bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of force on ablation depth for a XeCl excimer laser beam delivered by an optical fiber in contact with arterial tissue under saline
Authors: Gijsbers Geert H. M. , van den Broecke Duco G. , Sprangers René L. H. , van Gemert Martin J. C.
Published: March 2007

The effect of force applied to a 430 üm single fiber, delivering 60 pulses of 308 nm XeC1 laser radiation at 20 Hz, on the ablation depth in porcine aortic tissue under saline has been investigated. Energy densities of 8,15,25, 28, 31, 37, and 45 mJ/mm2 were used. Force was applied by adding weights from 0 to 10 grams to the fiber. The fiber penetration was monitored by means of a position transducer. At 0 grams, the ablation depth increased linearly with incident energy density, but the fiber did not penetrate the tissue; with any weight added, the fiber penetrated the tissue at energy densities above 15 mJ/mm2. The fiber did not penetrate during the first several pulses, possibly due to gas trapped under the fiber. After these first pulses, a smooth linear advancement of the fiber began, which lasted until the pulse train stopped. The ablation depth increased with increasing energy densities and weights. This effect was largest above 25 mJ/mm2 where the ablation efficiencies (unit mm3 /J), with weights added to the fiber, were substantially larger than values found in 308 nm ablation experiments described in the literature, which were conducted with either a focused laser beam or a fiber without additional force. The results imply that in 308 nm excimer laser angioplasty, force must be applied to the beam delivery catheter for efficient recanalization, and that experiments performed with a focused beam or without actual penetration of the fiber do not represent the situation encountered in excimer laser angioplasty. © 1992 Wiley‐Liss, Inc.
Laser reflections from surgical instruments
Authors: Wood Rodney L. , Sliney David H. , Basye Robert A.
Published: March 2007

The potential hazards to the eye and skin from accidental exposures caused by reflected laser beams from surgical instruments has long been of concern to operating room staff members. Reflectance values for argon neodymium:YAG and CO2 laser wavelengths were measured from 29 reference surfaces used on surgical instruments. From these measurements, nominal hazard zones could be determined for typical reflection hazards. © 1992 Wiley‐Liss, Inc.
Absence of rhodamine 123‐photochemotoxicity in human tumor xenografts
Authors: Ris Hans‐Beat , Altermatt Hans Jörg , Schaffner Thomas , Lim Chang Kee , Potter William R. , Althaus Ulrich
Published: March 2007

Rhodamine 123 (R123)‐photochemotoxicity was assessed in BALB/c nude mice bearing a xenografted human squamous cell carcinoma at various power densities and wavelengths and a given incident fluence of 150 Joules/cm2. One hour before light delivery, 1 mg R123/kg was injected i.p. in 20 animals. Surface irradiance was performed on the tumor and an equal size hind leg area of 40 animals. Three groups of 10 animals were treated at 514.5 nm and 0.1 W/cm2, 1 W/cm2, and 30 W/cm2, and one at 488 nm and 30 W/cm2. In each group, five animals received R123. The R123 concentration was measured in the tumor (0.023 ± 0.007 μg/g) and tumor‐free tissue (0.023 ± 0.008 μg/g) in three additional animals by high performance liquid chromatography 1 hour after R123‐administration. Histologic assessment 72 hours after light delivery revealed no tissue damage at nonthermal power densities, either in the tumor or in the tumor‐free tissue, irrespective of R123‐administration. At 30 W/cm2, neither in the tumor nor in tumor‐free tissues was there any significant difference in the depth of necrosis, irrespective of R123‐administration and the wavelength applied. Our results question the validity of R123 as a photosensitizer, at least in this rodent tumor model. © 1993 Wiley‐Liss, Inc.
Low power laser irradiation alters the rate of regeneration of the rat facial nerve
Authors: Anders Juanita J. , Borke Rosemary C. , Woolery Sara K. , van de Merwe Willem P.
Published: March 2007

