The article analyzes a traditional idea on the description of Low Level Laser Irradiation (LLLI) resulting from some isolation (gap) of clinic-biological and optic studies in the sphere of Low Level Laser Medicine. The author uses a conventional parameter `Specific Power Density,' Ps (mW/cm³) connected with both power characteristics of laser and optical properties of irradiated biological subject. The attenuation of the LLLI in biotissue is described with a gradient P(x), where x is a distance to the source. If the distributed intensity of LLLI is integrated over the volume V so one can obtain integral intensity SP(mW). Let us divide integral intensity by the volume: SP/V. This very ratio is Specific Power Density P (mW/cm³). The calculation of energetic LLLI parameters of whole blood intravenously is submitted as an example of use of the Specific Power Density.

In experiments on male mice of CBA line the alteration of neutrophils cytochemical profile in peripheral blood He-Ne laser irradiation in vitro (4 mW/cm², 15 min) and modification of metabolic disturbances in polymorphonuclear leucocytes in stress by laser radiation were studied. It was found that direct laser irradiation of blood results in the decrease of glycogen and lipids content, the increase of ATP-ase, succinate dehydrogenase and myeloperoxidase activity, rise of lysosomal cationic proteins level, and membrane oxidase systems of neutrophils stimulation. In short-term immobilization stress conditions transcutaneous laser irradiation in vivo (19 mW/cm², 15 min) prevents the development of stress induced changes of metabolism and function of neutrophils.

Experimental results are reported on (low power) low-energy laser action on different kinds of enzymes. The laser-enzyme interaction is particularly evident in enzymatic systems related to energy control. We already reported that an increase of ATP is observed when cultured cells are submitted to HeNe laser radiation. More specifically relative activation is reported following irradiation by laser light (HeNe, 2 mW delivered power) as the number of experimental points is increased.

The effect of He-Ne laser radiation on the cryoconserved leukemic cells has been investigated in order to increase the efficiency of myeloproliferative diseases immunotherapy. The transplantation of laser irradiated cryoconserved cells to mice-hybrids enhances the reaction on the recipient's antigens as compared to the transplantation of nonirradiated ones. Hence the He-Ne laser radiation can serve as the modifier of tumor cells antigen structure.

The biological activity of cryoconserved fetal liver cells of mice (FLM) having undergone the He-Ne laser action has been estimated by the efficiency of their transplantation to mice- recipients exposed to lethal x-ray dose. The survival rate 30 days after x-ray exposure for those mice was 75% in comparison with 70% for mice with cryoconserved nonirradiated graft. The trial animals' peripheral blood investigations have been made. The obtained results indicate that the laser method of cryoconserved cells stimulation can help to increase the therapeutic efficiency of mielotransplantation.

In this work the influence of He-Ne laser irradiation (wavelength 632.8 nm, power density 1 mW/cm², 15 and 30 min) on giant polytene chromosomes from salivary gland cells of larvae Chironomus plumosus and Chironomus balatonicus was studied. Increase of chromosome compactness depending on the dose, as well as formation of puffs de novo in different loci of different chromosomes, were revealed. The activity of the nucleolar organizer increased only in the case of initially low activity of this zone. Indices of genetic activity of Balbiani ring-7 in chromosome 4 and Balbiani ring-16 in chromosome 1 did not change.

We investigated the influence of intravenous laser irradiation of blood (ILIB) on the immune system of the organism at vertebrogenic disorders of the peripheral nervous system (PNS) with a prominent pain syndrome. It has been found that ILIB produces a positive effect on the immunity T-link increasing the proliferative activity of T-lymphocytes, has positive dynamics in clinics, doesn't cause any side or negative effects.

Laser radiation causes microscopical changes in the follicular cells relative to dose intensity. So, we have observed focal degenerative phenomena, at maximal doses, and activation of cellular function similar to the ones observed after stimulation with TSH, at minimal doses. In order to evaluate the evolution of these changes we have planned an ultrastructural study of rats thyroid capillaries treated with IR laser radiation.

