bluuebunny/crossref_metadata_2025 huggingface dataset:
Ablation of polymethylmethacrylate by Ho:YAG, Nd:YAG, and Erb:YAG lasers
Authors: Buchelt Martin , Kutschera Hans‐Paul , Katterschafka Thomas , Kiss Harald , Lang Susanne
Published: March 2007

Ho:YAG, Nd:YAG, and Erb:YAG laser ablation of Polymethylmethacrylate (PMMA) was investigated under in vitro and simulated clinical conditions. Ablation rates were measured for all lasers and after ablation, macroscopic and microscopic appearance of the ablation site was investigated. The mean ablation rates of the Erb:YAG, Ho:YAG, and Nd:YAG laser increased from 8 μm per pulse at 100 mJ to 44 μm per pulse at 300 mJ from 100 μm per pulse at 200 mJ to 222 μm per pulse at 800 mJ and from 28 μm per pulse at 100 mJ to 189 μm per pulse at 800 mJ, respectively. Macroscopic investigation exhibited melting of bone cement for the Ho:YAG and Nd:YAG lasers and pulse‐to‐pulse vaporization for the Erb:YAG laser. The width of thermal alteration, however, was comparable for all lasers used. Removal of cement from bone specimens under simulated clinical conditions showed good detachment of cement when the fiber was used parallel; in case of perpendicular use, remainders of cement and carbonization of bone could be observed upon histological investigation. © 1993 Wiley‐Liss, Inc.
Selecting source locations in multifiber interstitial laser photocoagulation
Authors: Wyman Douglas R.
Published: March 2007

A theoretical basis and practical algorithm are described for selecting optimal fiber source locations in multifiber interstitial laser photocoagulation (ILP). By analyzing the shape of overlapping coagulation patterns, the optimal separation of adjacent point heat sources inside a flat target volume boundary is shown to be d* = 2√2rc, where rc is the coagulation radius of a single source. Against a curved boundary, the algorithm specifies how d* should be altered. To assess the validity of the theory, ILP was conducted in bovine muscle by delivering 1064 nm laser energy through two or four plane‐cut optical fibers simultaneously. Delivered power, exposure duration, and source separation were varied. The observed coagulation patterns matched the theorypredicted patterns at delivered powers of 1.60W and 1.85W, but not at 2.40W. Also, the experiments indicate that reciprocity of delivered power and exposure duration is invalid for ILP. © 1993 Wiley‐Liss, Inc.
Effect of radiation therapy and Photofrin® on tissue response in a rat model
Authors: Biel Merrill A. , Kim Tae , Trump Michael J.
Published: March 2007

Treatment of advanced carcinomas of the head and neck may benefit from adjuvant photodynamic therapy and brachyradiotherapy. To date, however, there has been no controlled study to evaluate whether high‐dose irradiation can be safely accomplished without major tissue reaction in the presence of high circulating doses of Photofrin, the photosensitizing agent used in photodynamic therapy. Thirty adult male white rats were involved in the study. Fifteen rats received Photofrin 5 mg/kg intravenously, and 15 rats received the same volume of sterile saline intravenously. At 48 hours following injection, each rat received 1,000 cGy of radiation to a 3 × 5 cm area of dorsal skin using a cobalt linear accelerator unit. Skin changes postradiation were observed for degree of erythema, blistering, necrosis, and sloughing. Five rats from the Photofrin and control radiation groups were sacrificed on days 2, 7, and 21 postradiotherapy. Skin changes in each animal were identical with mild erythema lasting from 10–14 days postradiotherapy. There was no evidence of blistering, necrosis, or sloughing of skin in any of the animals studied. Histologic evaluation of the irradiated skin after sacrifice demonstrated no difference between the Photofrin and saline‐irradiated groups. As well, the histologic recovery from acute radiation injury was also identical. This controlled study demonstrates that radiation therapy may be safely administered without increased morbidity when tissue concentrations necessary to perform photodynamic therapy are present. © 1993 Wiley‐Liss, Inc.
Photodynamic therapy for esophageal cancer using a 180° windowed esophageal balloon
Authors: Overholt Bergein F. , Panjehpour Masoud , Denovo Robert C. , Petersen Mark G.
Published: March 2007

Although delivery of uniform circumferential light is desirable during photodynamic therapy of advanced esophageal cancer in humans, early esophageal cancer may need only targeted treatment. Studies were performed in the canine esophagus of eight animals to investigate whether use of a “windowed” (shaded) centering balloon would improve targeted illumination of esophageal mucosa for photodynamic therapy. Shaded balloons were developed with a 2‐cm‐long, 360° or 180° clear “window.” Photofrin 4 mg/Kg was used as the photosensitizer. Light at 630 nm was delivered at 300 J/cm or 600 J/cm. Isotropic probes placed on the balloon wall allowed real‐time measurement and verification of relatively uniform light doses delivered to esophageal mucosa during balloon photodynamic therapy. With the windowed balloon, targeted delivery of photodynamic therapy was possible. Using the 180° balloon, mucosa exposed to illumination was destroyed, whereas mucosa protected from light by the balloon shading was undamaged. Healing was complete and strictures did not occur. The shading of the balloon protected normal mucosa and prevents the formation of esophageal strictures. The “windowed” centering balloon provides a technology and technique that allows targeted delivery of uniform light during esophageal PDT. © 1994 Wiley‐Liss, Inc.
Low intensity laser irradiation inhibits tritiated thymidine incorporation in the hemopoietic cell lines HL‐60 and U937
Authors: O'Kane Sharon , Shields T. Dolores , Gilmore William S. , Allen James M.
Published: March 2007

