A case report of photo dynamic therapy (PDT) using a pulsed gold vapor laser was described. Hematoporphyrin derivative (HpD, 3mg/kg) was used as a photosensitizer. Patient was a 72 y.o. male and he has a lesion of early gastric cancer. Power of PDT was 330mW and total energy was set to be 160J /cm₂(2.5cm₂) and 132J/cm₂(1.5cm₂). Resection surgery was carried out after PDT. Pathological examination of the resected stomach revealed that the PDT effect to the tissue was extended to the muscle layer. This case suggects that a gold vapor laser is effective in the treatment of gastrointestinal cancer.

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The absorption, fluorescence spectra and fluorescence life time of hematoporphyrin oligomers (Hpos: mean molecular weight=2000, 3000, 5000 and 12000) and gerumanium hematoporphyrin derivatives (Ge HpD) were compared with those of photofrin II which has been using in photodynamic therapy (PDT). The proportion of the major lifetime component (14.5ns) of photofrin II was 90.5%.The fluorescence lifetime of Hpo (3000) was 13.3ns. The proportion of the major lifetime component of Hpo (3000) was 89.8%. From these results obtained, it was suggested that the probability of the photosensitizing react ion of Hpo 3000 might be high.

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The relation between the lifetimes of the triplet states of various porphyrins and their photosensitizing effects on the photodynamic therapy (PDT) of tumor has been examined. Ga-DP, Zn-DP, Mn-DP and P-II are used as the photosensitizer. The triplet lifetimes are obtained to be 57 ms (Ga-DP), 26ms (Zn-DP), <10 us (Mn-DP) and 9 ms (PII). The phosphorescence of Ga-DP in tumor-bearing golden hamsters are measured both in tumor tissue and in liver. They show bi-expo-nential decay with the lifetimes of about 5 and 20ms. The PDT effects have been quantitatively investigated for in vitro experiments; upon irradiation the growth inhibitions of mouse p388 leukemia cells are obtained as a function of concentration of Ga-DP, Zn-DP, Mn-DP and PIT. The experimental results indicate that the PDT effects depend essentially on the triplet lifetimes of the photosensitizers.

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1978年以来、我々は血色素、葉緑素由来の各種ポルフィリン誘導体を470種合成し、その化学構造と腫瘍組織親和性の関係を検討してきた。1)2)そして得られた基礎的研究の成果を基にして固形癌の診断、治療法の研究開発をめざし、それぞれ目的別に各種ポルフィリン誘導体を合成し、検討を行っている。
今回これらの研究開発の一環としてYagレーザーによる癌のPDT治療の基礎的検討を行った。
最近我々はポルフィリン誘導体の外部エネルギー励起による一重項酸素発生の要因である三重項寿命を生体組織中に於いて常温下に於いて測定することに成功した。3)そしてGa、Znか等の金属ポルフィリン化合物が光に対して著しい反応性を有することを明らかにした。他方Mn, Fe, Cu等の誘導体はこの逆の結果を得た。そこで現状の光化学療法 (PDT) の限界を克服することを目的として、世界で最も普及しているYagレーザーを用い、パルス波で2光子吸収4)によって反応する新しい腫瘍組織集積性金属ポルフィリン誘導体を開発し、動物実験により良好な治療効果を得たので報告する。

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Hematoporphyrin oligomers in cetyl trimethyl ammonium bromide (CTAB) micellar solution were irradiated by an argon laser. The spectroscopic property of the solution before and after the photoirradation was investigated by the measurements of spectra of fluorescence and triplet-triplet (Tn-Ti) absorption, and lifetimes of the excited singlet and triplet stats. From the results, the irradiated oligomers were concluded to form stable aggregates which would be photoactive sensitizers.

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We investigated the time course of Hematoporphyrin oligomer (HpO) uptake after intraperitoneal (i. p.)-injection to squamous cell carcinoma (SCC) transplanted into C3H mice by measuring of the relative fluorescence intensity. The intensity was maximum at 83 hr after the i. p.-injection.
Furthermore, we investigated the therapeutic effect of photodynamic therapy (PDT) or microwave hyperthermia at varying time intervals after HpO i. p.-injection. The effect was strongest at 83 hr after the i. p.-injection in each therapy. And the sensitization effect of HpO by microwave action was clarified in vivo.

