bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies in fiber guided excimer laser surgery for cutting and drilling bone and meniscus
Authors: Dressel Martin , Jahn Renate , Neu Walter , Jungbluth Karl‐Heinz
Published: March 2007

Our experiments on transmitting high‐power excimer laser pulses through optical fibers and our investigations on excimer laser ablation of hard tissue show the feasibility of using the excimer laser as an additional instrument in general and accident surgery involving minimal invasive surgery. By combining XeCl‐excimer lasers and tapered fused silica fibers we obtained output fluences up to 32 J/cm2 and ablation rates of 3 μm/pulse of hard tissue. This enables us to cut bone and cartilage in a period of time which is suitable for clinical operations. Various experiments were carried out on cadavers in order to optimize the parameters of the excimer laser and fibers: e.g., wavelength, pulse duration, energy, repetition rate, fiber core diameter. The surfaces of the cut tissue are comparable to cuts with conventional instruments. No carbonisation was observed. The temperature increase is below 40°C in the tissue surrounding the laser spot. The healing rate of an excimer laser cut is not slower than mechanical treatments; the quality is comparable.
Laser beam diameter for port wine stain treatment
Authors: Keijzer Marleen , Pickering John W. , van Gemert Martin J. C.
Published: March 2007

Optimal port wine stain treatment requires the selective absorption of light by the ectatic blood vessels. We investigated whether deeper blood vessels can be coagulated, without damaging other cutaneous structures, by varying the laser beam diameter. The penetration of the light was simulated with a random walk (Monte Carlo) program. Scattering of the light plays a major role: practically all light that is absorbed in a blood vessel in the dermis is scattered light. In the epidermis, where the distribution is more centered, a larger beam diameter does not increase the energy density as much as deeper within the dermis where the blood vessels lie and where the light is totally diffuse. Increasing the laser beam diameter from 200 μm to 1 mm or more, makes a typical blood vessel absorb 2.5 times more energy, while the energy absorbed by the epidermis remains the same. The larger the laser beam diameter the better the treatment.
Preliminary results of intraoperative excimer laser angioplasty: Phase 1: An adjunct to coronary artery bypass surgery
Authors: Frazier O. H. , Diethrich Edward B. , Johansson Bo , Conger Jeff L. , Burnett Clay M. , Bylock Anders , Kadipasaoglu Kamuran A.
Published: March 2007

The excimer laser underwent phase I clinical trials at three centers to determine its safety for intraoperative coronary laser angioplasty as an adjunct to coronary artery bypass grafting. A 308‐nm Xenon‐Chloride, pulsed‐wave excimer laser was used to perform angioplasty in 30 patients undergoing coronary artery bypass surgery. Forty vessels (30 patients) were treated, in which the extent of occlusion ranged from 30% to 100%, with complete occlusion in 40% of all vessels. Improvement in vessel luminal caliber was achieved in 33 (79%) vessels, with perforations occurring in 4 (12%) vessels, 2 of which required surgical repair. The lumens of the remaining 8 (19%) vessels were not enlarged, and 2 (5%) of these vessels were perforated. Luminal enlargement was most often achieved in totalled occluded vessels in which 16/17 (94%) were recanalized. No patients died within 30 days post‐operatively. Five patients demonstrated biochemical and electrocardiographic evidence of myocardial injury 48 hr postoperatively, and one patient died of cardiac arrest 139 days postoperatively. On the basis of these results, we believe that excimer laser angioplasty can be performed safely to improve coronary luminal patency, even in totally occluded vessels, in an operative setting. The long‐term value of this procedure remains to be elucidated.
Dye‐enhanced laser welding for skin closure
Authors: DeCoste Susan D. , Farinelli William , Flotte Thomas , Anderson R. Rox
Published: March 2007

The use of a laser to weld tissue in combination with a topical photosensitizing dye permits selective delivery of energy to the target tissue. A combination of indocyanine green (IG), absorption peak 780 nm, and the near‐infrared (IR) alexandrite laser was studied with albino guinea pig skin. IG was shown to bind to the outer 25 μm of guinea pig dermis and appeared to be bound to collagen. The optical transmittance of full‐thickness guinea pig skin in the near IR was 40% indicating that the alexandrite laser should provide adequate tissue penetration. Laser “welding” of skin in vivo was achieved at various concentrations of IG from 0.03 to 3 mg/cc using the alexandrite at 780 nm, 250‐μsec pulse duration, 8 Hz, and a 4‐mm spot size. A spectrum of welds was obtained from 1‐ to 20‐W/cm average irradiance. Weak welds occurred with no thermal damage obtained at lower irradiances: stronger welds with thermal damage confined to the weld site occurred at higher irradiances. At still higher irradiances, local vaporization occurred with failure to “weld.” Thus, there was an optimal range of irradiances for “welding,” which varied inversely with dye concentration. Histology confirmed the thermal damage results that were evident clinically. IG dye‐enhanced laser welding is possible in skin and with further optimization may have practical application.
Bone ablation with Er:YAG and CO2 laser: Study of thermal and acoustic effects
Authors: Li Zhao‐Zhang , Reinisch Lou , Van de Merwe Willem P.
Published: March 2007