The ultrastructural alterations of the chondrocytes in the growing cartilage after radiation by IR laser at a dose of 2 J/cm² are described. Twenty albino Wistar rats have been used. The radiation was carried out on the left knee of the animals. Consequently, the animals were killed, and as soon as the pieces had been obtained they were subjected to the conventional techniques of fixation and inclusion for electron microscopy. Their ER is scarcely developed with disrupted and dilated cisternae noting few secretory vesicles in relation to the control animals. Likewise, degenerative phenomena in the mitochondria membranes and the endomembrane system were observed, in the shape of myelin. In the chondrocytes of the contralateral knee, few alterations were noted in relation to the controls.

Therapeutic applications of low—energy laser irradiation (LELI) of human patients suffering different diseases is currently experiencing fast progress in a number of countries including Russia (1] . This can hardly be clearly justified without efficient diagnostic technique which can provide objective and quantitative registration and monitoring of patients individual responses to the phototherapeutic treatment. This is particularly true in relation to the LELI of blood which is considered a very efficient way of treatment of a number of pathologies, including pulmanory, cardio-vascular, ischaemic, etc. A number of diagnostic techniques currently in clinical practice include, in addition to the conventional clinical blood tests, the measurements of refraction indeces and absorbance of whole blood and plasma which have been shown sensitive to LELI in vitro and in vivo at different wavelengths including 632.8 and 1234 nm [2,33, alternations in leycocyte metabolism under He-S-Ne 1 aser irradiation [4] , index of erythrocytes deformabi 1 ity (5], etc. We have tested the technique of laser backscattering nepheloznetry (LBN) which we have been developing for the diagnosis of blood pathologies [6,7] in respect to its sensitivity to laser irradiation of blood at in vitro and in vivo experimental conditions. The advantages of the LBN technique is that we deal with the whole blood but not with delute solutions or single blood cells and, also, this technique yeilds two characteristics of blood: deformability of erythrocyte which was previously shown sensitive to laser irradiation [3] and aggregation and disaggregation kinetics. In this paper we present preliminary results of our experiments showing the sensitivity of aggregation— disaggregation kinetics to LELI at certain experimental conditions and pathologies.

The effect of a pulsed gallium arsenide infrared laser radiation was studied on 64 patients with post traumatic swellings, allergic vasculitis and varicose crural ulcers, therapy resistant. The soft laser therapy was conducted in combination with classical therapy and was compared with a non irradiated control group of 52 patients treated only by classical therapy. Laser irradiation was directed to the skin damage by laser scanning. Segmental and dermatomic areas of the skin lesions were irradiated by laserpuncture. Therapeutic protocol included an average of nine sessions. The statistical analysis shows a significant difference of the efficiency between Ga-As pulsed laser treated group and the control group, especially in the case of post-traumatic swellings and less in the case of allergic vasculitis. The effects reported by this study are relevant for clinical application of infrared pulsed low lasers in dermatology.

After more than 30 years of applications of low-energy laser, many hypotheses remain about the mechanisms underlying its biologic and therapeutic effects. The majority of hypotheses are based on bioeffects as a function of the photoinduction of biochemical processes. This approach is problematic, however, because it is difficult to single out biochemical processes that could not be altered by laser action. An alternative view to understanding the bioactivity of laser exposure is that such activity, either by cells, tissue, organ systems, or the whole organism, is an adaptive response to stress. This paper summarizes briefly three experiments conducted in our clinic utilizing low-level laser, and describes in some detail an experiment comparing the action of laser with a known nonspecific, chemical adaptogen.

An influence of IR laser irradiation (up to 60 mW) and magnetic field (up to 200 mT1) on reparative process and proliferative potency of cells has been studied in experiments. Irradiation modulation by the frequencies from 1 to 1000 Hz has varied an output laser power. The parameters of magneto-laser action used in this work make it possible to deliver laser energy to maximum depth in biological tissues. It has been shown that there are concrete diapasons of biostimulating doses and frequencies of IR laser irradiation and low magnetic field. An increase of wound closure rate in vivo and proliferative activity of cells in vitro takes place under the magneto-laser effect.

