bluuebunny/crossref_metadata_2025 huggingface dataset:
Electroresection followed by neodymium–YAG laser photocoagulation of the dog prostate for establishment of safety parameters
Authors: Finkelstein Leonard H. , Frantz Bruce , Longendorfer Lillian Hynes , DeBias Domenic , Greene Charlotte , Monson Frederic
Published: March 2007

Electroresection of the prostate followed by Nd‐YAG laser coagulation of residual prostate was carried out in eight dogs. All dogs voided spontaneously without significant bleeding in the immediate postoperative period. At the time of sacrifice in 6 to 8 weeks, no damage to adjacent tissue was seen on microscopic examination. Re‐epithelization had occurred. This study suggests that the addition of neodymium‐YAG coagulation to residual tissue after TURP in humans can be done safely.
Danazol versus carbon dioxide laser plus postoperative danazol: Treatment of infertility due to mild pelvic endometriosis
Authors: Chong Augusto P.
Published: March 2007

The mechanism of action by which mild pelvic endometriosis causes infertility is still unknown. Danazol has been proposed as the sole agent to treat this condition; however, the results for pregnancy rates do not give as much cause for enthusiasm at the present time as they did when this drug was introduced. To ascertain the role of laser via the laparoscopic approach, this retrospective study looks at the pregnancy success rate in two groups of patients. Group I was treated with danazol alone; group II was treated with danazol after laser surgery. Although the success rate is better in group II, the population sample in both groups is modest and does not allow one to draw meaningful statistical conclusions at the present time, but the use of carbon dioxide laser with the laparoscope plus postoperative danazol seems to be a better approach to this condition that affects the infertile female.
Argon and neodymium YAG laser therapy of dark nodular port wine stains in older patients
Authors: Dixon J.A. , Gilbertson Jeffrey J.
Published: March 2007

Thirty‐seven patients of mean age 52 with large dark nodular port wine stains were treated with argon and neodymium YAG lasers. The level of patient satisfaction was high (mean 7.1 on scale of 10) despite residual color in 36 of 37 patients. It was possible to accomplish flattening of the lesion and removal of nodules in all patients. In four patients, it was necessary to use neodymium YAG laser for removal of residual large vascular nodules following previous argon therapy. Twenty‐nine patients required a mean number of 1.6 retreatments for residual tufts of vessels. An unusual finding was that of recurrent color deepening of lesion in three patients after initial improvement. This recurrence responded to treatment.

Spontaneous bleeding or bleeding initiated by trauma such as shaving was a problem noted in 13 out of 37 patients.
Preliminary investigation of KTP/532 laser light in the treatment of hemangiomas and tattoos
Authors: Apfelberg David B. , Bailin Phillip , Rosenberg Howard
Published: March 2007

Preliminary investigation of a frequency‐doubled YAG laser (KTP 532 nm) manufactured by Laserscope of Santa Clara was undertaken. Twenty‐five patients with either port wine hemangiomas or decorative tattoos were treated with a 532‐nm light and the results compared to argon laser at identical power settings. Clinical and histological results were identical between the two lasers.
The low‐output carbon dioxide laser for cutaneous wound closure of scalpel incisions: Comparative tensile strength studies of the laser to the suture and staple for wound closure
Authors: Garden Jerome M. , Robinson June K. , Marie Taute P. , Lautenschlager Eugene P. , Joseph Leibovich S. , Hartz Renee S.
Published: March 2007

The low‐output carbon dioxide (CO2) laser was used for cutaneous wound closure of scalpel incisions. Cutaneous scalpel incisions were placed over the dorsum of three minipigs and were then closed by either the laser, sutures, or staples. At multiple time points after wound closure, up to day 90, the tensile strengths of these wounds were comparatively evaluated. All wounds, including those closed with the laser, clinically appeared to heal similarly with no evidence of wound dehiscence or infection. Tensile strength studies revealed similar sigmoid curves for all wound closure modalities with low initial tensile strengths up to days 14 to 21, which afterwards increased rapidly, with a plateau toward day 90. From our study, it appears that the CO2 laser, in the low‐output mode, can be used for cutaneous wound closure and that similar clinical healing and tensile strength measurements are obtained relative to the conventional cutaneous wound closure modalities of the suture or staple.
Management of 633 cervical intraepithelial neoplasias by CO2 laser: Persistent diseases and recurrences
Authors: Sadoul George D. , Beuret Thérèse M.
Published: March 2007

During the past 6 years, we have managed 633 cervical intraepithelial neoplasias with the Co2 laser. If the lesion is located on the ectocervix, the CO2 laser is used to vaporize it under the microscope. If the lesion is located in the endocervical canal, the CO2 laser is used to excise a cylinder‐shaped tissue with a handpiece.

Colposcopic examination is performed 21 days after treatment. Persistent disease is recognized at this examination; healing is obtained spontaneously in 66% of those with persistent disease without second treatment.

There were eight with recurrent disease with abnormal Pap tests and abnormal colposcopic findings, and 12 with recurrent disease with abnormal Pap tests and normal colposcopic findings (recurrent koilocytis cells).