The purpose of this study was to determine the effect of low intensity laser irradiation (660 nm, 12 mW, 5 kHz) on tritiated thymidine incorporation in two hemopoietic cell lines, HL‐60 and U937. Cells were suspended at a concentration of 1 × 106/ml in their respective serum‐free media and irradiated at energy densities from 1.0 to 11.5 J/cm2. Twenty‐four hours after irradiation the cells were assayed for their ability to incorporate tritiated thymidine (3H‐TdR) in comparison with nonirradiated cells. Analysis by two‐way analysis of variance (ANOVA) for unrelated groups showed that laser irradiation at all energy densities ⩾ 5.8 J/cm produced a significant decrease in 3H‐TdR incorporation (P < 0.05) into HL‐60 cells. In U937 cells, irradiation at energy densities of 5.8, 7.2, and 11.5 J/cm2 caused a similar reduction in 3H‐TdR incorporation (P < 0.01), although not at 8.6 and 9.6 J/cm2. The temperature of each cell suspension was recorded both during and immediately postirradiation, and no significant thermal changes were observed. These findings demonstrate a direct photobiological effect of laser irradiation on these two cell lines. The precise mechanism for this effect is unknown but may have significance in understanding the biological action of laser's known therapeutic effectiveness in promoting wound repair. © 1994 Wiley‐Liss, Inc.
Effect of low intensity laser (830 nm) irradiation on skin temperature and antidromic conduction latencies in the human median nerve: Relevance of radiant exposure
Authors: Lowe Andrea S. , Baxter G. David , Walsh Deirdre M. , Allen James M.
Published: March 2007

The effects of low intensity near‐infrared laser radiation (830 nm; 1.5–12 J/cm2; continuous wave) on peripheral neurophysiology and skin temperature were investigated using antidromic conduction studies in the human median nerve in vivo. Healthy human volunteers (n = 80) were recruited and randomly allocated to one of two control (n = 30) or five laser groups (1.5, 3.0, 6.0, 9.0, and 12 J/cm2; n = 10 per group). Analysis of variance (ANOVA) in negative peak latency difference scores (NPLDs) and skin temperature over a 20 min period post‐irradiation demonstrated a significant decrease in skin temperature following irradiation at the lowest radiant exposure (1.5 J/cm2) coupled with a significant increase in NPLDs (P < 0.05). While no such (significant) changes were found in the other laser groups, it was found that observed changes (increases and decreases) in NPLDs were inversely related to changes in skin temperature. These findings demonstrate measurable peripheral neurophysiological effects of laser radiation concomitant with changes in skin temperature; however, further studies are indicated to establish the precise relationship between the observed effects on skin temperature and nerve Conduction. © 1994 Wiley‐Liss, Inc.
Comparison of the thermal tissue effects produced by aged sapphire and silica hemispherical tips
Authors: Royston David D. , Torres Jorge H. , Thomsen Sharon , Sriram P. S. , Welch Ashley J.
Published: March 2007

This study evaluated the performance of sapphire and fused silica hemispherical tips under the same exposure conditions. Lesions produced in the chicken breast and a blood field were sectioned for light and transmission polarizing microscopy. Lesion size and thermal damage area were recorded as a function of the tips accumulated exposure. The tips transmission was measured after every 1,000 J of exposure. Fused silica tips lasted for ∼5,000 J and experienced significant surface and transmission deterioration. The sapphire hemispherical tips lasted for > 12,000 J with no surface and transmission deterioration. Lesions produced with the fused silica tips generally increased in depth with use, and depths of 6 mm were common. Lesions produced by the sapphire tips were subsurface spherical areas of coagulation with the tissue surface relatively intact. This difference in resulting lesions may be attributed to the higher thermal conductivity of sapphire. © 1994 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Dependence of laser photocoagulation on interstitial delivery parameters
Authors: Wyman Douglas , Wilson Brian , Adams Kathryn
Published: March 2007

Photocoagulation was performed ex vivo between tissue slabs by delivering continuous‐wave laser energy from an optical fiber either directly, or by depositing the energy into a 2.4 mm diameter steel sphere at the fiber tip. The dependence of photocoagulation lesions on the following variables was assessed: (1) energy source: Nd:YAG‐532 nm, 1,064 nm ± steel sphere, (2) tissue type: porcine muscle (light), bovine muscle (dark), (3) delivered power: P = 1.5–3.0 W (porcine), 1.0–2.5 W (bovine), (4) exposure duration: T = 300–1500 s. The resulting cross‐sectional photocoagulation lesions are summarized as follows: 532 nm: elongated; central charring in all cases; 1,064 nm: circular; central charring only in bovine for P ⩾ 2.0 W, T ⩾ 500 s; sphere: circular; central charring in bovine for P ⩾ 1.5 W and porcine for P ⩾ 2.0 W. These experiments suggest photocoagulation lesion size decreases as optical penetration increases. The results indicate that interstitial laser photocoagulation lesions >10 mm diameter can be made without charring in both lightly and heavily pigmented tissues ex vivo by delivering 1,064 nm laser energy at sufficiently low power for at least 1,000 s from well‐polished optical fibers. © 1994 Wiley‐Liss, Inc.
Vasal anastomoses in dogs using contact neodymium: Yttrium aluminum garnet (Nd:YAG) laser
Authors: Cho Yong‐Hyun , Lee Ji Youl , Hahn Hong Gil , Daikuzono Norio , Yoon Moon Soo
Published: March 2007