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Human aorta treated with mono-l-asparatylchlorin e6 (NPe6) or hematoporphyrin derivative (HpD) as photosensitizer, was examined by fluorescence microscopy and fluorescence spectram detector. To compare in vitro with in vivo photosensitizer uptake by plaques, aorota in rabbit was examined by the same methods. The accumulation of fluorescent NPe6 and HpD, was observed selectively within the thickened intima of each atheromatous plaques. Characteristic emission of those was obtained from each atheroma, but not from normal vessel walls. These results suggest that human atheromatous plaques should take up HpD and NPe6 in vivo, and, therefore, be able to diagnose by detecting those fluorescences.

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Pheophorbide derivative (Hamari-1126) is newly synthesized compound for photodynamic therapy (PDT). Hamari-1126 and the other photosensitizers were investigated by the measurements of absorption spectra, fluorescence spectra, triplet-triplet (T_n-T₁) absorption spectra, singlet oxygen yield and lifetime of triplet state. It was resulted that Hamari-1126 was excellent photoreactive sensitizer compound in this spectroscopic examination.

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The new photosensitizer, we have helped to develop, PH-1126 has amine in the D-ring of pheophorbide structure. Comparing PH-1126 and hematoporphyrin derivative (HpD) in terms of the longest absorption peak of Q band, the wavelength of PH-1126 is 35nm longer. In terms of the absorption rate at the longest absorption peak of Q band with PH-1126 and HpD on same concentration showd the absorption of 10 value. Therefore, photodynamic effects using PH-1126 would probably be greater than those of HpD becouse of the distance of absorption band from that at hemoglobin. Comparing the fluorescence intensity rate of normal tissue to transplanted mice tumor tissues with i. v. injection and p. o. administration of PH-1126 taking the intensity of tumor fluorescence as 100% at 48 hour after administration, that of PH-1126 at i. v. injectiuon was 25.7 in skin, 20.9% in intestin and below 20% in other tissues, whereas PH-1126 of p. o. administration was 49.0% in intestin, 16% in stomach and below 20% in other tissues. The oral administration of PH-1126 showd the same tissue distribution as i. v. injection. After photodynamic therapy with Kr' laser (50mw, 30J/cm₂) following oral administration of PH-1126 (50mg/kg b. w.), the tumor decreased significantly.

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The capacity of pheophorbide-a (PpA) as a photosensitizing agent for photodynamic therapy of cancer was evaluated in vitro by human gastric cancer cells.
When the concentration of PpA in culture medium was 10, 100, 250μg/ml, intracellular concentration of PpA was 36.5, 153.5, 157.5μg/ml respectively.
Under the exposure of lamp (20 Watt, distance 40cm) for two hours, the optical density of MTT assay for cancer cells with a PpA concentration of 250μg/ml decreased to 8.1% against PpA free cells. In the dark room, it remained within 86.8% suggesting that PpA was very sensitive to light. Photodynamic therapy by administration of dye (100-250μg/ml) and Nd-YAG laser light irradiation with Q switch (1064nm, 200pps, mean power 1.5 Watt, duration 1, 3, 5min) after 2 hours incubation brought about a significant cell death. Lipid peroxide levels were elevated as increasing of laser irradiation time or the concentration of PpA.

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Cellular uptake and excretion of Zn-tetrasulfophthalocyanine (ZnTSPc) was determined by spectrophotometric analysis of the supernatant. After incubation time of 15, 30, 60, 1440 min. with ZnTSPc, cellular uptake was found to be 1.9 pico g per single Hela cell that corresponds to about 10⁹ molecules of ZnTSPc localized in or on one cell. This indicates that cellular uptake rate of ZnTSPc is fast. Cellular excretion of ZnTSPc was observed after removal of this photosensitizer from the medium. Though 16 percent of ZnTSPc that was taken in or on cells was excreted after 72 hr., no significant differences in efficiency of Photodynamic effects on cell inactivation was observed.

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ZnPc [(OCH₂CH₂)₃ OH]₄ (ZnTEPc) was compared with zinc-tetra-sulfo-phthalocyanine (ZnTSPc) in their photochemical properties and ability to sensitize cells to red light in vitro. Both Pc were added to F-10 medium and incubated with HeLa cells for 30min. After wash-out of the dye, they were exposed to red light. Cells were damaged only by ZnTSPc. ZnTSPc has a longer triplet life time. It generates much singlet oxygen and is incorporated more to cells.

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ZnTSPc was administered to C3H/He mice via a tail vein (15mg/kg). At different times after injection, they were sacrificed. The tumor (transplanted MH-134 cells) as well as some organs was prepared for fluorescent assay. Accumulation of ZnTSPc in the tumor was higher than other organs except for the liver at 8 hours after administration. ZnTSPc was observed in the liver even after 50 days. The brain had no accumulation of ZnTSPc at any time.

