bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study of CO2‐laser‐induced histological effects on human fallopian tube: Determination of CO2 laser parameters to be used in microsurgery
Authors: Foulot Hervé , Lefebvre Gilles , Jagueux Michel , Darbois Yves
Published: March 2007

This experiment investigates CO2‐laser‐induced histological effects on fallopian tubes obtained during hysterectomies in women. Tubal transversal sections were performed at isthmic and ampullar sites. Forty strips were available for histological study of the cut section area. The role of different parameters such as radiation power and beam fractionation (continuous versus pulsed) on tissue lesions was assessed. In tubal microsurgery, the CO2 laser can be used as a scalpel with the predominant advantage of minimal tissular alterations. As a result of this study, our recommended parameters are the following: radiation power, 7–10 W; beam focalization zone, 0.2 mm; energy density, 20,000–35,000 W/cm2; continuous operation; moving speed, 1 cm/s.
Use of the CO2 laser in soft tissue dental surgery
Authors: Pick Robert M. , Pecaro Bernard C.
Published: March 2007

The use of the carbon dioxide laser for the removal of soft tissue lesions in the oral cavity is presented. The laser was used to remove numerous benign lesions and growths, for incisional and excisional biopsies, and for the removal of microinvasive and macroinvasive carcinomas. Owing to its coagulation properties, the laser was used effectively in treating patients with oral lesions compounded by blood dyscrasias. Because of the advantages of a relatively bloodless surgery; decreased postoperative discomfort; minimal swelling and scarring; and the laser's ability to coagulate, vaporize, or cut, the CO2 surgical laser offers the dental surgeon a viable and in many cases an improved alternative to the scalpel. Laser techniques and several case reports are discussed.
An alternative method of vascular anastomosis by laser: Experimental and clinical study
Authors: Okada Masayoshi , Shimizu Kazuta , Ikuta Hiroshi , Horii Hiroyuki , Nakamura Kazuo
Published: March 2007

In vascular surgery, it is now very difficult to maintain the long‐term patency after a conventional vascular anastomosis, especially for small‐caliber vessels. A low‐energy CO2 laser was experimentally employed to make a vascular anastomosis with only a few sutures. Subsequently, it could be confirmed that optimal conditions for vascular anastomosis by laser were 20–40 mW in output and 6–12 sec/mm in irradiation time. On the other hand, pressure tolerance test as well as tensile strength test and microscopic examinations at the sites of anastomoses by laser were compared with the conventional suture method. There were no significant differences between laser and suture methods. On the basis of the excellent results of this study, the laser was clinically applied for anastomoses of the peripheral vessels in 35 patients. The first clinical laser application in the world was successful in a 44‐year‐old female patient with chronic renal failure in 1985. All patients are doing well without any complications from vascular anastomosis by laser. From these experimental and clinical studies, it can be concluded that anastomosis by laser should be recommended for small‐caliber vessels such as aortocoronary bypass surgery.
Tissue interactions and measurement of ablation rates with ultraviolet and visible lasers in canine and human arteries
Authors: Sartori Michele , Henry Philip D. , Sauerbrey Roland , Tittel Frank K. , Weibaecher Donald , Roberts Robert
Published: March 2007

Ablation rates measured as the depth of tissue excavation per unit time were determined in human and canine aortas subjected to radiation with ultraviolet (UV) excimer (ArF 193 nm, KrF 248 nm, XeF 351 nm) and visible lasers [continuous wave (cw) and 50‐ms chopped argon ion, 478 nm‐514 nm: pulsed double‐frequency Nd:YAG, 532 nm]. For UV and pulsed double‐frequency Nd:YAG lasers ablation rates were constant in time and depended linearly on average laser power, but for cw and chopped argon lasers ablation rates varied with irradiation time and were nonlinearly dependent on laser power. In human aortas, atherosclerosis without gross calcification had no influence on ablation rates. Charring and tissue disruption were observed with cw and chopped argon ion, whereas excimer and pulsed Nd:YAG lasers produced only minimal injury to surrounding tissue. We conclude that the determination of ablation rates is useful for the selection of laser wavelengths and power densities applicable to angioplasty and that UV and pulsed visible lasers permit a better control of ablation compared to continuous wave lasers.
NADH in situ laser fluorimetry: Effect of pentobarbital on continuously monitored myocardial redox state
Authors: Renault Guy , Muffat‐Joly Martine , Polianski Juliette , Hardy Roger Ian , Boutineau Jean‐Louis , Duvent Jean‐Louis , Pocidalo PhD Jean‐Jacques
Published: March 2007

NAHD laser fluorimetry was applied to in situ monitoring of pentobarbital overload effect on myocardial redox state in rats. Experiments were carried out on open‐chest rats anesthetized with pentobarbital. Use of very thin optical probes allowed measurements of NADH fluorescence directly within the myocardial wall. Quantitative analysis of fluorescent and backscattered light signals was made possible on‐line.