After laser treatment cervical function was good and pregnancies were normal.
Renal evaluation after cusa plus Nd: YAG laser for partial nephrectomy
Authors: Landau Stewart T. , Wood Thomas W. , Melzer Richard B. , Smith Joseph A. , Lee Randall G.
Published: March 2007

A technique for partial nephrectomy using a combination of an Ultrasonic Surgical Aspirator and a neodymium:YAG laser provided better hemostasis and decreased total operative time compared to standard methods. Delayed hemorrhage was not seen, and thermal damage to the remaining renal parenchyma was minimal.
Effects at the periphery of the laser lesion in human brain and its tumors after Co2, Nd: YAG, and CO2 high‐peak pulsed radiation
Authors: Fasano Victor Aldo , Ponzio Roberto Maria , Lanotte Michele Maria , Peirone Saverio Maria , Merighi Adalberto
Published: March 2007

The histological changes in various tissues irradiated with lasers are well known. Our own previous observations with the optical microscope confirm those already reported in the laser literature. If tissue is treated with various laser sources, the results are similar, with the characteristic three layers from the outside toward the inside of carbonization, coagulative necrosis, and edema. Otherwise, only the shapes and sizes of the lesions differ, with craters of different depths.

In this paper, we report an ultrastructural study of the changes occurring in the periphery of the laser lesions in both normal human brain and neoplastic tissues (gliomas and meningiomas). Continuous‐wave CO2 and Nd:YAG lasers were used at different exposure times and powers and the effects of high‐peak pulsed CO2 laser radiation has also been investigated.

The study, performed during neurosurgical procedures was mostly focused on microcirculation at 1.5–3 mm outside the area of coagulative necrosis, at the level of the edema zone.

Only lesions of the blood brain barrier are produced in normal brain by CO2 radiation (power ranging from 40 to 80 W; exposure time from 3 to 10 seconds). The same results were achieved by Nd:YAG radiation of short duration (3 seconds) regardless of the power used (40 and 80 W). Long‐duration Nd:YAG radiation (10 sec; power: 40–80 W) produces endoluminal phenomena leading to the complete occlusion of the capillaries.

In neoplastic brain tissues, microcirculation does not seem to be impaired by CO2 radiation. More marked lesions are produced in tumors even after Nd:YAG short‐time radiation. Endoluminal obliteration is observed in meningiomas and perivascular hemorrhage occurs in highly vascularized gliomas.

According to these results, the risk of delayed post‐operative hemorrhages, noticed in some patients with glioblastoma operated on by Nd:YAG lasers, suggests dial residual tumor in the cavity should be treated by CO2 laser because of its minimal damage of microcirculation.
Hematoporphyrin derivative fluorescence: Photographic techniques for the localization of malignant tissue
Authors: Lanzafame Raymond J. , Rogers David W. , Nairn John O. , Pennino Ralph P. , Raymond Hinshaw J. , Blackman Jeffrey R.
Published: March 2007

Three simple methods for the detection of malignancy by the photography of hematoporphyrin derivative (HPD) fluorescence are presented. Two methods employ a single lens reflex camera with macrolens and Kodak high‐speed Ektachrome (EL 400) film. Both employ a Corning Glass #3482 filter as a barrier on the lens. In method I, a single Kodak Wratten #39 filter is placed over a fluorescent “black light” source (two General Electric F20T12BL 20‐W bulbs). In method II, twin electronic flash units (5,500 BCPS unfiltered) with a double thickness of Kodak Wratten #39 filter over them provide the light of excitation. Method III employs an adapted Polaroid® SLR 680E Sun camera with two electronic flash units (5,500 BCPS, total unfiltered) rigged with a slave trigger. A Corning Glass #3482 filter is placed on the lens to act as a barrier, and two filters of Kodak Wratten #39 glass are placed on each flash unit. Photographs are taken in a darkened room.
Effect of CO2 laser irradiation on experimental fracture healing: A transmission electron microscopic study
Authors: Tang X. M. , Chai B. P.
Published: March 2007

The healing of standardized fracture of rabbit radius was expedited as a result of treatment with low‐power CO2 laser irradiation. Observation with transmission electron microscope revealed the following favorable effects of CO2 laser irradiation: (1) The red blood cells were induced to disintegrate, thus promoting the absorption of the hematoma. (2) The macrophages emerged early and increased in number so that debridement of the necrotic tissues was enhanced. (3) The fibroblasts were more active in producing the fibrous callus. (4) The chondrocytes were unusually active in forming bone tissues. (5) The early and sustained appearance of osteoclasts favored the bone remodeling process. (6) Increased capillary formation endowed the fracture healing with rich blood supply. (7) Deposition of calcium salts took place early.
Bactericidal effects of the neodymium: YAG laser: In vitro study
Authors: Schultz Robert J. , Harvey Gregory P. , Krishnamurthy Shanker , Rodriguez Jose E. , Fernandez‐Beros Maria E. , Cabello Felipe
Published: March 2007

The effects of laser energy on three bacterial strains, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were studied utilizing the neodymium: YAG laser. Cell suspensions of each strain were divided into four groups. In group I, suspensions from each strain were exposed to laser energy densities of 555–3,333 J/cm2. In groups II and III, two artificial dyes, congo red or methylene blue, were added to the suspensions prior to lasing. In group IVa, no laser energy was used, and group IVb was used to measure the bactericidal thermal effects of the laser. It was concluded that: 1) Low dosages of laser energy exceeding 1,667 J/cm2 resulted in a 2 to 8 log decline in the number of viable bacterial colonies in vitro. 2) Compared to the other two bacterial strains, P aeruginosa was the most senstive to YAG laser irradiation. 3) Addition of methylene blue, a dark‐colored dye, enhanced the bactericidal effects of the YAG laser as indicated by the significantly reduced viability of P aeruginosa after irradiation with 2,222 J/cm2.
The use of laser in rectal surgery
Authors: Pfeffermann Reuven , Merhav Hadar , Rofhstein Harry , Simon Dan
Published: March 2007

Ten patients with rectal tumors were treated by surgical excision of the tumor using a CO2 laser Sharplan 733 CO2 laser, Laser Industries Ltd., Israel. The laser permitted sharp excision, evaporization, or fulguration of tissue. Good hemostasis was achieved. Anesthesia was unnecessary in cooperative, calm patients. There was no mortality or morbidity related to the procedure.