We investigated the ability of fluorescence spectroscopy, and photosensitizers to differentiate normal, hyperplastic and atherosclerotic arterial wall lesions in vivo. Hyperplastic lesions were induced in the abdominal aorta (AB) of 24 rabbits by balloon injury (BI). Atherosclerotic arterial wall lesions were induced by BI and diet. Fluorescence signals from thoracic n equals 16 and AB n equals 15 sites were analyzed by computer. A ratio was used as an index of drug presence. Use of PPS or BPD and LIFS may be a feasible, in vivo method for the differentiation between normal, hyperplastic and atherosclerotic arterial wall lesions.

Percutaneous transluminal intervention techniques are playing an increasingJy important role in the treatment of peripheral vascular disease. Conventional balloon angioplasty remains the most commonly used method, correctly enlarging the huninaJ narrowing in the majority of cases by impacting the atheroma plaque in the wall. This method has, however, its limitations, particularly in segmented occlusions which are sometimes impoSS1ble to traverse by traditional mechanical means, even when using the new hydrophilic guides. The same applies to certain stenoses which are very dense, fibrous, long, ec.centric, and often calcified, and which cannot be traversed by the dilatation guide or balloon. It is for this reason that laser energy has been used over the last few years to recanalire the artery, thereby creating a small channel for balloon angioplasty to be carried out. Different types of laser have been proposed to recsmali:ze an artery (5). They can be distinguished by their source or their transmission time (pulsed or continuous). Various sources are used: solid laser (ND YAG), continuous emission (Argon) or pulsed (Excimer) gas laser, holmium laser, and dye lasers. The transmission of laser energy can currently be achieved through small gauge optical fibres, allowing percutaneous endovascular use (2, 4, and 6). Thermic lasers have, until the present time, been the most widely used in clinical practice (7). It has not yet been demonstrated that pulsed lasers, which have a more selective ablative effect, produce better results in the shorter and longer term. As the use of bare fibres was not without its drawbacks (8), fixing a synthetic sapphire at the end of the fibre seemed to facilitate and improve the procedure (9 - 10). The experience gained in a medico-surgical centre orientated towards the treatment of vascular diseases, since the introduction in May 1988 of sapphire laser angioplasty into the range of intervention radiology techniques used, is presented in this article.

During the last three years we have systematically studied the possible uses of rotational ablation at the peripheral and coronary levels. In this article we review the different modalities and results of peripheral rotational ablation according to our experience.

To overcome problems associated with angioplasty, placement of a balloon-expandable vascular prosthesis was studied. Two hundred sixty-eight patients had a stent or stents implanted for reasons of restenosis, occlusion or dissection. One hundred forty-eight patients presented with iliac lesions, 108 with femoro-popliteal lesions and 12 patients had lesions within bypass grafts. Patients were followed up for an average of 19.89 months with angiographic, Doppler ultrasound and clinical evaluation. Only five cases of restenosis were not able to be corrected by secondary angioplasty. The primary patency rate at 3 years for iliac stents was 91%, and for femoropopliteal lesions was 72%. Secondary patency rates did not differ appreciable for femoropopliteal and iliac lesions and for stenoses and occlusions.

Angina pectoris with normal coronary artery on the coronary angiography is an intriguing issue. Intracoronary infusion of acetylcholine has recently been used to test the integrity of endothelial cells. We studied 16 patients with this syndrome. A relationship has been found between the acetylcholine test and the exercise stress test in normotensive patients. The presence of hypertension makes the evaluation of the test more unpredictable, probably because of the damage on the endothelial cells related to systemic hypertension.

