeal circulation (ECC) using a pump-oxygenator is indispensable support for cardiovascular surgery. However, problems remain because of erythrocytic damage. So we studied the protective effect of low power He-Ne laser as a novel means of alleviating the erythrocytic damage caused by pump-oxygenator, in the absence of drug administration.
Experiments were using a hollow-fiber type membrane oxygenator, connected to a closed circuit filled with a human erythrocyte suspension (leucocytes and plasma were excluded). One of the circuits was used for laser irradiated group and the other for control. Two circuits were inserted into one double roller pump, and experienced same time, using the same sample. The laser group demonstrated significantly higher erythrocyte deformability, and lower free hemoglobin levels. Furthermore, in subsequent morphological observations using a scanning electron microscope, there were fewer spinous erythrocytes and more normal discocytes in the laser group when compared to the control group.
Low power He-Ne laser irradiation was shown to protect human erythrocytes from the damage caused by experimental pump-oxygenator, and the clinical application of low power He-Ne laser irradiation for ECC might be indicated.

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Fifty cases of postherpetic neuralgia (PHN) were treated with diode low power laser therapy. Two diode low power laser systems were used. One of them was model MLD-1002 (Mochida, Tokyo), a GaAlAs producing an output power 60mW at 830nm in a continuous wave and the other was model MLD-1003 (same above), a GaAlAs producing an output power 150mW at 830nm in a continuous wave. The laser was irradiated to the nueralgic area. In the case of facial neuralgy, the laser was also irradiated to the stellate ganglion area. Seventeen cases healed and sixteen cases exhibited remarkable improvements. Nine cases improved to a lesser extent and seven cases improved slightly, while one case remained no change. The rate of improvement was 84.0%and the rate of remarkable improvement was 66.0%. No clinically significant adverse effect resulting from the diode low power laser therapy was noted. Our results suggest that the diode low power laser therapy may be an effective and safe therapy for PHN.

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Many researchers reported successfully using low-power lasers such as the ruby, He-Ne, Nd: YAG, and Ga-Al-As, and other diode lasers to relieve pain and promote wound healing. However, the output power of He-Ne and diode lasers has not been completely satisfactory. Those laser are also referred to as non thermal, cold, or soft lasers because it is thought that their effect is electromagnetic rather than thermal. Recently diode lasers with greater output power have been developed, and we have had considerable success in the clinical application of laser irradiation with an approximate output of 300mW. For quite some time, we have obtained good results in the treatment of neurological disorders such as paresthesia in the lower lip and mental region after minor surgery or facial palsy by low power irradiation of the stellate ganglion with 300mW output of Nd: YAG, and other diode lasers. Also, the results in the treatment of temporomandibular joint disorder patients are satisfactory. This paper reports clinical usefulness and therapeutic results of low-power laser therapy in the treatment of oral and maxillofacial region.

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Patients visited our clinic were divided into two groups, that is, the one of laser irradiation over the stellate ganglion (LISG Group; N=76) and the other of conventional stellate ganglion block using a local anesthetics (SGB Group; N=82). In the LISG Group, pulse rate and systolic blood pressure decreased significantly, from 69±22bpm to 65±20bpm, 131±44mmHg to 122±40mmHg, respectively. Furthermore, in the LISG group, we observed a subjective warm feeling on the face (rate of frequency of appearance, 54%), flushed checks (26%), and mild conjunctival hyperemia of the eye (37%). Thus it is considered that abnormal sympathetic activity may be gradually controlled by laser irradiation over the stellate ganglion. LISG is, in the opinion of the authors, a non-invasive, side-effect free and painless therapy, which can be applied bilaterally with no appreciable adverse side effects.