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Using nude mice bearing transplanted tumor of a KK-47 human bladder cancer, the effects of photodynamic therapy (PDT) with Al-phthalocyanine (AlPC), In-phthalocyanine (InPC) and Ga-phthalocyanine (GaPC) were compared. Photodynamic effects were evaluated as the tumor growth curves. For tumor control, the following efficies were found: AlPC>InPC>GaPC.
And PDT effect with AlPC and laser light at 670nm were compared with that ofAlPC and laser light at 630nm, and that of hematoporphyrin derivative (HpD) and laser light at 630nm. The regression of tumor volume after PDT was more with AlPC and laser light at 670nm than with AlPC and laser light at 630nm, and with HpD and laser light at 630nm.
These results suggest that AlPC may be promicing photosensitizer for PDT in respect of the tumor destruction.

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In vitro investigation of endoscopic microsurgery with the laser diode (SONY 1W CW, 820nm) is described in this paper.
First, efficacy of carbon-coated fiber is examined. 400μm quartz fiber with carbon-coated end is prepared to introduce semiconductor laser power. With this fiber, contact irradiation to rabbits' femoral nerve, aorta, heart and goats' kidney is carried out under 830mW laser source. Each tissue can be vaporized in several seconds. Histologic observation shows heat degeneration layer with carbonized layer in each organ.
Next step, this laser fiber is introduced to endoscope, 1.7mm outer diameter. Under endoscopic observation, rabbit's left ventricle myocardium successfully vaporized.
For contact irradiation, metal-coated ceramic chip lower necessary power to vaporize tissue. With ceramic chip, however, energy loss and outer diameter increase at the connection. Then, we employ quartz fiber with carbon-coated end. Histologic observation shows little difference between ceramic chip and carbon-coated fiber.
With endoscope, the good aiming ability was demonstrated under several times magnification. As the next step, laser tissue welding under endoscopic observation is examined with this system. A compact endoscopic microsurgery system can be achieved with high power laser diode.

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The aim of this study was to test potential value of the carbon dioxide laser welding to coagulate and reinforce the slippery tyings of synthetic surgical sutures. This laser processing was found beneficial in increasing knot tensile strength and knot security for nylon monofilament sutures. Mechanical performance testing using an Instron tensiometer also indicated that with a proper choice of lasing parameters this technique could achieve reliable knot security with only two-throws of a granny as well as a square knot configuration for the slippery nylon suture. Some in vivo experiments in surgical patients suggested potential applicability of this modality for thermoplastic suture materials in routine surgical operations.

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Laser therapy for bile duct stones, such as the non-contact beam treatment using continuous wave of Nd:YAG laser or contact beam treatment using ceramics rod, has been done in our institute from 1980. As a result, the ratio of complete lithotomy has been increased from 31/47 (66%) to 66/71(93%). Recently, we are using the Lasertripter by Candera corp., which was deviced for urinary stones. The effectiveness of this new laser lithotripsy is different according to the kind of the stones, but it is better than those of conventional YAG Laser. Furthermore, as this method can be used with thin fiberscope, the benefit of this method is more effective to peripheral intrahepatic stones than YAG Laser.

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Sines 1986, we have studied P.I.L.D. (Percutaneous Intradiscal Laser Discectomy),as an alternative therapeutic method for lumbar disc herniation.
The purpose of this study is to intrduce our new needle-tip pressure transducer for measurement of intradiscal pressure, and to evaluate its feasibility for clinical use.
The diameter of transducer is 0.9mm, and sensor is composed of 4 semiconductors strain gauge.
Goat's intervertebral discs were used for in vitro experiment.There was fairly good lineality between vertical load and intradiscal pressure. After irradiation, primary intradiscal pressure was reduced, and the slope was flatter than that of before irradiation. The effect of decompression with laser was recognized.
Our chip-type transducer is superior to conventional diaphram-type in terms of thermodrift, term stability, lineality, and hystericis.
We have recognized the feasibility of this transducer for adequate indication and precise eva luation of efficacy in P. I.L.D.

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We have been studying Percutaneous Intradiscal Laser Discectomy for herniated lumbar discs. The efficasy of this method has been already comfirmed by the basic experiments using rabbit or goat lumbar discs. In this time the safety, the easiness and the accuracy of our original PILK system is going to introduce. And the procedure of our method was charachtered with the use of a tip type pressure tranceducer.