Direct diode laser assisted carotid end-to-end microanastomosis (LAMA) versus contralateral manual sutures microanastomosis (CMA) were performed in 70 Wistar rats. The laser beam- wavelength 830 nm, maximum power 3 W and continuous wave was transmitted through a micromanipulator and provided a focused spot of 300 micrometers in diameter. After placement of three 10.0 stitches for edge coaptation, LAMA was achieved on left common carotid (0.8 - 1.2 mm) using laser shots (average 3) of 500 mW power, 4.5 s duration and 700 W/cm² irradiance each. CMA was performed on right carotid by means of six 10.0 stitches. Light and scanning electron microscopy (n equals 82) showed in LAMA that re-endothelialization was complete on day 10 while collagenous fusion of media and adventitia was evident. The patency rate was 93% after LAMA versus 93% after CMA. The intra operative advantages of LAMA versus CMA: shorter operating time minimizing organ ischemia (13 min versus 22 min) and reduced endothelial trauma were evidenced. The technical advantages of diode laser were pointed out: small size of device, absence of water cooling system, no maintenance and decreasing price of diodes.

Diode laser-assisted microvascular anastomosis procedures have demonstrated reliable clinical operation and high success rate. Moreover, clinical and histological examinations on long times follow up have shown a better healing process for the laser-assisted technique, as compared with the conventional sutured one

Extracorporal shock wave lithotripsy (ESWL) is the standard therapy in the treatment of urinary calculi. the high rate of fragmentation and simultaneous stone selectivity makes laser lithotripsy an alternative method in the treatment of obstructing ureteral calculi. In comparison to the success rate of ESWL, laser lithotripsy as a minimally invasive endoscopic procedure seems to be superior in disintegrating calculi in the distal ureter. Together with the advance of miniaturized semiflexible endoscopes, intracorporal laser lithotripsy presents a new aspect in the treatment of urinary calculi.

Open surgeiy for the removal of renal and ureteric calculi has been rendered almost obsolete in the last ten years. The development ofthe extracorporeal and the intiOCOTpOTeaI lithotripters has permitted many patients to have their stones treated without operation. Several kinds ofalternative disintegration methods such as electrohydraulic lithotripsy, ultrasound lithotiipsy, stone disintegration by laser irradiation, electric drill disintegration, microexplosion lithotripsy and extracorporeal shock wave lithotripsy have contributed to this advancement.

This paper presents an overview of the important processes which are responsible for stone fragmentation. The efficiency of these processes in dependence of wavelength and laser pulse duration is discussed. Beside shockwaves and cavitation phenomena the role of a compressional shock acting on the stone and the plasma confinement is emphasized. As a conclusion the concept of a passively Q-switched solid state laser with a fiber-based resonator which prolongs the pulse duration is presented.

Acquired ureteral strictures are still treated either with a stent, balloon dilatation, by open surgery or by endoscopic therapy with a `cold knife' or high current density as intubated ureterotomy. The success rates described in the literature range between 50% and 90%. Using the experimental CTH:YAG laser (wavelength 2120 nm) and CT:YAG laser (wavelength 1950 nm), the reduction of invasiveness and of morbidity was evaluated. First, the CTH:YAG laser was investigated on 540 fresh porcine ureters varying the parameters. With a computerized morphometry system, defect depth, defect width, coagulation depth and coagulation width were measured. Then 21 female pigs underwent 7.5 F - 12 F ureteroscopy with CTH:YAG laser, CT:YAG laser, high current density and `cold knife' ureterotomy. An IVP and sacrification with explanation of the whole urinary tract was done on day 6 and around day 60. In practice, laser application via the endoscope was easy to handle and exact cutting was always seen. The CT:YAG laser seems to have the best success results with low ureteral stricture recurrence rates. However, its clinical use remains to be proven.

Low-level laser radiation has been shown to be effective therapy in the treatment of a variety of urological diseases, and in some cases can be utilized in lieu of surgical treatment. This report summarize a number of clinical applications of low-level laser therapy in urological disease. Laser therapy offers an effective, low-cost, and simple treatment alternative and/or addition to conventional therapies.