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Pain Low power laser analgesic effect was generally accepted in clinical cases, whereas there was no direct evidence to indicate that low power laser irradiation suppressed an impulse conduction within a peripheral nerve. The effects of low power laser irradiation on electrically evoked responses within the sural nerve was electrophysiologically analyzed in unanesthetized, decerebrate cats and in anesthetized rabbits. Firstly, the effect of a low power (1mW; 632.5nm) helium-neon laser irradiation to the cord dorsum potentials evoked by the sural nerve stimulation was analyzed in unanesthetized, decerebrate cats. The cord dorsum potentials which were induced by the electrical nerve stimulation applied to a distal portion of exposed sural nerve was significantly suppressed during a low power laser irradiation. Secondary, the effects of low power laser irradiation upon multiple units' discharges within a peripheral nerve, which were induced by a noxious stimulation, were analyzed in anesthetized rabbits. Responding to a pinch stimulation of plantar skin, transitory increase of neuronal discharges, which reduced within a minute, and persistent increases, which continued during a period of the stimulation, were induced in the sural nerve. These increases became significantly smaller than the control value during low power laser irradiation that applied to the exposed sural nerve at distal to the recording site. Thirdly, the effects of low power laser irradiation on electrically evoked responses within the sural nerve were analyzed in anesthetized rabbits. Only high threshold evoked responses (unmyelinated A delta) which was induced by an electrical stimulation to the peripheral stamp of the nerve were significantly suppressed during low power laser irradiation which applied to the exposed sural nerve between the stimulus site and the recording site. The suppressive effect was reversible and recovered to the control level after the irradiation, Experimental evidences indicated that low power laser irradiation suppressed the impulse conduction of unmyelinated A delta afferents in peripheral sensory nerve which caused a pain sensation. Our data suggest that low power laser act as a reversible direct suppressor of neuronal activity.
Wound healing Although many clinical studies have tested usefulness of low power laser (LPL) irradiation for the wound healing, the mechanism of the effects by LPL irradiation has not been fully elucidated. The present study demonstrated that the enhanced LPL irradiation effect to the procollagen production was consistently observed in the serum-starved medium, not in the FCS-contained medium. These results suggested that some factors in FCS might interfere with LPL irradiation onto procollagen synthesis. This view is supported by the fact that LPL irradiation was much more effective in intractable ulcers and bloodless wounds, which could be lack in FCS. The LPL irradiation effect was not blocked by dexamethasone but methylene blue. It seems probable that the LPL enhanced effects to the procollagen product of the fibroblast might be occurred at the translational level not at the pretranslational level of the mRNA synthesis and cGMP might be involved in the enhanced effect of the procollagen synthesis in fibroblast.
In vivo study, the effect of the low power laser on the inflammatory stage of wound healing was investigated using delayed wound healing animal model. Round open wounds were made on the bilateral backs of doxorubicin treated pigs. After making wounds, low power laser was ipsilaterally irradiated on the wounds for 3 minutes everyday. On the 5th day, the wounds were removed and immunohistologocally stained using anti-fibronectin antibody and anti-keratin antibody. Intensity of the fibronectin-like immunoreactivity, the length of new epithelium and the number of the inflammatory cells were measured and compared in the presence and absence of LPL irradiation by using computed analyzing method.

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There are no good therapies for Raynaud's phenomenon and skin ulcers in progressive systemic sclerosis (PSS). Recently it is reported that polarized light irradiation near the stellate ganglion is one of the good therapies for blocking sympathetic nerve function to reduce pain and to increase peripheral blood flow.
In 10 cases of collagen diseases with Raynaud's phenomenon, we analyzed the thermography of hand fingers after one irradiation near the lateral (right or left) stellate ganglion using by the polarized light irradiation system (Super Lizer HA-550: KSK Tokyo Iken Co.). And we analyzed the thermal response of skin ulcers on feet in PSS cases suffering from multiple ulcers. The duration of irradiation is 70%power of 1800mW, 1 second irradiation and 2 seconds resting cycles for 10 minutes at once.
In 10 collagen diseases with Raynaud's phenomenon, there are no abnormal reaction and discomfort feelings by the irradiation therapy. All of the mean temperatures of fingers of both hands increased after the irradiation, and there were statistical significance in 1, 3. 4 and 5th fingers in the irradiated side.
In a PSS patient, the temperature of skin ulcer more quickly increased after one irradiation than after the injection of Prostaglandin E1.
It was considered that the polarized light therapy is one of the useful methods for treatment of Raynaud's phenomenon in collagen diseases.

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The authors evaluated potential of photodynamic therapy with a new photosensitizer, mono-L-aspartyl chlorin e6 (NPe6) that tissue uptake and clearance are rapid. Firstly, NPe6 solution was exposed to diode laser at 664nm that fits to maximum absorption of NPe6. Immediately after laser exposure, these solutions were subjected to electron spin resonance (ESR) to detect generation of activated oxygen species. With ESR, signals of O₂, OH, and ¹O₂ were detected on NPe6 solution. Contrary to this, signals of O₂ and OH dissipated when dissolved with superoxide dismutase. Fundi of pigmented rabbits were then irradiated to diode laser after administration of NPe6. Histopathologically, there showed necrosis of endothelial cells and vascular occlusion in choroid, especially in choriocapillaris. Retinal pigment epithelial cells were also injured. In contrast, sensory retina was approximately preserved even with a large amount of dye. A new combination of NPe6 and diode laser at 664nm enables us to occlude choroidal vessels efficiently by generating various activated oxygens. This fact proposed potential of photodynamic therapy with NPe6 in treating retinochoroidal involvement.

