bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of laser ablation in an absorbing fluid field
Authors: Isner Jeffrey M. , Dejesus Steven R. , Clarke Richard H. , Gal Dov , Rongione Anthony J. , Donaldson Roberta F. 
Published: March 2007

AbstractSelection of a laser source for intravascular applications has frequently been predicated upon assumptions involving transmissability in blood of the wavelength of light emitted by a given laser. Standard absorption curves for ultraviolet radiation in blood and infrared radiation in water would suggest that transmission of ultraviolet radiation through a blood field and infrared radiation through any aqueous fluid field would be insufficient for tissue ablation. The present series of experiments was undertaken to determine whether these theoretical predictions would in fact obviate the use of these wavelengths in a blood field. Specimens of normal human myocardium and/or polyvinylchloride were submerged under blood and water and irradiated with ultraviolet radiation (351 nm) delivered as a focused beam and via an optical fiber and infrared radiation (10,600 nm) delivered as a focused beam. Ablation of myocardium was successfully accomplished with a focused beam of both ultraviolet and infrared radiation under as much as 5 mm of blood and with ultraviolet radiation via an optical fiber with the fiber tip up to 3 mm distant from the tissue specimen. High‐speed cine recordings of ablation carried out using a focused beam of laser radiation demonstrated that formation of a dynamic optical cavity is the basis for successful pulsed ultraviolet and infrared laser transanguineous tissue ablation. These results thus demonstrate that prediction of wavelength transmission through fluid media based on optical properties of a static fluid does not predict ability to accomplish ablation under dynamic circumstances of laser irradiation.
Comparison of wound healing between chopped mode‐superpulse mode CO2 laser and steel knife incision
Authors: Ben‐Baruch Gilad , Fidler James P. , Wessler Terry , Bendick Phillip , Schellhas Helmut F. 
Published: March 2007

AbstractThe healing of surgical incisions made with the steel knife and CO2 laser chopped wave mode (ChW) or rapid superpulse (RSP) mode were compared using histologic parameters and breaking strength of the scars on postoperative day 14. Using a miniature pig model the Sharplan 1100 laser incisions were made with an average power of 15 W and power density of 7.68 kW/cm2. Histological sections on postoperative day 14 revealed the knife scar measured .49 mm, was hypocellular, and contained visible bundles of collagen fibers. Both CO2 laser scars were less mature, the ChW scar measured 1.04 mm, the RSP scar measured 1.37 mm, and both contained cellular granulation tissue without visible collagen fibers. The breaking strength of the scars was measured with a tensiometer. Laser wounds were weaker than the knife wound. Scheffe test for variables was significant at P = .01 between the two laser modes and the knife. No significant difference was noted in the breaking strengths of incisions made with the chopped mode and superpulse mode.
Laser‐assisted vasovasostomy
Authors: Gilbert Peter T. O. , Beckert Rainer 
Published: March 2007

AbstractTo find a less time‐consuming alternative to conventional microsurgical vasovasostomy, we performed vasal anastomosis in four sterilized men by means of a Nd:YAG laser (wavelength 1,060 nm) under macroscopic conditions. After dissection of the vasal ends, the ends were approximated using 6‐0 prolene sutures as intervasal stents. The apposed tissue edges were welded by laser pulses of 0.5 sec in duration and 10 W in power. Postoperative sperm counts proved normal in two patients; one of them reported a successful pregnancy in his wife 12 months after vasovasostomy. One patient had cryptospermia and one patient oligoasthenospermia. Laser‐assisted vasovasostomy is a simple procedure and shortens the operative time. More patients still need to be studied to allow a favorable comparison with conventional suture techniques.
Effect of helium‐neon and infrared laser irradiation on wound healing in rabbits
Authors: Braverman Berton , McCarthy Robert J. , Ivankovich Anthony D. , Forde Danon E. , Overfield Michael , Bapna Mahapna S. 
Published: March 2007