Low power laser irradiation has been reported to cause biological effects due to the photochemical and/or photophysical action of the radiation. This study determined quantitatively if transcu‐taneous low power laser irradiation can affect the regeneration of the rat facial nerve. The facial nerve was crushed unilaterally in anesthetized rats and transcutaneously irradiated daily with a laser beam directed at the area of the crush injury. Laser treatment began on the day of the crush injury and was continued daily for 7, 8, or 9 days. Preliminary experiments determined the most effective wavelength, laser power, length of irradiation, and treatment schedule. The wavelengths examined were 361, 457, 514, 633, 720, and 1064. The laser powers and lengths of irradiation examined ranged from 8.5 to 40 mW and 13 to 120 min. Irradiation treatment was done daily, on alternating days and on the first 4 days postcrush. The most effective laser parameters for the low power treatment included daily irradiation with a helium‐neon (HeNe) or argon pumped tunable dye laser a wavelength of 633 nm, with a power of 8.5 mW for 90 minutes (45.9 J, 162.4 J/cm2). The number of horseradish peroxidase (HRP) labeled neurons in the facial motor nucleus was used as an assay of the degree of regeneration. In rats in which the facial nerve was crushed but not irradiated, the average number of HRP labeled neurons in the facial nucleus was 22 on day 7 postcrush, 54 on day 8, 116 on day 9, and 1,149 on day 10. After HeNe or argon pumped tunable dye laser irradiation, the average number of HRP‐labeled neurons increased to 34 on day 7 postcrush, 148 on day 8, and 1,725 on day 9. There was a statistically significant difference between the control and irradiated rats on day 9 post‐crush (P < 0.01). These data indicate that transcutaneous low power irradiation with the lasers and parameters involved in this study increased the rate of regeneration of rat facial nerve following crush injury. © 1993 Wiley‐Liss, Inc.
XeCl laser ablation of atherosclerotic aorta: Luminescence spectroscopy of ablation products
Authors: Oraevsky Alexander A. , Jacques Steven L. , Pettit George H. , Tittel Frank K. , Henry Philip D.
Published: March 2007

XeCl laser ablation of atherosclerotic aorta tissue was investigated. Luminescence spectra of ablation products were measured for soft and hard arterial tissues. A pronounced difference observed between plume luminescence for various plaques and normal vessel wall correlates with the chemical composition of the tissue. The mechanism of plume luminescence appeared to be thermochemical excitation of ablation products (particles, atoms, molecules, etc.) in the air. The process of soft tissue ablation was delayed with respect to the exciting laser pulse at relatively low laser fluences close to the ablation threshold. The kinetics of the ablation process as a function of laser‐pulse energy fluence is reported. The data indicate that tissue ejection mechanism, which involves vapor bubbles formation, expansion and explosion, is suitable for the description of the XeCl excimer laser ablation of soft tissues. © 1993 Wiley‐Liss, Inc.
Injury and adhesion formation following ovarian wedge resection with different thermal surgical modalities
Authors: Bhatta N. , Isaacson Keith , Flotte Thomas , Schiff Isaac , Anderson R. Rox
Published: March 2007

The purpose of this study is to determine the role of bleeding, acute thermal damage, and charring in adhesion formation. Postoperative adhesions were compared following ovarian wedge resection in 48 rabbits using different lasers, electrosurgery, and scalpel. Twelve ovaries were sectioned per modality, in randomized pairs. Acute thermal injury as assessed by histology, bleeding, and charring differed amonge the modalities used. Adhesions were assessed 4 weeks later, by an investigator completely blinded of the treatment protocol. The adhesion scores were 11.6 ± 8.0 with pulsed Er:YAG laser; 11.9 ± 7.5 with scalpel; 8.3 ± 9.3 with electrocautery; 6.7 ± 8.8 with a continuous (c.w.) Nd:YAG laser; 5.3 ± 4.8 with c.w. CO2 laser; 3.1 ± 2.7 with pulsed CO2 laser; 1.7 ± 1.8 with pulsed Ho:YAG laser; and 0.8 ± 1.5 in the control (no resection) group. Ho:YAG, Nd:YAG, and electrocautery were completely hemostatic. Bleeding was minimal with the CO2 lasers. Er:YAG and scalpel caused maximum bleeding, requiring hemostatic measures to prevent exanguination. Charring occurred with electrocautery, CO2 laser, and Nd:YAG laser. Bleeding and charring correlated with adhesion formation, but the histological depth of thermal damage did not. The Ho:YAG laser is a hemostatic, fiber‐optic compatible laser causing significantly fewer adhesions (P<0.04) than scalpel, electrocautery, Nd:YAG, Er:YAG, and c.w. CO2 lasers. Clinical use of the Ho:YAG laser, and the role of carbonization in promoting adhesions, deserve further study. © 1993 Wiley‐Liss, Inc.
Alteration of argon laser–induced scars by the pulsed dye laser
Authors: Alster Tina S. , Kurban Amal K. , Grove Gary L. , Grove Mary J. , Tan Oon Tian
Published: March 2007