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Wister rats bearing corneal neovascularization, with or without pretreatment of heparin, were subjected to photodynamic therapy (PDT) with ATX-S10, and the mechanism of vascular injury was estimated by electron microscopic analysis. After laser irradiation, neovascular endotherial cells exhibited surface irregularity, swelling of mitochondria, dilatation of endoplasmic reticulum and finally dissolution of the cytoplasm. In heparinized rats where ischemic influences derived from hemostasis were excluded, we still observed swelling of mitochondria but no dissolution of the cytoplasm. These results suggested that the target site of ATX-S10 was endotherial cell surface and mitochondria and the main mechanism might be ischemia accompanied by thrombosis. Uptake of ATX-S10 in corneal neovascularization was investigated by angiography using ATX-S10, nitrogen-pulsed laser spectrofluorometry and fluorescence microscope. These results suggested that the difference in ATX-S10 accumulation between new vessels and surrounding normal tissue increased at two to four hours after dye injection and this time period was supposed to be optimal to start laser irradiation. The optimal treatment parameters for achieving selective closure of new vessels was determined. For rabbit corneal neovascularization, the optimal irradiation fluences were 107-153J/cm² and 38.2-76.4J/cm² with dye doses of six and twelve mg/kg, respectively. For rat choroidal neovascularization, the optimal fluence was 22J/cm² with a dye dose of 16mg/kg. ATX-S10 is a promising new generation sensitizer which has rapid elimination from the body and little skin phototoxicity, and it appears to be useful in the treatment of ocular neovascularization.

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We have previously reported our tremedous results from phtodynamic therapy (PDT) for superficial squamous cell carcinoma of the esophagus. Patients with five submucosal and fifteen mucosal carcinoma recieved PDT from 1984. The average spread of submucosl carcinomas were 4.8cm², which was two times wider than mucosal carcinoma. Fourteen patients were treated with Argon-Dye laser, three with Excimer-Dye laser and three with Yag-OPO laser. As total light dose of explosure were 40-150 J/cm², wider submucosal carcinoma cases recieved less dose than smaller mucosal carcinoma cases. In evaluable 19 cases excluding 1 drop-out, three cases remained remnant lesion and two cases were relapsed locally. The cause of treatment failure was supposed to be from inadequate light dose and laser sourse. Although three remnant cases recieved re-PDT and achieved CR finally, one of the two relapsed patient was dead of metastatic cancer and another patient was performed surgical redection recently. Closing response rate as a local treatment was 89.5%. In summary PDT is considered to have a great potential for controlling the localized superficial carcinoma of the esophagus.

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From 1981 to 1990, we had treated thirty-seven cases with early gastric cancer by PDT with HpD (Photofrin ^RI) or DHE (Photofrin ^RII) and an argon dye laser (ADL). However, the rates of cure were only 59%(13 out of 22 cases) in mucosal cancer, 53%(8 out of 15 cases) in submucosal cancer, and 57%in total. In order to improve the therapeutic effectiveness of PDT with DHE for early gastric cancer, we employed an excimer dye laser (EDL; Hamamatsu Photonics, Hamamatsu, Japan) instead of an ADL in 1990, and then improved the EDL in 1993 to apply PDT to the wider lesion, whose size is within 4cm in diameter and 13 cm² in arca. The characteristics of an New EDL are as follows: wavelength, 630nm; pulse energy, 4 mJ; peak power, 400kW; pulse width, 10 nsec; frequency of repetition, 80Hz; average output, 320mW. The entire lesion, plus a 5-mm wick, perimeter of mucosa, was irradiated uniformly with an EDL beam transmitted endoscopically. The energy intensity of an EDL was over 60 J/cm². By employing an EDL, the rates of cure were markedly improved up to 93%(14 out of 15 cases) in mucosal cancer, 73%(8 out of 11 cases) in submucosal cancer, and 85%in total. It was thought that an EDL can penetrate deeper and activate DHE more efficiently than an ADL. Since 1995, we have been treating early gastric cancer by PDT with DHE and an optical parametric oscillator system pumped by a Q-switched Nd YAG laser (YAG-OPO laser; Ishikawajima-Harima Heavy Industries, Tokyo, Japan). It has a high peak power of 700kW though its average output is 250mW. By employing a YAG-OPO laser, a wide cancerous lesion was cured, whose size was 19cm² in area. In conclusion, PDT with a pulsed laser, which has a high peak power, is more effective for treating early gastric cancer than that with an ADL.

