bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rate process parameters of albumen
Authors: Yang Y. , Welch A. J. , Rylander H. G. 
Published: March 2007

AbstractBoth egg white and egg yolk are excellent media for studying photocoagulation due to thermal response of tissue to laser light. They are readily available, consistently the same, and provide a standard biological medium for different labs to compare results. The irradiation parameters for laser coagulation of these media depend upon their optical properties and their temperature‐dependent rate reactions.Estimates of the rate process damage coefficients were obtained from constant‐temperature water bath experiments. The activation energy E for egg white was estimated to be 92,000 (cal/(M*K)) and the integration constant A was found to be 3.8 × 1057 (second−1).
Fluorescence guided excimer laser ablation of intervertebral discs in vitro
Authors: Buchelts Martin , Katterschafka Thomas , Horvat Rainhard , Kutschera Hans‐Paul , Kickinger Wolfgang , Laufer Günther 
Published: March 2007

AbstractLaser induced fluorescence of intervertebral discs was investigated in this study for the first time in order to develop a fluorescence guided percutaneous excimer laser discectomy. For this purpose 35 human cadaveric intervetebral discs from level L1 to L5 were irradiated with a 308 nm XeCl excimer laser with a 60 nsec pulse width at 10, 20 and 30 mj/mm2. Laser light was transmitted over a 1000 μm core optical fiber. Fluorescence emitted from the irradiated tissue was transmitted back over the same fiber over a semireflective mirror to another optical fiber, coupled into a spectrograph and O‐SMA optical simultaneous multichannel spectral analyzer system. The spectral lineshape of both the annulus fibrosus and the nucleus pulposus was characterized by a broadband emission between 320 nm and 616 nm with 3 peak emissions at 358, 423 and 457 nm. Relative intensities were calculated by forming two ratios of the peak intensities of the three peaks (R1 = I 423 / I 358; R2 = I 423 / I 457). Statistical analysis of both ratios revealed a highly significant discrimination between annulus fibrosus and nucleus pulposus (P < 0.001). Under penetrating conditions multiple recorded spectra showed the spectral profile of subsequently ablated nucleus and annulus. The results of this study demonstrate that discrimination between annulus fibrosus and nucleus pulposus by excimer laser‐induced fluorescence is feasible under laboratory conditions. Fluorescence spectroscopy could possibly be developed into a valuable guiding system for percutaneous laser discectomy.
Laser resistant stainless steel endotracheal tube: Experimental and clinical evaluation
Authors: Fried Marvin P. , Rao Mallampati S. , Liu Fang‐Cheng , Kaplan Stuart , Caminear David S. , Samonte Bernadette R. 
Published: March 2007

AbstractA fire due to endotracheal tube (ET) ignition is a catastrophic event that may occur during laser surgery of the upper airway, regardless of the wavelength utilized. Although methods exist that permit laser surgery without an ET, this is frequently not feasible. The current investigation was undertaken to evaluate the efficacy of a double‐cuffed stainless steel ET, first in the laboratory and subsequently in a clinical setting. Bench testing was performed using CO2, (both standard and milliwatt) and KTP/532 lasers. Only the distal polyvinyl chloride cuffed end of the tube was potentially ignitable, however, the appropriate use of saline to fill the cuffs allowed only for cuff perforation without ignition. Canine testing was performed in 10 animals: 4 dogs were intubated from 3 to 4.5 hours with the laser resistant stainless steel endotracheal tube (LRSS‐ET) (Laser‐Flex Tracheal Tube; Mallinckrodt Anesthesia Products, St. Louis, MO) and 2 with an aluminum tape wrapped red rubber ET. Visual and histological examination were performed in both groups at 3 and 7 days. Four dogs underwent CO2, laser laryngeal surgery with visual and histological examination performed at 7 days postoperatively. No untoward effects could be demonstrated due to the LRSS‐ET. A clinical study was then performed in 24 patients who underwent laser surgery of the upper aerodigestive tract with either a CO2 or KTP/532 laser. In all cases ventilation was adequate, the shaft of the LRSS‐ET proved impervious to the laser, and the distal end of the tube protected the tracheobronchial tree safely. It is concluded that the LRSS‐ET is effective and safe in both CO2 and KTP‐532 laser surgery of the upper airway when ET intubation is deemed necessary.
Optical properties of human sclera, and their consequences for transscleral laser applications
Authors: Vogel Alfred , Dlugos Christian , Nuffer Roland , Birngruber Reginald 
Published: March 2007