In 8 animals, a slow IV infusion of 6% pentobarbital (2 mg·min−1 for 10 min) induced an average twofold increase in NADH fluorescence, with constant return to baseline level prior to injection after a maximum period of 50 min. Thus, pentobarbital overload strongly affects the myocardial energetic state, and this effect was precisely evaluated with NADH fluorescence monitoring. In situmonitored myocardial redox state variations during pentobarbital infusion can constitute a reference for similar studies on pharmacological agents aimed at protecting tissues against ischemic biochemical damages.
Smoke from laser surgery: Is there a health hazard?
Authors: Nezhat Camran , Winer Wendy K. , Nezhat Farr , Nezhat Ceana , Forrest Deborah , Reeves William G.
Published: March 2007

The composition of plume produced during carbon dioxide laser endoscopic treatment for endometriosis was examined to determine whether it represented a hazard to the surgical staff. A total of 32 plume samples were collected from 17 women undergoing laser laparoscopic treatment for endometriosis and/or adhesions. The smoke was found to consist of particles having a median aerodynamic diameter of 0.31 μm with a range of 0.10–0.80 μm. The size range has two consequences: (1) using a human red blood cell as a model for all cells, it can be stated with greater than 99.9999% certainty that no cell‐size particles, including cancer cells, are present in the plume; (2) particles in this size range are too small to be effectively filtered by currently available surgical masks.
Sutureless bowel anastomosis using Nd:YAG laser
Authors: Mercer C. D. , Minich P. , Pauli B.
Published: March 2007

Small bowel anastomoses were performed without sutures by using the Nd:YAG laser to produce welded enterotomies. Optimal energy levels for contact and noncontact laser were determined. Anastomoses produced using five target energy levels between 100 and 500 J were examined. Short‐term anastomotic strength of these enterotomies was measured 1 min after the welding. Bursting pressure of the laser welded enterotomies was compared to the bursting pressure of traditional two‐layer, inverting, interrupted sutured bowel anastomoses. The overall mean bursting pressure of non‐contact‐welded enterotomies was 50.6 mmHg. Optimal laser settings determined in this initial phase were then used to produce anastomoses in rabbits which are recovered postoperatively for 1 or 2 weeks in order to examine long‐term viability and integrity of the anastomoses. All chronic rabbit preparations recovered without complication. The mean bursting pressure was 200 mmHg, not significantly different from that of uncut bowel or two‐layer sutured anastomosis.
Phycocyanin: Laser activation, cytotoxic effects, and uptake in human atherosclerotic plaque
Authors: Morcos N. Charle , Berns Michael , Henry Walter L.
Published: March 2007

Phycocyanin is a phycobiliprotein with peak absorption at 620 nm. The laser activation, cytotoxic effects, and uptake into atherosclerotic plaque of phycocyanin was studied. Optimal activation was produced by argon dye laser at 0.5 W and a total energy dose of 300 J/cm2 at 620 nm and 650 nm, irradiated through blood with a hematocrit of 8%. Activation was evidenced by reduction of optical density by 0.3 units at 340 nm caused by oxidation of the reduced nicotinamide adenine dinucleotide phosphate (NADPH) in a buffered reaction solution containing 0.1 mg/ml of phycocyanin. Cytotoxicity was evaluated by measuring viability of mouse myeloma cells in culture after incubation with phycocyanin (0.25 mg/ml) and irradiated by 300 J/cm2 at 514 nm. After 72 hours post‐treatment the cells showed 15% viability compared to 69% and 71% for control cells exposed to laser only or phycocyanin only, respectively. Atherosclerotic artery segments obtained within 5 hours postmortem were perfused with 0.1 mg/ml phycocyanin in oxygenated Krebs Ringer solution at 30 mm Hg for 5 minutes followed by washout with phycocyanin‐free Krebs for 10 minutes. Artery sections examined histologically by light and fluorescence microscopy showed specific fluorescence localization within the plaque particularly at the elastic laminae and to a larger extent at the internal elastic lamina but not in the medial muscle layer. In conclusion, phycocyanin is a cytotoxic photosensitizer that exhibits specific binding to plaque and is activated at a wavelength minimally absorbed by blood. These properties suggest potential therapeutic use for plaque localization and regression.
Mechanism of tissue fusion in argon laser‐welded vein‐artery anastomoses
Authors: White Rodney A. , Kopchok George E. , Donayre Carlos E. , Peng Shi‐Kaung , Fujitani Roy M. , White Geoffrey H. , Uitto Jouni
Published: March 2007

The mechanism of laser vascular tissue welding remains unknown. This study compared the acute tissue response and long‐term healing of sutured and laser‐welded anastomoses of vein segments used to bypass ligated canine femoral arteries. For each procedure, one anastomosis was formed using running 6‐0 polypropylene suture (control), and the other anastomosis was formed using argon laser tissue welding (experimental). The vein grafts were harvested at 4 (n = 2), 8 (n = 1), 12 (n = 1), and 16 (n = 2) weeks, and selected samples were evaluated by histologic examination, electron microscopy, tensile strength testing, and by measuring the formation of [3H]hydroxyproline as an index of collagen synthesis. Examination of successful laser fusions immediately after they were formed showed bonding of collagen to collagen and elastin to collagen. Follow‐up evaluations showed that the precision of tissue apposition affected the rate of healing and tensile strength. Laser‐welded anastomoses demonstrated a progression of healing similar to sutured repairs, with remodeling of fibrous tissue and collagen being the primary component of weld integrity. This study demonstrates that sutured and argon laser‐welded vein‐artery anastomoses heal comparably up to 16 weeks postoperatively, and that laser welding is a satisfactory alternative to sutured anastomoses.
Robotized scanning laser handpiece for the treatment of port wine stains and other angiodysplasias
Authors: Rotteleur G. , Mordon S. , Buys B. , Sozanski J. P. , Brunetaud J. M.
Published: March 2007