AbstractWe examined the biostimulating effects of helium‐neon laser radiation (HeNe; 632.8 nm), pulsed infrared laser radiation (IR; 904 nm), and the two combined on skin wound healing in New Zealand white rabbits. Seventy‐two rabbits received either (1) no exposure, (2) 1.65 J/cm2 HeNe, (3) 8.25 J/cm2 pulsed IR, or (4) both HeNe and IR together to one of two dorsal full‐thickness skin wounds, daily, for 21 days. Wound areas were measured photographically at periodic intervals. Tissue samples were analyzed for tensile strength, and histology was done to measure epidermal thickness and cross‐sectional collagen area. Significant differences were found in the tensile strength of all laser‐treated groups (both the irradiated and nonirradiated lesion) compared to group 1. No differences were found in the rate of wound healing or collagen area. Epidermal growth was greater in the HeNe‐lased area compared to unexposed tissue, but the difference was not significant. Thus, laser irradiation at 632.8 nm and 904 nm alone or in combination increased tensile strength during wound healing and may have released tissue factors into the systemic circulation that increased tensile strength on the opposite side as well.
Effect of semiconductor GaAs laser irradiation on pain perception in mice
Authors: Žarković Neven , Manev Hari , Peričić Danka , Skala Karolj , Jurin Mislav , Peršin Anton , Kubović Milan 
Published: March 2007

AbstractThe influence of subacute exposure (11 exposures within 16 days) of mice to the low power (GaAs) semiconductive laser‐stimulated irradiation on pain perception was investigated. The pain perception was determined by the latency of foot‐licking or jumping from the surface of a 53°C hot plate.Repeated hot‐plate testing resulted in shortening of latencies in both sham‐ and laser‐irradiated mice. Laser treatment (wavelength, 905 nm; frequency, 256 Hz; irradiation time, 50 sec; pulse duration, 100 nsec; distance, 3 cm; peak irradiance, 50 W/cm2 in irradiated area; and total exposure, 0.41 mJ/cm2) induced further shortening of latencies, suggesting its stimulatory influence on pain perception.Administration of morphine (20 mg/kg) prolonged the latency of response to the hot plate in both sham‐ and laser‐irradiated mice. This prolongation tended to be lesser in laser‐irradiated animals.Further investigations are required to elucidate the mechanism of the observed effect of laser.
Role of primary photoacceptors in low‐power laser effects: Action of He‐Ne laser radiation on bacteriophage T4‐Escherichia coli interaction
Authors: Tiphlova Olga , Karu Tiina 
Published: March 2007

AbstractThe effect of He‐Ne laser radiation (λ = 632.8 nm) on bacteriophage T4‐Escherichia coli WP2 interactions was studied. Irradiation of bacteria having respiratory chain components as primary photoacceptors accelerated their division in a dose‐dependent manner, but irradiation had no effect on the properties of the phage (measured as its ability to infect host cells). At the same time, exposure of bacteria to stimulating doses of He‐Ne laser radiation (from 103 to 6 × 104 J/m2) increased their ability to promote the growth of unexposed phages. These results clearly indicate that low‐power laser effects require primary photoacceptors (phage contains no chromophores for red light).
Laser vaporization of leiomyoma of the esophagus
Authors: Lange V. , Wenk H. , Schildberg F. W. 
Published: March 2007

AbstractWe present the case of a 67‐year‐old man with a stenosing leiomyoma of the esophagus, which led to dysphagia. Because of severe concomitant diseases, thoracotomy was not possible in this patient. Endoscopic laser ablation was a fast and successful treatment; more than 2 years have passed without any sign of recurrence.
Welding of gallbladder tissue with a pulsed 2.15 μm thulium‐holmium‐chromium:YAG laser
Authors: Popp Howard W. , Oz Mehmet C. , Bass Lawrence S. , Chuck Roy S. , Trokel Stephen L. , Treat Michael R. 
Published: March 2007

AbstractPercutaneous endoscopic approaches to cholelithiasis would be facilitated by methods for welding gallbladder tissues. We evaluated the bursting pressure and histologic appearance of canine gallbladder tissue welded with a thulium‐holmium‐chromium:YAG (THC:YAG) laser producing a 2.15 μm pulsed output. The tissue absorption characteristics at this wavelength as well as the pulsed nature of the output permit tissue welding with limited collateral thermal damage. The THC:YAG is compatible with a flexible fiberoptic delivery system. Bursting strengths of the welded junctions averaged 42 mm Hg, which is above physiologically encountered pressures. Histologic sections of the bonded tissues revealed tissue fusion and limited thermal injury to the surrounding tissue. We feel that THC:YAG laser welding may be a useful technique in the clinical development of percutaneous endoscopic biliary surgery.
Microvascular anastomosis using a new diode laser system with a contact probe
Authors: Unno Naoki , Sakaguchi Shukichi , Koyano Kenichi 
Published: March 2007