The purpose of this study is to evaluate the contact NdrYAG laser system for vasal anatomosis in the animal model. Eighteen mongrel dogs were used. In this study, two major groups—control and laser—were defined. In the control group, vas anastomoses were performed with conventional microsurgical technique in six dogs. In the laser group, we performed contact laser assisted vas anatomosis (CLAVA) in 12 dogs by means of a contact Nd: YAG laser with synthetic sapphire probe (ERP4), emitted 2.0 sec pulse duration of minimum 1 watt to maximum 10 watts power. The time needed for completion of the vasal anatomosis in CLAVA group was 2–3 min; in the control group, ∼ 25 min. The patency rate did not differ in these two groups; however, microscopic sperm granuloma formation was 16.7% (2/12) in the control group but 0%(0/12) in the CLAVA group. In conclusion, CLAVA is a fast and simple technique for vasal anatomosis and there were no significant complications, sperm granuloma, or even significant swelling or hematoma in any animal in this experiment. © 1994 Wiley‐Liss, Inc.
Effects of various laser types and beam transmission methods on female organ tissue in the pig: An in vitro study
Authors: Spörri Stefan , Frenz Martin , Altermatt Hans J. , Bratschi Hans U. , Romano Valerio , Forrer Martin , Dreher Ekkehard , Weber Heinz P.
Published: March 2007

The purpose of this in vitro study was to investigate and compare effects of various laser types (CO2, Argon, Erbium:YAG, Erbium: YSGG, and Holmium:YAG) and laser beam transmission methods (optical lens and flexible fiber) on ovarian and uterine tissue of the pig. The Erbium laser radiation was transmitted through Zirconium fluoride fibers (ZrF4). To circumvent the low mechanical stability of these fibers, we developed a special microlens system, which refocuses the radiation and protects the distal end from damage. Tissue lesions were performed with 1 and 5 joule. Histologic analysis of acute Er:YAG laser lesions reveal precise cutting effects with a minimal thermal damage zone of 40 μm and a high damage resistance of the fiber microlens systems. The extent of thermal damage caused by the Erbium:YSGG and CO2laser is about two times larger, whereas the Argon and Holmium laser tissue lesions show a damage of the surrounding tissue of 200–300 μm. This study suggests that for precise cutting and coagulation, Erbium and Holmium lasers transmitted via our modified fiber tip may render the use of these lasers possible in a wide range of laparoscopic surgery applications. © 1994 Wiley‐Liss, Inc.
Pathologic changes following transurethral canine prostatectomy with a cylindrically diffusing fiber
Authors: Cromeens Douglas M. , Price Roger E. , Johnson Douglas E.
Published: March 2007

Transurethral laser prostatectomy was performed on eight mongrel dogs employing a cylindrically diffusing fiber delivery system and a 1.06 μ Nd:YAG laser. Each dog received 15,000 joules of laser energy delivered to the prostate in one continuous dose of 25 watts for 10 minutes. Gross and histopathologic examinations of serial sections of the prostate were performed postoperatively after intervals of 2 hours to 7 weeks. Grossly, a spherical zone of destruction averaging 2.8 cm in diameter was present in dogs except one. Histopathologic changes in the prostate consisted of acute coagulative necrosis with interstitial edema at 2 hours, becoming hemorrhagic by 24 hours. A prominent circular area of acute coagulative necrosis with progressively larger areas of liquefaction and hemorrhage was present in prostates harvested from 4 days to 1 week after lasing. Initial re‐epithelization of the resulting cavity was observed at 3 weeks with nearly complete epithelialization 7 weeks after laser treatment. The simplified fiber placement and lack of postoperative complications in this small group of dogs suggest that the cylindrically diffusing fiber could offer significant advantages over laterally deflecting fibers for transurethral prostatectomies in the dog model. © 1994 Wiley‐Liss, inc.
Optical properties of human aorta: Are they affected by cryopreservation?
Authors: Çilesiz Inci F. , Welch A. J.
Published: March 2007

This study was undertaken to investigate the effects of freezing upon the in vitro optical properties of human aorta from 300 nm to 800 nm. Freezing significantly decreased absorption coefficient over most of the spectrum from 300 nm to 800 nm. The only significant changes in the reduced scattering coefficient were from 300 nm to 335 nm. © 1994 wiley‐Liss, Inc.
Retinal and choroidal vessel closure using phthalocyanine photodynamic therapy
Authors: Kliman Gilbert H. , Puliafito Carmen A. , Grossman Gayle A. , Gregory William A.
Published: March 2007

Chloro‐aluminum sulfonated phthalocyanine (CASPc) is a photoactive dye capable of generating photochemical reactions when excited with 675 nm light. We used CASPc to produce photochemical closure of retinal medullary ray vessels and choroidal vessels in normal rabbits. Irradiation prior to CASPc injection produced no photographic, angiographic, or histologic lesions in any eyes. Identical irradiation of medullary ray and choroidal vessels after CASPc injection produced complete vessel closure in all eyes. Histopathologic examination showed marked thrombosis of medullary ray and choroidal vessels, with minimal damage to contiguous tissues including the neurosensory retina. We conclude that CASPc can produce profound closure of normal retinal and choroidal vessels with minimal deleterious effect on surrounding tissues. © 1994 Wiley‐Liss, Inc.
Mechanisms of intraocular photodisruption with picosecond and nanosecond laser pulses
Authors: Vogel Alfred , Busch Stefan , Jungnickel Kerstin , Birngruber Reginald
Published: March 2007