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Among early gastric carcinomas as relative indications for endoscopic treatment, poorly-differentiated adenocarcinoma has been considered to be difficult to radically treat by endoscopic operation. This is because lymph node metastasis occurs when the depth of tumor invasion is still slight. To determine the range of poorly-differentiated early gastric adenocarcinoma that can be radically treated using laser irradiation, we evaluated the results of laser therapy for this carcinoma by observing the course.
The subjects were 34 patients (20 males and 14 females) with poorly-differentiated early gastric adenocarcinoma encountered between 1981 and October 1998. Their age at the time of treatment ranged from 35 to 84 years (mean; 66.2 years). The estimated depth of tumor invasion before treatment was M in 14 patients and SM in 20. The macroscopic type was II_a in 3 patients, II_c in 19, II_c+III in 11, and II_c+II_b in 1, the depressed type, which is frequently observed in poorly-differentiated adenocarcinoma, accounted for a large percentage. Laser therapy was performed using a Nd-YAG laser at the tip output of 50-70Watt by the non-contact method. Cancer was negative in 11 (32.4%) of the 34 patients. Three patients died of cancer; the mean interval between laser therapy and death was 3.0 years. Thus survival in some patients was prolonged by laser therapy. Observation of the course for 1 year or more showed no residual cancer in all 4 patients with M as the estimated depth of tumor invasion but only 40% of those with SM. Laser therapy may be useful in patients with M cancer.

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Endoscopic diode laser ablation using indocyanine green (ICG) as a photosensitizer was studied to develop the treatment for early gastric cancer. The ICG solution with Img/ml concentration was administrated to the submucosal layer. When 25W diode laser emitted with 0.2seconds repeated irradiation with 0.2seconds interval, the submucosa was not ablated because of mucosal carbonization. Histology of the specimen in this case revealed total submucosal coagulation without any proper muscle damage. When the irradiation condition was 1 seconds irradiation repeated with foot switch control with an output of 25W, the mucosa was removed and submucosa was ablated progressively. The proper muscle was intact from thermal and direct laser injury as far as the ICG containing submucosal tissue remained. We could control the ablated depth by the endoscopic observation of the ablated surface. We think our therapy might be useful for the early gastric cancer with/without the submucosal invasion, in particular inoperable case.

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the spectrum which are absorbed by dentin and enamel.(1981, The Japanese journal of Conservative Dentistry.)
These studies show that dentin and enamel absorb light in the regions of the spectrum around 3 μm and 10 μm. Water also absorbs light in the 3 μm region.
Er: YAG laser is effective in the 3 μm region and the CO₂ laser in the 10 μm region. However, the CO₂ laser has a clinical drawback: it causes heating which cracks the tooth surface. This makes the Er: YAG laser the best possibility for clinical application. (1990, The Japanese Society for Laser Dentistry)
It has also been shown that the Er: YAG laser removes hard dental tissue through the micro-explosive reaction of OOH-Stem of the hydroxy apatite the hydration shell inside the crystal is instantly vaporized.
The complete absence of pain during the procedure is especially noteworthy.

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We developed a high power diode laser in cooperation with Osada Electrics Industry Company Limited.
This device with the maximum output power of 3 watts is compact, portable and easy to operate for the treatment of disease on oral soft tissue.
This device was evaluated as effective to dental treatment by basical research and clinical trial.
In this presentation, I will show several cases applied to disease on oral soft tissue and discuss about the applicable capacity and the future.

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It is evident that promoting the wound healing of tissue around dental implant increase success rate of dental implant procedure. In this study, to evaluate the effect of laser on wound healing of gingiva and mandibular bone, in vivo and in vitro studies were done. In vivo studies showed that laser promotes the turnover rate of collagen, hone resorption and sequentially bone formation, during the healing stage. In vitro, laser stimulates DNA and protein synthesis and expression of ALP activity. These results suggest that the low power laser irradiation exerts beneficial effects on wound healing of gingiva and bone.