Port wine stains are currently treated by the argon laser with the “point‐by‐point” technique, or the “painting technique.” In both cases, the quality of the results depends greatly on the dermatologist's experience. Furthermore, the first technique is slow, and the second is painful and requires anesthesia. Therefore, we have decided to design a robotized system with the following specifications: easy, fast, nonpainful treatment giving a homogeneous and reproduceable blanching. The system is made of a handpiece with the scanning mechanism and a control box with the microprocessor. The system is independent of the laser (no electrical connection) and has its own power meter. The deposit of energy was optimized in function of heat diffusion in the skin. Over a 12‐month period, 123 patients were treated with the robotized handpiece. The treatment modalities and the results conformed to the above‐mentioned specifications. Hypertrophic scars were not reported. Therefore, we think that this system will be an interesting tool for the laser treatment of port wine stains and other cutaneous angiodysplasias.
Photodynamic therapy: Response of normal canine urethra using a cylindrical fiber
Authors: Manyak Michael J. , Matthews Donna M. , Smith Paul D. , Nochomovitz Lucien E. , Russo Angelo
Published: March 2007

Normal urethral response to photodynamic therapy (PDT) utilizing a cylindrical fiber was assessed in ten study and two control NIH foxhounds. The canine urethras were treated 48 hours after intravenous injection of 3 mg/kg dihematoporphyrin ether (Photofrin II). A 1‐mm fused silica optical fiber, with the distal 2–3 cm modified for cylindrical light distribution (660‐μm diameter), was placed in the pendulous urethra. An argon‐pumped dye laser delivered 100 mW of 630‐nm light for 7 minutes (42 J) to the treatment area. Urethroscopy using either a 2.5‐mm or a 2.8‐mm flexible pediatric bronchoscope with video recording capability was performed immediately after PDT (12 animals) and 6 weeks later (nine animals); intravenous urography was performed 3 days and 6 weeks after PDT. There was no evidence of either urethral damage or stricture formation in any animal. Histopathology of the first three study specimens, obtained at 6 weeks, confirmed the absence of any pathology. Flexible instrumentation facilitates post‐treatment assessment. This study demonstrates for the first time that, when a cylindrical fiber is used, photodynamic therapy may be applied to the urethra without damage to the normal urethral mucosa. This result has implications for potential treatment of initial or recurrent carcinoma in situ of the urethra using PDT.
CO2 and argon laser vascular welding: Acute histologic and thermodynamic comparison
Authors: Kopchok George E. , White Rodney A. , White Geoffrey H. , Fujitani Roy , Vlasak Jerry , Dykhovsky Leon , Grundfest Warren S.
Published: March 2007

CO2 and argon lasers have been used successfully for vascular welding in both experimental and clinical settings. This study compared the thermodynamics during CO2 and argon laser welding of 1‐cm longitudinal arteriotomies in a canine model. Continuous recordings using an AGA 782 digital thermographic system with spatial and thermal resolution of ±0.2 mm and ±0.2°C, respectively, were analyzed. A HGM argon laser using a 300‐μm optic fiber held at 1 cm from the vessel edges (spot diameter = 2.8 mm) with concomitant room temperature saline irrigation (1 drop/sec) was used for argon welds. Total exposure time was 150 sec/cm. CO2 welds were performed with a Sharplan CO2 laser (spot diameter = 0.22 mm) with no irrigation for total exposure time of 10 sec/cm. Thermodynamic results and laser parameters are summarized as follows: Argon–n = 20; power = 500 mW; energy fluence = 1,400 J/cm2; Tmax = 48.8°C; T mean ± S.D. = 45.1 ± 2.7°C; CO2–n = 20; power = 150 mW; energy fluence = 3,000 J/cm2; Tmax 84.0°C; T mean ± S.D. = 60.7 ± 9.8°C. There was a significant difference (P < .05) in thermal measurements between successful CO2 and argon vascular welds. Temperature rise during the argon welds was limited by saline irrigation. In contrast, during CO2 laser welding, the temperature rose quickly to its maximum and was maintained at a relatively high level as the laser progressed (0.1 cm/sec) along the anastomosis. Histologic examination revealed charring at the CO2 weld site but absence of thermal damage at the argon laser weld. These thermodynamic differences may account for the different welding mechanisms currently described.
The first sutureless, laser‐welded, end‐to‐end bowel anastomosis
Authors: Sauer Jude S. , Hinshaw J. Raymond , McGuire Kevin P.
Published: March 2007

The use of laser energy to weld together tissue offers great promise in the expanding field of laser surgery. The published results of laser welding intestinal tissue have, to date, been limited to the successful laser closures of small enterotomies. This is the first report of using laser energy alone to create an end‐to‐end small bowel anastomosis. A biocompatible, water‐soluble, intraluminal stent was employed during the laser welding of this sutureless, stapleless ileal anastomosis in a rabbit model. Excellent recovery and healing were observed. The rapidity, ease, and potential for full precision automation of laser welding mandates further research.
Fluorescence spectroscopy guidance of laser ablation of atherosclerotic plaque
Authors: Deckelbaum Lawrence I. , Stetz Mark L. , O'Brien Ken M. , Cutruzzola Francis W. , Gmitro Arthur F. , Laifer Lawrence I. , Gindi Gene R.
Published: March 2007

Laser‐induced fluorescence (LIF) spectroscopy can only be used for laser angioplasty guidance if high‐power laser ablation does not significantly alter the pattern of tissue fluorescence. Although the spectra of normal and atherosclerotic arteries differ, the change in fluorescence spectra following laser angioplasty has not been well studied. Therefore, the purpose of this study was to assess whether laser‐induced fluorescence spectroscopy could guide selective laser ablation of atherosclerotic plaque and, if so, to develop a quantitative LIF score that could be used to control a “smart” laser angioplasty system.

Baseline LIF spectroscopy of 50 normal and 50 atherosclerotic human aortic specimens was performed using an optical fiber coupled to a He‐Cd laser and optical multichannel analyzer. LIF was then serially recorded during erbium:YAG laser ablation of 27 atherosclerotic specimens. Laser ablation was terminated when the arterial LIF spectrum visually appeared normal. Histologic analysis revealed a mean initial plaque thickness of 1,228 ± 54 μm and mean residual plaque thickness of 198 ± 27 μm. Ablation of the media occurred in only three specimens.