Nd:YAG laser photodisruption with nanosecond (ns) pulses is an established method for intraocular surgery. In order to assess whether an increased precision can be achieved by the use of picosecond (ps) pulses, the plasma size, the shock wave characteristics, and the cavitation bubble expansion after optical breakdown with ps‐ and ns‐laser pulses were investigated by time‐resolved photography and acoustic measurements. Nd:YAG laser pulses with a duration of 30 ps and 6 ns, respectively, were focused into a water‐filled glass cuvette. Frequency doubled light from the same laser pulses was optically delayed between 2 ns and 136 ns and used as illumination light source for photography. Since the individual events were well reproducible, the shock wave and bubble wall position could be determined as a function of time. From the slope of these r(t) curves, the shock wave and bubble wall velocities were determined, and the shock wave pressure was calculated from the shock velocity. The plasma size at various laser pulse energies was measured from photographs of the plasma radiation. The breakdown thresholds at 30 ps and 6 ns pulse duration were found to be 15 μJ and 200 μJ, respectively. At threshold, ps‐plasmas are shorter than ns‐plasmas, but at the same pulse energy they are always ∼2.5 times longer. The initial shock pressures were 17 kbar after ps‐pulses with an energy of 50 μJ, and 21 kbar after 1 mJ ns‐pulses. The pressure amplitude decayed much faster after the ps‐pulses. The maximum expansion velocity of the cavitation bubble was 350 m/s after a 50 μJ ps‐pulse, but 1,600 m/s after a 1 mJ ns‐pulse. The side effects of intraocular microsurgery associated with shock wave emission and cavitation bubble expansion can be considerably reduced by the use of ps‐pulses, and new applications of photodisruption may become possible. © 1994 Wiley‐Liss, Inc.
Dynamic reflectometer for control of laser photocoagulation on the retina
Authors: Inderfurth Jörg H. C. , Ferguson R. Daniel , Frish Michael B. , Birngruber Reginald
Published: March 2007

In retinal laser photocoagulation, constant exposure parameters do not result in identical lesions. This lack of reproducibility increases the rate of complications from over‐or undertreatment and inhibits determination of the optimal treatment endpoints for different retinal disorders. To this end, a feedback‐controlled photocoagulator could make retinal photocoagulation a safer, more reproducible, and faster procedure. A dynamic confocal reflectometer was integrated into a slit lamp laser delivery system. Real‐time reflectance changes on the retinas of pigmented rabbits were obtained by monitoring the increasing back‐scattered light of the coagulating beam during argon laser photocoagulation. Reproducible temporal reflectance patterns were measured that correlated with ophthalmoscopically assessed lesion intensity independent of the exposure parameters, the transparency of the optical media, and the focusing conditions. As a step toward the development of a feedback‐controlled photocoagulator, the confocal reflectometer has been proven in animal trials closely resembling clinical practice. © 1994 Wiley‐Liss, Inc.
Erbium‐YAG and holmium‐YAG laser ablation of the lens
Authors: Ross Bonnie S. , Puliafito Carmen A.
Published: March 2007

Er‐YAG (2.9 μm, 200 JJLS pulsewidth) and Ho‐YAG (2.12 μm, 250 μS pulsewidth) lasers were used to irradiate bovine crystalline lenses. Mass ablated increased with increasing fluence for both lasers and was greater for the Er‐YAG than the Ho‐YAG laser at all fluences. The mass loss vs. fluence curve was nonlinear for the Er‐YAG and linear for the Ho‐YAG laser. Ablation threshold was lower for the Er‐YAG. Grossly, the Er‐YAG laser produced less charring and expressed fewer, smaller tissue pieces than the Ho‐YAG. Scanning electron microscopy indicated that the Er‐YAG produced smoother walled craters. The Ho‐YAG laser produced more dessicated and disrupted craters. The Er‐YAG radiation, delivered by fiberoptic probes, may provide a method of performing minimally invasive cataract surgery. © 1994 Wiley‐Liss, Inc.
Expression of growth factors in early wound healing in rat skin
Authors: Yu Wei , Nairn John O. , Lanzafame Raymond J.
Published: March 2007

Growth factors are a group of hormone‐like polypeptides that have been shown to play a central role in different phases of wound healing. The expression of these growth factors in early wound healing has not been quantified, and the pattern and distribution of these growth factors in early wound healing has not been described completely. Furthermore the quantity and pattern of distribution of these growth factors have not been investigated in early wounds produced by various methods of surgical incision. Comparison of the rate of healing between the CO2 laser wound and the scalpel wound has produced conflicting results. The present immunohistochemical study uses polyclonal antibodies specific for epidermal growth factor (EGF), platelet‐derived growth factor (PDGF), transforming growth factor p (TGF‐β), and basic fibroblast growth factor (bFGF) to observe the pattern and distribution of these growth factors in rat skin wound and elucidate whether there are differences in the expression of these growth factors which might account for the delayed healing of the CO2 laser wounds compared to the scalpel as has been observed by some authors. Our results indicate that EGF, TGF‐β, PDGF, and bFGF are expressed and distributed in same areas of the early skin wound. The area of expression of these growth factors was associated with presence of wound inflammatory cells and wound fibroblasts. Our study found that there were no significant differences in the expression of growth factors in the majority of time points between the CO2 laser wounds and the scalpel wounds. © 1994 wiley‐Liss, Inc.
Cardiovascular applications of laser technology
Authors: Deckelbaum Lawrence I.
Published: March 2007

Laser technology has been evaluated for the treatment of coronary artery disease, ventricular and supraventricular arrythmias, hypertrophic cardiomyopathy, and congenital heart disease. Developments in laser angioplasty, laser thrombolysis, transmyocardial laser revascularization, photochemotherapy, laser treatment of arrythymias and/or laser diagnostics are directed at improving upon conventional non‐laser approaches, and providing new therapeutic and diagnostic options. This review will summarize the current status of the multiple applications of laser technology for cardiovascular diagnosis and therapy. © 1994 Wiley‐Liss, Inc.
Clinical uses of lasers in dermatology
Authors: Wheeland Ronald G.
Published: March 2007