Condylomata acuminata of the urogenital and anal region are sexually transmitted warts caused by infection of human papilloma virus. In the literature different treatment modalities are reported. We report the treatment of 323 patients (315 male, 8 female) with a mean age of 27.9 years using the Nd:YAG laser. In 65% the lesions were located in the fossa navicularis, in 37% at the glans, in 30% at the foreskin. Thirty-five percent of all patients required endoscopic treatment of the distal urethra. Two-hundred-seventy-nine patients had recurrence after unsuccessful pretreatment with surgical and chemical therapy. After a mean follow-up of 15.5 months (2 - 43 months) of 95 evaluable patients 15 showed recurrences all within the first 6 months. The advantages of Nd:YAG laser treatment of condylomata acuminata, which might be done in local anaesthesia, are a low rate of recurrences and complications, the option of endoscopic treatment and the excellent cosmetic results.

Laser energy has been used by many for transurethral incision of small, obstructive prostates, vesical neck contractures, and urethral strictures. The customary techniques of moving the tip of the laser fiber through a cystoscope with a conventional laser guide, almost tangentially to the tissue to be incised, or drilling radially arranged holes in the scar, or both, have been cumbersome and imprecise. To provide exact control of the laser fiber and precise delivery of laser energy, a new guide was devised. It conducts the quartz fiber through the sheath and along the lens of an optical urethrotome. The tip of the quartz fiber contacts the tissue at an angle of 20 degree(s). KTP/532 laser energy is used to perform internal urethrotomy for urethral stricture, transurethral incision of postoperative contracture of the vesical neck, and transurethral incision of the small prostate under constant visual control.

Transurethral ultrasound guided laser prostatectomy is one of the most promising alternative invasive treatment modalities for benign prostatic hyperplasia. The principle feature is an on- line 3-D controlling of Nd:YAG laser denaturation of the periurethral tissue. Necrotic tissue is not removed, but sloughs away with the urinary stream within weeks. The bleeding hazard during and after the operation is minimal. By leaving the bladder neck untouched, sexual function is not endangered. Thirty-one patients with symptomatic BPH were treated with the TULIP system and followed up for at least 12 weeks. Suprapubic bladder drainage had to be maintained for a mean time of 37 days. Conventional TURP was performed in four patients due to chronic infection, recurrent bleeding, and poor results. Our initial experience with the TULIP system shows it to be very efficient and safe. A longer follow up of a larger patient population is necessary to compare the therapeutic efficiency to conventional transurethral resection.

We describe the laser coagulation of the prostate using a conventional bare fiber inserted in a modified Albarran bridge which presents at the distal tip, a newly designed gold-plated reflector, connected by a deflecting mechanism. This allows delivery of laser energy (40 - 80 W) by direct reflection of the Nd:YAG laser light, an angularity more accentuated compared with other systems. Transurethral laser coagulation was performed on 25 patients for prostatic obstruction benign prostatic hyperplasia (BPH) and 6 selected patients for carcinoma of the prostate (December 91 - January 93). Patient selection (BPH) was limited to median lobe (range 50 - 55 years), small prostates, older and high-risk patients. Successful results were noted in 20 of the 25 cases of BPH group (80%). A significant reduction of obstructive symptoms was associated with an increase of maximal a medium flow rates. In the early prostate cancer group, the method has resulted in 3 patients with no evidence of disease, despite repeated biopsy, biochemical, and clinical investigations (PSA range level > 20 ng/ml to < 0.5 ng/ml at one year). The results are encouraging at this stage.

Among the commonly available surgical lasers, the CO₂ laser has acquired a unique role in oral, laryngeal, and tracheo-bronchial surgery. Other wavelengths, and in particular, frequency doubled Nd:YAG laser, the KTP-532 is also gaining ground, offering the advantage of the fiber transmissivity. A number of new lasers are being introduced. The question of their usefulness in the field of otolaryngology can best be answered by systematic study of the peculiar requirement of the surgical procedure, the tissue interactions of any particular wavelength/s, the ease with which the beam can be targeted, and so on.