A pulsed Er:YAG laser at 2.94 μm and a superpulsed CO2 laser at 10.6 μm are used to investigate bone ablation applications in otolaryngology. Quantitative measurements of mass removal and the ablation depth of cat skull bone and rat femur are presented with the Er:YAG laser at fluences of 9–117 J/cm2. Histological results show that the minimal thermal injury zone from the edge of the lesion is 5–10 μm. Comparison of the photoacoustic and thermal effects during the ablation process indicates that the temperature rise from the 10.6–μm light was higher than that from the 2.94–μm light but that the photoacoustic wave amplitude produced with the Er:YAG laser was higher than that with the CO2 laser. The fluence used for the efficient ablation of bone tissues produces a photoacoustic wave ranging from 100 to 120 dB. The ear can tolerate this level for a short time period. Results of this study suggest that the Er:YAG laser can be an important surgical tool in otolaryngology.
Complications of laparoscopic cholecystectomy: A prospective review of an initial 100 consecutive cases
Authors: Graber John N. , Schultz Leonard S. , Pietrafitta Joseph J. , Hickok David F.
Published: March 2007

In order to identify problems in concept or technique with lap‐aroscopic cholecystectomy, a prospective analysis of the initial consecutive 100 procedures was accomplished. Ongoing review of the results led to modifications in order to improve operative outcome. Minor complications such as nausea for more than 12 h (20%) and right shoulder pain (29%) were self‐limiting. There were no deaths, two bile duct injuries, two abscesses, two retained common duct stones, and one case requiring transfusion, totaling a 7% major complication rate. In the subsequent 200 laparoscopic cholecystectomies, there was a 1.5% rate of major complications. Specific measures and modifications in technique that account for this improvement are detailed. Complications of laparoscopic cholecystectomy are more frequent in initial cases but can be minimized by observing specific intraoperative principles.
Tissue response following CO2 laser application in apical surgery: Light microscopic assessment in dogs
Authors: Friedman Shimon , Rotstein Ilan , Bab Itai
Published: March 2007

The potential advantages of CO2 laser in apical surgery have not been established histologically. Therefore, the long‐term effects of CO2 laser on the apical and periapical tissues were examined histologically in dogs 6 months after apical surgery. Lased specimens and unlased controls showed periapical inflammatory and osteogenic reactions. Lased root surfaces revealed craters with a superficial charred layer closely associated with new cementum‐like matrix. The subjacent dentin appeared tubule‐free and eosinophylic. Lased bone trabeculae showed a charred layer with a deeper osteocyte‐free zone. The charred layer was covered by new bone. Detached charred segments in the marrow space and periapical inflammatory infiltrate were intimately associated with multinucleated giant cells, some containing minute char particles. Such cells were absent from the root and trabecular char linings. In addition, the charred surfaces were free of hard tissue resorption. These results suggest that CO2 laser does not hinder healing when applied in apical surgery.
Mechanical effects of erbium:YAG laser bone ablation
Authors: Hibst Raimund
Published: March 2007

When intending to use pulsed erbium:YAG laser radiation for the ablation of small bones, e.g., the ossicular chain or footplate, not only temperature and thermal damage, but also mechanical side effects become important. In studies on desiccated bone the total recoil momentum caused by laser ablation was measured using a sensitive pendulum. The momentum depends linearly on the radiant energy of the laser pulse with a slope of 10−4 kg m s−1/J. The temporal course of the recoil force during ablation observed by means of a piezoelectric transducer is nearly proportional to the laser pulse intensity. By evaluating recoil momentum and mass loss data, the average initial velocity of the plume was calculated to be 230 to 280 m s−1. The kinetic energy is approximately 1% of the input energy. The measurements support to the hypothesis of a thermally induced explosive process. © 1992 Wiley‐Liss, Inc.
Some morphologic changes induced by Nd:YAG laser on the noncoated enamel surface: A scanning electron microscopy study
Authors: Quintana Eugenio , Márquez Francisco , Roca Inmaculada , Torres Vicente , Salgado Jesús
Published: March 2007

The enamel surface layer of some human teeth was treated with the low‐energy Nd:YAG laser at 8 mJ pulse energy. These samples were previously etched with 0.05 M orthophosphoric acid to reduce the surface reflection. The treated samples, as well as the control samples, were widely studied by scanning electron microscopy, and, in the lased group, significant morphologic changes affecting the enamel surface were observed. Those changes reveal principally the loss of the typical surface structure of the acid‐etched enamel. The hydroxyapatite prisms were not discernible, and there was a decrease in the roughness of the lased surface enamel. These laser‐induced structural changes may be related to the increased resistance to the calcification reported by many authors. © 1992 Wiley‐Liss, Inc.
Effect of steroids or tissue preceding on edema and tissue thermal coagulation after CO2 laser impact
Authors: Sheppard LisaMarie , Werkhaven Jay , Mickelson Samuel , Crissman John D. , Peterson Edward , Jacobsen Gordon
Published: March 2007

The carbon dioxide laser is frequently used in laryngeal microsurgery. Some surgeons have empirically used preoperative steroids or precooling with ice prior to laser impact to limit the resultant tissue thermal coagulation and/or edema. An animal model was designed to quantitatively test these effects. Depillated areas of rat skin were exposed to a CO2 beam of 1 mm diameter at 15 W for 0.1 sec after either administration of Decadron (0.25 mg/kg) immediately prior to impact or precooling more than 10oC below basal body temperature. Measurement of edema was quantitated as extravasation of Evan's blue dye that had been injected intravenously. Tissue thermal coagulation was measured on hematoxylin and eosin stained histologic sections. In comparison to controls, statistically significant reduction in edema was seen only at the 24 hour time period after laser exposure for the steroid group (P<.002) but not for the precooling group. Tissue thermal coagulation was significantly smaller for both the steroid and the ice group (P < .006 and P < .001, respectively) when compared to controls. © 1992 Wiley‐Liss, Inc.
Relation between polyporphyrin distribution and blood brain barrier changes in the rat glioma model
Authors: Ji Ying , Walstad Diana L. , Brown J. Tony , Powers Stephen K.
Published: March 2007