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Medical lasers can be divided into two general groups: High powered lasers (e. g. CO², argon, Nd-YAG etc.) which utilize the thermal effect for cutting or coagulation, and low-power lasers (e. g. diode, He-Ne etc.) which utilize photoactivation or photo-chemical reactions to relieve pain or promote wound healing. It is good indication of soft tissue tumours resection using high powered CO², or Nd-YAG lasers. Various low-power output lasers are used frequently in the oral region. We have obtained good results by treating neurological ailments such as facial palsy and pain in the maxillofacial region by irradiating the stellate ganglion with 300mW output power of Nd: YAG laser and diode lasers.

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338 cases of oral mucous diseases were treated with high power laser, during 1979 and 1996. 75 cases were malignant tumors and the other cases were benign oral mucous diseases. Histopathologicaly, 68 of 75 cases were squamous cell carcinoma and 41 of them were treated radically with laser therapy. 20 of 41 cases were treated with laser therapy only and their site was the tongue in 16, gingiva in 2, buccal mucosa and floor of the mouth in one case each. They included 3 cases (tongue 2, gingiva 1) of T2, 17 cases of T 1. Excepting one of T 1 case of tongue there was no local recurrence.
22 patients received interstitial irradiation were compared with 15 patients with laser therapy, concerning secondary lymph node metastasis. It was found in 8 cases (36.4%) of the former, in one case (6.7%) of the latter.
The most common lesion was leukoplakia in 263 benign oral mucous diseases. We compared a recurrence rate with 25 cases treated with CO 2 laser and 41 cases with Nd-YAG laser. A higher recurrence rate was shown in patients treated with CO 2 laser.

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As compared with electrocautery,the clinical usefulness of laser treatment is still completly unclear for laparoscopic surgery on gynecologic field. We investigated the correlation of clinical features,such as the degree of pain relief and adverse effects, recurrence reate after ovarian cystectomy with use of laser and/or electorocautery during laparoscopic management. From Jan. 1991 to May 1996, 80 endometriosis, 59 patiens with sever dysmenorrhea and 35 patiens with intra-abdomnal adhesion after anather surgical managements examined by laparoscope,were selected for this study. The surgical effect with laser treatment of 174 patiens could be evaluated: 83% case of functional dysmenorrhea were in clinically good effect, 72.5% of postoperative adhesion ingood effect and only 17.5% of chocolate cyst showed in recurrense of cyst. three results show that laparoscopic surgery with laser treatment are good surgical management for gynecologic fields.

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Laparoscopic surgery demands flexibility in that it requires selection of the method most suited to the patient, technician, and circumstances. The instruments used are also an important factor in determining the safety and ease with which laparoscopic surgery is conducted. Here we introduce procedures for the enucleation of uterine myoma and the laparoscopic, techniques we use, and compare the electric scalpel, laser scalpel, and ultrasound scalpel (harmonic scalpel). While the laser scalpel is an important tool in laparoscopic surgery, we did not find it to have any clear advantages over the electric scalpel. As for the harmonic scalpel, although it transiently produces a smoke-like vapor, the field of vision remains clear. The harmonic scalpel was equal to the laser scalpel in terms of incision and coagulation ability, and is expected to become an important tool in the futere.
Ultimately, the advisability of surgery and the type of operations that are possible will depend not only on the instruments used, but also on the views of the surgeon regarding a particular procedure and the surgen's level of technical skill.

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Laser conization using contact Nd-YAG laser system was performed in 184 patients with dysplasia and early cancer. Hysterectomy was avoided in 142 cases because of complete excision or mighty wish for continuation of pregnancy in pregnant cases at the conization. In these 142 preservation cases, there were 6 recurrent cases in 19 of incomplete excision cases. On the other hand, there was no recurrent case in 123 of complete excision cases. Adverse effect of laser conization was suspected up to 30% in pregnant cases. Post operative bleeding, stenosis of external os and adhesion of cervical canal were observed in several cases. It was expected that these adverse effects were decreased by the betterment of operation technique and the improvement of laser devices.