AbstractThe spectral dependence of the optical properties of human sclera adjacent to the limbus was investigated and related to the potentials of transscleral photocoagulation. The total transmission, absorption, and reflection, as well as the angular distribution of the transmitted and reflected light were measured at five laser wavelengths (442 nm, 514 nm, 633 nm, 804 nm, and 1,064 nm), both for noncontact and contact applications. Absorption and scattering coefficients were determined using the Kubelka‐Munk model for light propagation through a scattering tissue. The scleral transmission is only 6% at 442 nm but increases to 35% at 804 nm and to 53% at 1,064 nm. The absorption is high at short wavelengths with 40% at 442 nm but it is only 6% at 804 nm and 1,064 nm. The reflection is generally higher than 40% and shows little wavelength dependence. The transmitted light is scattered diffusely at short wavelengths, but at 804 nm and 1,064 nm it exhibits a fairly narrow angular distribution in forward direction. Fiber contact leads to an increase of transmission, with a factor of 3.5 at 442 nm, of 2.0 at 804 nm, and 1.5 at 1,064 nm. Our results indicate that the diode laser (804 nm) and the Nd:YAG laser (1,064 nm) with contact delivery are best suited for transscleral photocoagulation.
Laser trabecular ablation (LTA)
Authors: Hill Richard A. , Baerveldt George , Ozler Serdar A. , Pickford Michael , Profeta Glen A. , Berns Michael W. 
Published: March 2007

AbstractAs part of a pilot study for glaucoma surgery, the use of 3 infrared solid state lasers with 4 fiber optic delivery systems to ablate human trabecular meshwork was investigated. Laser trabecular ablation (LTA) was attempted with the Erbium:YAG (2.94 μm), Erbium:YSGG (2.79 μm), and Holmium:YSGG (2.1 μm) lasers. Laser energy was delivered as a single pulse (250 μs) by tissue fiber optic contact with low hydroxyl‐fused silica (200 and 500 μm), zirconium fluoride (250 μm), or sapphire (250 μm) fiber optics. Total energy required and thermal effects decreased as laser wavelength increased. LTA was best achieved at 2.94 μm (4 mJ total energy; energy densities = 8.2–12.7 J/cm2; pulse length 250 μs) with average thermal damage zones of 5.3–10.3 ± 1.3–2.4 μm (means ± SDs) to contiguous structures. This finding has potential applications in the surgical treatment of open‐angle and congenital glaucoma and may minimize failure rates seen in other types of surgery on the trabecular meshwork where disrupted trabecular meshwork is not removed.
Photodynamic therapy in gastrointestinal cancer
Authors: Karanov Strashimir , Shopova Maria , Getov Hristo 
Published: March 2007

AbstractSix patients with an early stage of gastrointestinal (GI) cancer (T1NoMo, stage I) were successfully treated by photodynamic therapy (PDT) as follows: esophagus‐1, stomach‐2, rectum‐3. The patients were photosensitized 72 hrs prior to treatment with pure hematoporphyrin at a dose of 5.10−6 kg/kg b.w. in a slow intravenous infusion. Argon‐pumped dye laser light at 0.630 μm wave‐length was used in single and multiple treatment sessions with the power density ranging from 0.015 to 0.192 W.m−2 and a dose varying from 0.320 to 1.600 kJ.m−2. Tumor eradication (complete response) was obtained in each of the patients. No early or late treatment related complications were recorded. The patients were followed‐up in the course of 7–16 months after treatment and no local recurrence or general development of disease (metastases) were reported. PDT in the early stage of GI carcinoma was recognized as a radical therapeutic method in clinical oncology.
Direct comparison of in‐vitro and in‐vivo photofrin‐II mediated photosensitization using a pulsed KTP pumped dye laser and a continuous wave argon ion pumped dye laser
Authors: Ferrario Angela , Rucker Natalie , Ryter Stefan W. , Doiron Daniel R. , Gomer Charles J. 
Published: March 2007

AbstractA pulsed KTP pumped dye laser (25 kHz repetition rate and 470 nsec pulse width) has been compared to a continuous wave argon ion pumped dye laser as the source of 630 nm light during in‐vitro and in‐vivo Photofrin‐II mediated photosensitization studies. Individual experiments documented the effectiveness of each laser system on a) photosensitizer induced cytotoxicity and induction of stress protein synthesis using Chinese hamster fibroblasts; b) photobleaching of Photofrin‐II in aqueous solution; c) Photofrin II mediated photosensitization of normal mouse skin; d) Photofrin II mediated photodynamic therapy of a mouse mammary carcinoma; and e) tumor temperature levels generated during laser exposure. Comparable results were obtained for both laser systems in all experiments.
Excimer laser corneal ablation: Absence of a significant “incubation” effect
Authors: Pettit G. H. , Ediger M. N. , Weiblinger R. P. 
Published: March 2007