In five patients with villous adenoma the tumor was resected with one recurrence as yet (followup 4–16 months). Five patients with inoperable carcinoma were treated for palliation with good results. Our preliminary results indicate that the CO2 laser can be a useful asset in rectal tumor surgery, especially in elderly, moribund patients and in the definite treatment of benign tumors of the rectum.
Nd: YAG laser irradiation of an eye model: Experimental analysis
Authors: Docchio F. , Sacchi Carlo A.
Published: March 2007

This work reviews a series of experiments performed on an eye model to study physical effect relevant for a safe and effective use of the Q‐switched Nd.YAG laser in ophthalmic microsurgery. The breakdown probability per laser pulse has been found to depend exponentially on the reciprocal laser field. This indicates that, as in trasparent solids, electron avalanche ionization is likely the main mechanism for optical breakdown in liquids. Shielding of the retina, by the laser‐induced plasma, is not very effective, but an appreciable degree of shielding is present, in burst operation, even after membrane disruption. A backscattered beam, which presents the typical properties of stimulated Brillouin scattering, has been observed in the eye model, with a threshold of ∼ 5·109 W/cm2. This beam, which presents an irregular spatial structure with peaks of irradiance well above the average value, may produce damage of the internal wall of the cornea.
Laser modulation of human immune system: Inhibition of lymphocyte proliferation by a gallium‐arsenide laser at low energy
Authors: Ohta Akihide , Abergel R. Patrick , Uitto Jouni
Published: March 2007

Cultured human lymphocytes were subjected to irradiation with a gallium‐arsenide laser at energy fluence varying from 2.17 to 651 mJ/cm2, and the cell proliferation was assessed by [3H]thymidine incorporation. Both mitogenic proliferation in response to phytohemagglutinin and spontaneous cell proliferation were markedly inhibited by the laser irradiation at energy fluence as low as 10.85 mJ/cm2. Similarly, the functional response of cells to antigen stimulation in a one‐way mixed‐lymphocyte reaction was also diminished as a result of laser irradiation. The results indicate that laser irradiation at low energy can interfere with immune system in vitro, and similar modulation could potentially occur in human subjects exposed to laser irradiation in vivo.
Effect of hematoporphyrin derivative 2 on estrogen receptors in experimental mammary tumors
Authors: Lanzafame Raymond J. , Rogers David W. , Naim John O. , Herrera H. Raul , Hinshaw J. Raymond
Published: March 2007

This study reports the effect of hematoporphyrin derivative 2 (HPD2) on estrogen receptors (ER) in the animal model used to develop the clinical ER assay. Fifty 200‐g female Sprague‐Dawley rats were given 20 mg of dimethylbenzanthracene by gastric intubation. Spontaneous mammary tumors occurred in 35 animals. Animals were anesthetized and 50% of each tumor was removed when the tumors were 2 cm in diameter. Animals were then randomized to receive 5 mg/kg (group A), 10 mg/kg (group B), or 0 mg/kg (group C) HPD2 intravenously 48 hours after biopsy. The remaining tumor was excised 48 hours post HPD2 injection. All samples were weighed, placed on ice, and frozen to −70°C. ER assay was performed by batch run. Results (fmol/mg cytosol) were as follows: All animals (n=35) pre HPD2 34.2 ± 5.4, post HPD2 34.2 ± 5.8; group A: (n=11) pre HPD2 33.9 ± 7.9, post HPD2 37.1 ± 7.8; group B: (n=13) pre HPD2 29.2 ± 3.8, post HPD2 25.5 ± 3.6; group C: (n=11) pre HPD2 40.3 ± 5.2, post HPD2 41.5 ± 7.9. HPD2 does not affect ER in this animal model. Confirmatory studies with human tumor material must be completed.
Thermographic study of laser on arteries
Authors: Mnitentag J. , Marques E. F. , Ribeiro M. P. , Braga G. A. , Navarro M. R. , Veratti A. B. , Armelin E. , Macruz R. , Jatene A. D.
Published: March 2007

We analyzed the different effects of CO2, Nd‐YAG, and argon lasers on aorta by using a Thermovision infrared system that registered the laser interaction with mongrel dog aorta. The images (thermograms) obtained were processed by a computer, which associated each area of the same temperature with a determined color. These thermograms were compared to histological analysis of the respective samples and the following results were obtained: (1) After the application of each laser there is very little propagation of heat in tissue. (2) The CO2 laser makes tissue reach 100°C in less than 0.05 seconds. (3) The heat dissipation time was higher with the Nd‐YAG laser due to higher scattering on tissue.

Based on this research we conclude that the CO2 laser was best absorbed, the Nd‐YAG laser penetrated human tissue with the best results, and the argon laser had the most significant backscattering.
Discrimination of normal and atherosclerotic aorta by laser‐induced fluorescence
Authors: Deckelbaum Lawrence I. , Lam Joseph K. , Cabin Henry S. , Clubb K. Soni , Long Marshall B.
Published: March 2007