Ten patients with portwine stains (PWS) with test sites previously exposed to an argon laser were evaluated and subsequently treated with five pulsed dye (585 nm) laser treatments over a 10 month period. Clinical assessments, skin surface texture analyses using optical profilometry, and light microscopic histological evaluations were performed prior to commencement and at the end of the study in all ten patients. A change in the skin texture with return of skin markings approximating those of normal skin measured by optical profilometry was observed in the argon treated PWS skin following pulsed dye laser treatments. © 1993 Wiley‐Liss, Inc.
Studies of acoustical and shock waves in the pulsed laser ablation of biotissue
Authors: Esenaliev Rinat O. , Oraevsky Alexander A. , Letokhov Vladilen S. , Karabutov Alexander A. , Malinsky Taras V.
Published: March 2007

Quantitative studies are conducted into the absolute pressure values of the acoustical and shock waves generated and propagating in a biotissue under pulsed (τP = 50 ns) UV (λ = 308 nm) laser irradiation (below and above the ablation threshold). Powerful (several hundreds of bars in pressure) high‐frequency (f ≃ 107 Hz) acoustic compression and rarefaction pulses are found to be generated in the biotissue. The amplitudes and profiles of the acoustic pulses developing in atherosclerotic human aorta tissues and an aqueous CuCl2 solution under laser irradiation are investigated as a function of the laser pulse energy fluence. The results obtained point to the absence of the cold spallation of the objects of study by rarefaction waves. Based on experimental data, the rise rates, pressure gradients, and propagation velocities of shock waves in the biotissue are calculated. The experimental data are found to agree well with the theoretical estimates. © 1993 Wiley‐Liss, Inc.
Argon laser oral safety parameters for teeth
Authors: Powell G. Lynn , Morton Thomas H. , Whisenant Brian K.
Published: March 2007

Argon lasers have been reported to prevent or reduce demineralization of enamel in extracted teeth and to polymerize dental composites (using 25–100 J/cm2). Prior to clinical trials on caries prevention and curing composites, safety parameters for intraoral use of the argon laser need to be established. This study was conducted to determine the enamel damage, pulp temperature changes, and associated pulpal tissue damage following irradiation at various argon laser energy levels using 1.6–6.0 watts, ∼ 1 and 2 mm diameter beam for 0.2–5.0 seconds. To evaluate pulpal damage, selected dogs' teeth were irradiated in vivo, extracted 7 days postlasing, fixed, decalcified, sectioned, stained, and read for pulpal damage. Pulp temperature and enamel damage tests utilized extracted dog and human teeth. Temperature probes were inserted in the pulp chambers and temperature changes recorded as enamel surface was lased. Enamel surface damage was evaluated by visual and microscope examination. Results showed that histologic pulpal damage occurred at > 600 J/cm2. Temperature changes were < 6° F in human teeth with ∼ 900 J/cm2. No enamel damage was observed at these energy densities. At energy densities needed for proposed uses, no apparent damage would be expected to pulp or enamel. © 1993 Wiley‐Liss, Inc.
Optical modelling of light distributions in skin tissue following laser irradiation
Authors: Miller Iain D. , Veitch A. Roy
Published: March 2007

A Monte‐Carlo method is used to compute light distributions in a multilayer skin model for variable width finite beams. By means of a 4‐layer skin model in which blood may be represented as a discrete layer, vascular lesions such as portwine stains may be studied. Light distributions and thermal profiles are simulated, representing the irradiation of a portwine stain using 577 nm and 585 nm wavelengths. Damage thresholds at 585 nm are found to substantially exceed those predicted at 577 nm, although the nature of the damage differs at the two wavelengths. Variations due to beam width are found to be unimportant if the diameter exceeds 1 mm. The predictions are compared with clinical results, and a novel 5‐layer approach based on new optical parameters is adopted to account for discrepancies in epidermal temperature. © 1993 Wiley‐Liss, Inc.
Effect of irradiation by semiconductor laser on responses evoked in trigeminal caudal neurons by tooth pulp stimulation
Authors: Wakabayashi Hajime , Hamba Michiko , Matsumoto Koukichi , Tachibana Hitoshi
Published: March 2007

The effect of irradiation with a gallium‐aluminum‐arsenide semiconductor laser on responses evoked in trigeminal subnucleus caudal neurons by tooth pulp stimulation was investigated electrophysiologically in Wistar rats anesthetized with urethane plus α‐chloralose. The pulp of lower incisor was electrically stimulated and the evoked action potentials were extracellularly recorded in the ipsilateral caudal neurons. The laser beam was applied on the cervical surface of the stimulated incisor. The rate of firing discharges and the numbers of spikes evoked in the caudal neurons were compared before and after laser irradiation. Laser irradiation suppressed the late discharges in the response of the caudal neurons which were evoked by excitatory inputs from C‐fiber afferents, but did not suppress the early discharges evoked by inputs from Aδ‐fiber afferents. This indicates that low power laser irradiation (semiconductor laser: 830 nm, 350 mW, CW, through the tooth structures, for 120 s) inhibited the excitation of unmyelinated fibers of the pulp without affecting fine myelinated fibers. These results suggest that low power laser irradiation has a suppressive effect on injured tissue by blocking the depolarization of C‐fiber afferents. © 1993 Wiley‐Liss, Inc.
Cell vitality in cartilage tissue culture following excimer laser radiation: An in vitro examination
Authors: Fischer R. , Krebs R. , Scharf H.‐P.
Published: March 2007