A discriminant function was derived to discriminate atherosclerotic from normal tissue for computer guidance of laser angioplasty. The LIF score, derived from stepwise multivariate linear regression analysis of the LIF spectra, correctly classified 93% of aortic specimens. The spectra obtained from the atherosclerotic specimens subjected to fluorescence‐guided laser revealed a change in score from “atherosclerotic” to “normal” following plaque ablation. Seven atherosclerotic specimens were subjected to laser angioplasty with on‐line computer control using the LIF score. Mean initial plaque thickness was 1,014 ± 86 μm, and mean residual plaque thickness was 78 ± 29 μm. There was no evidence of ablation of the media. Therefore, LIF guidance of laser ablation resulted in minimal residual plaque without arterial perforation. These findings support the feasibility of an LIF‐guided laser angioplasty system for selective atherosclerotic plaque ablation.
Photofrin II localization in rat cecum
Authors: Bjorkman David J. , Brigham Earl J. , Peterson Brian J. , Straight Richard C.
Published: March 2007

Laser excitation of photodynamic agents localizing in colonic tumors may allow the early diagnosis and treatment of colon cancer. The efficacy of these agents requires a high ratio of tumor to background photosensitizer accumulation and fluorescence. To assess normal colonic background fluorescence and hematoporphyrin accumulation 31 rats were studied after an intravenous injection of Photofrin II (PF‐II) at a dose of 5 mg/kg. An increase in mucosal fluorescence and porphyrin content was noted in the cecum 24 hours after injection.

Cecal accumulation of PF‐II may affect its efficacy in the localization and treatment of cecal tumors. Further investigation into the mechanism and clinical significance of this finding is needed.
Spectroscopic differences between human cancer and normal lung and breast tissues
Authors: Tang G. C. , Pradhan A. , Alfano R. R.
Published: March 2007

Steady‐state spectra, time‐resolved spectroscopic, and excitation spectra from human cancer and normal tissues have been measured. Spectroscopic differences between normal and cancerous tissues have been found that could be used as a basis for an instrument for the early detection of cancer.
Er:YAG laser ablation of tissue: Effect of pulse duration and tissue type on thermal damage
Authors: Walsh Joseph T. , Flotte Thomas J. , Deutsch Thomas F.
Published: March 2007

The thermal damage caused by 2.94‐μm Er:YAG laser ablation of skin, cornea, aorta, and bone was quantified. The zone of residual thermal damage produced by normal‐spiking‐mode pulses (pulse duration ≈ 200 μs) and Q‐switched pulses (pulse duration ≈ 90 ns) was compared. Normal‐spiking‐mode pulses typically leave 10–50 μm of collagen damage at the smooth wall of the incisions; however, at the highest fluences (≈ 80 J/cm2) tears were produced in cornea and aorta and as much as 100 μm of damaged collagen is found at the incision edge. Q‐switched pulses caused less thermal damage, typically 5–10 μm of damage in all tissues.
Er:YAG laser ablation of tissue: Measurement of ablation rates
Authors: Walsh Joseph T. , Deutsch Thomas F.
Published: March 2007

The ablation of both soft and hard tissue using the normal‐spiking‐mode Er:YAG laser has been quantified by measuring the number of pulses needed to perforate a measured thickness of tissue. Bone is readily ablated by 2.94 μm radiation; however, at per pulse fluences greater than 20 J/cm2, plasma formation decreases ablation efficiency. At low fluence, desiccation can prevent efficient ablation of bone. The ablation efficiency for aorta and skin is higher than for bone. The ablation efficiency, 540 μg/J, and the ablation depth per pulse, >400 μm, for skin are too high to be readily explained by simple models of ablation and thus provide evidence for a more complex explosive removal process.
Laser dentistry: A new application of excimer laser in root canal therapy
Authors: Pini Roberto , Salimbeni Renzo , Vannini Matteo , Barone Roberto , Clauser Carlo
Published: March 2007

We report the first study of the application of excimer lasers in dentistry for the treatment of dental root canals. High‐energy ultraviolet (UV) radiation emitted by an XeCl excimer laser (308 nm) and delivered through suitable optical fibers can be used to remove residual organic tissue from the canals. To this aim, UV ablation thresholds of dental tissues have been measured, showing a preferential etching of infiltrated dentin in respect to healthy dentin, at laser fluences of 0.5–1.5 J/cm2. This technique has been tested on extracted tooth samples, simulating a clinical procedure. Fibers of decreasing core diameters have been used to treat different sections of the root canal down to its apical portion, resulting in an effective, easy, and fast cleaning action. Possible advantages of excimer laser clinical applications in respect to usual procedures are also discussed.
Ocular fluorometry: Principles, fluorophores, instrumentation, and clinical applications
Authors: Docchio Franco
Published: March 2007

Ocular fluorometry is rapidly evolving as a versatile technique for research and diagnosis in ophthalmology. The main reasons for this increasing success are (1) the ideal characteristics of the eye as an optical device for excitation of tissue fluorescence and for the detection of the fluorescent emission; (2) the development of novel fluorometric techniques, including differential and time‐resolved fluorescence spectroscopy; and (3) the increasing use of coupling geometries with high‐resolution and high spatial selectivity. Both endogenous and exogenous fluorophores are of interest to ocular fluorometry. The most significant among endogenous fluorophores are the fluorescing pigments of the lens and of the retinal pigment epithelium (RPE). The nature, topography, and fluorescence properties of such pigments depend on age and pathology and on the level of light exposure. Exogenous fluorophores of interest are both intentionally induced and unintentionally accumulated drugs (some of which are phototoxic). Laser‐based fluorometric techniques play a leading role in ocular fluorometry. The peculiar properties of the laser for the excitation of fluorescence make this source a favorite candidate for ocular fluorometry both in vitro and in vivo.
Endometrial laser ablation in rabbits: A comparative study of three laser types
Authors: Rosenberg Carlos , Tadir Yona , Braslavsky Diana , Fisch Benjamin , Karni Ziv , Ovadia Jardena
Published: March 2007