The accessibility of the skin to examination and study has permitted dermatologists to play an extremely important role in defining the clinical usefulness and limitations of many laser systems as well as developing innovative concepts, techniques and devices that further improved the effectiveness of laser treatment. As new laser technology evolved over the years, dermatologists have also helped define the specificity of laser‐tissue interaction and employed the newly developed laser technologies in innovative ways which further expanded the usefulness of these devices. One of the most important concepts to be developed by dermatologists‐selective photothermolysis—has led to the creation of a series of laser systems which have provided numerous unique advantages in the management of many common vascular and pigmented conditions of the skin and mucous membranes, even in infants and children. The net result of these technologic advances has been the creation of new and effective treatment techniques which have been so profoundly superior to existing technology that they have been rapidly incorporated into the daily practice of most dermatologists. © 1995 Wiley‐Liss, Inc.
Plastic hollow waveguides: Properties and possibilities as a flexible radiation delivery system for CO2‐laser radiation
Authors: Cossmann Peter H. , Romano Valerio , Spörri Stefan , Altermatt Hans Jörg , Croitoru Nathan , Frenz Martin , Weber Heinz P.
Published: March 2007

Background and Objectives: One significant inconvenience of the CO2 laser is the lack of flexible fibers essential for endoscopic applications. The goal of this study is to test the feasibility of hollow waveguides in view of a practical use in medicine.

Study Design/Materials and Methods: Various types of plastic hollow waveguides for flexible delivery of CO2 laser radiation were examined. The transmission losses, divergence angle, damage threshold, and input and output beam profiles were determined. The interaction process between radiation transmitted through these guides with soft as well as hard tissues was studied.

Results: Plastic hollow waveguides can transmit high power (up to 50 W) with low losses (straight guide 1 dB/m) even through bendings. The divergence angle is < 13°. Cutting quality and extent of thermal damage are comparable to incisions performed with a free laser beam.

Conclusion: The results of this study show good cutting quality and durability of these flexible plastic hollow waveguides, which render possible to deliver CO2 radiation in the power range needed for most surgical applications with affordable transmission losses. Plastic hollow waveguides are, therefore, a real alternative to replace the mirror arms. © 1995 Wiley‐Liss, Inc.
Wavelengths for laser treatment of port wine stains and telangiectasia
Authors: Van Gemert Martin J. C. , Welch A. J. , Pickering John W. , Tan Oon Tian , Gijsbers Geert H. M.
Published: March 2007

Background and Objective: This report presents analytical modelling of the influence of wavelength on the amount of volumetric rate of heat produced in dermal blood vessels by millisecond laser radiation.

Study design/Materials and Methods: A new anatomical model is proposed that represents port wine stains as well as telangiectatic lesions. It consists of a target blood vessel, representing the deepest dermal blood vessel that requires irreversible injury, and a layer of whole blood, representing all other dermal blood vessels above the target vessel. The laser light that interacts with the blood vessels is assumed to be diffuse. Selective photothermolysis is the basis for the analysis. We consider wavelengths between 577 nm and 600 nm, the argon laser wavelengths at 488/515 nm, and the frequency doubled Nd:YAG laser wavelength at 532 nm.

Results: The rate of volumetric heat production of absorbed laser light in the target blood vessel is expressed analytically as a function of blood absorption, the concentration of additional dermal blood, and the depth of the target vessel.

Conclusion: The model explains why 585 nm is a good compromise for treating port wine stains that vary widely in number of dermal blood vessels. It predicts that wavelengths between 577 nm and 582 nm are excellent for the treatment of port wine stains in young children, and it suggests a possible explanation as to why the argon laser is sometimes said to be capable of treating dark mature port wine stains. The copper vapour laser wavelenght at 578 nm, and the frequency doubled Nd:YAG laser wavelength at 532 nm, are predicted to be suitable for the treatment of port wine stains that contain, respectively, a small to moderate and a moderate number of dermal blood vessels. When laser beam spotsize becomes smaller, the best wavelength for producing maximal rate of heat in the target vessel is predicted to shift to 577 nm. © 1995 Wiley‐Liss, Inc.
Intravasular ultrasound can be used to evaluate pulsed laser ablation of arterial tissue
Authors: Friedl Stephan E. , Mathews Eric D. , Miyamoto Akira , Abela George S.
Published: March 2007

Background and Objective: Intravascular ultrasound (IVUS) has been used successfully to detect intravascular lesions. This study evaluates the ability of IVUS to detect acoustic damage to the arterial wall following high power, pulsed laser ablation.

Study Design/Materials and Methods: Arterial ablation and disruption were performed in necropsy bovine aorta with a Ho:YAG laser using energy ranging from 140–720 mJ/pulse at 5 Hz. Laser energy was delivered with 2 mm diameter, multifiber over‐the‐wire catheters. A 20‐MHz IVUS catheter was used to image the arterial damage prior to tissue fixation and morphometry.

Results: IVUS images revealed ablation craters surrounded by high acoustically backscattering zones. By histology, the arteries revealed ablation craters lined with thermal coagulation surrounded by a region of dissection and vacuolization. The depth and width of the highly backscattering zones on IVUS images correlated strongly with the corresponding morphometric measurements of tissue dissection (r = 0.92, P = 0.0001 and r = 0.80, P = 0.0001, respectively). Morphometric measurements of the ablation crater depth correlated strongly with laser energy (r = 0.90, P= 0.0001), whereas crater width was not correlated with laser energy (r = 0.27, P = 0.09).