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Three hundred and eighteen women with dysplasia, carcinoma in situ (CIS) and microinvasive carcinoma (MIC) were treated by CO²laser excision conization. One hundred and ninety eight patients (62.2%) were performed laser conization in the outpatient unit. Two hundred and fifteen patients (67.6%) after conization were followed up by cytology, colposcopy and histology. The recurrence rate after lyear was 3.4%. Postoperative bleeding rate was 1.7% in the inpatient laser conization group, while 10.6% in the outpatient group because of the lack of bed rest at home. Bed rest at home for a few days after conization must be insisted on in the outpatient group. Twenty one women after conization had given birth (after 24th week). Six of these cases (28.5%) were delivered preterm. Laser conization seemed to increase the risk of preterm delivery in subsequent pregnancies. Pregnant women with prior conization need careful antenatal care. These results suggested that CO2 laser conization was a highly effective method treating early cervical neoplasia, although we have to consider some complications.

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Studies with KTP/YAG Surgical Laser System and Nd-YAG laser were performed. In fundamental study,the effect of KTP laser was examined by using of extirpated uteri and compared with other laser sources.The vaporizing ability by KTP was in the midist of YAG and CO2 laser. The degenerated layer formed by KTP was similar to that by YAG. In clinical study with KTP/YAG laser, twenty-six with dysplasia or CIS, and one with questionable microinvasive cancer were treated at outpatient basis under local anesthesia. Laser conization was used in all cases. The primery cure rates of dysplasia and CIS were 100% and 92.3%,respectively.Concerning side effects, slight pain and hotness were only complained. Cervical stenosis was experienced in two cases. With Nd-YAG laser, sixteen caes with mild dysplasia, six cases with moderate dysplasia, three cases with severe dysplasia, seven cases with CIS and three cases with microinvasive cancer were treated under local anesthesia by hospitalization.Vaporization was used for eight cases with dysplasia and conization was usde for other cases. The primary cure rates were 100% in each case. Complications during and post operation were minimal. Conizated specimens were placed to examine HPV-DNA by means of PCP method. Primers for HPV types 16, 18, 31, 33, 35, 52b, 58 (M type) and types 6, 11 (B type) were used. We detected M type HPV in 1 case of 4 mild dysplasias, 1 case of 4 moderate dysplasias, 5 cases of 11 severe dysplasias, 6 cases of 19 CISs, and B type IIPV in 2cases of 4 moderate dysplasias, 4 cases of 11 severe dysplasias and 5 cases of 19 CISs. There was no significant differenses however, in the detection of HPV DNA between the results with and without the positive lesion on the edge of conizated specimens.

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Nd-YAG laser conization was performed in 83 patients with early cervical neoplasia and the uterus was preserved in 57 (moderate dysplasia: 2, severe dysplasia: 16, CIS: 37, stage Ia cervical cancer: 2). They were investigated for survival, Papanicolau smear findings, pregnancy and delivery and cervical stenosis.
Results
1) Aside form one patient dying of another disease, the survival rate of the 57 patients with uterine preservation was 100% (median follow-up: 72.5 months).
2) Fifty-four patients with uterine preservation (94.7%) were followed up for 61.8 months (median). Class IIIa cytology was detected in eight patients (14.8%), but it disappeared subsequently during continued observation. Histopathologic examination revealed recurrence in one patient with mild dysplasia (1.9%).
3) Among 41 patients desiring children, all 24 fertile women became pregnant and 19 of them delivered a total 29 children. The cesarean section rate was 17.2%. There were no stillbirths or neonatal deaths.
4) When the cone was 5-15mm long (n=10), there was no second trimester spontaneous abortion, premature delivery, or threatened premature delivery, and only Shirodkar operation. When the cone was 16-24mm long (n=22), second trimester abortion, premature delivery, and threatened premature delivery occurred in 13.6%(n=3), 13.6%(n=3), and 9.2%(n=2), and the Shirodkar operation was done in 40.9%(n=9).
5) The incidence of cervical stenosis could be decreased by resecting the tip of the cone with curved scissors instead of the laser scalpel.
Conclusion
The survival rate after laser conization was comparable to that after hysterectomy. When the cone is over 16mm long, attention should be paid to the possible risk of second trimester abortion and premature delivery.

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Laser surgical devices are widely applied to head and neck surgery today, and will be more commonly used to day surgery because of their great ability of hemostasis, which would widen the indication of day surgery in Otolaryngology. We have been using a KTP/532 laser device as a substitute of electric scalpel for in-patient cases since 1992, and have used another one in out-patient clinic for about a year. We have found that KTP/532 laser is very useful for day surgery after the experience of 160 day surgeries with the device.

