bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractPrecise 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

AbstractTraumatic 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

AbstractThe 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

AbstractHigh‐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

AbstractCatheter‐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

AbstractA 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

AbstractThis 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

AbstractActinic 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

AbstractWe 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

AbstractEffects 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

AbstractDespite 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

AbstractPulsed 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

AbstractContact 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

AbstractPlatelet 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

AbstractAneurysms 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

AbstractLaser 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

AbstractThe 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

AbstractIn 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

AbstractThe 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.