Conclusion: This study demonstrates that IVUS can detect and measure the extent of arterial damage following pulsed laser ablation. This may provide a means of detecting the extent of tissue disruption and help develop approaches to reduce or prevent extensive tissue damage. © 1995 Wiley‐Liss, Inc.
Lifetime testing of sapphire and sculpted silica fiber scalpels
Authors: Royston David D. , Torres Jorge H. , Thomsen Sharon , Sriram P. S. , Welch Ashley J.
Published: March 2007

Background and Objective: Sapphire and sculpted silica fiber scalpels were evaluated for performance as they aged. Performance was determined by measuring their useful lifetime, forward transmission, incision depth, and the thermal coagulation thickness at the sides and bottom of the incision.

Study Design/Materials, and Methods: Aging was performed with a chicken breast model. Performance measurements were made at periodic intervals. Sapphire scalpels were cooled with air or saline.

Results: The air‐cooled, frosted sapphire scalpels had the longest useful lifetime, whereas the saline‐cooled, frosted sapphire scalpels had the shortest. Aging deteriorated the forward transmission of the sculpted silica fiber scalpels the most. Little difference was found between the averages of all incision measurements. Two of the saline‐cooled, frosted sapphire scalpels fractured during the aging process.

Conclusion: Aging influences the scalpel lifetime, but there was no evidence that the aging process significantly affected the incision size. © 1995 Wiley‐Liss, Inc.
Lethal photosensitisation of Staphylococcus aureus in vitro: Effect of growth phase, serum, and pre‐irradiation time
Authors: Wilson Michael , Pratten Jonathan
Published: March 2007

Background and objective: Staphylococcus aureus can be killed by low‐power laser light in the presence of aluminium disulphonated phthalocyanine (AIPcS2). The purpose of this study was to determine the effect of pre‐irradiation time (PIT), the presence of serum, and the physiological state of the organism on the kills achieved.

Study Design/Materials and Methods: To determine the effect of PIT on killing, suspension of methicillin‐resistant S. aureus (MRSA) were incubated in the dark with 12.5 μg/ml of AIPcS2 for 60 s or 300 s, and survivors were enumerated after exposure to 1.2 J of light from an 11‐mW gallium aluminium arsenide laser. The susceptibility of MRSA in its various growth phases was determined in a similar manner using a PIT of 300 s. The effect of serum on killing was determined using stationary phase cells resuspended in horse serum.

Results: Using a PIT of either 60 s or 300 s, 106 cfu (99.9%) of MRSA were killed. There was little difference in the susceptibility of lag‐, logarithmic‐, or stationary‐phase cells, the kills being 99.9%, 99.8%, and 99.9%, respectively. Although kills were reduced in the presence of serum, 99.6% of MRSA were killed using a light dose of 1.2 J.

Conclusion: These results demonstrate that MRSA can be rapidly sensitised by AIPcS2 to killing by low‐power laser light, that killing is not dependent on the organism's growth phase, and that substantial kills can be achieved in the presence of serum. © 1995 Wiley‐Liss, Inc.
Thermal effects of CO2 laser on the pulpal chamber and enamel of human primary teeth: An in vitro investigation
Authors: Arrastia Anna Marie A. , Wilder‐Smith Petra , Berns Michael W.
Published: March 2007

Background and Objective: Thermal effects of direct exposure of the pulp chamber to CO2 laser irradiation were evaluated and potentially safe parameters for its clinical application were determined.

Study Design/Meterials and Methods: Using conventional methods, the pulp chambers of freshly extracted primary cuspids were exposed and then subjected to CO2 laser irradiation at the following parameters: 2, 4, 6, 8, 10, 15, and 20 Watts power settings; 0.76 mm diameter spot size; total energy densities between 4–1,058 J/cm2; exposure time between.01–60 s. Exposures in the continuous wave mode were performed in some specimens. In others, single firings of a.01 s pulse duration and a 1 s pulse interval were conducted. Temperature measurements were conducted using a thermocouple and thermal camera.

Results: Significant statistical differences in maximum temperature rise on enamel were observed in groups that received total energy densities ≥ 8 J/cm2 (P ≤ 0.01); within the pulp chambers these were observed in groups that used ≥ 44 J/cm2 (P ≤ 0.01).

Conclusion: Parameters appropriate for pulpotomy were observed at energy densities up to 176 J/cm2 in the continuous wave mode and 264 J/cm2 using single pulses, wherein temperature rises below 5.5°C were recorded on tooth surface. © 1995 Wiley‐Liss, Inc.
Alteration of pulse configuration affects the pain response during diode laser photocoagulation
Authors: Friberg Thomas R. , Venkatesh Md S.
Published: March 2007

Background and Objective: The shape of the treatment pulse of the diode laser (810 nm) can be easily altered electronically in contrast to ion laser photocoagulators. We investigated whether changes in laser pulse shape influenced the subjective pain response in patients undergoing retinal photocoagulation when only topical anesthesia was used.

Study Design/Materials and Methods: Twenty consecutive patients required peripheral retinal photocoagulation for proliferative diabetic retinopathy or extensive retinal breaks. Three diode pulse waveforms including a square wave, shaped‐wave, and an envelope of micropulses were compared to one another. Power was adjusted so that each waveform delivered the same total energy. The patients subjectively ranked the intensity of any pain they experienced for each group of lesions. Responses were compared to one another using an analysis of variance.

Results: 40% of patients found the standard square wave pulse to be significantly more painful (P < 0.05) than the shaped pulse mode and 30% found the square wave significantly more painful (P < 0.05) than the micropulse mode.