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The CO₂ laser in microlaryngosurgery is used for the treatment of benign laryngeal tumor, selected early laryngeal carcinoma and so on. We will report the clinical experiences of our clinic and some experimentations.
For 5 years from 1991, we performed this surgery in 83 patients with laryngeal diseases that are carcinoma (36 cases), leukoplakia (14 cases). papilloma (8 cases), polyp (14 cases) and stenosis (11 cases). We had no severe complication under or after this surgery. Minor complications were granulation in wound and adhesion of anterior commisure.
We studied the limitation of this technique from pathological point of view. For an excised larynx, we did the CO₂ laser surgery with the same condition as an ordinary microlaryngosurgery, After laser irradiation, we determined the three dimensional limitation (sagital, coronal and horizontal) pathologically. From this study, we concluded as follow; The CO₂ Laser is useful for the lesion on membranous portion of vocal fold. On the contrary, the anterior portion of the larynx cannot be radiated by the laser because of the anatomical reasons.
To perform laser surgery in safety under general anesthesia, we tried to develop the intubation tube which has a high resistance to laser beam. As a result, silastic tube was stronger than vinyl chloride tube for CO₂ laser beam. Of course, users need to grasp of the characteristics of laser beam and other related instruments.

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Laryngeal stenosis has been difficult to be repair and numerous surgical procedures have been used to try to treat this disorder.
Thirteen cases with the laryngeal stenosis (8 with bilateral vocal cord paralysis; BVCP and 5 with cicatricial laryngeal stenosis) were treated by micro carbon dioxide laser surgery including posterior partial cordectomy and incision and/or vaporization of the scar in our clinic during 5 years from 1992.
Twelve patients (8 with BVCP and 4 with cicatricial stenosis) achieved adequite airway and decannuration and subjectively good voice quality. Our only failure was in a patient with cicatricial glottic and subglottic stenosis.
The success of CO2 laser surgery for cicatricial laryngeal stenosis depends on re-epithlialization of the raw surface before scar formation.Therefore, epithelial coverage of the postoperative wound is an important factor in preventing restenosis.
We emphasized that technical development on the endoscopic transplantation of a free graft without stents or sutures has been expected for a significant therapeutic advance.

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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 2.1μm. 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.
We studied the effects of Holmium: YAG laser irradiation on vital tissue macroscopiccaly and histopathologically. This time, we report our experience of Ho: YAG laser application to head and neck region. Additionally, we discuss its characteristics by comparing it with CO₂ laser, Nd: YAG laser and KTP laser those are already in wide use clinically. Much expectation is placed on further clinical application of this laser, to head and neck region.

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The Laser Bipolar Dissector (LBD, SLT Japan, Co., Ltd.) hemostatically cut through veins up to 5mm and arteries up to 3mm in diameter. The interluminal bursting pressure was above 346mm Hg after transection. It was clear during laparoscopic procedure that avoiding rebleeding was necessary to observe the operative goals. This report describes the use of the LBD that was attached to a newly developed Kelly clamb to perform a laparoscopic splenectomy. The LBD hemostatically cut the short gastric vessels and the vessels in the attaching ligaments of spleen without clipping.In the LBD procedure, one action, in which the laser energy is initiated through the bipolar probes with simultaneous compression of vessel with them, is necessary to accomplish the transection of vessels. Because the goal of laparoscopic surgery is to be a minimum of operative techniques, it is therefore reasonable to attempt to use the LBD in laparoscopic surgery.

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The Nd-YAG laser, which is known to penetrate tissues well and is within the infrared wavelength, mainly produce tissue coagulation and vaporization with heat. Through preliminary experiments, it was found that by cooling the tissue surface, only the deep area forms the various shapes of laser coagulation corresponding to different irradiation pattern and different cooling environment, even though no change can be detected on the tissue surface with naked eyes. The device manufactured for this research, named Cooling Laser Irradiation Device, consists laser irradiation part, water circulation pump with a constant temperature apparatus, and a super-high sensitivity video monitor. This device selectively forms desired shape of coagulation in the deep tissues while the surface remains undamaged. Under video observation, the convex lens tip can slide smoothly over the concerned lesion while maintaining contact with the surface tissue. Adjustable irradiation pattern of the laser beam can be applied to the tissue surface while its temperature is controlled by the flow velocity and temperature of the cooling water. With the use of the Cooling Laser Irradiation Device, the temperature distribution of the deep tissue was analyzed using multiple thermo-coupling system. In the future, this device will contribute significantly in the development of less, or even non-invasive surgery.