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To select a proper laser for arthroscopic laser meniscotomy, we studied the menisci ablation rate and damaged layer thickness made by various laser irradiations. The pig knee-joint menisci were used as sample materials. We use eight different lasers from UV region to IR region, pulsed or cw: ArF, KrF, XeCl, XeF excimer lasers, Ar⁺ UV, Ar⁺ visible, CO and CO₂ lasers. We irradiated these lasers on menisci at an input power density of 60J/cm²/sec.
The proper laser for the arthroscopic laser meniscotomy must indicate high ablation rate and thin damaged layer for menisci. Furthermore it can be delivered by flexible fibers. In this point of view, we concluded that the proper laser satisfying those requirements may be XeC1 excimer laser.

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To get a locally destroyed cochlea of a guinea pig, the Nd-YAG laser was applied as the instrument. Before the animal experiments, following basic experiments were performed, 1) how the permeability of the Nd-YAG laser to bony-tissue is, compared with the argon laser. 2) how much the temperature is, at the irradiated portion in aqua.
According to the results of these basic experiments, a laser of adequate power and time was irradiated to the cochlea of the guinea pig. And then, extremely localized destructions of the inner and outer hair cells were produced.

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Four hundred eight patients with head and neck diseases were treated using contact Nd: YAG laser during 5 years from 1984 to 1988. They include 98 cases with oropharyngeal tumors. The oropharyngeal space is very narrow and a little bleeding in this space disturbs a field of vision of operators. It is important for speaking and swallowing to operate finely with less bleeding. The contact Nd: YAG laser is very useful to this purpose.

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Our experience with the use of a new fibrin tissue adhesive (Tisseel) in treating the web formation and supraglottic stenosis by means of a microscopic laser surgery is reported. In a case of web formation, the fibrin tissue adhesion for prevention of adhesion was applied to the removed anterior commissure by laser. In two cases of the supraglottic stenosis following hemilaryngectomy and cicatricial pemphigoid, removed stenotic lesions were covered with the mucosa by means of the fibrin tissue adhesive.
Considering from its excellent wound healing effect and the prevention of adhesion, fibrin tissue adhesive (Tisseel) was usefull for endlaryngeal microscopic laser surgery.

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An ablation of eschar (necrotic burn skin) by various excimer irradiations are described in this paper. The eschar which is generated on heavily burn-injured skin may be caused fatal infectious diseased to a burn patient. It is necessary to completely remove this eschar as soon as possible to perform skin graft, which is a sole treatment to save the patient. Escharectomy debridement is performed by scalpel or hand-dermatome with huge skillfulness. In order to improve debridement, it is necessary to develop more efficient (faster and easier) treatment. Since eschar may be high protein concentration with less water content comparing to a normal skin tissue, the use of the uv laser ablation may induce an efficient ablation.
As a fundamental investigation for the uv laser ablation, the ablation rates of the rabbit eschar by ArF, KrF, XeF and XeCl excimer laser irradiations were measured. And extracted skin samples were examined histologically. KrF laser irradiations indicate the efficient ablation rate with a sufficient selectivity from a normal skin.
Following this ablation rate and using KrF laser with 20W average power, 30cm³ (for example; 10 cm squares with 3mm depth) of the eschar could be ablated within 45s. This speed of the debridement is supposed to be ten times faster than the current debridement.

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We suggest that an applicability of a multi-wavelength laser system which is consisted by a high-power Ar laser (uv and visible) and Ti: Sapphire solid-state laser. This laser system can generate uv (350nm), visible (515, 480nm), and near-ir (700-1100nm) with continuous wave oscillation. In this paper, an ablation characteristics of continuous wave uv Ar laser irradiation was experimentally studied. This ablation indicated sharp cutting groove with thin coagulation and no charring materials. The 2W cutting capability was corresponded to the cutting capability of 5W CO or CO₂laser irradiation.

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Recently a new endoscopic modality which is used an endoscope attached a special balloon to the end of the instrument was developed. The high transparency rate of the balloon provides a good observation in a cavity and when irradiation of Nd: YAG laser is carried out through the balloon, a certain coagulation can be performed on the target tissue. With this modality the urological application was investigated fundamentally and clinically.
Fundamental studies of laser irradiation through the balloon were experimented on the kidney of an anesthetized rabbit. When a total of 204 joules of Nd: YAG laser was irradiated, the area of coagulation in the tissue was recognised homogenously 4×3mm in width and depth.
For clinical use, a prototype urethrocystoscope which could be attached the balloon was designed for the observation of bladder lumen and the irradiation to the bladder tumor. The visualization via balloon-urethrocystoscope could be obtained clearly in a condition of severe hematuria. The laser coagulation of bladder tumor could be performed satisfactorily without rupture of the balloon in a total of 3000 joules of the irradiation.
The remarks of the modality“urethrocystoscopic maneuver through balloon”can be described as ensuring of a visualization and laser irradiation through balloon under direct vision.
However further experimental and clinical studies will be required to estimate this modality.