Excimer laser is used for cartilage debridement, although the resulting cell damage is yet unclear. For examination of cartilage survival after treatment, we used short‐term tissue cultures of human joint cartilage. Specimens were treated with a XeCl‐Excimer laser using different laser parameters, pulse energies, and repetition rates. Following treatment, discs were cultured for 8 days prior to examination. In contrast to the 20 μm damage zone as instant visible effect in histomorphologic examinations, we found a 0.3 mm zone in which ∼ 50% of cartilage cells had morphological signs of damage on light microscopic examinations. Autoradiography revealed that cartilage cells in an 0.5–0.7 mm area surrounding the laser craters had no collagen synthesis. This examination indicates that cell damage of excimer laser is higher than expected from prior studies. © 1993 Wiley‐Liss, Inc.
Tolerance of small bowel anastomoses in rabbits to photodynamic therapy with dihematoporphyrin ethers and 630 nm red light
Authors: Delaney Thomas F. , Sindelar William F. , Thomas Gunter F. , Deluca Anne M. , Taubenberger Jeffery K.
Published: March 2007

Photodynamic therapy (PDT) is being evaluated in experimental clinical trials in patients with peritoneal malignancies. Some patients require partial small bowel resection with re‐anastomosis prior to PDT because of bulky tumor or focal involvement of the small bowel by tumor. To assess the safety of PDT in this setting, the tolerance of small bowel anastomoses in New Zealand white rabbits to PDT with dihematoporphyrin ethers (DHE) and 630 nm light was studied. With conventional DHE doses of 1.5–2.5 mg/kg given 24 hours prior to surgery and light doses of 0–20 J/cm2 of 630 nm light, no adverse effects were seen on the healing of small bowel anastomoses. Higher photosensitizer doses of 10 mg/kg and 20 mg/kg in conjunction with 20 J/cm2, however, induced failure and breakdown of fresh anastomoses in 2/3 and 4/4 animals, respectively. © 1993 Wiley‐Liss, Inc.
Formation of pressure waves during in vitro excimer laser irradiation in whole blood and the effect of dilution with contrast media and saline
Authors: Baumbach Andreas , Haase Karl K. , Rose Carsten , Oberhoff Martin , Hanke Hartmut , Karsch Karl R.
Published: March 2007

Pressure waves during excimer laser ablation of vascular tissue may be responsible for complications of coronary excimer laser angioplasty. In this experimental study, pressure waves were measured during excimer laser irradiation in blood and contrast media using a polyvinilidenefluoride hydrophone. At a distance of 4 mm lateral to the tip of a 1.7 mm multifiber laser catheter, excimer laser irradiation in blood resulted in a linear increase of peak pressures from 1,365 ± 165 kPa at 30 mJ/mm2 to 2,866 ± 404 kPa at 60 mJ/mm2. In contrast media, peak pressure increased from 3,172 ± 573 kPa (30 mJ/mm2) to 5,763 ± 467 kPa (60 mJ/mm2). Contrast media and saline were added to blood. At a concentration of 60% contrast in blood, a 3.4 fold increase of peak pressures was documented as compared to pure blood. Further increase of the concentration did not result in higher pressure waves. Concentrations of saline in blood of 90% and 96% reduced the peak pressures by 16% and >50%, respectively, as compared to pure blood. © 1994 Wiley‐Liss, Inc.
Acute biological response to laser balloon angioplasty in the atherosclerotic rabbit
Authors: Alexopouios Dimitrios , Sanborn Timothy A. , Marmur Jonathan D. , Badimon Juan J. , Badimon Una , Dische Renate , Fuster Valentin
Published: March 2007