AbstractPulse‐to‐pulse consistency of excimer laser etching of cornea has been examined via two noncontact techniques: photoacoustic probe beam deflection, and time‐resolved excimer pulse reflectometry. These methods clearly document the incubation phenomenon accompanying excimer laser ablation of polymethylmethacrylate and the absence of the effect during polyimide ablation. In comparison, results for corneal ablation indicate consistent tissue etching over a train of pulses. Consequently, incubation appears to have negligible impact on corneal ablation.
Hyperthermia potentiates the effects of aluminum phthalocyanine tetrasulfonate‐mediated photodynamic toxicity in human malignant and normal cell lines
Authors: Glassberg Edward , Lewandowski Lawrence , Halcin Cynthia , Lask Gary , Uitto Jouni 
Published: March 2007

AbstractThe purpose of this study was to examine the effects of photodynamic therapy utilizing aluminum phthalocyanine tetrasulfonate in vitro on several human malignant and normal cell types, with or without hyperthermia. Cells examined included normal skin fibroblasts, HT‐1080 fibrosarcoma cells, SCC‐25 (squamous cell carcinoma) and malignant melanoma cells. An argon‐pumped continuous wave tunable dye laser at 675 nm was used as the light source, hyperthermia groups were heated to 42.5°C, and radioisotope incorporation was used to measure DNA and protein synthesis as toxicity assays. Results showed an energy‐dose, and AlPcS‐concentration dependent toxicity in all cell lines examined, with moderate selectivity toward malignant cells. Hyperthermia lone was slightly toxic in melanomas and HT‐1080 cell lines but had no effect in normal fibroblasts or SCC‐25 cells. Hyperthermia synergistically potentiated the effects of PDT in all cell lines, and the combined modality was significantly more toxic in all malignant cell lines compared with normal cells. Thus, addition of hyperthermia to PDT protocols may enhance the efficacy of this treatment modality in vitro.
Internal sclerostomy with laser: A new approach to glaucoma surgery
Authors: Melamed Shlomo , Neumann Doron 
Published: March 2007

AbstractThe creation of a fistula that permits controlled flow of aqueous from the anterior chamber to the subconjunctival space has been and remains the main technical goal of glaucoma filtering surgery. Currently, most complications are secondary to the surgical manipulation of the conjunctiva (mainly leakage from bleb and conjunctival fibrosis) or flattening of the anterior chamber. To overcome this problem, new methods are evolving in which the fistula is created from within the eye, with no conjunctival dissection. The performing of the sclerostomy by means of externally delivered laser energy is a further step in the same direction.
Selectivity, efficiency, and surface characteristics of hard dental tissues ablated with ArF pulsed excimer lasers
Authors: Neev Joseph , Liaw Lih‐Huei L. , Raney Dan V. , Fujishige Jack T. , Ho Peter D. , Berns Michael W. 
Published: March 2007

AbstractLasers are finding expanding applications in the field of dentistry. Cutting in soft tissue, hard dental material ablation, caries removal, and root canal therapy are only a few examples of dental laser uses.In this article, the application of short pulse ArF excimer laser to ablation of dentin and enamel is investigated. In particular, the effect of laser pulse repetition rates (PRR) and fluence levels on the efficiency of the ablation process and on the average thermal response of ablated surfaces is investigated.Ablation of dentin was found to be considerably more efficient than the ablation of enamel and depends exponentially on the laser fluence. Both dentin and enamel surfaces showed an increase in surface temperature with repetition rate. At lower PRR, however, temperature increases are very small. Surface temperature was also found to increase with laser fluence, although this increase is very small at laser PRR of 5 Hz or less. Tissue ablation rates were found to be comparable to or better than other nanosecond lasers, and left smooth surfaces, free of thermal damage.Microscopic examination of the ablated surface shows no crack formation, charring, discoloration, or any other thermal damage. The ablated surfaces appear to be very smooth, highly polished, and glossy looking as if they were subjected to thermal melting. This observation is indeed confirmed under scanning electron microscopy (SEM), where evidence of localized melting of the tissue is observed. Furthermore, a close SEM examination of the dentin surface reveals a selectively ablated intertubular dentin, while the remaining pillar‐like dentin tubules are sealed off with fused peritubular dentin.At all fluence levels and PRR, the first three to four pulses impinging on an untreated enamel surface produced unusually large plumes of debris which were different in size, texture, and fluorescence emission characteristics from the ablation products of subsequent pulses. It is believed that these different ablation characteristics are a consequence of the pulsed ArF laser's ability to selectively remove residual matter from the more resistant enamel surface.
Comparison of tissue effects with sculptured fiberoptic cables and other Nd:YAG laser and argon laser treatments
Authors: Shirk Gerald J. , Gimpelson Richard J. , Krewer Keith 
Published: March 2007