Photofrin™ (a polyporphyrin mixture) distribution in a rat glioma model was studied in relation to changes in the blood brain barrier (BBB). At selected intervals after intraperitoneal injection of Photofrin™, the concentration of polyporphyrins (PP) and Evans Blue Dye, an indicator of BBB permeability, were determined for tumor, brain adjacent to tumor (BAT), and normal brain tissue. Contrary to earlier reports of maximal accumulation at 4–24 hours, tumor levels of PP increased throughout the 96 hour measurement period. During the early stages of tumor development, PP uptake by tumor appeared to be less correlated to BBB disruption. We conclude that passive diffusion through an incompetent BBB does not completely explain PP accumulation in tumor tissue. © 1992 Wiley‐Liss, Inc.
Comparison of a pulsed dye laser and electrohydraulic lithotripsy on porcine gallbladder and common bile duct in vitro
Authors: Birkett Desmond H. , Lamont Jeffrey S. , O'Keane J. Conor , Babayan Richard K.
Published: March 2007

With the advent of minimal access biliary procedures there is a need for a safe intracorporal lithotripsy technique that can be used through small flexible endoscopes. Currently, the two techniques available are electrohydraulic lithotripsy and laser induced shock wave lithotripsy. In this study we compare the effect of a 504 nm coumarin pulsed dye laser and electrohydraulic lithotripsy on in vitro porcine gallbladder and common bile duct. Electrohydraulic lithotripsy at the lowest energy the generator would deliver caused perforation of both tissues in only a few pulses when a 1.9‐F probe was placed in direct contact with the tissue. Energy from a 504 nm coumarin pulsed dye laser delivered through a 320‐μ fiber placed in light contact with the tissue caused an energy dependent perforation after 50 pulses in from none to 44% of tissues. It was also found that there was a higher incidence of perforation in more vascular than non‐vascular tissue. When the EHL probe and the laser fiber were held 1–2 mm from the tissue surface, discharge of each resulted in no perforation. On histological examination of the tissues, the perforations were found to be very small with laser lithotripsy and considerably larger with the electrohydraulic lithotripsy. It was felt that laser lithotripsy in the clinical situation was likely to be much safer than electrohydraulic lithotripsy. © 1992 Wiley‐Liss, Inc.
Mid‐Infrared laser ablation of the cornea: A comparative study
Authors: Ren Qiushi , Venugopalan Vasan , Schomacker Kevin , Deutsch Thomas F. , Flotte Thomas J. , Puliafito Carmen A. , Birngruber Reginald
Published: March 2007

The ablation thresholds and patterns of collateral damage in cornea produced by Er:YAG (2.94 μm) and Er:YSGG (2.79 μm) lasers were measured. Two different pulse durations, 200 μs (normal spiking mode) and 100 ns (Q–switched mode), were used at both wavelengths. In the normal spiking mode, damage zones of 16 ± 2 μm and 39 ± 7 μm and ablation thresholds of 250 ± 20 mJ/cm2 and 420 ± 35 mJ/cm2 were measured at 2.94 μm and 2.79 μm, respectively. In the Q–switched mode, damage zones of 4 ± 2 μm and ablation thresholds of 150 ± 10 mJ/cm2 were found irrespective of the laser used. The similarity between the results using the Er:YAG and Er:YSGG lasers in the Q–switched mode suggest that either laser can be used with equal effectiveness for corneal trephination. © 1992 Wiley‐Liss, Inc.
Reduced tumor cell transfer with contact neodymlum‐yttrium‐aluminium
Authors: Maker Vijay K. , Elseth Kim M. , Radosevich James A.
Published: March 2007

The local recurrence of tumor growth after surgery is thought, in part, to be a consequence of seeding of tumor cells from the primary lesion. This study was directed at determining if the contact Nd:YAG laser provides any advantage over the use of traditional scalpel disection for tumor resection. Five human tumor tissue culture cell lines were studied in this report. They included MCF‐7 (breast), HeLa (cervical), SW‐780 (bladder), HT29 (colon), and A549 (lung). Using a scalpel blade or contact laser scalpel (with or without laser energy), the ability to transfer viable cells from dense cell stocks to new tissue culture wells was tested. Using the A549 cell line, the extent that these instruments were able to “seed” tumor cells was also assessed in a soft agar, in vitro, “incision” model. Results from these studies suggest that the contact laser scalpel has a significantly lower potential to transmit tumor cells, when compared to traditional scalpel blades. © 1992 Wiley‐Liss, Inc.
Holmium‐laser synovectomy of immune synovitis in rabbits
Authors: Möller Karl O. , Lind Barbara M. , Schramm Uda , Trautmann Christoph , Hohlbach Gerd
Published: March 2007

Holmium‐laser synovectomy was carried out to remove allergically inflamed synovial membranes in rabbit knee joints. The healing process was then investigated at different periods. Left knee joints of 12 rabbits were exposed to Ho:YAG‐laser radiation at a wavelength of 2.1 μm, pulse energy of 600 mJ, pulse length of 1 ms, and repetition rate of 3 Hz. Twelve others were treated conventionally and 12 served as controls. After 1 day, 1 week, and 1 and 3 months, respectively, 3 animals from each group were sacrificed and the synovialis grossly and microscopically examined. Coagulation necrosis, inflammation, and edema resulted following laser therapy. After 1 week, the synovial layer consisted of a scarlike formation of fibers and within 1 month, its surface appeared smooth. The mechanical abrasion caused hemorrhage and necrosis. Fibrosis developed in the capsular layers, and after 3 months, the surface appeared coarse and villous. Based on these preliminary findings, holmium‐laser synovectomy may offer an alternative method to existing therapeutic techniques. © 1992 Wiley‐Liss, Inc.
Laser etching of teeth for orthodontic bracket placement: A preliminary clinical study
Authors: Roberts‐Harry Dai P.
Published: March 2007