Conclusion: Modification of the laser pulse waveform may ameliorate pain induced by diode laser photocoagulation of the retinal periphery. © 1995 Wiley‐Liss, Inc.
Dynamics of ablation plume particles generated during excimer laser corneal ablation
Authors: Hahn D. W. , Ediger M. N. , Pettit G. H.
Published: March 2007

Background and Objective: Although the empirical characteristics of ArF excimer laser corneal ablation have been well documented, the exact ablation mechanisms are not well understood. The present paper reports a quantitative analysis of corneal ablation plumes using in situ time resolved laser light scattering and Raman spectroscopy.

Study Design/Materials and Methods: Bovine corneas were used as the ArF excimer laser ablation targets. Light scattering data were recorded from the ablation plume as a function of height above the tissue surface and as function of delay time with respect to the ablative ArF laser pulse.

Results: Raman spectra of the ablation plume allow identification of the particles as water. Mean plume particle diameters are found to decrease with height, while the particle volume fractions are relatively constant. The total volume of plume particles correlates well with the total volume of water in the ablated corneal tissue.

Conclusion: The finding of a non‐evolving plume composed of water spherules, combined with the excellent agreement between total volume of water in the plume and the content of water in the ablated corneal tissue, support the concept of photodecomposition or “cold ablation” for corneal tissue during ArF excimer laser ablation. © 1995 Wiley‐Liss, Inc.
Ultrastructural alterations in heated canine myocardium
Authors: Bosman Saskia , Pickering John W. , Van Marle Jan , Van Gemert Martin J. C.
Published: March 2007

Background and Objective: The anisotropy factor of light scattering (g) (wavelength 632.8 nm) in heated myocardium decreases as a function of temperature, suggesting, on the basis of Mie theory of light scattering, formation of an increasing number of particles with diameters smaller than the incident wavelength. Study Design/Materials and Methods: To test this hypothesis, fresh myocardium was heated at constant temperatures between 37°C and 75°C for 1,000 s. Changes in size and number of granules generated by disintegrating organelles and sarcomeres were studied as a function of temperature by transmission electron microscopy, planimetry and particle counting.

Results: The mitochondria started to disintegrate at 45°C and myofibrils between 45°C and 50°C into increasing numbers of small electron dense granules (diameter 50–200 nm), which correlated with the observed decrease of g from 0.93 ± 0.02 (at room temperature to 45°C) to 0.77 ± 0.05 at 75°C.

Conclusion: The scattering coefficient μs of 161 ± 33 cm−1 did not change significantly. © 1995 Wiley‐Liss, Inc.
Antioxidants reduce corneal light scattering after excimer keratectomy in rabbits
Authors: Jain Sandeep , Hahn Tae‐Won , McCally Russell L. , Azar Dimitri T.
Published: March 2007

Background and Objective: Excimer laser‐corneal tissue interaction liberates highly reactive free radicals. Our aim was to determine if intraoperative application of antioxidants reduces the postoperative corneal light scattering by minimizing free radical‐mediated cellular injury.

Study design/materials and methods: Phototherapeutic keratectomy (PTK) was performed in 20 rabbit eyes. Following 40‐μm epithelial ablation, rabbits were divided into two groups and received 1‐minute intraoperative application of either 50% dimethyl sulfoxide and 1% superoxide dismutase or vehicle (balanced salt solution) only. This was followed by a 6‐mm diameter 100‐μm PTK. Corneal light scattering was measured for 18 weeks using scatterometry. A light scattering index (SI) ranging from 0–10 was calculated;SI = 1 represents normal scattering. Light microscopic examination was performed in selected corneas.

Results: The mean baseline SI was similar for both groups (P‐= 0.95). Corneal haze followed a pattern of gradually increasing to peak at 2–3 weeks, and regressing partially thereafter. The decrease in mean SI following antioxidant application (dimethyl sulfoxide and superoxide dismutase) as compared to control group approached significance at 3 weeks (0.1 > P > 0.05) and was highly significant at 9 weeks (P < 0.05).

Conclusion: Intraoperative application of antioxidants decreases light scattering following excimer keratectomy in rabbit corneas. UV‐induced free radicals may play a role in the pathogenesis of corneal light scattering following excimer laser keratectomy.
Photodynamic laser cyclodestruction with chloroaluminum sulfonated Phthalocyanine (CASPc) or photofrin®(PII) Vs. Nd:YAG laser cyclodestruction in a pigmented rabbit model
Authors: Hill Richard A. , Esterowitz Terri , Ryan Julie , Liaw Lih‐Huei L. , Nelson J. Stuart , Yashiro Hideko , Krasieva Tatiana , Berns Michael W.
Published: March 2007

Background and Objective: To investigate Photofrin® (PII) and CASPc for photodynamic therapy (PDT) of the ciliary body in rabbits.

Study Design/Materials and Methods: PII (10 mg/kg) or CASPc (1 mg/kg) was given by ear vein. Pharmacokinetics were studied in frozen sections by fluorescence microscopy (CCD camera based low light detection system with digital image processing) at 1 and 24 h (8 rabbits;16 eyes). Laser light was delivered (argon pumped dye laser;630 and 675 nm;8 rabbits;16 eyes) by contact fiberoptic. To compensate for iris attenuation, irradiance was 125 mW/cm2 (20, 40, 80, or 160 J/cm2). Controls (4 rabbits;8 eyes) received laser light without photochemicals (OD) and for comparison, continuous wave Nd:YAG laser by fiberoptic (0.8–1.2J;OS).