Endometrial laser ablation is one of the alternatives to hysterectomy in cases of intractable uterine bleeding. It is currently performed using the Nd:YAG laser at 1.06 μm. The aim of this study was to compare the tissue effect of three types of laser irradiation (Nd:YAG laser at 1.06 and 1.32 μm and holmium laser at 2.12 μm) on the rabbit endometrium. Crater formation, coagulation necrosis, and muscle necrosis were evaluated at the time of ablation, as well as at 1 week and 4 weeks postablation. The results were assessed by determining the depth and width of the affected portion in the uterine wall (lumen to serosa). It was shown that Nd:YAG laser at 1.32 μm caused more generalized and extended effects as compared with the other laser types examined. Endometrial regeneration was faster after ablation by the Nd:YAG laser at 1.06 μm and the holmium laser than by the Nd:YAG laser at 1.32 μm. The widest range of “ablation energy” (defined as that causing ablation without muscle damage) was achieved by applying the holmium laser. Further evaluation of the holmium laser for this indication is recommended.
Effects of Nd:YAG laser coagulation of myocardium on coronary vessels
Authors: Weber Helmut , Enders Susanne , Coppenrath Klaus , Murray A. Beatrice , Schad Hubert , Mendler Nikolaus
Published: March 2007

Laser coagulation of arrhythmogenic myocardium proved to be an effective surgical therapy for refractory arrhythmias. To determine the influence of NdYAG laser coagulation of myocardium on coronary vessels, a total of 48 transcatheter laser impacts (10 W, 10 sec, 7 W mm2) were directed to the left ventricular free wall via endocardial (24 lesions in 2 dogs) or epicardial (24 lesions in 2 dogs) approach. In 8 of 24 endomyocardial lesions (2 and 6 months old) coronary vessels with a diameter of > 50 μm were found within the coagulation zones. The volume of these lesions was significantly (P < 0.0l) smaller (139 ± 43 mm3) than those (n = 16) with coronary vessels measuring <50 μm (311 ± 87 mm3). Volumes of epimyocardial lesions (1‐2 hours old) produced by transcoronary irradiation with normal coronary blood flow were significantly (P < 0.01) smaller (31 ± 17 mm3) than with reduced (73 ± 22) or interrupted (119 ± 34 mm3) blood flow (n = 8, each). Both directly irradiated coronary vessels and those found within the coagulation zones and scars appeared histologically normal through all layers with an intact intima without fibrosis or thrombosis. The ultrastructure of irradiated arteries, even with total interruption of blood flow, was no different from that of non‐irradiated controls. Thus, coronary artery blood flow significantly reduces the volume of coagulated myocardium, whereas the vessels themselves appear to remain undamaged by laser irradiation as used for myocardial coagulation.
Early and late arterial healing response to catheter‐Induced laser, thermal, and mechanical wall damage in the rabbit
Authors: Oornen Antonius , Van Erven Lieselotte , Vandenbroucke Walda V. A. , Verdaasdonk Rudolf M. , Slager Cornelius J. , Thornsen Sharon L. , Borst Cornelius
Published: March 2007

Pulsed lasers are being promoted for laser angioplasty because of their capacity to ablate obstructions without producing adjacent thermal tissue injury. The implicit assumption that thermal injury to the artery is to be avoided was tested. Thermal lesions were produced in the iliac arteries and aorta of normal rabbits by a) electrical spark erosion, b) the metal laser probe, and c) continuous wave neodymium‐yttrium aluminum garnet (Nd‐YAG) laser energy through the sapphire contact probe. High‐energy doses were used to induce substantial damage without perforating the vessel wall. Thermal lesions (n=77) were compared with mechanical lesions (n=22) induced by oversized balloon dilation. Medial necrosis was induced by all four injury methods. Provided no extravascular contrast was observed after the injury, all damaged segments were patent after 1 to 56 days. The progression of healing with myointimal proliferation was remarkably similar for all injuries. At 56 days, the neointima measured up to 370 μm. In conclusion, provided no perforation with contrast extravasation occurred, the normal rabbit artery recovered well from transmural thermal injury. The wall healing response is largely nonspecific.
Carbon dioxide laser‐assisted thyroarytenoid myomectomy
Authors: Woo Peak
Published: March 2007

CO2 laser‐assisted myomectomy of the thyroarytenoid muscle (TA) was carried out through a thyroplasty approach in ten la‐ryngeal specimens and the TA was examined histologically. Using the CO2 laser at super‐pulsed mode, the TA can be cut or resected using 3–5 W of laser power. There is good control of the depth and extent of TA resection. Histologically, there is little evidence of collateral injury, with sparing of vital surrounding vocal structures. The use of CO2 laser for TA resection offers better access and surgical hemostasis in an otherwise difficult surgical field. Laser‐assisted myomectomy may be a feasible alternative to current methods to treat spasmodic dysphonia.
Scanning electron microscopic study of laser‐induced morphologic changes of a coated enamel surface
Authors: Hess John A.
Published: March 2007