Precise targeting of laser energy to atherosclerotic plaque is crucial for the safe performance of laser angioplasty. The present study was designed to evaluate whether laser‐induced fluorescence could distinguish atherosclerotic from normal aorta. Segments of human aorta obtained at necropsy were classified grossly and histologically as normal aorta (n = 7), thin yellow fatty plaque (n = 5), and thick white atheromatous plaque (n = 9), and analyzed by laser‐induced fluorescence spectroscopy using a pulsed nitrogen laser. Fluorescence spectra were recorded over a wavelength range from 385 to 725 nm. Normal specimens had maximal fluorescence intensity at 514 nm. A prominent fluorescence peak at 448 nm was present in specimens characterized as white atheromatous plaque and at 538 nm in specimens characterized as yellow fatty plaque. The ratios of fluorescence intensity at 448 nm/514 nm and at 538 nm/514 nm correctly classified all specimens according to their gross and histologic type (p < .001). Thus, a “smart” laser angioplasty catheter system might incorporate low‐power laser radiation for arterial fluorescence spectroscopy to guide delivery of high‐power laser radiation for plaque ablation.
Dental pulp exposed to the CO2 laser beam
Authors: Melcer J. , Chaumette M.‐T. , Melcer F.
Published: March 2007

Traumatic inflammation due to application of CO2 laser beam on teeth (dentin and pulp) of Beagle dogs and Macaca Monkeys, stimulate in dentino‐pulpal tissue morphological phenomena studied after 5 days, 1, and 3 months by microscopy and microradiography. After a dentin exposure to a density of energy from 2 × 103 J/cm2, the first cell layers of the pulp tissue show a rarefaction and a cellular degeneration, followed by a neoformation of cacified dentin, of about 300 μm thick in 3 months, due to the excitation of odontoblasts or produced by pulpal cells functioning before. A density of energy of 103J/cm2 order applied to the pulp beads to its partial necrosis, to various inflammatory aspects and to a quasi‐constant regeneration by a neo‐dentin bridge of 200 μm at 1 month. The analysis of cell activity seems able to be investigated from this method.
Comparison of the maximum coagulation depth in human skin for different types of medical lasers
Authors: Haina D. , Landthaler M. , Braun‐Falco O. , Waidelich W.
Published: March 2007

The values for the maximum coagulation depth (MCD) of various types of lasers which are specified in the literature are not comparable, because often different irradiation times were used. MCD depends not only on the wavelength of laser light, but also on the time of action of the laser beam, because of heat transfer.

In excised human skin MCD was determined histologically for irradiation with the argon laser, Nd:YAG laser, and CO2 laser. Extending the irradiation time from 0.2 s to 10 s results in a 4–6‐fold increase in MCD. Coagulation experiments performed with a soldering iron have shown results similar to those obtained with the CO2 laser. Enlargement of the laser‐beam diameter from 1 to 2 mm leads to a 50% increase in MCD. Additional chilling of the skin with water during laser irradiation protects the skin from evaporation, and the values for MCD increase to 3.5 mm for the argon laser and 5.5 mm for Nd:YAG laser. Detailed knowledge of the MCD is necessary to obtain the desired therapeutic effect, and also to avoid unwanted effects.
Microsecond‐long flash photography of laser‐induced ablation of biliary and urinary calculi
Authors: PhD Peter Teng , Nishioka Norman S. , Farinelli William A. , Anderson R. Rox , Deutsch Thomas F.
Published: March 2007

High‐speed flash photographs of laser‐induced fragmentation of biliary and renal calculi under water were obtained using one‐microsecond‐long dye‐laser pulses for both illumination and ablation. The photographs show the presence of a bubble with irregularities on the surface that suggest the early presence of debris or microbubbles. Fragmentation occurs before the bubble collapses, suggesting that fragmentation is due to laser‐induced acoustic transients rather than to collapse of a laser‐induced cavitation bubble.
Laser catheter ablation of simulated ventricular tachycardia
Authors: Vincent G. Michael , Fox Jolene , Benedick Bruce A. , Hunter John , Dixon John A.
Published: March 2007

Catheter‐directed laser injury of the left ventricular endocardium for ablation of ventricular tachycardia was studied in a canine model of simulated ventricular tachycardia. Bipolar plunge electrodes were placed at thoracotomy into the left ventricular endocardium in nine anesthetized dogs. Ventricular tachycardia was simulated by pacing at 200 beats per minute. After four days of recovery, catheter‐directed neodymium:yttrium‐aluminum‐garnet laser injury was produced at the site of earliest recorded electrical activation during pacing tachycardia as detected by endocardial catheter mapping. Immediately after laser injury and again five days after injury, pacing tachycardia was attempted. Failure to pace after laser injury was defined as successful arrhythmia ablation.

In 3/9 (33%) experiments, the laser‐injured tissue surrounded the tachycardia source (pacing wires), and pacing‐simulated ventricular tachycardia was prevented. When the laser injury did not involve the tachycardia source, 6/9 animals, due to limitations of the mapping system, pacing was not prevented.

One animal developed sustained ventricular tachycardia during laser injury, with conversion to sinus rhythm by lidocaine. One animal, without recognized ventricular arrhythmia, died five days after laser injury. No unusual findings were noted at autopsy.

These preliminary data suggest that catheter‐directed laser‐induced injury can ablate arrhythmia sources. Further studies are indicated in a more physiologic model, and the safety and risks of the procedure need further evaluation.
Laser injury to multiple retinal foci
Authors: Kearney John J. , Cohen Howard B. , Stuck Bruce E. , Rudd G. Patrick , Beresky Donald E. , Wertz Fleming D.
Published: March 2007

A 21‐year‐old man received and accidental laser injury to three separate foci of the retina of his right eye from a Q‐swithched Nd:YAG laser target disignator emitting at 1,064 nm, operating at 10 Hz, with a pulse duration of 20 ns. The nominal output of this device was 50 mJ, and the diameter of the output beam was approximately 4 cm. The extent of injury consisted of retinal necrosis, subretinal hemorrhage, vitreous hemorrhage, and striate retinopathy. The initial visual acuity was 20/400, but quickly recovered to 20/30. One year following injury the visual acuity was 20/40. Mature chorioretinal scars were apparent. A preretinal membrane was evident with marked wrinkling effect on the macular area of the retina.
Energy requirements for osteotomy of femora and tibiae with a moving CW CO2 laser
Authors: Biyikli PhD Suleyman , Modest Michael F.
Published: March 2007