Results: Localization studies showed intravascular distribution with some selective ciliary body distribution at 24 h (PII > CASPc). Rabbits treated with PII or CASPc exhibited variable amounts of gross ciliary body edema, infarction, and necrosis by 24–48 h. This response was not seen in PDT control tissues;damage was seen in the iris and ciliary body, with partial vacuolization of the pigment epithelium.

Conclusion: PDT may offer a more selective approach to ciliary body destruction. A small but significant thermal effect was seen during PDT from melanin photon uptake with damage to iris and ciliary body. Thermal damage and potential interaction with ocular visual pigments may limit use of these photochemicals and wavelengths for PDT of the ciliary body © 1995 Wiley‐Liss, Inc.
In vivo uptake of liposomal benzoporphyrin derivative and photothrombosis in experimental corneal neovascularization
Authors: Schmidt‐Erfurth Ursula , Hasan Tayyaba , Schomacker Kevin , Flotte Thomas , Birngruber Reginald
Published: March 2007

Background and Objective: Photodynamic therapy (PDT) has been used successfully to occlude neovascularizations experimentally. We evaluated the vasoocclusive potential of benzoporphyrin derivative (BPD), a new photosensitizer currently in clinical trials. Since liposomally formulated BPD strongly binds to endogenous low density lipoproteins (LDL) after i.v. injection, LDL act as carrier to deliver BPD preferentially to proliferating endothelial cells.

Study Design/Materials and Methods: Corneal neovascularizations in rabbits were used as model. Time‐dependent uptake and retention of liposomal BPD were measured in vivo by monitoring the laser‐induced fluorescence (LIF). Photothrombosis was induced using a dye laser emitting at 692 nm.

Results: A maximal BPD concentration was measured at 60–90 minutes postinjection determining the optimal time interval for treatment. Exposures as low as 10 J/cm2 allowed complete and irreversible neovascular occlusion as documented angiographically. Histology revealed selective endothelial damage, adjacent corneal stroma, or iris vessels, remained intact. Identical results were obtained using BPD directly complexed with LDL suggesting use of a LDL‐mediated pathway.

Conclusion: We suggest BPD‐PDT for a selective treatment of neovascular diseases. © 1995 Wiley‐Liss, Inc.
Reduced in vivo local recurrence with contact neodymium: Yttrium‐aluminium‐garnet (Nd:YAG) laser scalpels
Authors: Maker Vijay K. , Elseth Kim M. , Radosevich James A.
Published: March 2007

Background and Objective: Local recurrence after surgical resection for breast cancer is a significant problem and is often not controlled by radiation or chemotherapy treatments. Local recurrence is thought to be, at least in part, due to residual disease, and/or due to the contamination of the surgical field during resection.

Study Design Materials and Methods: To address this later concern, we defined a model system using the mouse mammary cell line, EMT6. Using this model system, we have directly compared the rate of local recurrence of two different surgical approaches. One approach employed the use of traditional surgical instruments, and the other used a comparatively new contact Nd:YAG laser system. Tumor‐bearing animals (242) were randomized into three groups. One group consisted of 50 animals that were not treated; 103 animals were randomized into a treatment group that received surgical resection using traditional instruments; 89 annuals were resected using the contact laser system. In both surgical procedures, an intentional incision was made through the tumor and then through an uninvolved portion of the surgical field in an attempt to “seed” the incision using the contaminated surgical instrument.

Results: Twenty‐one of the 103 scalpel‐treated animals had local recurrence; only seven of the 89 laser‐treated animal had local recurrence. The untreated group died of disease within 8 weeks. In the treatment groups, recurrences were palpable within 1 week. At the time of death for all groups, no metastatic lesions were noted.

Conclusion: These findings support the conclusions that the EMT6 cell line is a useful model to study local recurrence and that contact laser surgery provides about a 50% improvement in the control of local disease in vivo (P<0.05). © 1995 Wiley‐Liss, Inc.
Influence of self‐perceived incontinence severity on quality of life and sexual function in women with urinary incontinence
Authors: Paick Jae‐Seung , Cho Min Chul , Oh Seung‐June , Kim Soo Woong , Ku Ja Hyeon
Published: March 2007

Aims

We examined the impact of patient‐perceived incontinence severity (PPIS) on health‐related quality of life (QoL) and sexual function in women with urinary incontinence (UI).

Methods

Patients were recruited from clinic practices at one hospital. Between May 2004 and June 2006, 353 women 27–79 years old (mean 55.7) underwent detailed evaluations. To obtain health‐related QoL and sexual function assessments, the patients were asked to fill the questionnaires including the incontinence quality of life (I‐QoL) and female sexual function index (FSFI). Patients were categorized into the three groups according to the PPIS; ‘mild,’ ‘moderate,’ and ‘severe.’

Results

Among groups, the duration of symptoms, rate of mixed UI, mean number of treatment visits over the past year, rate of UI associated without any activity, and Valsalva leak point pressure (VLPP) was significantly different (P < 0.05). The I‐QoL total score and subscale scores deteriorated significantly as the PPIS increased (P < 0.001). Of the six domains in the FSFI questionnaire, four domains, namely, ‘arousal’ (P = 0.026), ‘lubrication’ (P = 0.012), ‘orgasm’ (P = 0.017), and ‘pain’ (P = 0.037) as well as the FSFI total score (P = 0.004) were significantly different among the groups.

Conclusions

Our findings suggest that PPIS significantly influences health‐related QoL and sexual function, and that strategies for assessing PPIS should be incorporated for assessing patients with UI. Neurourol. Urodynam. 26:828–835, 2007. © 2007 Wiley‐Liss, Inc.