AbstractThe aim of the present study was to demonstrate the usefulness of our newly produced diode laser device (an 830‐nm output of 190 mW CW) for microvascular end‐to‐end anastomoses. In the device, diode laser energy is delivered to a contact ceramic tip with a 200‐μm diameter output end. Its wavelength is 830 nm and its power 60 mW. This device is small (30 × 25 × 10 cm), light weight (gross weight 3kg), and easy to manipulate. Compared with conventional microvascular suture anastomosis (CMSA), the time required for the laser‐assisted vascular anastomoses (LAVA) was reduced by almost half. Anastomosed portions of both methods were examined 1, 2, 4, 12, and 24 weeks later for patency and aneurysm formation. The patency rate and incidence of aneurysmal formation were the same in both groups. Histological examination revealed that LAVA is superior to CMSA in the smoothness of the inner surface, less inflammatory reaction, and normal collagen and elastic reorientation. The tensile strength and bursting pressure measured immediately after anastomosis demonstrated no significant difference between the two groups. It was concluded that this diode laser contact method may be clinically useful for microvascular surgery.
Laser balloon angioplasty versus balloon angioplasty in normal rabbit iliac arteries
Authors: Jenkins Ronald D. , Sinclair I. Nigel , Leonard Bradley M. , Sandor Tamas , Schoen Frederick J. , Spears J. Richard 
Published: March 2007

AbstractReduction of vascular recoil is an important goal of laser balloon angioplasty (LBA), wherein Nd:YAG laser radiation is delivered radially during balloon inflation. To define the acute and chronic effects of LBA on the normal arterial lumen in comparison with those of balloon angioplasty (BA), 36 New Zealand White male rabbits (3–4 kg) were subjected to LBA of an external iliac artery and to BA of the contralateral artery with two 1‐minute balloon inflations. During LBA, which was performed during the second balloon inflation, either 300 (n = 26) or 176 (n = 10) J were delivered to achieve high and moderate laser doses, respectively, in different LBA groups. Angiography was performed pre‐ and post‐LBA/BA and subsequently at intervals of either 1, 2, 7, 28, 48, or 223 days. Automated analysis of digitized images was used to measure lumen diameter. No instance of perforation or thrombosis occurred. LBA‐treated arteries acutely showed an increase in mean diameter over baseline (+.5 mm, P<.01) and that of BA‐treated arteries (+.4 mm, P<.01). While arteries treated with the high laser dose showed a loss of the initial gain in lumen diameter by 1 month, caused by both extravascular fibrosis of the thin‐walled (<0.1 mm) artery and mild neointimal proliferation which were not reduced by daily administration of aspirin in seven rabbits, arteries treated with the moderate laser dose retained the increment in mean diameter at 1 month over that of BA‐treated arteries (+.5 mm, P<.05). Thus, unlike BA, LBA increases luminal diameter acutely and, at a moderate laser dose, chronically.
Experimental studies of the application of the Er:YAG laser on dental hard substances: I. Measurement of the ablation rate
Authors: Hibst Raimund , Keller Ulrich 
Published: March 2007

AbstractUp to now lasers have not achieved any practical importance in dentistry for drilling teeth because of considerable damage to the surrounding tissue. We studied the application of pulsed 2.94 μm Er:YAG laser radiation in vitro on extracted teeth to remove enamel, dentin, and carious lesions. The depth and diameter of laser‐drilled holes were measured as a function of pulse number and radiant exposure. The tissue removal is very effective both for dentin and enamel.
Failure of carbon dioxide laser excision of keloids
Authors: Apfelberg David B. , Maser Morton R. , White David N. , Lash Harvey 
Published: March 2007

AbstractSeven patients with nine keloids have been treated by excision with the carbon dioxide laser. Eight of the nine keloids have recurred to their original or close to original size as early as 10 months following treatment and as late as 22 months. Keloids included in this study were located on the trunk, nuchal region, back, and earlobe. Only one patient (who underwent earlobe keloid excision) has greatly improved keloids after only 9 months follow‐up, but this patient needs to wear pressure earrings continuously. The long‐term benefits of keloid excision with the carbon dioxide laser is not demonstrated in this case study series.
Time constants in thermal laser medicine
Authors: van Gemert Martin J. C. , Welch A. J. 
Published: March 2007