Laser balloon angioplasty with Nd:YAG energy has been proposed as a method to seal intimal dissection and prevent elastic recoil after balloon angioplasty. To better define the vessel response to laser balloon angioplasty, its effects on luminal diameter, Indium‐111 labelled platelet deposition, and histology were studied in 10 atherosclerotic rabbits. Balloon angioplasty was performed in both iliac arteries and was followed by laser balloon angioplasty in only one iliac artery. The nonlased artery served as a control. Single (15–35 W for 20 sec) or repetitive laser pulses (12–25 W for 20 sec × 3) were used. Platelet deposition was quantified 2 hr after the intervention. Lumen diameter (mm) increased following balloon angioplasty from 0.99 ± 0.47 (mean ± SD) to 1.92 ± 0.43 and 0.89 ± 0.46 to 1.99 ± 0.57 in the balloon and laser‐treated arteries, respectively (P < 0.001 for both groups for comparisons to baseline, P = NS for between groups comparison). Laser balloon angioplasty resulted in a further increase in luminal diameter to 2.42 ± 0.53 (P < 0.02) when compared to the post balloon angioplasty diameter. Platelet deposition (106/cm vessel) was higher following laser balloon angioplasty (26.9, 10.2–189; median range) than after balloon angioplasty (10.6, 3.4–30), P < 0.001. Histologic evidence of laser “sealing” was present in only one artery. Thus although laser balloon angioplasty results in an improved lumen diameter, it is accompanied by increased platelet deposition. In the atherosclerotic rabbit model, abolition of vascular recoil rather than “sealing” seems to be the most important advantage of laser balloon angioplasty over conventional balloon angioplasty. © 1994 Wiley‐Liss, Inc.
Toxicity of photodynamic therapy with photofrin in the normal rat brain
Authors: Ji Ying , Powers Stephen K. , Brown J. Tony , Walstad Diana , Maliner Lloyd
Published: March 2007

The widespread acceptance of photodynamic therapy (PDT), a potential adjuvant brain tumor therapy under clinical evaluation since 1980, has been partially restrained by its potential toxicity toward normal brain tissue. This study examined PDT‐produced injury of normal rat brain as a function of photosensitizer dose. Brain injury was characterized by correlating measurements of the area of cerebral edema using T2‐weighted magnetic resonance images, measurement of brain water content at the lesion site, microscopic examination of histological sections through the PDT lesion, and by evaluation of the area of blood brain barrier (BBB) disruption using computerized morphometric analysis of the region of Evans blue (EB) dye‐labelled albumin extravasation. Monochromatic red light (630 nm) was delivered intracere‐brally using a 5‐mm‐long cylindrical, diffusion‐tip optical fiber at a constant energy dose of 15 joules.

A Photofrin dose of 2 mg/kg of body weight produced a transient breakdown in the blood brain barrier around the site of the implanted optical fiber demonstrated by magnetic resonance imaging (MRI), extravasation of EB dye and pallor on hematoxylin and eosin‐stained microscopic tissue sections. A much larger area of BBB disruption was seen at a dose of 4 mg/kg of Photofrin, and this drug dose resulted in significant permanent brain injury. In this model, a Photofrin dose of 4 mg/kg body weight is not tolerated by the normal brain. © 1994 Wiley‐Liss, Inc.
Thermal side effects of fiber‐guided XeCl excimer laser drilling of cartilage
Authors: Fischer R. , Hibst R. , Schröder D. , Puhl W. , Steiner R.
Published: March 2007

We examined thermal effects during ablation of human joint cartilage using two XeCl excimer lasers with pulse durations of ∼ 20 ns and 60 ns. An increase in radiant exposure or repetition rate caused a rise in tissue temperature up to 82°C at a 100‐ μm distance. With increasing distance from the crater edge, the temperature dropped exponentially. Radiant exposures higher than 1.8 J/cm2 and repetition rates above 20 Hz lead to a formation of hot gaseous products escaping from the laser crater. When os‐teoarthritic cartilage is irradiated, these gases spread inside the tissue causing a temperature rise of > 50°C at a distance of 1 mm from the crater edge. In the contact mode, we found a linear rise of ablation rate with increasing repetition rate both in air or saline. But ablation rates in saline were only half the rates achieved in air. Both phenomenons can be explained by additional thermal effects of excimer lasers working in the range of higher repetition rates and pulse energies. © 1994 Wiley‐Liss, Inc.
Development and experimental in vivo validation of mathematical modeling of laser coagulation
Authors: Beacco C. M. , Mordon S. R. , Brunetaud J. M.
Published: March 2007