This paper describes the laser cutting and the amount of laser energy needed to remove a unit mass of compact or cancellous human cadaveric bones (“heat‐of‐removal”) by using a CO2 laser. Data are collected under different operating conditions, such as laser power, scanning speed, and lens focusing for fresh and fixed human bones from male and female femora and tibiae samples with ages varying between 28 and 73 years old. The aim of the present experiments was to demonstrate the feasibility of laser osteotomy, to find the energy requirements for given groove depths or bone removal rates, and to shed some light on optimum conditions for laser osteotomy. Only cadaveric bones were used in this study, since the present aim did not include the investigation of heating rates and the extent and effect of thermal necrosis adjacent to the cut. In vivo properties may be somewhat different from those of cadaveric material. While blood circulation within the living bone may contribute to the laser cutting characteristics, it cannot be addressed here. Experiments showed that very deep cuts are difficult to achieve with a CO2 laser, as at high‐power/low‐scan‐speed the groove becomes rather wide, with unacceptable thermal damage adjacent to the cut, while multiple passes do not easily attain large depths. There was no significant difference for the laser heat‐of‐removal for different age groups and for male and female samples. The laser heat‐of‐removal was found to be higher for compact bone than for cancellous bone samples. Comparison of cross‐sections of the cuts with an existing model gave good agreement.
Microscopically proven cure of actinic cheilitis by CO2 laser
Authors: Whitaker Duane C.
Published: March 2007

Actinic cheilitis is a premalignant condition of the lip frequently seen in individuals with chronic sun exposure. Various surgical and ablative therapies have been employed, but microscopic outcome has not been well documented. In this study CO2 laser ablation was performed on 16 patients with actinic cheilitis that involved 50% or greater of the lower lip. Pre‐ and post‐treatment biopsies were performed to assess results of therapy. After treatment all 16 patients showed microscopic clearing of atypical cells and disorderly maturation characteristic of actinic cheilitis. One patient had clinical recurrence at 14 months, which was retreated with laser.
Remote biomedical spectroscopic imaging of human artery wall
Authors: Hoyt C. C. , Richards‐Kortum R. R. , Costello B. , Sacks B. A. , Kittrell C. , Ratliff N. B. , Kramer J. R. , Feld M. S.
Published: March 2007

We discuss a general technique, laser spectroscopic imaging (LSI), remote acquisition of spectroscopic images of biological tissues and tissue conditions. The technique employs laser‐induced spectroscopic signals, collected and transmitted via an array of optical fibers, to produce discrete pixels of information from which a map or image of a desired tissue characteristic is constructed. We describe a prototype LSI catheter that produces spectral images of the interior of human arteries for diagnosis of atherosclerosis. The diagnostic is based on the fact that normal artery wall and atherosclerotic plaque exhibit distinct fluorescence spectra in the 500–650 nm range when excited by 476‐nm laser light; the fluorescence from blood is minimal. The catheter is composed of 19 optical fibers enclosed in a transparent, protective shield. Argon ion laser radiation is used for excitation, and an optical multichannel spectral analyzer is used for detection. Sequential sampling is used to minimize crosstalk among fibers and reduce blurring of the image. Computer‐processed 19‐pixel spectroscopic images are produced of fresh cadaver artery in vitro. Regions of normal tissue, plaque, and blood are identified, and the diagnoses are confirmed histologically and by direct spatial correlation. The results demonstrate the concept of using this laser catheter system for real‐time imaging.
Effect of laser‐heated tip angioplasty on human atherosclerotic coronary arteries
Authors: Morcos N. Charle , Berns Michael , Henry Walter L.
Published: March 2007

Effects of laser‐heated‐tip angioplasty on arteries is not fully understood. We report histology, ultrasound image properties, and vasoreactivity of human atherosclerotic cornary arteries after exposure to the laser‐heated tip catheter. Segments of isolated human coronary arteries were obtained within 5–8 hours postmortem. Side branches were ligated and perfused with Krebs‐Ringer solution. Coronary occlusions were recanalized during perfusion using a 1.5‐mm tip heated twice with a 10 W argon laser for 10 seconds while two‐dimensional 12‐MHz ultrasound images were recorded. Images documented vessel recanalization and an increase in ultrasound refractile properties of vessel walls adjacent and 2–5 mm distal to the heated tip. Histologic studies showed charring along the neolumen and extensive coagulation pattern within the plaque. Vasoreactivity was assessed by measuring flow rate changes during perfusion with 100 ml of 10−5 M serotonin followed by washout with serotonin‐free solution. Recanalized arteries showed a 50% increase in magnitude of vasospasm, which was persistent for 5 hours, compared to control atherosclerotic vessels, which relaxed within 30 minutes. In conclusion, laser‐heated‐tip‐irradiated vessels demonstrated plaque coagulation, increased ultrasound refractile properties of plaque, and increased vasospasm, which persisted for several hours.
Pulsed laser angioplasty: Wavelength power and energy dependencies relevant to clinical application
Authors: Litvack Frank , Grundfest Warren S. , Goldenberg Tsvi , Laudenslager James , Pacala Thomas , Segalowitz Jacob , Forrester James S.
Published: March 2007