AbstractTemperature rise of laser‐irradiated tissue due to direct absorption of laser light is related to laser parameters (power, spot size, irradiation time, and repetition rate) and tissue parameters (absorption and scattering coefficients, density, heat capacity, and thermal conductivity). Solutions to the bio‐heat equation are approximated by introducing axial (z) and radial (r) time constants for heat conduction that represent two parallel channels for heat conduction. These axial (τz) and radial (τr) time constants are found proportional to squared distances (zO2, rO2) that represent the extent of axial and radial temperatures respectively. For convenience, zO and rO are approximated to the axial and radial extent of laser light in the tissue. The resulting solution of the bioheat equation, expressed as temperature rise as function of time and position, is obviously exact for irradiation times short compared to τz, τr (adiabatic heating), but is also a quite reasonable approximation up to irradiation times three times the overall time constant. Comparison with (exact) numerical computations show that this holds for all ratios of (light) penetration depth to laser‐beam radius; for strongly scattering materials, smaller laser beams give better predictions than do larger laser beams. Several examples of clinical relevance are discussed, such as multiple‐laser‐pulse irradiation of high‐ and low‐absorbing tissues and laser treatment of port‐wine stains, with some unexpected results that also show potential clinical relevance.
Catheter‐directed neodymium:YAG laser injury of the left ventricle for arrhythmia ablation: Dosimetry and hemodynamic, hematologic, and electrophysiologic effects
Authors: Vincent G. Michael , Fox Jolene , Knowlton Kirk , Dixon John A. 
Published: March 2007

AbstractThe study evaluated catheter‐directed laser injury of the left ventricular myocardium in a canine model as a potential method for treatment of resistant ventricular tachycardia. The relationship between laser energy delivered, the laser delivery characteristics, and the lesion size was evaluated both in vitro and in vivo. The effect of laser injury on several hematologic and hemodynamic parameters was studied. Programmed electrical stimulation studies were performed to assess the proarrhythmia potential of laser injury of the myocardium.The results showed the depth and diameter of myocardial injury to be directly related to total laser energy applied. Both depth and diameter of injury were increased by multiple applications of laser energy to the same myocardial location. One‐half to full thickness left ventricular injury was produced without perforation or embolization. Endocardial vaporization occurred only with laser powers higher than necessary to produce full‐thickness injury. There was no sustained effect on the hemodynamic or hematologic variables studied, nor were proarrhythmia effects identified. The laser injury produced in these studies was of smaller magnitude than might be necessary for clinical arrhythmia ablation, and the lack of sustained hemodynamic effects and pro‐arrhythmia potential needs to be verified in subsequent studies with larger laser lesions. The results support continued evaluation of catheter‐directed laser injury of the myocardium as a potential method for elimination of life‐threatening ventricular arrhythmias.
Pulsed holmium laser ablation of cardiac valves
Authors: Lilge Lothar , Radtke Wolfgang , Nishioka Norman S. 
Published: March 2007

AbstractAblation efficiency and residual thermal damage produced by pulsed holmium laser radiation were investigated in vitro for bovine mitral valves and human calcified and noncalcified cardiac valves. Low‐OH quartz fibers (200 and 600 μm core diameter) were used in direct contact perpendicular to the specimen under saline or blood. Etch rate was measured with a linear motion transducer. Radiant exposure was varied from 0 to 3 kJ/cm2. For 200‐μm fibers, the energy of ablation was approximately 5 kJ/cm3 in noncalcified and 15 kJ/cm3 in calcified valves. Etch rates were dependent on mechanical tissue properties. Maximum etch rate at 1,000 J/cm2 was 1–2 mm/pulse at 3 Hz repetition rate. Microscopic examination revealed a zone of thermal damage extending 300 μm lateral into adjacent tissue. Thermal damage was independent of radiant exposure beyond twice threshold.
Argon laser vascular fusion: Venous and arterial bursting pressures
Authors: Vlasak Jerry W. , Kopchok George E. , Fujitani Roy M. , White Rodney A. 
Published: March 2007