Most clinical procedures using the laser are based on thermal laser‐tissue interactions. The treatment often consists of inducing damage of given degree and extent by heating the tissue. The aim of this study was to develop a model called HELIOS. The ability of HELIOS to predict thermal coagulation was evaluated by comparison with in vivo experimental results. Conversion of laser light in tissue was studied using the beam‐broadening model. Temperature was described by the heat conduction equation solved using the finite difference method. The tissue dena‐turation was modeled by the Henriques equation leading to the determination of the damage coefficient ω. For a given set of laser and tissue parameters, HELIOS makes a graphic representation of coagulation necrosis and temperature evolution in tissue. HELIOS was validated by experimental studies in vivo on rat liver using a CW Nd:YAG laser, a CO2laser, and an argon laser. For given sets of laser parameters, temperature measurements were performed using an infrared camera. Histological examinations were carried out on samples to quantify the depth of coagulation necrosis. Experimental data obtained in vivo were compared with those calculated using HELIOS and similar sets of parameters. The difference between the predicted temperature evolution on tissue surface and that measured by the infrared camera was < 5°C in all cases. The difference between the predicted coagulation necrosis depth and the corresponding experimental one was < 10%. In conclusion, HELIOS allows good prediction of tissue temperature and coagulation necrosis. © 1994 Wiley‐Liss, inc.
Intraocular microsurgery with a picosecond Nd:YAG laser
Authors: Lin Charles P. , Weaver Yaffa K. , Birngruber Reginald , Fujimoto James G. , Puliafito Carmen A.
Published: March 2007

We investigated the use of picosecond Nd:YAG laser pulses for intraocular microsurgery. With a pulse duration of 100 picoseconds, only 70 μJ of pulse energy is required to consistently produce optical breakdown in the deep vitreous. This pulse energy is nearly two orders of magnitude less than the typical pulse energies used in conventional (nanosecond) photodisruptors. The reduced pulse energy results in a smaller zone of tissue damage, an important consideration when operating close to the retina or other sensitive ocular structures. Efficient cutting action is achieved by applying multiple pulses at a moderately high repetition rate of 50–200 Hz. An in vitro model was developed to assess axial confinement of picosecond photodisruption. In vivo vitreous membrane surgery was performed in experimental rabbit eyes to demonstrate a potential clinical application of picosecond laser—induced optical breakdown. © 1994 Wiley‐Liss, inc.
Dynamics of shock waves and cavitation bubbles generated by picosecond laser pulses in corneal tissue and water
Authors: Juhasz Tibor , Hu Xin H. , Turi Laszlo , Bor Zsolt
Published: March 2007

Time‐resolved flash photography was used to investigate the dynamics of shock waves and cavitation bubbles generated by picosecond optical breakdown in bovine corneal tissue and water. A picosecond Nd:YLF laser was employed. A rapid decay of the shock waves was observed in both materials, with similar temporal characteristics, indicating that water serves as a good model for shock wave studies. In contrast, differences in the cavitation bubble dynamics were found between cornea and water, which are related to differences in the mechanical and thermal properties of the two media, suggesting that water should not be used to model cavitation dynamics in cornea. The experimental results also suggest that the efficiency of intrastromal ablation may be increased by using short pulses and moderate pulse energies in order to avoid the creation of large cavitation bubbles. The experiment indicates that the optimum laser repetition rate for intrastromal ablation is between 1 and 5 kHz. © 1994 Wiley‐Liss, Inc.
Determination of efficient parameters for argon laser‐assisted anastomoses in rats: Macroscopic, thermal, and histological evaluation
Authors: Martinot V. L. , Mordon S. R. , Mitchell V. A. , Pellerin P. N. , Brunetaud J. M.
Published: March 2007

The aim of this study was to determine efficient parameters for an argon laser (spot diameter = 200 μm) to obtain and reproduce vessel anastomoses. It was performed in two groups of Wistar rats. In the first group (89 Laser impacts on 10 carotids), the fluence was continuously adjusted from 30 to 3,000 J/cm2 in order to determine efficient sets of parameters (power from 90–200 mW, pulse duration from 0.1 to 5 seconds, pulsed or continuous mode). In the second group, 30 end‐to‐end carotid anastomoses were performed. The results were evaluated by macroscopic thermal, and histological studies. The second group proved the efficiency of the selected parameters. Vessel welding was obtained with 100 mW, 3 seconds, continuous mode (fluence = 950 J/cm2, irradiance = 320 W/cm2) for a mean temperature of 77°C corresponding to collagen denaturation. In the second group the patency rate was 93% (28/30) with three pseudo‐aneurisms and two thromboses. Histological studies noted slight modifications of the media. © 1994 Wiley‐Liss, Inc.
Comparison of laser vascular welding, interrupted sutures, and continuous sutures in growing vascular anastomoses
Authors: Chikamatsu Eiji , Sakurai Tsunehisa , Nishikimi Naomichi , Yano Takashi , Nimura Yuji
Published: March 2007

Background and Objectives: The argon laser‐assisted vascular anastomosis may solve the problems of conventional sutured anastomosis, such as vascular stenosis and arrest of growth owing to a foreign‐body reaction to suture material.