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Nd: YAG laser has been evaluated to act the living tissue by its thermal effect and coagulation. Many urologists have carried out by using Nd: YAG laser for the urological surgery, i. e.. transurethral laser surgery of bladder tumor (TULS-BT), laser plasty of urethral stricture and laser lithotripsy. Most of the reports were concentrated in the high power effect to the tissue irradiated, while the effects of lower power laser have not been concluded in terms of the relations between power density and tissue damage. In this report, we tried to demonstrate the relationship between the laser power and tissue damage, which was investigated by H-E staining and enzyme histochemistry using Alkaline phosphatase.
Al-P staining was performed after the irradiation. Compared with H-E staining, the lesions of carbonization, coagulation and edematous changes became negative for Al-P staining, and were clearly distinguished from surrounding positive area. Therefore; Al-P staining showed useful to determine the extent of the laser thermal effect. It became clear that thermal effect was induced even in the lower safety power of Nd: YAG laser.

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This study was performed to compare argon laser welded arteriovenous anastomosis to conventional manual anastomosis between femoral vessels of dogs. In 4 animals, anastomosis was done with running 6-0 polypropylene sutures. In 12 animals, anastomosis was carried out with argon laser. All anastomotic sites were patent without aneurysmal change or luminal narrowing at biopsy. Histologic examintion revealed granulomatous tissue reaction in conventional group, but minimal inflammatory response in laser group. Argon laser welding of vascular anastomoses may be indicated for reconstruction of medium and small caliber vessels in view of improved wound healing wjthout foreign body response.

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We have performed experiments using CO₂ Laser assisted microvascular anastomosis and demonstrated the following features: easy in technigue, less time consuming, less tissue inflamation, eary wound healing, same patency rate, same inner pressure tolerance but about 50% of the tensile strength compared with the manual suture anastomosis.
We present here sixteen vessels of six clinical applications using this procedure.
The preliminary results of these cases would appear to be the first successful replantations and free tissue transfer using CO₂ Laser assisted microvascular anastomosis in man.
This procedure offers increased safty and speed in microvascular anastomosis.

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In vascular surgery, there is a great problem to keep high patency rate after reconstructive surgery especially for small-caliber vessels. For resolving of this problem, laser was applied to make vascular anastomosis with few stay sutures. Optimal conditions of vascular anastomosis by lasing were 20~40mW in output and 6~12sec/mm in irradiation time. Histological examination revealed good healing at the sites of anastomosis by laser. And adequate in of the anastomotic sites by laser was also confirmed. On the basis of excellent experimental studies, laser was employed to make vascular anastomosis in 91 patients with intermittent claudication and anginal pain and renal failure. The first successful clinical application was carried out in 44year-old female patient with renal failure on 21st February 1985 in the world. Coronary artery bypass surgery was also performed clinically by using low output Co₂ laser. All patients are now doing well without any complications throughout the laser. The longest survivor has been passed 4years 9months after laser surgery. Laser application in this field was useful and inevitable to make vascular anastomosis especially for small-caliber vessels.

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We examined effects of excimer laser irradiation on blood. Five vials, each of which contained 3ml of blood, were exposed to 37.5mJ laser beam at 10 PPS in repetition rate for 10, 20, 30, 40, 50 seconds. One vial was left untreated as a control. No change in hematocrit value was observed after excimer laser irradiation. In contrast, the level of plasma free hemoglobin rose progressively with each increased duration of exposure. This study indicates that the lysis of erythrocytes does not occur in the laser-exposed cells. However, the damage to erythrocyte membrane took place as it was evidenced by progressive hemoglobin leakage into plasma.

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Fundamental experiments as to temperature of the arterial wall for laser angioplasty was carried out using Nd-YAG laser with a bare laser fiber and ceramic tipped probe.
40.4 J of the average energy was needed to cauterize the normal aortic walls, when a bare fiber was used in contact method.
In the case of ceramic tipped probe by pressure method the normal aortic walls were not burnt, and peripheral layers were not carbonized. However, the aortic walls can be heated locally up to about 100°C.
In both cases the rise of temperature is very slight at a point beyond 4mm from the lasing site, and Nd-YAG laser was effective in elevating the temperature only in the very limited area near the laser probe tip.