There has recently been a wide interest in endoscopes with minimized diameter for medical and technical applications. A small diameter of the endoscope can be realized by use of fiber optic multirod with arranged structure, instead of a system of many sequentially placed lenses. With fiber optic technique it is possible to manufacture rods with square and circular sections, 1 mm, and even below, in diameter and as much as 1 m in length. Successful experimental manufacturing of such fiber optic image guide rods has been performed at the Institute of Electronic Materials Technology in Warsaw. Various technological problems (like image cleanliness improvement, enhancing of relayed image contrast and resolution, choice of proper rod cladding and EMA glasses) were encountered.

The paper presents the distinctive features of biotissue destruction by a pulsed/periodic laser beam providing emission in the yellow-green region (copper vapor laser). Surgical set up is described with monofiber delivering the laser emission into the surgical zone. The laser emission is useful for surgery based on low volumes of evaporation, coagulation, and destruction of biotissues.

Laser Doppler Vibrometry is a useful method to measure vibrations of the tympanic membrane. It is suitable to objectively diagnose the middle ear. A correlation between the displacement function of the umbo and the experimentally created middle ear disorders could be demonstrated.

Among the commonly available surgical lasers, the CO₂ laser has acquired a unique role in oral, laryngeal and tracheo-bronchial surgery. Other wavelengths, and in particular, frequency doubled Nd:YAG laser, the KTP-532 is also gaining ground, offering the advantage of the fiber transmissivity. A number of new lasers are being introduced. The question of their usefulness in the application for nasal surgery can best be answered by systematic study of the peculiar requirement of the surgical procedure, the tissue interactions of any particular wavelength/s, the ease with which the beam can be targeted and so on.

In a limited series of patients, different types of delivery systems for the carbon dioxide laser were evaluated for their clinical efficiency and practicability. The spectrum of disease submitted to laser surgery ranged from recurrent paranasal sinus polyposis to M. Osler. The systems used were an operation microscope with micromanipulator, a handpiece, two rigid, tubular waveguides and one recently developed flexible waveguide. The characteristics of each instrument are discussed, and so are the indications for endonasal laser surgery.

The data is presented referring to the details of contact YAG-Nd laser surgery technique under experimental and clinical conditions. Essentially, the contact method is compared with the effect of the scalpel in the surgeon's hands and biologically there is no tangible difference between the carbon dioxide laser and the YAG-Nd laser when the latter is applied in the contact manner. Laryngeal application of the laser contact technique proved to be very beneficial clinically. Tracheal puncture approach with jet ventilation of the lungs ensured absolute safety of the endoscopic laser operative procedure. On the basis of almost 300 operations it has been concluded that the laryngeal neoplasms (benign and T1 - T2 cancer) can be successfully treated in this manner.

Experiences in the use of a new design of flashlamp pumped dye laser operating at 585 nm are outlined. This includes explanation of laser parameters and early clinical results on a cross section of medical conditions. In excess of 1500 patients have been treated with a good therapeutic outcome.

Because of the different step programs concerning the preoperative diagnostic and the onset of therapy for the various types of congenital vascular disorders (CVD) a clear classification is important. One has to discern the vascular malformations, including the port wine stain, from the real hemangiomas which are vascular tumors. As former classification, mostly based on histological findings, showed little evidence to a clinical step program, we developed a descriptive classification which allows an early differentiation between the two groups of CVD. In most cases this can be done by a precise medical history of the onset and development of the disorder, a close look to the clinical signs and by Duplex-Ultrasound and MRI-diagnostic. With this protocol and the case adapted use of different lasers and laser techniques we have not seen any severe complications as skin necrosis or nerve lesions.

In-vivo remission spectra of the human skin in the spectral region of 400 nm to 800 nm were recorded using a xenon lamp as an excitation source, a fiberoptical sensor combined with a polychromator, and a multichannel analyzer. The remission of amateur tattoos before and after laser treatment (Q-switched Nd:YAG) was measured and the degree of blanching determined. It was found that the process of blanching proceeds partly reversible. In another study, the time-dependent remission of human skin after topical administration of the photosensitizer Methylene Blue was studied. The additional application of the ceratolytic agent urea promotes the penetration of the thiazine dye. The experimental data were analyzed by the Kubelka Munk theory.