A low‐energy Nd:YAG laser was used to irradiate extracted human teeth coated with a black energy‐absorbent laser initiator in a study to determine the extent of the morphologic changes produced in the enamel surface. The laser initiator was applied to a cleaned enamel surface and irradiated at an energy output of 30 mJ or 75 mJ. Both energy levels produced morphologic changes of the surface. There was a sharp line of demarcation between the coated, irradiated area and the surrounding noncoated enamel surface. The scanning electron microscope view at the lower energy level showed that the surface had melted and reformed with numerous small, bubble‐like inclusions. The 75 mJ energy level showed individual impact craters with shallow centers and raised edges containing numerous pores and large, bubble‐like inclusions. Etching is a dental procedure in which an acid is normally used to remove a thin outer layer of the tooth structure. This is necessary to create a roughened, irregular surface in order to provide mechanical retention for dental restorative materials. The changes produced by the laser in this study suggest a simple, effective, and controlled method of etching the enamel surface of a tooth by altering its surface characteristics.
Cutaneous phototoxic occurrences in patients receiving Photofrin®
Authors: Dougherty Thomas J. , Cooper Michele T. , Mang Thomas S.
Published: March 2007

Incidence of cutaneous phototoxic reactions induced by intravenous injection of Photofrin polyporphyrin was assessed in a series of 180 patients (266 injections) undergoing photodynamic therapy (PDT) at Roswell Park Cancer Institute during the period 1986–1989. In addition to the usual verbal questions regarding phototoxic reactions solicited at follow‐up, forty‐two patients in this group also responded to a written questionnaire designed to solicit answers to specific questions. Photofrin doses ranged from 0.5 to 2.0 mg/kg. Overall, 20‐40% of patients reported some type of phototoxic response.
Effect of blood upon the selective ablation of atherosclerotic plaque witha pulsed dye laser
Authors: Gregory Kenton W. , Prince Martin R. , Lamuraglia Gleen M. , Flotte Thomas J. , Buckley Lisa , Tobin Jill M. , Ziskind Andrew A. , Caplin John , Anderson R. Rox
Published: March 2007

Laser angioplasty systems with laser energy preferentially absorbed by atherosclerotic plaque may offer a safe method of plaque removal. This study evaluated the effect of blood upon selective energy absorption using a pulsed dye lasser at 480 nm. Intra‐arterial laser irradiation of normal rabbit femoral arteries demonstrated a perforation threshold energy with blood perfusion of 13.1 mJ per pulse compared to 87.9 mJ with saline (P < .0001), indicating a deleterious effect in the presence of blood. An adverse effect upon arterial healingt at 3 days was noted in sheep following intra‐arterial irradiation during blood but not saline nerfusion. Normal and atherosclerotic human aorta ablation thresholds differed significantly (P < .0002) under saline (plaque: 20 mJ and normal: 20 mJ) was not significant. We conclude that absorption of laser energy by blood can reduce the effect of differential absorption by endogenous chromophores in normal and pathologic vascular tissues and, therefore, removal of blood may be a prerequisite for selective ablation of atherosclerotic plaques.
Presence of human immunodeficiency virus DNA in laser smoke
Authors: Baggish Michael S. , Polesz Bernard J. , Joret Dale , Williamson Patrick , Refai Ashraf
Published: March 2007

Concentrated tissue culture pellets infected with human immunodeficiency virus (HIV) containing 1 ± 107 cells/ml were vaporized by means of a carbon dioxide laser. The vaporous debris resulting from the laser's impact were evacuated through sterile silastic tubing, then bubbled through sterile culture medium (RPMI) positioned in series with a commercial smoke evacuator. No HIV DNA was detected in the culture medium flask. Tissue culture studies of the silastic collection tubing revealed p24 HIV gag antigen in 3 of 12 tube segments at the end of 1 week and in 1 of 12 tube segments at 2 weeks. No sustained infection of HIV cultured cells was observed at the 28th day. Polymerase chain reaction (PCR) analysis of particulate debris obtained from the silastic collection tubing was positive from proviral HIV DNA in both immediately sampled and day 14 cultured material.
Wavelength dependence of pulsed laser ablation of calcified tissue
Authors: Izatt Joseph A. , Albagli Douglas , Britton Matthew , Jubas Jay M. , Itzkan Irving , Feld Michael S.
Published: March 2007

Pulsed laser ablation of calcified biological tissue was studied at several wavelengths in the near‐ultraviolet, visible, near‐ and mid‐infrared regions of the spectrum. The primary tissue model was bovine shank bone, while human arterial calcified plaque and normal human artery wall were also studied at selected wavelengths for comparison. Laser irradiances were on the order of MW/mm2, fluences ranged up to 1000 mJ/mm2, and repetition rates varied between 0.3–10 Hz. Spot sizes on the tissue surface ranged from 150 to 850 μm. Laser craters made with wavelengths between λ=295 nm and λ=375 nm and in the λ =3 pm region exhibited the highest quality ablation with clean, sharp cuts following closely the spatial contour of the incident beam. Craters drilled with visible wavelengths between λ =450 nm and λ =590 nm were generally larger than the incident laser beam spot, irregular in shape and often surrounded by large flakes of tissue debris. Ablation fluence thresholds increased with wavelength through the visible wavelengths and into the mid‐infrared, but dropped to their lowest values near λ=3 pm. Fluence thresholds obtained with the tissue under a 1 mm depth of saline were approximately twice air thresholds. Ablation yields also varied with wavelength, probably due to increased scattering in the visible region, and were the same under saline as in air.
Excimer laser ablation of fibrocartilage: An in vitro and in vivo study
Authors: Buchelt Martin , Papaioannou Thanassis , Fishbein Mike , Peters Werner , Beeder Clain , Grundfest Warren S.
Published: March 2007

To date, lasers have found only limited applications in orthopedics. We employed a 308 nm XeCl excimer laser for ablation of fibrocartilage, in order to investigate the feasibility of excimer laser assisted meniscectomy.