Current interest in the use of layers in clinical dentistry has suggested that this technique may be applicable to enamel etching in orthodontics. A pulsed Nd:YAG laser was used to etch the enamel surfaces of teeth in vivo prior to the bonding of orthodontic brackets with composite resin. Overall laser bonding took considerably longer, was less reliable in terms of bond strength, and produced more discomfort than conventional acid etching. The use of the ND:YAG laser for etching teeth prior to bonding orthodontic brackets is not recommended. © 1992 Wiley‐Liss, Inc.
Endoscopic laser therapy of the watermelon stomach
Authors: Bjorkman David J. , Buchi Kenneth N.
Published: March 2007

Endoscopic laser therapy has been used in the treatment of vascular lesions throughout the gastrointestinal tract. The “watermelon stomach” is a pattern of vascular ectasia in the gastric antrum that results in chronic gastrointestinal blood loss and iron deficiency anemia.

We have treated 7 transfusion dependent patients with a watermelon stomach using endoscopic laser therapy. Four of these patients were treated with the argon laser and 3 with the Nd:YAG laser. Patient age and prior transfusion requirements were similar in both groups. The mean number of treatments to obliterate vascular lesions and eliminate the need for transfusions was 5.75 ± 0.89 (SEM) for the argon laser and 2.33 ± 0.27 for the Nd:YAG laser (P < 0.05). Lesions recurred and required retreatment in 1 patient treated with the NdrYAG laser and 3 patients treated with the argon laser (mean follow‐up of 35 months). We conclude that endoscopic laser therapy with either the argon or Nd:YAG laser is an effective treatment modality for antral vascular ectasia (watermelon stomach). The Nd:YAG laser requires fewer treatment sessions than the argon laser to obliterate the lesions without increased risk of complications. © 1992 Wiley‐Liss, Inc.
Optical properties of intralipid: A phantom medium for light propagation studies
Authors: Flock Stephen T. , Jacques Steven L. , Wilson Brian C. , Star Willem M. , van Gemert Martin J. C.
Published: March 2007

Intralipid™ is an intravenous nutrient consisting of an emulsion of phospholipid micelles and water. Because Intralipid is turbid and has no strong absorption bands in the visible region of the electromagnetic spectrum, and is readily available and relatively inexpensive, it is often used as a tissue simulating phantom medium in light dosimetry experiments. In order to assist investigators requiring a controllable medium that over a finite range of wavelengths is optically equivalent to tissue, we have compiled previously published values of the optical interaction coefficients of Intralipid, most of which were measured at a wavelength of 633 nm. We have extended the measurements of the absorption and reduced scattering coefficients from 460 to 690 nm and the total attenuation coefficient from 500 to 890 nm. These measurements show that, for stock 10% Intralipid, the absorption coefficient varies from 0.015 to 0.001 cm−1 between 460 and 690 nm, the reduced scattering coefficient varies from 92 to 50 cm−1 between 460 and 690 nm, the total attenuation coefficient varies from 575 to 150 cm−1 between 500 and 890 nm, and the average cosine of scatter varies from 0.87 to 0.82 between 460 and 690 nm. With these data, we discuss the design of an optically tissue‐equivalent phantom consisting of Intralipid and black India ink. © 1992 Wiley‐Liss, Inc.
Cornea epithelial damage thresholds in rabbits exposed to Tm:YAG laser radiation at 2.02 μm
Authors: McCally Russell L. , Farrell Richard A. , Bargeron C. Brent
Published: March 2007

We have determined exposure conditions for minimal damage to the corneal epithelium in rabbit using a continuous wave Tm: YAG laser operating in the TEMoo mode at incident powers between 80 and 450 mW. The 1/e beam diameter was 0.94 mm and exposure durations for threshold damage ranged from 4.3 to 0.08 sec. Calculated temperature increases on the beam axis 10 μm beneath the surface at the measured thresholds were essentially constant and averaged 44°C. This is basically the same temperature increase found for threshold CO2 laser damage and suggests that the critical temperature damage model, which correlates CO2 laser damage, can predict damage thresholds for mid‐infrared laser radiation. We also showed that reliable thresholds can be determined in freshly enucleated eyes, thus opening up the possibility of using available laser sources in laboratories not equipped and approved for animal experiments to determine damage thresholds. © 1992 Wiley‐Liss, Inc.
Percutaneous laser discectomy with the Ho:YAG laser
Authors: Quigley Matthew R. , Shih Tommy , Elrifai Amr , Maroon Joseph C. , Lesiecki Michael L.
Published: March 2007

A prototype Ho:YAG (2.15 μm) laser operating at 2‐J/pulse, 3 Hz through a 600‐μm fiber was employed to perform laser discectomies at the L3–4 disc through an 18G needle in five juvenile pigs. No temperature elevations were recorded in the posterior longitudinal ligament at the disc level and all animals recovered fully with no adverse sequelae, even immediately upon awakening from anesthesia. Pathologic examination demonstrated a wide swath of coagulation necrosis confined to the disc space. The Ho:YAG laser, owing to its close approximation to the intense 2.0 μm absorption band of water, appears to be a viable candidate for clinical trials of laser discectomy. © 1992 Wiley‐Liss, Inc.
Er:YAG laser ablation of enamel and dentin of human teeth: Determination of ablation rates at various fluences and pulse repetition rates
Authors: Li Zhao‐Zhang , Code James E. , Van de Merwe Willem P.
Published: March 2007