Low energy laser therapy (LELT) was used to treat chronic leg ulcers. Seven patients, aged 59 to 96 years, with 11 leg ulcers were referred for laser therapy by plastic surgeons. They had a history of ulceration of 3 - 50 years and five of the patients had breakdown of previous skin grafts. Laser treatments were administered with a microprocessor-controlled device. A 22 red ((lambda) equals 660 nm) laser head was utilized to provide a dose of (4 - 6) J/cm² and 7 infrared ((lambda) equals 880 nm) head to provide a dose of (4 - 8) J/cm². The patients were treated three to five times per week, 25 - 30 treatments per course. Three patients underwent two courses of laser therapy with three weeks interval between them. All patients, after 5 - 10 laser treatments, have gotten relief of pain and decreased the amount of analgesics used. All ulcers in six patients were completely healed and two ulcers in the seventh patient decreased in size by 75%. One may conclude the developed laser methodology might be used as a preventative measure to avoid plastic surgery or improve its success.

When used in continuous wave (cw) mode the CO₂ laser is an effective tool for vaporizing unwanted tissue, however, there is the possibility of the accumulation of thermal energy in the good tissue close to the point of treatment. If this thermal energy is high then post operative pain and scarring could result. This is avoidable by delivering the energy in short pulses with the gap between those pulses being greater than the thermal relaxation time of the tissue (which can vary according to tissue type that is typically 0.5 to 3.0 ms). Simply chopping the laser beam rapidly would produce the desired thermal effect but would waste a large percentage of the laser energy and greatly extend the treatment time since the average output power of the laser is compromised. The ideal scenario is where the laser power is enhanced for the on period producing an average power similar to that obtained in cw mode.

PUVA is a well established phototreatment modality for various dermatoses, like T cell lymphomas, using long-wavelength UV radiation. In contrast, PDT bases on the combination of photosensitizers, especially porphyrins, and radiation mainly in the red spectral region. We analyzed the photochemical effects of both treatments on cell lines MyLa and HuT78, established from patients with cutaneous T cell lymphomas. Our observations document the capability of PDT to inhibit proliferation of transformed T cells similar to PUVA thus pointing out its potential in the treatment of cutaneous T cell lymphomas.

A dichroic filter was adjusted in order to make use of the green line of an argon laser for the treatment of pigmented lesions (actinic and senile lentigo, ephelis, cafe-au-lait marks and spilus nevus). Using a power of 1.5 W, a spot size of 0.5 mm and pulse lengths of 200 or 300 ms, satisfactory elimination of 620 pigmented cutaneous lesions was achieved. Although the pulse lengths used were much longer than the thermal relaxation time of the melanosomes, the histology after treatment showed little damage of adjacent structures. Good restoration of the epidermis and a return of normal pigmentation led to excellent cosmetic results, with few complications.

In order to investigate histological results produced by laser wavelengths 514 and 585 nm (Monoline Argon Laser and cw Dye Argon Laser), tests were carried out on a haemangioma situated on the neck of a male adult. The tests were done using the hexascan, previously modified to receive two fibers, which could separately direct the wavelengths 514 and 585 nm (1 watts and 30 ms pulses), with slight pauses during the treatment of one area and another, but both areas having identical characteristics. Random histological samples were taken previous to treatment, immediately after, and a month following treatment, processing them with Mason's Trichromic. Analysis and evaluation of the samples were performed by two researchers, strange to the investigation. In addition to the typical tissue reactions to relatively long Argon pulses (longer than 100 ms), it was found that there were no significant differences in the skin and vessels histological reactions, when both wavelengths 514 and 585 nm were used.