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Sungical results of laser angioplasty still remained to be unsettled in spite of the technical advance.
Recently, a new type of laser for angioplasty, Er-YAG (wave length: 2.94μm), was developed and we studied to make clear the pathological difference of irradiation properties on the human cadaver aorta between Argon and Er-YAG laser.
The intima around the irradiation spot of Argon laser was elevated and disrupted. The vaporized surface was rough and the carbonized and degenerative layer was widely recognized around the crater.
On the other hand, the vaporized surface of Er-YAG laser was very smooth and the degenerative layer was distinctly minimized.
In conclusion, Er-YAG laser is suitable for laser angioplasty than Argon laser.

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To diagnose vascular tissues to prevent a perforation during infrared laser angioplasty, we studied the Pulsed Photo-Thermal Radiometry (PPTR) technique. A recent advance of infrared fibers makes it possible to apply this PPTR technique to in vivo analysis.
The segments of human abdominal aorta were used as specimens. Using chopped 5.4μm CO laser as an excitation beam, the calcified plaques were easily discriminated by the analysis of the PPTR signals.
PPTR technique may be useful for the analysis of an ablated surface during laser angioplasty.

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An applicability of an continuous-wave uv Ar laser for the laser coronary angioplasty was studied. A delivery by a thin silica glass fiber of this continuous wave laser was studied. The thin silica fiber with 100μm in core diameter could delivered over 3W power of this laser beam with 38kW/cm2 in intensity at the end of the fiber. We could not investigate the damage threshold of this delivery due to a limitation of the laser power. An ablation characteristics of the continuous-wave uv Ar laser irradiation in saline was also investigated. The results showed that this ablation had a sufficient ablation speed with a good selectivity for atheromatous lesions. Comparing these characteristics with excimer laser performances, we conclude that this laser would be one of the most suitable treatment laser for the laser coronary angioplasty.

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This experiment was studied for examining the possibility of safety making atherosclerotic foci regress with photodynamic therapy (PDT) using Hematoporphyrin Derivative (HpD). The 2% cholesterol feeded rabbits were devided into two groups, that is, group C and group H. The group C is consisted of rabbits non-treated with HpD and the group H treated with HpD. The argon dye laser introduced by fiber was irradiated on the atheromatous lesion of abdominal aorta in vivo. These rabbits were sacrificed immediately,2 and 7 days. In the group C, any change was not recognized in the atheromatous lasion of aorta. However, in the group H, the endothelial and intimal cells were distructed by laser irradiation. From the above data, it is suggested that PDT may be effective for treatment of atheromatous lesion of artery.

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An excimer laser, which ablates vascular tissue precisely without thermal injury, is expected for the application to the coronary laser angioplasty. In this study, we used a 400μm quartz fiber to transmit a wavelength of 308 nm from a XeCl excimer laser with a pulse duration of 20 nsec. The excimer laser angioplasty was then performed with angioscope for 4 totally occluded femoral arteries of 4 canine models. As a result, we experienced successful recanalization in all arteries using 2.5-6mJ/pulse, 20-30Hz and 6000 shots cumulative exposures. Histological examination of all recanalized arteries revealed favorable results of clear neolumens with no signs of thermal injury. However, perforations were observed in 2 of 4 arteries. Therefore, further investigation are necesarry about several problems, such as operation of the opitical fiber, angioscope, guidance system and transmission of a laser energy through the optical fiber, before a clinical use in the future.

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We have been developing laser angioplasty system using contact ceramic tip. In order to stabilize the required power for plaque ablation, ceramic coating tip was designed and developed by implanting metal at the point of the surface of ceramic tip, and the special endoscope with 7F size was designed and developed from the points of percutaneous approach and ceramic tip usage. The laser probe was designed to be separated at the part of laser fiber and able to be inserted from the top of the endoscope.
The special endoscope and laser probe with ceramic coating tip were very useful for atheroma ablation inside the aorta of atherosclerotic rabbits under the visual field. The required power for plaque ablation with ceramic coating tip was 5-15W, and was able to be stabilized.

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CO laser may be effective for thermal fusion of intima of arterial wall without adventitial tissue damage because of high tissue absorption. To investigate the efficacy of CO laser as laser beam for laser balloon angio-platy (LBA), CO laser irradiated aortic tissue through 30μ polyethyrene membrane and tissue temperature (TT) was measured by a thermistor. At 20 watt/cm2 200 joules/cm² continuous laser exposure (CE), TT was above 100°C within a depth of 1mm and rapidly decreased to 60°C or below between 2 and 3mm in depth. Moreover, TT could be decreased by changing duty ratio (exposure duration/interval) of intermittent laser exposure (IE) despite of the same laser energy. Light microscopy showed high degree of medial coagulation necrosis in 200 joules/cm²CE, but thermal coagulation was observed only at the surface of intima of aortic tissue in 200 joules/cm2 IE at duty ratio 1/2. These findings suggested CO laser could coagulate intimal layer with less deep thermal damage compared to Nd-YAG laser and that IE was better for superficial welding than CE at the same energy. We concluded that CO laser might be more efficient as laser beam for LBA than Nd-YAG laser.