Despite the theoretical advantages of submicrosecond pulsing for clinical laser angioplasty systems, the optimal laser parameters for clinical application are undefined. Further, the enormous peak powers achieved by submicrosecond pulses destroy available fiberoptics. We irradiated 797 segments of cadaver atherosclerotic aorta with nanosecond pulses at 266, 308, 355, 532, and 1064 nanometers. Effective cutting occurred at lower energy fluences in the ultraviolet than in the visible or infrared. For 308 nanometers, at any energy density, number of pulses to perforation was relatively independent of power density. Therefore, long‐pulse ultraviolet wavelengths which could be transmitted through fiberoptics were identified as well suited for a clinical, submicrosecond pulsed laser angioplasty system.
Percutaneous, in vivo excimer laser angioplasty: Results in two experimental animal models
Authors: Isner Jeffrey M. , Gal Dov , Steg P. Gabriel , DeJesus Stephen T. , Rongione Anthony J. , Halaburka Kimberly R. , Slovenkai Geralyn A. , Clarke Richard H.
Published: March 2007

Pulsed ultraviolet light from an excimer laser was successfully transmitted via conventional fused silica optical fibers and used to accomplish recanalization of stenotic or totally occluded arteries in an intact, flowing blood field of two atherosclerotic animal models. The fibers, 300–600 μm in diameter, were delivered percutaneously in wire‐guided multilumen catheters and then used to transmit wavelengths of 308 or 351 nm from excimer lasers with pulse durations of 12 nsec or less. Lesions from 70–100% diameter narrowing, and 0.6 to 5.5 cm in length were successfully recanalized (<50% residual diameter narrowing) in eight animals, using 3–4 J/cm2/pulse, 10–50 Hz, and 48–370‐sec cumulative exposure. Necropsy examination in six of the eight animals disclosed no signs of thermal injury. Perforations were observed in four of eight animals. Thus, while use of an excimer laser power source did not obviate vascular perforation as a complication of laser angioplasty, these preliminary results indicate that energies of pulsed ultraviolet light sufficient to ablate atherosclerotic plaque can be both transmitted via conventional fused silica optical fibers and used successfully within an intact, flowing blood field. It may therefore be possible to use pulsed ultraviolet light from an excimer laser to accomplish percutaneous ablation of atherosclerotic arterial obstructions in humans.
Laserthermia: A new computer‐controlled contact Nd:YAG system for interstitial local hyperthermia
Authors: Daikuzono Norio , Suzuki Soutaro , Tajiri Hisao , Tsunekawa Hiroshi , Ohyama Masaru , Joffe Stephen N.
Published: March 2007

Contact Nd:YAG laser surgery is assuming a greater importance in endoscopic and open surgery, allowing coagulation, cutting, and vaporization with greater precision and safety. A new contact probe allows a wider angle of irradiation and diffusion of low‐power laser energy (less than 5 watts), using the interstitial technique for producing local hyperthermia. Temperature sensors that monitor continuously can be placed directly into the surrounding tissue or tumor. Using a computer program interfaced with the laser and sensors, a controlled and stable temperature (e.g., 42°C) can be produced in a known volume of tissue over a prolonged period of time (e.g., 20–40 min). This new laserthermia system, using a single low‐power Nd:YAG laser for interstitial local hyperthermia, may offer many new advantages in the experimental treatment and clinical management of carcinoma. A multiple system is now being developed.
Carbon dioxide laser effect on platelet function and surface ultrastructure in vitro
Authors: Eldar Michael , Gal Dov , Djaldetti Meir , Douer Dan , Rosner Ester , Katzir Abraham , Neufeld Henry N. , Battler Alexander
Published: March 2007

Platelet aggregation may be an important factor in the feasibility of transcatheter laser angioplasty. The in vitro effects of increasing doses of CO2 laser irradiation on platelet number, function, and surface ultrastructure were examined. Results indicated a progressive doseresponse reduction of both platelet number and function following laser irradiation. By scanning electron microscopy the irradiated platelets showed dose‐related changes in pseudopods as well as progressive damage of the cell membrane.
Pathology of laser‐induced experimental aneurysms
Authors: Ammirati Mario , Ostertag Helmut , Rabin Eleanor , Ciric Ivan
Published: March 2007

Aneurysms were produced in the common carotid artery of 35 rats by milliwatt CO2 laser welding of an adventitia patch over a hole. The aneurysmal sac was formed by collagen; the lumen was covered by an endothelial‐like lining and partially thrombosed. The pathology of these aneurysms is similar to spontaneously occurring intracranial human aneurysms. This aneurysm model has properties (reliability, spontaneous bleeding tendency, minimal vessel manipulation, and pathological features) that make it theoretically advantageous for the induction of experimental intracranial aneurysms in larger animals.
Plaque‐media rewelding with reversible tissue optical property changes during receptive CW Nd:YAG laser exposure
Authors: Spears J. Richard , James Leslie M. , Leonard Bradley M. , Sinclair I. Nigel , Jenkins Ronald D. , Motamedi Massoud , Sinofsky Edward L.
Published: March 2007

Laser dosimetry for thermal fusion of plaque‐wall separations during laser balloon angioplasty (LBA) is dependent upon the optical properties of the atheromatous arterial wall during one or more exposures to cw Nd:YAG laser radiation. An integrating sphere technique was used to measure relative transmission and reflection continuously during irradiation of human postmortem atheromatous aortic sections. Tissue luminal surface temperature was recorded continuously with a thermographic video imager during repetitive 20–30‐sec, 8–15‐watt exposure of a 3‐mm nominal spot. In all specimens, transmission fell progressively during each exposure by 10–70% of baseline values. This effect was reversible with normalization of transmission during the initial phase of each subsequent exposure. Changes in transmission were inversely related to temperature over a 50–170°C range, wherease relative reflection remained constant. Accompanying reversible transmission changes was the observation that the weld strength of plaqueaortic wall separations was unchanged by repetitive laser welding and tissue separation of individual sections. In conclusion, temperaturedependent reversible optical and physical properties of plaque occur during exposure to 1.06 μm cw laser radiation.
Photodynamic assay of light distributions in tissue phantoms
Authors: Mason Larry W. , Welch A. J. , van Gemert Martin J. C.
Published: March 2007