A pulsed Er:YAG laser (2.94 μm) was used to determine ablation depths per pulse of laser energy at 2 Hz and 5 Hz in human teeth cross sections of enamel and dentin. Ablation depths per pulse at 2 Hz in enamel of intact human teeth were measured and compared to ablation depths per pulse determined in enamel cross sections at 2 Hz. Close correlation was observed for ablation depths per pulse of laser energy between teeth cross sections and intact teeth for enamel. Photographs of lased holes at 2 Hz and 5 Hz indicated minimal thermal effects in enamel at fluences below 80 J/cm2. Minimal thermal effects in dentin were noted below 74 J/cm2. Scanning Electron Microscopy (SEM) pictures of lased dentin showed an irregular serrated surface. Results of this study suggest that the Er:YAG laser can effectively ablate enamel and dentin with minimal thermal effects at 2 Hz and 5 Hz. © 1992 Wiley‐Liss, Inc.
Centering balloon to improve esophageal photodynamic therapy
Authors: Panjehpour Masoud , Overholt Bergein F. , Denovo Robert C. , Sneed Rick E. , Petersen Mark G.
Published: March 2007

A cylindrical balloon was developed to improve delivery of circumferential light for photodynamic therapy (PDT) of esophageal carcinoma. The balloon consisted of a 36‐mm‐long clear cylindrical membrane and a central tube to hold a cylindrical diffuser in the center of the lumen. Three isotropic probes were placed on the outside of the balloon to allow measurement of delivered light dose to the esophageal mucosa. The balloon was tested in the normal esophagus of 8 dogs that were injected with 4.0 mg/kg of PHOTOFRINR. Endoscopy was performed 48 hours following the injection, and under endoscopic observation the balloon assembly was passed, fixed in place, and inflated. A 1‐cm cylindrical diffuser was passed into the central tube and 150,300, and 600 Joules/cm of 630 nm laser light was delivered at 25 cm, 15 cm, and 5 cm proximal to the gastroesophageal junction. One control dog was illuminated using the cylindrical diffuser alone at doses of 300 and 600 Joules/cm of diffuser. Complete circumferential tissue response was obtained when the balloon was used. Relatively uniform light intensities were measured around the lumen. In contrast, noncircumferential and unpredictable PDT responses were generated when the cylindrical diffuser was used without the balloon. © 1992 Wiley‐Liss, Inc.
Locomotory characteristics of fibroblasts within a three‐dimensional collagen lattice: Modulation by a helium/neon soft laser
Authors: Noble Peter B. , Shields Edward D. , Blecher Peter D. M. , Bentley Kenneth C.
Published: March 2007

It has been postulated that low energy (soft) lasers can enhance wound healing. Considering the importance of cell locomotion in the wound healing process, we have studied the effects of a helium/neon laser upon the locomotory behaviour of a population of fibroblasts migrating within a three‐dimensional hydrated collagen lattice. Statistical methods were used to quantify cell three‐dimensional trajectories obtained using a computer‐assisted tracking system. A two‐minute exposure of embryonic fibroblasts to soft laser light decreased the speed and increased the frequency and duration of stops compared to controls. The locomotory phenotype induced in embryonic fibroblasts by the laser light resembled that of the developmentally older c20 fibroblasts, which are known to express a more mature locomotory phenotype. The relevance of these results to wound healing is discussed. © 1992 Wiley‐Liss, Inc.
Evaluation of thermal cooling mechanisms for laser application to teeth
Authors: Miserendino Leo J. , Abt Elliot , Wigdor Harvey , Miserendino Catherine A.
Published: March 2007

Experimental cooling methods for the prevention of thermal damage to dental pulp during laser application to teeth were compared to conventional treatment in vitro. Pulp temperature measurements were made via electrical thermistors implanted within the pulp chambers of extracted human third molar teeth. Experimental treatments consisted of lasing without cooling, lasing with cooling, laser pulsing, and high‐speed dental rotary drilling.

Comparisons of pulp temperature elevation measurements for each group demonstrated that cooling by an air and water spray during lasing significantly reduced heat transfer to dental pulp. Laser exposures followed by an air and water spray resulted in pulp temperature changes comparable to conventional treatment by drilling.

Cooling by an air water spray with evacuation appears to be an effective method for the prevention of thermal damage to vital teeth following laser exposure. © 1993 Wiley‐Liss, Inc.
Beta carotene uptake into atherosclerotic plaque: Enhanced staining and preferential ablation with the pulsed dye laser
Authors: Mitchell David C. , Prince Martin R. , Frisoli Joan K. , Smith Roy E. , Wood Richard F. M.
Published: March 2007

The yellow color of atherosclerotic plaque is due to the presence of carotenoids, which absorb light between 430–530 nm and account for the preferential ablation of plaque by the pulsed dye laser operating at 480 nm. This study was designed to examine tissue uptake of β‐carotene and the effect of uptake on arterial plaque ablation. Forty‐two atherosclerotic NZW rabbits were given intravenous β‐carotene at a dose of 40 mg/kg, twice weekly and killed between 1 hour and 28 days after the initial injection. β‐carotene was not detected in control specimens but was significantly greater in plaque than in normal wall at all time points following β‐carotene injection (P < 0.04 Mann Whitney U test). The ablation threshold was significantly lower in β‐carotene treated plaque than in untreated plaque or normal arterial wall (P < 0.01, Fisher's exact test). In this model β‐carotene is preferentially taken up into arterial plaque, resulting in increased absorption of laser radiation at 480 nm and enhanced tissue ablation. © 1993 Wiley‐Liss, Inc.
Improved excimer laser photorefractive keratectomy system
Authors: van Saarloos Paul P. , Constable Ian J.
Published: March 2007