Experiments were conducted both in vitro and in vivo. For the in vitro study, human menisci, obtained during surgery and autopsy, were irradiated via a 600μm core fiber at radiant exposures ranging between 20 mj/mm2 and 80 mj/mm2, at 20 Hz. Ablation rate measurements and histological analysis of the samples were performed. The ablation rates were found to range from 3 μm/pulse to 100 μm/pulse depending on the radiant exposure and/or the applied pressure on the fiber delivery system. Thermographic analysis was also performed during pulsed excimer as well as CW Nd:Yag and CW Co2 laser irradiation. Temperatures were lower for excimer laser (Tmax <65°) than CW ND:Yag (Tmax <210°) or CW Co2 (Tmax <202°) laser.

For the in vitro study, medial meniscectomy was performed in 15 rabbits with the excimer laser and a CW Nd:Yag laser in the right and left knee respectively. Excimer laser irradiation was performed at 70 mj/mm2. Nd:Yag irradiation was performed via a 600 μm core fiber at power outputs between 20 to 40 W for 10 and 20 seconds duration.

The healing response to injury was investigated by histological analysis of the menisci after 1 day, 1, 2, 4, and 8 weeks following the laser procedure. Excimer laser treated menisci showed less inflammatory reaction and noticeable repair with minimal inflammatory response. Carbonization, induced in the Nd:Yag treated menisci remained up to 8 weeks and only minimal healing was observed. The results suggest that, with the development of an appropriate delivery system, excimer laser ablation may be useful in arthroscopic meniscectomy.
Dependence of subcellular damage on various laser beam parameters
Authors: Oyog Shirley S. , Smith Michael J. , van de Merwe Willem P.
Published: March 2007

A cw argon laser operating at the multiline UV TEM00 mode was used to create lesions in the nucleoli of fibroblast cells. Laser powers emitted through the objective were varied from 5–8 mW and laser pulse durations ranged from 50 to 600 ms. Our study showed lesion diameters ranging from 0.7 μm to 2.9 μm and an average lesion diameter of 1.77 μm. All cells were exposed to at most a laser spotsize of 2.2 μm diameter and for a laser spotsize of this diameter, we calculated that the central 18.3% of the total energy was in the central area of 0.7 μm diameter. We also found that as little as 0.3 mJ of energy could produce a lesion. No absolute threshold correlation was found between the size or type of lesion and the laser parameters used.
Endoscopic palliation of malignancies of the upper gastrointestinal tract using Nd:YAG laser: Results and survival in 308 treated patients
Authors: Spinelli Pasquale , Fante Marco Dal , Mancini Andrea
Published: March 2007

Three hundred eight patients with obstructing malignant tumors of the gastrointestinal tract were submitted to endoscopic Nd:YAG laser palliation. The number of sessions as well as the number of days and total energy required for initial recanalization of the stenosis were related to tumor length. Luminal patency was obtained in 94% of patients, but improved swallowing was achieved in 74% of patients. The technical success rate did not depend on tumor site, whereas functional positive results are related to the location of the stenosis, with worst results for tumors involving the upper third of the esophagus. Life‐table analysis revealed that 1‐year survival was 23% when a luminal patency was achieved and 7%when treatment failed.
Contact Nd:YAG laser potentiates the tumor cell killing effect of hyperthermia
Authors: Castrén‐Persons M. , Schröder T. , Rämö O. J. , Puolakkainen P. , Lehtonen E.
Published: March 2007

This study was carried out to investigate the effects of Nd:YAG laser‐induced hyperthermia on murine F9 embryonal carcinoma cells in vitro using various power settings, temperatures, and exposure times. F9 cells were plated on gelatin‐coated dishes, treated on the following day, and cultured overnight. The following day the killing efficiency of the treatments was estimated by staining the dishes or by labeling the cells with 3H‐thymidine. A contact Nd:YAG laser with a frosted‐end probe was used. After laser treatments at 39°C, no significant changes were observed in the viability of the cells. Laser treatment at 43°C killed F9 cells, and the effect was related to the power setting used. Using 6 W, the quantity of viable cells progressively decreased after 1‐, 2‐, and 5‐min treatments, and no viable cells were found after a 10‐min treatment. Using 10 W, approximately 10% of the cells survived a 1‐min laser treatment, but all cells were killed after a 2‐min treatment. In the control wells, heated in a water bath for up to 40 min, all cells regularly survived at 43°C. There were much less viable cells in those laser‐treated wells where the temperature exceeded 44°C than in those where the temperature was kept at 44°C. In conclusion, the tumoricidic effect of hyperthermia can be potentiated by the use of the contact Nd:YAG laser. At a set temperature the cell killing effect of laser treatment is dependent on the power used and the duration of the treatment. This suggests that laser irradiation effects tumor cells in vitro by a mechanism not solely dependent on heating.
Ultraviolet laser‐induced fluorescence of colonic tissue: Basic biology and diagnostic potential
Authors: Schomacker Kevin T. , Frisoli Joan K. , Compton Carolyn C. , Flotte Thomas J. , Richter James M. , Nishioka Norman S. , Deutsch Thomas F.
Published: March 2007