AbstractThe use of a fiber optic cable in contact with tissue results in a complex thermal interaction between the cable and the tissue. The effect of the laser‐tissue interaction was investigated using sculptured quartz fiber optic cables, sapphire contact rods, and bare fiber optic cables attached to the Nd:YAG laser. The laser‐tissue effects of the Nd:YAG and argon lasers were compared. Examination of treated animals showed there to be a significant difference between immediate and 48‐hour thermal effects. The sculptured fibers created significantly less tissue damage than the sapphire contact tips, the 0.6‐mm bare fiber, or the argon laser with a 0.3‐mm bare fiber either with or without contact. All Nd:YAG laser contact treatments were less damaging than the argon laser treatments.
Monitoring myocardial reperfusion injury with NADH fluorometry
Authors: Horvath Keith A. , Torchiana David F. , Daggett Willard M. , Nishioka Norman S. 
Published: March 2007

AbstractUsing NADH fluorometry to monitor myocardial metabolism, the mechanism of reperfusion injury was investigated after the delivery of an experimental reperfusate. Using an isolated working heart preparation, rat hearts underwent 15 min of global ischemia at 37°C. Following the ischemic insult, an oxygenated enriched reperfusion solution was given for 5 min. The hearts were then returned to a working state and aortic flow recorded to evaluate recovery. NADH levels were monitored throughout the experiment with a fluorometer and glycogen, AMP, ADP, and ATP were measured biochemically pre‐ and postischemia, after reperfusion and after recovery. In this study, reperfusion injury was best abated by an enriched reperfusate. Our results indicate the mechanism for this amelioration is not high‐energy phosphate replenishment. Rather, as indicated by NADH fluorescence, the hearts attain an intermediate level of metabolism that permits glycogen to be restored and functional recovery to be improved.
Transurethral laser prostatectomy in the canine model
Authors: Kandel Laurence B. , Harrison Lloyd H. , McCullough David L. , Woodruff Ralph D. , Dyer Raymond B. 
Published: March 2007

AbstractA technique for performing transurethral prostatectomy was devised using a Neodymium:Yttrium Aluminum Garnet laser in a canine model. Six dogs underwent transurethral laser prostatectomy following establishment of a perineal urethrostomy. The efficacy of the prostatectomies was judged by retrograde urethrography, transrectal prostate ultrasonography, cystoscopy, and histologic examination. The method of applying laser energy while holding the tip of the fiberoptic light guide 2–3 mm away from the prostate was ineffective; with power ranging from 40 to 70 watts, this technique resulted mainly in coagulation necrosis and removal of only a small amount of tissue. However, placing the tip of the light guide in direct contact with the prostate and using power from 70 to 100 watts produced impressively large prostatectomy defects by tissue vaporization. We conclude that this newly devised technique for transurethral prostatectomy in the canine model can be performed safely and effectively using a Neodymium: Yttrium Aluminum Garnet laser (Neodymium:YAG).
Microbeam laser‐injured neurons increase in vitro astrocytic gap junctional communication as measured by fluorescence recovery after laser photobleaching
Authors: Anders Juanita J. , Woolery Sara 
Published: March 2007