An improved 193 nm excimer laser photorefractive keratectomy system is described here. The delivery system was optimised to produce a smooth keratectomy bed, to minimise the healing response, and to reduce the regression of the refractive result. A spatial filtering system was used to smooth the energy distribution within each pulse, and the iris was adjusted for every pulse, to eliminate steps and other irregularities from the keratectomy profile. An image rotator was used to average out any remaining non‐uniformities in the energy distribution. The results from the first 39 eyes treated with this laser system with a maximum follow‐up of 18 months, are summarised. No epithelial healing problems were noticed, and little or no loss of corneal clarity was noted at any stage during healing. Twenty of the keratectomy procedures were normally sighted myopic corrections, with a maximum follow‐up of 5 months. Minimal regression of the refractive correction was seen during the first 8 weeks. © 1993 Wiley‐Liss, Inc.
Fine structure of zonal changes in experimental Nd:YAG laser–induced interstitial hyperthermia
Authors: Schober Ralf , Bettag Martin , Sabel Michael , Ulrich Frank , Hessel Stefan
Published: March 2007

Interstitial thermotherapy using Nd:YAG‐laser induced hyperthermia is a new stereotactic method for the treatment of brain tumors in poorly accessible regions. To provide a basis for the underlying tissue alterations, we have analyzed the spatial and temporal pattern of interstitial laser hyperthermia lesions in the normal rat brain by histological, immunohistochemical, and electron microscopical methods. The acute changes corresponded to the temperature gradient surrounding the laser probe and showed a distinct zonal architecture. Membrane destruction on a cellular and subcellular level appears to be of major significance in the pathogenesis of the laser lesion. The tissue reaction followed the course known for coagulation necrosis and resulted in a well‐defined defect. These results, although limited by the choice of the experimental model, may be helpful in the interpretation of images obtained in future applications of interstitial thermotherapy. © 1993 Wiley‐Liss, Inc.
Effects of plume produced by the Nd:YAG laser and electrocautery on the respiratory system
Authors: Wenig Barry L. , Stenson Kerstin M. , Wenig Bruce M. , Tracey Diana
Published: March 2007

Sprague‐Dawley rats were exposed to Nd:YAG laser exhaust (contact and noncontact) as well as to electrocautery exhaust passed through smoke evacuation filters. Exposure periods for each group were equal and increasing in time. Histologic analysis revealed alveolar congestion and emphysematous changes in all modes. Controls exhibited similar change but to a milder degree. It appears that any plume produced by lasers or electrosurgical devices produces pathologic change in rat lungs and that effective smoke evacuation will help control these effects. © 1993 Wiley‐Liss, Inc.
Laser vaporization of Peyronie's plaques
Authors: Costello Russell T.
Published: March 2007

A series of four cases of surgical excision or vaporization of Peyronie's plaques using the Neodynium/Yag laser is presented. This technique would appear to decrease the need for grafting procedures with minimal blood loss. It results in straight erections without shortening the penis. © 1993 Wiley‐Liss, Inc.
Characterization of pulsed‐dye laser‐mediated vasodilatation in a rabbit femoral artery model of vasoconstriction
Authors: Schwengel Robert H. , Gregory Kenton W. , Hearne Steven E. , Scott Helen J. , Beauman Glenn J. , Mergner Wolfgang J. , Caplin John L. , Ziskind Andrew A.
Published: March 2007

Vasoconstriction is a clinical problem associated with invasive vascular procedures, microvascular reconstruction and subarachnoid hemorrhage. We sought to characterize the ability of pulsed‐dye laser irradiation to reverse and prevent vasoconstriction in an anesthetized rabbit model of surgically and pharmacologically induced vasoconstriction.

Five groups of experiments were performed to study the effect of pulsed‐dye laser irradiation delivered through a 320 μm core ball‐tip fiber into the femoral artery. The studies demonstrated that pulsed‐dye irradiation can reproducibly cause vascular dilatation. The zone of vasodilatation propagated equally proximal and distal to the site of irradiation within the vessel. When saline was infused into the vessel to replace flowing blood during delivery of laser irradiation, no significant vasodilatation occurred. After laser irradiation reversed surgical and pharmacologic vasoconstriction, the vessel was resistant to further pharmacologic Vasoconstriction. This resistance to pharmacologic vasoconstriction did not occur if the vessel was pharmacologically predilated before delivery of laser irradiation. Pathologic analysis of the vessels revealed endothelial damage and mild to moderate medial necrosis, most significant at the site of energy delivery.