AbstractThis study was designed to determine the optimal laser power (watts) for maximal strength of argon laser vascular fusions by measuring bursting pressures of repairs. Longitudinal incisions (n = 105) measuring either 2.5 or 5 mm in length were performed in canine femoral, carotid, and jugular veins and arteries and were fused with the argon laser at 0.3, 0.5, 0.7, or 0.9 W power. Total exposure time for each repair (50 to 80 sec/0.5 cm) was adjusted to yield identical energy fluences of 1,100 J/cm2. Bursting pressure of the fusions was determined by monitored infusion of anticoagulated blood into an isolated segment of the vessel that contained the fusion. Mean bursting pressures for venous and arterial repairs were significantly higher in the 2.5 mm incisions compared with the 5 mm incisions (P < 0.05). Venous and arterial repairs of equal length performed at each power resulted in equivalent bursting strengths, except that 5 mm venous segments fused with 0.9 W withstood lower pressures than all other venous repairs (P < 0.05), and 5 mm arterial segments were in turn significantly weaker at 0.3 W (P < 0.02). We conclude that argon laser fusion is equally suitable for repair of medium‐sized veins and arteries and that immediate strength decreases with increasing length of repair. To maximize strength of longer repairs, venotomies should be welded at power settings between 0.3 and 0.7 W while arteriotomies should be fused at power settings between 0.5 and 0.9 W. The differences in optimal power may be explained by variable wall composition and thickness between veins and arteries.
In utero fetal surgery using a milliwatt carbon dioxide laser
Authors: Hallock Geoffrey G. , Rice David C. 
Published: March 2007

AbstractIn utero surgery represents a future new frontier with unknown possibilities for medical intervention. Since the presently available microsurgery instruments are too cumbersome or indelicate, low‐energy carbon dioxide lasers have been investigated as a tool that holds promise as a fetal scalpel and hemastatic device. Preliminary results demonstrate that continued investigation is necessary to limit the zone of tissue destruction in these most diminutive patients.
Effect of excimer laser radiant exposure on uniformity of ablated corneal surface
Authors: Fantes Francisco E. , Waring George O. 
Published: March 2007

AbstractThe argon fluoride (193 nm) excimer laser is being used to change the anterior corneal curvature for correction of refractive errors. Uniformity of the surface following laser ablation may play an important role in the rate of epithelial healing and amount and type of stromal scarring. To test the effect of radiant exposure (fluence) on surface smoothness, we ablated rabbit corneas with the 193 nm argon fluoride excimer laser at nine radiant exposures from 50 to 850 mJ/cm2. A total energy of 100 J/cm2 was used for each ablation at a frequency of 1 Hz. Scanning electron microscopy demonstrated progressive improvement of surface smoothness with increasing radiant exposures. Transmission electron microscopy demonstrated no consistent increase in thickness to the surface condensate (pseudomembrane) with increasing radiant exposure. Improvement in surface quality associated with increasing radiant exposures may result from a more uniform depth of ablation per pulse in the corneal lamellae that absorb laser wavelengths differently. Radiant exposures at levels where the depth of ablation is the same regardless of increasing energy densities achieve a more uniform surface because inhomogeneities in the beam and variation in energy from pulse to pulse do not affect the ablation rate.
Lactate dehydrogenase in laser incisions: A comparative analysis of skin wounds made with steel scalpel, electrocautery, superpulse—continuous wave mode carbon‐dioxide lasers, and contact Nd:YAG laser
Authors: Hukki Jyri , Lipasti Jarmo , Castren Maaret , Puolakkainen Pauli , Schröder Tom 
Published: March 2007

AbstractA histochemical method for demonstrating lactate dehydrogenase activity was used in addition to standard Van Gieson stain to study early alterations near wounds made in pig skin by steel scalpel, electrocautery, two modes of CO2 laser (the rapid superpulse mode and the continuous wave mode), and contact Nd:YAG laser. The enzyme‐free zone near the wounds made using the thermal knives appeared to be twice as wide as the necrotic zone observed with Van Gieson stain. In polarized light, the enzyme‐free area showed two zones of equal width with respect to birefringence of collagen fibers. The zone lacking birefringence correlated well with that observed with Van Gieson stain. The birefringent zone represented functionally damaged tissue with more or less normal structures by light microscopy. The damage to adjacent tissue caused with the thermal knives seems to be considerably larger than has usually been reported.