bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThis 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

AbstractPhotocoagulation 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

AbstractThe 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

AbstractThe 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

AbstractTransurethral 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

AbstractThis 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

AbstractChloro‐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

AbstractNd: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

AbstractIn 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

AbstractEr‐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

AbstractGrowth 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

AbstractLaser 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

AbstractThe 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

AbstractBackground 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

AbstractBackground 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

AbstractBackground 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

AbstractBackground 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.