These studies provide characterization of pulsed‐dye laser‐mediated vasodilatation in an in vivo model. Delivery of pulsed‐ dye laser energy has potential clinical application and warrants further investigation. © 1993 Wiley‐Liss, Inc.
Effect of multidrug‐resistant P‐glycoprotein gene expression on chloroaluminum tetrasulfonate phthalocyanine concentration
Authors: Frazier Donita L. , Barnhill Mary Ann , Lu Xiaochen , Jones Emily , Niemeyer Glenn , Mishu Leslie , Lothrop Clint D.
Published: March 2007

The effect of multidrug‐resistant P‐glycoprotein gene expression (MDR1) in 3T3 cells on cellular concentrations and cytotoxicity induced by the photodynamic agent chloroaluminum tetrasulfonate phthalocyanine (AISPc) was evaluated. 3T3 cells transfected with a retroviral vector expressing human MDR1 cDNA were resistant to colchicine. Resistant cells incubated with daunomycin accumulated only 40–50% of the quantity of daunomycin accumulated in control cells. Resistant cells incubated with daunomycin in the presence of verapamil had intracellular daunomycin concentrations approximately equal to control cells without verapamil. When these MDR1 3T3 cells were incubated with AISPc, cellular concentrations of AISPc did not differ between cells resistant to colchicine and those that were not. Similarly, there was little difference in cytotoxicity demonstrated by 51Cromium release in the two cell lines exposed to AISPc and light (675 nm; 6 J/cm2). This study suggests photodynamic therapy using AISPc may be a useful treatment modality for tumors in which the MDR1 P‐glycoprotein confers resistance to cancer chemotherapeutics. © 1993 Wiley‐Liss, Inc.
Preparation of human albumin solder for laser tissue welding
Authors: Poppas Dix P. , Choma Theodore J. , Rooke Christopher T. , Klioze Scott D. , Schlossberg Steven M.
Published: March 2007

Previous studies have demonstrated that the addition of a protein solder to augment the laser tissue weld significantly improves postoperative results. Herein we describe a method for the preparation of human albumin for use as a laser tissue solder. We also review the brief history of laser tissue solders and discuss recent advances using this technology. © 1993 Wiley‐Liss, Inc.
Dose and temporal parameters in delaying injured optic nerve degeneration by low‐energy laser irradiation
Authors: Rosner Mordechai , Solomon Arieh , Assia Ehud , Belkin Michael , Caplan Michael , Cohen Shmuel , Duvdevani Revital , Schwartz Michal
Published: March 2007

Low‐energy laser irradiation has been reported to postpone the degenerative processes in crushed optic nerves of rats, which are part of the nonregenerable mammalian central nervous system. In the present study, we evaluated the optimal irradiation parameters for this purpose. Optic nerves of 141 rats were subjected to crush injury and then irradiated through the eye, starting at different points of time before or after the injury, for different durations and periods, using various intensities of either heliumneon laser or noncoherent infrared light (904 nm). The effect was evaluated by measurements of the compound action potentials of the nerve segments between the site of injury and the optic chiasm. The compound action potential amplitude of the crushed nonirradiated nerves, as measured 2 weeks after the injury, was found to be 0.51 ± 0.30 mV, in contrast to 3.10 ± 1.03 mV measured in 232 normal nerves. Irradiation with a 10.5 mW helium‐neon laser for 2 and 3 min once a day for 14 consecutive days resulted in maximal preservation of action potentials (1.78 ± 0.72 and 1.95 ± 0.71 mV, respectively). Irradiations beginning immediately prior to the injury were as effective as irradiations beginning soon after it. Irradiations for longer than 3 min or twice a day aggravated the damage. Noncoherent infrared light was ineffective or adversely affected the injured nerves. Our experiments suggest that optimal delay of posttraumatic optic nerve degeneration in rats is attainable with 10.5 mW helium‐neon laser irradiations for 2 or 3 min once a day for 14 consecutive days. © 1993 Wiley‐Liss, Inc.
In vitro evaluation of ablation parameters of normal and fibrous aorta using smooth excimer laser coronary angioplasty
Authors: Xie Dao Yin , Hassenstein Stefan , Oberhoff Martin , Hanke Hartmut , Baumbach Andreas , Hohla Kristian , Haase Karl Konstantin , Karsch Karl Rüdiger
Published: March 2007

A modified exeimer laser energy delivery system was used to irradiate 100 segments of normal and fibrous aorta in vitro. The laser beam was scanned into 8 fiber bundles consisting of 50 fibers each resulting in a reduction of the applied pulse energy. The total repetition rate was increased to 150 Hz in order to keep the repetition rate per fiber bundle close to 20 Hz and to minimize thermal injury. The results demonstrate that effective ablation (etch rate per 8 pulses > 2.0 μm) occurred at an energy fluency of 50 mJ/mm2 in both normal and fibrous aorta. Tissue damage (carbonization, tissue separation, fissures, cracks, and vacuolization) was in a range of 100 ± 28 to 152 ± 30 μm for normal aorta and in a range of 57 ± 35 to 110 ± 39 μm for fibrous aorta. We conclude that effective ablation of normal and fibrous human aorta can be achieved by the application of smooth excimer laser coronary angioplasty. This improvement of excimer laser technology may result in a reduction of shock wave‐ and cavitation‐induced damage leading to a reduction of tissue injury. However, this awaits further in vitro and in vivo confirmation. © 1993 Wiley‐Liss, Inc.
Ureteroscopic management of transitional cell carcinoma of the ureter using the neodymium:YAG laser
Authors: Kaufman Ronald P. , Carson Culley C.
Published: March 2007

Ureteroscopy offers an extension of endoscopic diagnosis and treatment to upper urinary tract malignancy. Combination of ureteroscopy and the Nd:YAG laser permits accurate and effective treatment of ureteral neoplasms. Nine highly selected patients, six males and three females, were treated with low grade papillary transitional cell carcinomas of the ureter with at least 24 months follow‐up. Follow‐up cytology and IVP have indicated no evidence for disease recurrence between the follow‐up periods and minimal morbidity to the ureteroscopy and laser treatment. © 1993 Wiley‐Liss, Inc.
Prostatectomy by transurethral balloon Laserthermia™ (PROSTALASE™) in the canine
Authors: Suzuki Takanori , Kurokama Kohei , Yamanaka Hidetoshi , Long Liong Men , Daikuzono Norio
Published: March 2007