Study Design/Materials and Methods: Twelve argon laser‐assisted vascular anastomoses, seven conventional anastomoses with interrupted sutures, and five conventional anastomoses with continuous sutures were performed in 12 young mongrel dogs.

Results: Five months later, the external diameter at the anastomosis had increased 70.5% in the laser group, 67.0% in the interrupted suture group, and 22.9% in the continuous suture group. Histological examination of the laser‐assisted anastomoses showed almost complete healing, with no granulomatous response around the anastomotic site. In the interrupted suture group, marked scaring and foreign body reactions were observed on the vessel wall at the site of the anastomosis. The continuous suture group showed more remarkable disorientation of the vascular layer and intimal hyperplasia than the interrupted suture group.

Conclusion: Vascular anastomosis using the argon laser offers advantages over the conventional procedure in growing vessels.
Evaluating the role of photodynamic therapy in the management of pancreatic cancer
Authors: Moesta K. Thomas , Schlag Peter , Douglass Harold O. , Mang Thomas S.
Published: March 2007

Background and Objective: Cancer of the pancreas constitutes one of the major causes of cancer related death throughout the world. A 5‐year survival rate of only 2% and a maximum of 20 months median survival in multi modality treatment studies dealing with the most favorable patients only, has been demonstrated. This review analyzes the principal treatments and available experimental data in view of a clinical application of photodynamic therapy (PDT) for the treatment of pancreatic cancer.

Study Design/Materials and Methods: On the basis of published results, we examined the palliation of pancreatic cancer by chemotherapy alone; radiation alone and multimodality schedules (radiation and chemotherapy). Radical tumor resection was examined as attempted curative treatment.

Results: In reported therapeutic procedures, palliative or potentially curative, median survival was below 2 years. The GTSG reported survival time increases from 10.9 to 21.0 months when surgery is followed by adjuvant chemotherapy and radiation. This combination postoperatively does not increase mortality, but adds 30% morbidity. Photodynamic therapy has been demonstrated in preclinical studies to have a selective effect on malignant versus the normal pancreas.

Conclusion: PDT is highly effective in eliciting the destruction of experimental pancreatic tumors with the lack of significant effect on the normal pancreas. The poor prognosis for patients with this disease, especially those patients with advanced disease, warrants closer examination of PDT for the treatment of pancreatic cancer.
Laser‐induced fluorescence: III. Quantitative analysis of atherosclerotic plaque content
Authors: Yan Wei‐Dong , Perk Masis , Chagpar Anees , Wen Yue , Stratoff Sharon , Schneider Wolfgang J. , Jugdutt Bodh I. , Tulip John , Lucas Alexandra
Published: March 2007

Background and Objective: Laser‐induced fluorescence (LF) spectroscopic analysis of the chemical composition of atherosclerotic plaque was examined.

Study Design/Materials and Methods: The intima of 18 dog aortas was injected with chemical compounds found in atherosclerotic plaque. Spectra were recorded in air prior to and after injection of collagens I, III and IV, elastin, cholesterol, triglyceride, and β‐nicotinamide adenine dinucleotide (NADH).

Results: Significant changes in LF intensity were detected after injection of collagens I and III, cholesterol and elastin in thoracic aorta (P < 0.001), but not with triglyceride or NADH. Minor changes were detected in abdominal aorta. Multiple regression analysis of LF intensity ratios demonstrated a clear correlation with the quantity of injected collagens I (R2 = 0.90–0.99) and III (R2 = 0.84–1.0), cholesterol (R2 = 0.72–0.76), and triglyceride (R2 = 0.68–0.80) in both thoracic and abdominal aorta. The correlation between LF and atherosclerotic plaque composition was confirmed in a rooster model of atherosclerosis where multiple regression analysis predicted the measured aortic cholesterol (R2 = 0.78) and triglyceride content (R2 = 0.96).