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To establish the method of coronary laser angioplasty by Argon, we have investigated that 1) the optimum condition of laser ablation, 2) relationship between the size of laser probe and the diameter of the vessel using bare ended probe (BEP) and metal tip probe (MTP) of 1.5mm in diameter. First of all, we examined the relationship between laser energy and the depth of crater on human cadaveric artery created by laser ablation. As a result, we were convinced that the most favorite condition of laser ablation is the repeated ablation, one of which is 1~5 watts in output and 1~2 seconds in ablation time using BEP, and 5~10 watts and 2 seconds using MTP. Secondly, laser ablation was carried out in the canine coronary artery under heating heart. In this experiment, perforations were seen in some cases using BEP, but no perforations and coronary spasms could be observed using MTP. However, if the size of metal tip was too large for the diameter of the vessel, the decrease of peripheral coronary artery pressure which would be induced by the vascular thermal constriction was clearly observed. So we examined intraluminal laser ablation using MTP in canine model, and confirmed that MTP/vessel diameter ratio should be 0.7 or less to avoid the vascular constriction.

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This study was performed on the possibility of clinical application of Percutaneous Transluminal Coronary Laser ANGIOPLASTY(PTLCA) by“Hot-Tip”lasing. The Nd-YAG laser fiber (metal coating special fiber) with the builtin guide wire. This special fiber was connected with Fine-Ceramics tip. The first, Nd-YAG laser through this fiber was irradiated to the postmortem human coronary arteries. The second, the PTLCA by Seldinger method was tried to dogs and 2% cholesterol feeded pigs in vivo.
From the above experiments, the amounts of adequate Laser energy for one time laser irradiation was decided 5 to 7 joules. Through this procedure, complication, that is, perforation of vessel or vasospasms,et al. were not recognized at all. So, it is considered that this PTLCA system will have possibility of clinical application.

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We investigated the implication of clinical use of Nd: YAG Laser delivery onto the atrioventricular groove area for a treatment of WPW syndrome. Eleven mongrel dogs were used in this experiment. After the dissection of the epi-annular fat pad, Nd; YAG Laser was delivered onto the annulus with varing energy levels with the lasing distance kept at 10mm using our new device. A mass of spherical denaturation was formed at the atrioventricular groove area, which would change to a well-demarcated fibrous scar in the chronic phase. When the epi-annular fat pad was completely dissected away, the lower energy lasing even less than 100J made myocardial thinning. The higher energy lasing more than 200J made the trasmural denaturation zone without wall thinning if the lasing to the annulus with the fat pad incompletely dissected and slightly remained should be done.

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We have been studied waterjet percutaneous transluminal angioplasty(PTA). This report describe a comparison of the waterjet and the conventional laser method in PTA using the modeling samples. Experimental facility consisted of roller pump which was developed by us for operations and a set of catheter. Catheter is pressure resisting and has the nozzle at the distal. Experiment was carried out with the coronary artery of the pig heart and the aorta of rabbit resected from each animals. Target lesion as the thrombus was made by agar-agar or blood coagula. Operative procedure was monitored in the video display which was connected to the small fiber scope in the modeling samples. Waterjet make a fine hole on the surface of the thrombus at first and penetrated through the whole thrombus. Then washed out the debris and remove the surrounding resting thrombus. This first trial showed that waterjet angioplasty have many advantages over the laser method.

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After 0.1ml of 2% carrageenin s. c. injection into a rat's pow, He-Ne laser with 632.8nm of wave length and 8.5 mW of power was continuously irradiated on the circular area of 7 mmo on the pow and its analgetic effect was examined by the Randall-Sellito method. Although the carrageenin injection caused a 70% decrease in the pain threshold 3hr later, it recover the control level just after 6 or 8min irradiation but not 2 or 4min irradiation of laser. While the inflamed rat's pow even 27 hr after the carrageenin injection, no differance in the pain threshold between them was recorded even 24hr after the 6 min laser irradiation.
These result indicate that the laser irradiation exerts an analgetic effect on the inflamed pow and effect lasts for at least 24hr.