Prostatectomy by transurethral balloon Laserthermia (PROSTA‐LASE™) was performed in a canine model. This balloon device monitored by transrectal ultrasound can cylindrically irradiate with a laser beam. The treatment was performed in 8 canines using 15 watts for 20 minutes at 60°C at a 5 mm depth of the prostate from the urethral surface. Immediately following the laser therapy, an area of coagulation necrosis was observed around the urethra to a depth of 4–5 mm from the surface. After 1 week, cavitation formation was seen in 3 or 4 canines by ultrasound, and the urethral reepithelialization was shown in 1 of 2 canines. After 2 weeks, cavitation formation was observed in both canines, and the urethra was completely reepithelialized in one canine. There was no tissue damage in the bladder neck of urethral sphincter and no urinary incontinence in any animal. This system is thought to be simple and, satisfactorily performed, is an effective transurethral prostatectomy. © 1994 Wiley‐Liss, Inc.
Use of the holmium:YAG (Ho:YAG) laser for treatment of superficial bladder carcinoma
Authors: Johnson Douglas E.
Published: March 2007

This is the first North American report describing the use of the holmium:YAG (Ho:YAG) laser to treat patients with superficial bladder carcinoma. Fifteen patients, with a total of 52 recurrent superficial bladder tumors, underwent endoscopic laser photoablation of their lesions. No intraoperative or delayed complications occurred. At follow‐up cystoscopy performed 3 months after lasing, four patients (27%) were without disease; eight patients (53%) had out‐of‐field recurrences; and three patients (20%) were classified as having in‐field recurrences. We conclude that using the Ho:YAG for endoscopic treatment of patients with superficial bladder tumors is both feasible and clinically useful and that the lack of perceived pain or discomfort during lasing, as well as the lack of need for an in‐dwelling urethral catheter, makes it advantageous for selected patients over conventional electroresection techniques. © 1994 Wiley‐Liss, Inc.
Tissue optical property measurements: Overestimation of absorption coefficient with spectrophotometric techniques
Authors: Torres Jorge H. , Welch Ashley J. , Çilesiz Inci , Motamedi Massoud
Published: March 2007

This study examines the validity of optical property measurements by comparing surface temperatures rises predicted by a well‐tested mathematical model with temperatures measured experimentally during laser irradiation. Analysis is based on the early temperature response that is proportional to the absorption coefficient. The results of the investigation suggest that values for tissue absorption coefficient can be greatly overestimated when current Spectrophotometric techniques are used. This seems especially true when a broad light beam and a low port‐to‐beam‐size ratio are used for transmission and reflection measurements with an integrating sphere. © 1994 Wiley‐Liss, Inc.
Interstitial laser prostatectomy
Authors: Johnson Douglas E. , Cromeens Douglas M. , Price Roger E.
Published: March 2007

Serial gross and histopathologic examinations of the prostate following interstitial laser prostatectomy in the canine model demonstrated distinct zonal thermal changes around the entire active area of the interstitial thermal therapy (ITT) fiber. A large, well‐demarcated area of acute coagulative necrosis immediately surrounded each fiber tract; beyond that were a prominent narrow peripheral zone of marked tissue disruption and an outer zone of hemorrhage. Liquefaction within these coagulative areas was evident within 24 hours, and by 4 days, each lobe of the prostate contained an irregular cavity that became lined by normal‐appearing transitional epithelium and that, by 5 weeks, communicated with the prostatic urethra. These postmortem pathologic observations, similar to findings previously reported following transurethral laser prostatectomy, suggest that interstitial laser thermal therapy may provide an additional means for treating benign prostatic hyperplasia in men. © 1994 Wiley‐Liss, inc.
Factors affecting size and configuration of neodymium:YAG (Nd:YAG) laser lesions in the prostate
Authors: Fournier George R. , Narayan Perinchery
Published: March 2007

Laser surgery for benign prostatic hypertrophy is a clinical reality and a promising alternative to traditional transurethral electroresection of the prostatic adenoma (TURP). Current methods of laser prostatectomy involve coagulation of prostate tissue using a quartz side‐firing fiber that redirects a Nd:YAG laser beam at 70–90° most commonly by means of a metal reflector. In this communication we describe a method of tissue evaporation using a side‐firing fiber that avoids use of a metal reflector by means of internal reflection. It is relatively resistant to damage when coming in contact with tissue. By placing the fiber tip in direct contact with tissue, much larger lesions are created because of more efficient energy transfer resulting in rapid evaporation of tissue under water. In prostate surgery, this phenomenon of accelerated evaporation can be used to bloodlessly evaporate adenomatous tissue creating a defect that resembles that of a traditional TURP. © 1994 Wiley‐Liss, Inc.
Enhanced ArF laser absorption in a collagen target under ablative conditions
Authors: Ediger M. N. , Pettit G. H. , Hahn D. W.
Published: March 2007

The time‐resolved transmission of collagen targets during ArF excimer laser ablation has been measured. The transmitted excimer pulse measurements demonstrate enhanced media attenuation that is a nonlinear function of incident laser fluence. Forward scattering of the transmitted pulse has been assessed to be a negligible contributor to the observed phenomena. Results of pump/probe interrogation of the ablation site indicate that the onset of enhanced attenuation occurs on the time course of the ablating laser pulse and persists for times on the order of hundreds of microseconds. © 1994 Wiley‐Liss, Inc.