We evaluated the effect of the 600 micrometers bare (flat tip) and 600/100 micrometers conical tip fibers on porcine skin. We compared their effect in both the continuous-wave (cw) and pulsed (P) modes (20 ms ON/OFF) at 20 W to that of the electrocautery at 100 W in the pure and blend 3 modes. On 11 farmer pigs, 6 cuts were made for each parameter combination. The samples were processed for histological evaluation. The cutting depth, cutting width, and total thermal damage (carbonization, coagulation and denaturation) were recorded for each parameter combination. The results show that the 600/100 micrometers conical fiber provides deeper resective capabilities than the 600 micrometers bare and electrocautery. In addition, the 600/100 micrometers conical tip fiber allows for narrower cuts with significantly less thermal necrosis when compared to the 600 micrometers bare and electrocautery. The results indicate that there is an advantage to using the sculptured tip fiber for creating incisions when compared to the bare fiber and electrocautery.

In this study the fluorescence intensity of photosensitizer in squamous cell tumors were quantified in terms of the tumor resolution rate. A He-Cd laser (442 nm - 17 mW) with a 600 micrometers core silica fiber was used for excitation. The same fiber was used for fluorescence acquisition and an optical multichannel analyzer (EG&G, OMA III) was used to analyze the fluorescence. Twelve days after carcinoma inoculation fluorescence signal from the tumor and skin (1 cm radius from the tumor) at the 12, 3, 6, and 9 o'clock positions were recorded. Benzoporphyrin Derivative (QLT, Canada -- 2 mg/kg of body weight) was then injected into the tail vein. The drug was photoactivated with a 690 nm modified argon pump cw-dye laser (Medtech) operating at 140 mW/cm² for 15 mins. LIFS is capable of localizing in situ malignancy and evaluating photosensitizers for photodynamic fluorescence detection and therapy of tumors.

Lower leg ulcer is sometimes a refractory disease. A recently developed copper vapor laser could be a promising light source for the treatment of these lesions. Preliminary results of clinical investigations of five patients with leg ulcer treated by copper vapor laser phototherapy are reported. Among them, three were cured, one obtained significant response, one had no response. Most patients were cured within 15 laser treatments. It was found that lower irradiation power and energy densities were required to obtain better results. Experiment details are given.

A method has been developed for measuring the biologically effective dose (BED) of solar radiation. The method applies phage T7 as a biosensor in a monitoring system. The work presents a series of dose measurements caused by direct and global irradiation. Comparisons are made of the results obtained in the same time in different places in Hungary in 1992 and 1993. A doubling of the measured BED was found which can not be explained with the ozone depletion only. An interpretation of phage T7 dose as well as transformation of the results into MED are presented. The influence of the photosensitization as an additive damage is discussed as well.

From a biological point of view, one of the most important targets of UV-radiation in living systems is the cell DNA. The spectral sensitivity of the photodimerization reaction of the uracil thin layer caused by UV-radiation is similar to that of DNA dimerization reaction. Appropriate modification of the spectral sensitivity of the uracil thin layer, using different covering filters, makes it suitable for measuring the exposure dose of natural and artificial UV-sources as well. Sensitivity curves with different filters, cross calibration possibilities and transformation of the measured doses into other known biologically effective doses are presented.

Biostimulation, as a non thermic laser irradiation provoked biological effect, results in the enhancement of reparative and regenerative processes. It is a strict dose dependent functional change in the range of 1 - 4 Joule/cm² incident energy density. Repeated low power irradiations in that particular dose range lead to a cumulative effect, which depends on the frequency of sessions. In the case of daily repetition the cumulation is much quicker than with one or two days interruption. Too high a dose per session or too quick a repetition with maximal doses for more than 20 consecutive irradiations (i.e., daily leads to the opposite effect, which is inhibition.

A number of reports and scientific publications, especially from recent years, prove that laser irradiation from several to a few dozen milliwatts has positive both local and general influence in many diseases. It is widely regarded that irradiation by a laser of low intensity improves energetic balance of cells, tissues, and the whole system, and works through following the mechanisms: direct absorption of photons, electromagnetic influence, and phosphorylation of ADP under the influence of photostimulation.