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This study was scheduled to investigate the effect of low power He-Ne laser (λ=632.8 nm, 8.5mW) on the sympathetic nerve activity and pain sensory nerve.
Five-minute irradiation of the laser beam was performed on the meeting point (Li4, Hoku) of ten male volunteers ( group G) and on the shousanli (Li10) of 13 male volunteers (group T). The skin temperature and pain threshold were measured at the meeting point of the irradiated arm by using a pain-threshold-meter (UDH104, Unique Medical Co., LTD, Tokyo, Japan) before, immediately after and 30 minutes after irradiation.
In group G, the skin temperature immediately and 30 minutes after irradiation elevated by 0.8 and 0.4°C, and pain threshold by 0.3 and 0.5°C, respectively. In group T, the skin temperature immediately and 30 minutes after irradiation rose by 0.9 and 0.4°C, but pain threshold declined by 0.2 and 0.4°C, respectively.
These results suggest that a laser irradiation may act in different fashions on the sympathetic nerve system and on the descending inhibitory system.

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About a period of 3 years, 50 cases of postherpetic neuralgia (PHN) were treated by low power Ga-Al-As laser therapy. The rapid efficient ratio of pain releaf from PHN was 90% and the long period efficient ratio was 90%.
Age of the onset influenced prognosis of PHN. The patients who showed slight effects of laser therapy for pain releaf were predominantly in old populations.
Laser therapy showed high effects except for the patients whose PHN lesion was on the abdominal region.
And laser therapy showed high effects in the patients whose treatments were started within 3 months after the onset of PHN while laser therapy showed slight effects in the patients whose treatments were started more than 3-6 months after the onset of PHN.

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We have been administering Low-power laser treatment for 5 years. Recently, we have been using a Nd: YAG laser at around
400mW out-put in combination with the intravenous administration of medication, and this has led to excellent result in the treatment of maladies such as paralysis of the lingual nerve, facial palsy, paralysis of lower lip, lichen planus, ane leukoplakia, all of which have been difficult to treat until now.
We have reported our treatment method and results since April of this year.

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The sixth report in this series follows reports already presented at the 5th, 6th, 7th and 9th meetings of the JSLMS, and continues to show the efficacy of the GaAlAs diode laser in LLLT for pain attenuation. The present study shows results obtained with a new LLLT system, the Luketron^®,(Mochida, Tokyo) developed jointly by the Japan Medical Laser Laboratory and Matsushita Electric Company, a second generation model of the Panalas 4000^® used in the previous trials. The present study brings the total number of patients treated to 4,442 (m=1,845, f=2,597), with a total of 8,073 treated conditions, and 107,200 treatment sessions. The period of the present study is 1 year, from March 1988 to March 1989, with a patient population of 807, average age 51 y. o. (m=365, average age 51.3 y. o.; f=442, average age 50.7 y. o.). This study is the first with the average male age greater than the female. The largest age group was of patients in the 5th decade, with smaller groups of both younger and older patients. The population average age is slightly lower than in the previous reports, which may account for the slightly shorter treatment times. 1468 conditions were treated, an average of 1.8 per patient: this is the same as the previous reports. Efficacy of pain removal is 83%, similar to the previous studies. Greatest efficacy was achieved with multiple treatments, peaking at the 16th-20th treatment with no significant improvement thereafter. This is in accord with the previous study, where we reported the greatest treatment efficacy at an average of 16.8 treatments. The data reinforce our previous conclusions, that LLLT with the GaAlAs diode laser system provides safe and effective alleviation of chronic pain.

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57 patients with osteoarthritis of the lumbar spine were treated by low power (Ga-Al-As Diode) laser irradiation. They were classified by clinical signs, symptoms and X-ray in three groups. The effective ratio of laser treatment in the first group with lumbar pains due to hypertension of muscles was 93.8%. Laser treatment proved ineffective for patients with extremely severe osteoporosis in the second group. 70% of patients in the third group with leg pains similar to ischial neuralgie improved remarkably. These results showed that low power laser irradiation was effective for osteoarthritis patients without miserable osteoporotic change.

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32 cases of RA affected joints were irradiated by He-Ne laser for more than 6 months. (32 joints irradiated and opposite 32 joints non-irradiated)
Assessment by radiograph of RA patients. Each bilateral joints were compared by the scores and assessed with clinical evaluation.
As for the bone errosion of 32 RA cases, improvement was observed in 12 cases (37.5%), but no improvement was observed in the non-irradiated joints. Progression was observed in 8 irradiated joints (25%), and 15 non-irradiated joints (46.8%).
Other changes such as sharp cut appearance of joint space, etc. were observed.

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