The distribution of light in tissues of varying blood content has been modeled using a gel agar system as a tissue phantom. Hematoporphyrin derivative (Photofrin I or HpD) was suspended in gels, along with a chemical indicator of its cytotoxic intermediate (singlet oxygen), and various amounts of red blood cells. The singlet oxygen detector used was tryptophan and its oxidation product. Qualitative analysis of the tryptophan photoproduct was determined using high‐pressure liquid chromatography analysis of individual gel sections. The relative amount of photoproduct was used as a measure of the fluence of actinic light at a given depth within the tissue phantoms. In this manner, the relative activation efficiencies of HpD were determined for light from an argon laser (mainly 488 and 514.5 nm) and an argon‐pumped dye laser (630 nm).
Closure of rabbit ileum enterotomies with the argon and CO2 lasers: Bursting pressures and histology
Authors: Vlasak Jerry W. , Kopchok George E. , White Rodney A.
Published: March 2007

In this study, we examined short‐term strength and histology of experimental argon and CO2 laser‐welded and control‐sutured enterotomies in a rabbit model. Longitudinal 1.0‐cm enterotomies were closed with the argon laser at 0.5 (n = 10) or 1.0 (n = 10) W power and a spot diameter of 2.8 mm resulting in energy fluences of 230 and 450 J/cm2, respectively. Similar enterotomies were closed using the CO2 laser at 0.5 (n = 10) or 1.0 (n = 10) W power and a spot diameter of 1.2 mm, resulting in energy fluences of 1,360 and 2,730 J/cm2. In all closures, continuous wave laser was delivered for 30 seconds. Using a pressuremonitored infusion system with normal saline, the pressure required to burst each weld as well as sutured controls (n = 10) was recorded approximately 1 minute following fusion. Mean bursting pressures for the argon laser at 0.5 W and 1.0 W were 34.1 ± 19.4 mm Hg (mean ± SD) and 17.3 ± 8.3 mm Hg, respectively, and for the CO2 laser were 23.5 ± 12.0 mm Hg and 31.8 ± 15.6 mm Hg, respectively. Sutured controls leaked at 45.2 ± 12.0 mm Hg. With the exception of argon‐laser welds at an energy fluence of 450 J/cm2, which were less than sutured repairs, the bursting pressures for welded closures were not significantly different from the sutured controls (Student's t distribution, P < .05). Histologic examination of both types of welds demonstrated a fibrin and red blood cell coagulum bridging the anastamosis, with some evidence of mild thermal injury at the mucosa. These findings suggest that both the argon and the CO2 lasers present an alternative means to suturing in closure of small‐bowel enterotomies.
Transport of biologically active material in laser cutting
Authors: Frenz Martin , Mathezloic Fabien , Stoffel Michael H. S. , Zweig Adrian D. , Romano Valerio , Weber Heinz P.
Published: March 2007

The transport of biologically active material during laser cutting with CO2 and Er lasers is demonstrated. This transport mechanism removes particles from the surface of gelatin, agar, and liver samples into the depth of the laser‐formed craters. The transport phenomenon is explained by a contraction and condensation of enclosed hot water vapor. We show by cultivating transported bacteria in agar that biological particles can survive the shock of the transport. Determination of the numbers of active cells evidences a more pronounced activity of the cultivated bacteria after impact with an Er laser than with a CO2 laser.
Low‐energy CO2 laser intestinal anastomosis: An experimental study
Authors: Rochkind Semion , Rabau Micha Y. , Goldman Gideon , Bar‐Nea Lilian , Wiznitzer Theodor
Published: March 2007

Intestinal anastomosis was performed in 17 Wistar rats via tissue welding by the low‐energy CO2 laser.

The postoperative course in the animals studied was uneventful. The integrity of the anastomosis was investigated manometrically, immediately upon completion of the anastomosis as well as 20 days later. Ten additional Wistar rats served as controls in which conventional interrupted one‐layer anastomosis was performed. The results show a significant superiority of the intestinal anastomoses that were constructed by means of laser tissue welding. The time to complete the anastomosis was also significantly shorter when laser rather than manual suturing was used.

Serial histological examinations for up to 90 days following surgery revealed complete healing and epithelization of the anastomotic site.
Effect of CO2 and blood media on laser probe temperature
Authors: Silverman Steven H. , Khoury Adib I. , Seeger James M. , Tomaru Takanoubu , Hawkins Irvin F. , Abela George S.
Published: March 2007

Blood may limit laser ablation of arterial plaque by decreasing thermal energy transfer from metal‐capped probes to arterial occlusions. Since a gas is a good insulator of heat, CO2 may be a better medium for laser recanalization. To study this possibility, a metal‐capped fiber was positioned in a segment of blood‐filled polyethylene tubing and activated with an argon laser. Probe temperatures were measured in blood and as the blood was displaced by flowing CO2 gas. Probe temperatures were higher at all powers studied in CO2 gas than in blood. Maximum probe temperatures averaged 518 ± 24°C after CO2 infusion versus 320 ± 7°C in blood, (P < 0.0001). Blood aggregate formation was noted on the probe surface in blood but not in CO2 medium. Thus CO2 gas may be a preferable medium for laser recanalization, since higher probe temperatures are achieved, and the probe surface remains free of insulating blood coagulate.
In vitro optical properties of human and canine brain and urinary bladder tissues at 633 nm
Authors: Splinter Robert , Cheong Wai Fung , van Gemert Martin J. C. , Welch A. J.
Published: March 2007