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Recent advances in lasers and their related technologies have been reviewed, in relation with potential medical applications. One of the most important achievements in laser source development is seen on the all-solid-state lasers which are based on the LD (Laser Diode) pumping technology. The all-solid-state lasers are characterized by their compactness, high efficiency and high beam quality, easy maintenance, durability, etc., which would offer the ideal laser source for medical applications. Characteristics of a cw green Nd: YVO₄ laser and a passively-Q-switched microchip laser are described, as examples. For flexible laser beam delivery, quartz fibers have been used, but they can transmit only near-infrared and some visible lasers such as a 1.06μm Nd: YAG laser and its 2nd harmonics. The newly-developed hollow waveguides are very attractive to deliver mid-infrared, uv, high peak power, and tunable laser lights. Some transmission characteristics of the hollow fibers are given. These advances in lasers and their beam delivery systems could realize new areas for medical treatment and diagnosis. But the lasers would also play a very important role in development of medical devices and instruments. Laser-based-micromachining, surface cleaning, and rapid prototyping are introduced as the potential applications in this new field.

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Red semiconductor lasers are put to practical use in the 635nm to 680nm wavelength range. These lasers are applied to the optical disks for the application of DVD (Digital Video Disk). These lasers have suitable wavelength for photodynamic therapy (PDT), but doesn't have enough output power for PDT.
So, we have developped high power red semiconductor lasers and laser systems for PDT:-664nm/5000mW system (1993), and 652nm/5000mW system (1996).
We believe that these laser system will contribute to the spread of PDT.

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Photodynamictherapy (PDT) is a new method to treatment malignant tumor using photosensitizer and exciting light. PDT has many advantages over surgical operations for early cancers as follows. As PDT can keep the organ's function, quality of life after treatment will be fine. As PDT is the endscopic treatment, it can apply to unoperable cases, such as high risk complications and the aged.
We have developed tunable and pulsed laser system for PDT. This system consists of optical parametric oscillator pumped by third harmonic of Q-switched Nd:YAG laser (we call YAG-OPO laser). As YAG-OPO laser is tunable from 620 to 670nm, it is available for exciting various photosensitizers.
Clinical trial with YAG-OPO laser and photofrin II has been finished last month to the following tumor, early lung cancer, early superficial gastric cancer, superficial esophageal cancer and early uterine cervix cancer. We have confirmed fine results up to the present.

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The basic concept and performance of the laser hot-balloon caterter are presented. To overcome excessive thermal damage in the vessel surroundings, which is major reason to restrict thermal device applications, we realize short heating time of 10 to 15s with uniform temperature distribution in the balloon. We employed thin fiber delivered laser enegry as a heat source to obtain sufficient heat power at the balloon to attain rapid temperature rise. The laser energy then was used to heat contrast medium which was irrigated in the balloon. The production of heated contrast medium liquid is useful to obtain uniform temperature distribution. Moreover, the irrigation of this liquid after laser shut-off produced sudden decrease of the temperature. We developed novel thermal balloon catheter using above mentioned design. We examined this unique balloon angioplasty using animal model in vitro and in vivo. The obtained results indicated that our short time heating concept obviously drastically improve chronic phase patency in thermal angioplasty.

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The number of the patients with coroanry artery disease has been recently increased in Japan. Coronary artery bypass grafting (CABG) has been mainly carried out for those patients. However, there are a few cases for whom CABG can not be performed, because of small, or diffuse stenoses of the coronary arteries. For revolbing of these problems. Since 1980's we have investigated transmyocardial revascularization by CO₂ laser. Optimal conditions were over 80W in output to creat a channel in the ventricular wall more than thickness of 8mm and irradiation time was 0.2 sec for each shot. Histological findings of laser channels revealed long-term patency even in 3 years observation. Based on excellent experimental studies a clinical application was done for the patient with severe anginal attack on 12. Nov. 1985. The patient is still alive under obervation of ambulance.

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The threshold of sensitizer consentration and light dose rate for PDT effects have been examined on the basis of a chemical reacton. The examination revealed that there exists basically threshold of drug and light dose-rate effects in PDT. It was evident that the threshod of light doserate originates from the self-growth and repair of the tissues.

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