Laser‐induced fluorescence (LIF) of colonic tissue was examined both in vitro and in vivo to assess the ability of the technique to distinguish neoplastic from hyperplastic and normal tissue and to relate the LIF spectra to specific constituents of the colon. Spectra from 86 normal colonic sites, 35 hyperplastic polyps, 49 adenomatous polyps, and 7 adenocarcinomas were recorded both in vivo and in vitro. With 337‐nm excitation, the fluorescence spectra all had peaks at 390 and 460 nm, believed to arise from collagen and NADH, and a minimum at 425 nm, consistent with absorption attributable to hemoglobin. The spectra of colonic tissue recorded both in vivo and in vitro are different, primarily in the NADH fluorescence component, which decays exponentially with time after resection. When normal colonic tissue is compared to hyperplastic or adenomatous polyps, the predominant changes in the fluorescence spectra are a decrease in collagen fluorescence and a slight increase in hemoglobin reabsorption. A multivariate linear regression (MVLR) analysis was used to distinguish neoplastic tissue from non‐neoplastic tissue with a sensitivity, specificity, predictive value positive, and predictive value negative toward neoplastic tissue of 80%, 92%, 82%, and 91%, respectively. When the MVLR technique was used to distinguish neoplastic polyps from non‐neoplastic polyps, values of 86%, 77%, 86%, and 77% respectively, were obtained. The data suggest that the LIF measurements sense changes in polyp morphology, rather than changes in fluorophores specific to polyps, and it is this change in morphology that leads indirectly to discrimination of polyps.
Nd:YAG laser ablation of the prostate as a treatment for benign prostatic hypertrophy
Authors: Costello Anthony J. , Johnson Douglas E. , Bolton Damien M.
Published: March 2007

Many techniques have been used to relieve obstructive symptoms associated with benign prostatic hypertrophy. Transurethral resection of the prostate (TURP) with an electrocautery loop is the most commonly performed operation to relieve bladder neck and urethral obstruction caused by prostatic adenoma. There is increased interest in alternative therapies to reduce prostatic size for symptom relief in this condition. We describe a technique using the neodymium:YAG (Nd:YAG) laser and a 600‐μm laser quartz fibre with an attached terminal gold‐plated metal alloy reflector to provide reliable deep penetration into prostatic tissue for prostatic adenoma ablation. We report the first use of this technique in three patients with benign prostatic obstruction and one with localised adenocarcinoma of the prostate. © 1992 Wiley‐Liss, Inc.
Preliminary observations of Holmium:YAG laser tissue interaction using human uterus
Authors: Duffy Sean , Davis Mike , Sharp Frank , Stamp John , Ginsberg Robert
Published: March 2007

Preliminary observations of a pulsed HorYAG laser on human uterine tissue in‐vitro are presented. The tissue effect on the uterine myometrium was demonstrated using fresh uteri which had been subjected to laser energy. The laser crater and surrounding zone of thermal necrosis (ZTN) was quantified. Measurements demonstrated a consistent narrow ZTN (0.8–1.8 mm) irrespective of power or pulse frequency used. The percentage forward transmission of laser energy through 1 mm of myometrium was investigated using a pyroelectric detector and found to be 0.41%. Finally, a visible and measurable photoacoustic component to the Ho:YAG laser was demonstrated using a water bath and needle hydrophone. © 1992 Wiley‐Liss, Inc.
Dye‐mediated bactericidal effect of He‐Ne laser irradiation on oral microorganisms
Authors: Okamoto Hayato , Iwase Tatsuo , Morioka Toshio
Published: March 2007

Little attention has been given to the bactericidal effect of laser irradiation, particularly using low‐power energy lasers. It has been demonstrated that He‐Ne laser light has an inhibitory action on dental plaque.

The purpose of this study was to investigate the bactericidal effect of He‐Ne laser irradiation on cariogenic microorganisms. The bactericidal effect was determined by the formation of a growth‐inhibitory zone or by the counting of viable bacterial colonies. Streptococcus sobrinus AHT that is a Gram‐positive microorganism was sensitive to He‐Ne laser light, but Escherichia coli, a Gram‐negative microorganism, was resistant. The effect of several dyes necessary to instigate a bactericidal action was also examined. A growth‐inhibitory zone was observed using 10 kinds of blue, purple, or green dyes, which were mainly phenylmethane dyes. The leakage of potassium from S. sobrinus AHT following laser irradiation was determined using an atomic absorption spectrophotometer. The leakage began to increase following irradiation for 2 min, and reached a plateau following irradiation for 30–60 min.

Moreover, to examine some changes in the dye itself following laser irradiation in the absence of bacteria, ultraviolet‐visible absorption spectra and 1H NMR spectra were recorded.

In this study, it was indicated that the bactericidal effect on cariogenic bacteria by He‐Ne laser irradiation was efficient only in the presence of specific dyes. It is suggested that this laser may be suitable for clinical applications in preventive dentistry. © 1992 Wiley‐Liss, Inc.
Pulsed dye laser treatment of benign cutaneous pigmented lesions
Authors: Tan O. T. , Morelli J. G. , Kurban A. K.
Published: March 2007

Superficial benign cutaneous pigmented lesions that commonly present to the dermatologists and plastic surgeons have been treated by many conventional modalities such as dermabrasion, depigmenting creams as well as several types of lasers. Many of these treatment modalities lack specificity of injury, which has meant that normally pigmented and even non‐pigment containing structures such as collagen as well as the hyperpigmented lesion itself have all been indiscriminately destroyed. This has resulted variously in hypopigmentation, hyperpigmentation, in addition to scar formation in some cases.

A coaxial 504 nm laser with a pulse duration of 300 nsec was used to treat fifty two patients with superficial benign cutaneous pigmented lesions. Although the number of treatments required to clear the lesion varied according to the type of lesions being treated, on average, between 2 and 4 treatments were required to completely eradicate the superficial benign cutaneous pigmented lesions using 504 nm pulsed dye laser. The skin at the site successfully cleared of the pigmented lesion remained normal in skin color, texture, markings, and mobility. © 1992 Wiley‐Liss, Inc.