Absorption and scattering coefficients and scattering anisotropy factor are presented for human and canine cadaver tissues at the helium‐neon wavelength (633 nm). Measurements were performed with an integrating sphere arrangement and analyzed with the diffusion approximation of the equation of radiative transfer adapted to Kubelka‐Munk techniques.
Dynamic aspects of rhodamine dye photosensitization in vitro with an argon‐ion Laser
Authors: Shea Christopher R. , Chen Norah , Hasan Tayyaba
Published: March 2007

Phototoxicity in cultured human bladder carcinoma cells treated by 514.5‐nm argon‐ion laser irradiation plus rhodamine‐123 (R123) or tetrabromo‐R123 (TBR) was assessed by counting total cell number and percent viability at 1, 24, 48, 72, and 96 h after irradiation. TBR was markedly more efficient than R123 at causing both reversible and persistent phototoxic cytostasis. Furthermore, TBR photosensitization caused net cytocidal effects at 0.5 J/cm2, which were not seen with R123 photosensitization at up to 40 J/cm2. The reduced phototoxic efficiency of R123 as compared to TBR appears, in part, to reflect the presence of a fraction of cells refractory to R123 photosensitization.
In vitro photosensitization II. An electron microscopy study of cellular destruction with mono‐L‐aspartyl chlorin e6and photofrin II
Authors: Roberts W. Gregory , Liaw L.‐H. L. , Berns Michael W.
Published: March 2007

Primary sites of subcellular destruction with photofrin II (PfII) and mono‐L‐aspartyl chlorin e6(MACE) were determined by transmission electron microscopy (TEM).Potorous tridactylus(PTK2) cells were grown in Rose chambers and incubated for 24 hr with a sensitizer concentration sufficient to provide 100% mortality. Cells were irradiated with laser light and fixed and processed for electron microscopy at various times post‐irradiation. The results indicate that PfII initially destroys mitochondria, whereas MACE destroys lysosomes. Both conclusions are consistent with fluorescence subcellular localization studies.
Change in laser‐induced arterial fluorescence during ablation of atherosclerotic plaque
Authors: Cutruzzola Francis W. , Stetz Mark L. , O'Brien Kenneth M. , Gindi Gene R. , Laifer Lawrence I. , Garrand Timothy J. , Deckelbaum Lawrence I.
Published: March 2007

Analysis of the change in arterial fluorescence during plaque ablation may provide the basis for developing a fluorescence guided ablation system capable of selective plaque ablation without risk of vessel perforation. Accordingly, fluorescence spectra were recorded from 91 normal and 91 atherosclerotic specimens of cadaveric human aorta. The ratio of the laser‐induced fluorescence intensity at 382 nm to 430 nm (LIF ratio) was capable of classifying these specimens with an 89% accuracy with a threshold value of 1.8 (atherosclerotic ⩾1.8, normal <1.8). To characterize the change in fluorescence during plaque ablation, mechanical plaque ablation with a cold microtome was performed on 16 atherosclerotic aortic specimens. Fluorescence spectra were recorded serially after each 100 μm of plaque ablation; recordings revealed a change in fluorescence spectra from atherosclerotic to a normal pattern. With an LIF ratio of 1.8 to signal termination of plaque ablation, 15 of the atherosclerotic plaques had a residual plaque thickness less than 200 μm; one specimen had a residual plaque thickness of 300 μm. No specimen demonstrated ablation of the media. There was a statistically significant correlation between LIF ratio and plaque thickness (r = .73, P < .001), but considerable variation in LIF ratio existed at each thickness. Therefore, laser‐induced fluorescence spectroscopy is capable of discriminating atherosclerotic from normal aorta and of signaling completion of plaque ablation.
Excimer ablation of human intervertebral disc at 308 nanometers
Authors: Wolgin Mark , Finkenberg John , Papaioannou Thanassis , Segil Clive , Soma Charles , Grundfest Warren
Published: March 2007

Excimer laser energy, which has been shown to photoablate tissue at a precisely controllable rate with minimal thermal damage, was applied to human intervertebral disc in an effort to develop a technique for percutaneous discectomy. Cadaveric samples of human disc were used. Excimer laser energy was produced by a XeCl, magnetically switched, long‐pulse laser working at 308 nm, 20 Hz. Annulus tissue of approximately 1 mm thickness was placed in contact with the output tip of a 400 μm core diameter quartz fiber, and measurements of ablation rate were made at different radiant exposures. Ablation rates were found to vary linearly with radiant exposure, from 0.7 μm/pulse at 10 mJ/mm2 to 11.0 μm/pulse at 55 mJ/mm2, with a correlation coefficient of 0.984. Threshold radiant exposure, calculated by extrapolation, was found to be about 7 mJ/mm2. Histologic analysis showed a minimum of thermal damage in these specimens, and when ablated with modification to maintain constant fiber‐tissue contact, thermal injury was nearly absent, as compared to samples ablated with Nd:YAG through a contact probe. Thermographic analysis, performed using the AGA 782 Digital Thermography system, showed increasing temperature with increasing radiant exposure, with a maximum temperature of 47.2°C at 55 mJ/mm2. In that precise tissue ablation was demonstrated with minimal generated heat, and excimer energy at 308 nm is transmissible through fiber optics, excimer holds great promise for the development of a percutaneous discectomy technique.