AbstractAn important aspect of the neuronal–astrocyte relationship is the interaction of reactive astrocytes with injured and/or dying neurons. Few studies have focused on the signaling of astrocytes by injured neurons or on the possibility that neurons can alter as‐trocytic gap Junctional communication. The purpose of this study was to determine whether the presence of injured neurons could alter astrocytic gap Junctional coupling by establishing an in vitro method of microbeam laser neuronal injury and coculturing these neurons with astrocytes. Neurons from two rat neuronal clonal cell lines were injured using a 20‐W argon laser operating on the ultraviolet (UV) multiline (351–361 nm) directed through a X40 objective of an inverted microscope. After laser injury, the glass slide with the injured neurons was sandwiched with a slide on which primary rat astrocytes were grown. Although the neurons and astrocytes were bathed in the same medium, they were not in direct contact during the coculture period (24,48, or 72 hr). Astrocytic gap Junctional dye coupling was examined using the fluorescence recovery after laser photobleaching (gap‐FRAP) analysis technique. Astrocytes cocultured with the injured neurons for 24 to 48 hr did not show a significant difference in fluorescence recovery when compared to control values. After 72 hr of coculture, there was a significant increase in the gap Junctional dye coupling. These results indicate that injured neurons influence in vitro astrocytic gap Junctional conductance after 72 hr of coculture as measured by dye coupling.
Histologic evaluation of rat mammary tumor necrosis by interstitial Nd:YAG laser hyperthermia
Authors: Dowlatshahi Kambiz , Babich Debra , Bangert Julee D. , Kluiber Rudolph 
Published: March 2007

AbstractThe extent of coagulative necrosis caused by interstitial laser hyperthermia was measured for different quantities of laser energy in a rat mammary tumor model. Continuous wave Nd:YAG laser at a power level of 5 W was focused onto a 600 JA diameter bare tip quartz fiber and placed inside a 19‐gauge needle, which allowed the para‐axial flow of normal saline at 1 cc/min. A microthermocouple soldered to the outside of the probe continuously provided the interstitial temperature. After the probe was inserted into the tumor, it was withdrawn as laser energy was administered at a rate sufficient to maintain the temperature within 42–45°C. Tumors were excised after 48 hours, fixed in formalin, cut in 3 mm slices, and the coagulated surfaces measured microscopically. Laser fiber transmission loss was 1% per 1,000 J of laser energy and the average time required to coagulate 1 cc of tumor was 2 minutes. There was a statistically significant correlation between the volume of tumor necrosis and the level of laser irradiation (r = 0.71, P<0.001). It is concluded that the described technique is an efficient method of tumor coagulation by interstitial laser hyperthermia and proportionally larger volumes of necrosis are created with greater amounts of laser energy. © 1992 Wiley‐Liss, Inc.
CO2 laser annular thermokeratoplasty: A preliminary study
Authors: Chandonnet Alain , Bazin Richard , Sirois Claude , Bélanger Pierre‐André 
Published: March 2007

AbstractSince most techniques of refractive surgery currently in use or being developed have the potential for significant side effects, there is a need for investigating alternative procedures. We herein report on the use of a pulsed CO2 laser beam delivered through a pair of complementary axicons to produce a ring of stromal collagen contraction resulting in the flattening of the corneal apex of cadaver eyes. Irradiances of 29 W/cm2 and 23 W/cm2 were used for rings of 5.5 mm and 7.0 mm, respectively. The creation of a ring of 7.0 mm in diameter did not affect the corneal curvature significantly but when the diameter was reduced to 5.5 mm, substantial flattening proportional to the dose of radiation took place. In our system, it was possible to achieve up to 11.3 diopters of mean keratometry flattening (90 joules, 5.5 mm of diameter). In addition, a 1 mm posterior displacement of the corneal dome without histological evidence of closure of the iridocorneal angle was observed. Annular thermokeratoplasty (ATK) may minimize side effects encountered with other refractive procedures since it does not require ablation, incisions, or interaction with the central optical zone. © 1992 Wiley‐Liss, Inc.
Pulse duration effects on cutaneous pigment
Authors: Kurban Amal K. , Morrison Paul R. , Trainor Shawn W. , Tan Oon T. 
Published: March 2007

AbstractMelanin, an endogenous chromophore in pigment containing cells in skin, is being specifically altered by lasers using the principle of selective photothermolysis (SPT). This implies that a combination of specific laser parameters of wavelength, pulse duration, spotsize, and energy density are required to confine the delivered laser energy to the targeted cells alone. Because the bulk of cutaneous pigment is localized to epidermal basal cells, pigmentary incontinence has been found to occur in skin exposed to laser irradiation. This study demonstrates that pulse duration or exposure time of the laser affect the severity of pigmentary incontinence induced. Pigment granules are more abundant, aggregated, and located deeper in the dermis following exposure to 500 nsec pulse duration than 100 nsec at a wavelength of 504 nm. This relationship appears to be independent of the laser energy density used. © 1992 Wiley‐Liss, Inc.