Conclusions: (1) Fluorescence spectra recorded from dog aorta were significantly altered by injection of collagens I and III, cholesterol, and elastin. (2) LF may allow quantitative assessment of plaque chemical content. © 1995 Wiley‐Liss, Inc.
Laser safety
Authors: Sliney David H.
Published: March 2007

Safetyhas always been an important aspect of any laser application in surgery and medicine. In any review of the laser surgery literature, several issues continue to dominate. These issues include: wearing eye protectors, dealing with the plume of vaporized tissue, and controlling potential fire hazards. No one denies that lasers can pose a serious hazard to the eye, but the decision to wear eye protectors in all procedures has been frequently questioned. The degree of effort needed to minimize the very serious risk from chronic breathing of vaporized tissue also requires judgment. Aside from a few eye injuries from a laser beam exposure, most serious accidental injuries (and even deaths) reported to date from the laser beam itself can be traced to the ignition of surgical drapes and airway tubes. © 1995 Wiley‐Liss, Inc.
Low intensity laser therapy: Still not an established clinical tool
Authors: Basford Jeffrey R.
Published: March 2007

The surgical, ophthalmological, and dermatological applications of high power lasers are well known and easily understood. What is neither as well known nor as easily understood is that lasers at powers that are orders of magnitude smaller have also been used in the laboratory and clinic for nearly 30 years to modulate cell function, lessen pain, and accelerate healing of soft tissue injuries. This article analyzes the rationale of this approach, examines the utility of laser therapy in its most common clinical applications, reviews and synthesizes the findings, and concludes that although laboratory findings seem authentic, clinical utility remains unestablished. © 1995 Wiley‐Liss, Inc.
Pigmentation‐dependent side effects to copper vapor laser and argon laser treatment
Authors: Hædersdal Merete , Wulf Hans Christian
Published: March 2007

Background and Objective: Melanin is a limiting factor for obtaining beneficial results in dermatological treatment of vascular malformations. The aim of our study was to establish a relation between pretreatment skin pigmentation and the occurrence of side effects.

Study Design/Materials and Methods: Thirteen human volunters selected to have a varying degree of skin pigmentation were laser‐treated on the inside of the brachium with an argon laser (AL, 488 nm and 514.5 nm) and a copper vapor laser (CVL, 578 nm), both connected to a Hexascan. Total exposure areas were 1.26 cm2 and beam diameters were 1 mm. Three intensities were used, 0.7, 1.0, and 1.3 W. Pulse duration was 200 ms, resulting in fluences of 17.8, 25.5, and 33.1 J/cm2. Pretreatment skin pigmentation was objectified by skin reflectance measurements.

Results: At 1, 2, and 6 months after laser treatment, significant correlations were demonstrated between pretreatment skin pigmentation and laser‐induced pigmentary changes and scar formation. At the 6‐month assessment, the AL induced significantly higher scores of clinically evaluated scar formation as compared with the CVL (1.0 and 1.3 W/spot) and tended to induce higher clinical scores of pigmentary changes (not significant, ns).

Conclusions: We recommend skin pigmentation to be taken into consideration in dermatological laser treatment of vascular malformations. © 1995 Wiley‐Liss, Inc.
Effects of Nd:YAG laser on wound healing processes: Clinical and immunohistochemical findings in rat skin
Authors: Romanos George E. , Pelekanos Stavros , Strub Jörg‐Rudolf
Published: March 2007

Background and Objective: The clinical effects of the Nd:YAG laser in the rat skin as well as alterations of the extracellular matrix during healing were presented in this study.

Study Design/Material and Methods: This study evaluated the clinical effects of the Nd:YAG laser used with different energy parameters (low energy: 1.75 W and 20 pps / high energy: 3.0 W and 30 pps) in a duration 20–40 s in rat skin. Control incisions were performed with a scalpel blade. Rat skin incisions were examined over a period of 28 days by clinical photographs as well as by using immunohistochemical techniques in order to find the distribution and the amount of the extracellular matrix fibrillar components, i.e., collagen types I and III.

Results: Low energy laser treatment caused a rapid wound healing without scar tissue formation (compared to the high energy laser group) and clinical signs of scar tissue formation (compared to control incisions with the conventional scalpel). During the study period, the laser‐induced lesions healed through reparative synthesis of the matrix proteins, which led to filling of the tissue defects. The regenerative processes were similar in the low‐energy laser group and in the control incisions. In the high‐energy lased tissues, we observed a delayed replacement of the defects by newly formed extracellular matrix proteins.

Conclusions: This study showed a slower wound healing in the high‐energy lased tissues. A similar healing in the low‐energy lased tissues and in the incisions with the conventional scalpel was observed. The differences in the distribution of matrix proteins during healing and the coagulation of the tissues, which were exposed to low‐energy laser treatment, might be the explanation for the minimal scarring, contraction, and pigmentation of the lased tissues as compared to conventional incisions. © 1995 Wiley‐Liss, Inc.
Combination sensor for measurement of light and temperature
Authors: Welch A. J. , Cain C. P.
Published: March 2007

This report describes light and temperature measurements made in a gel cell using a single probe. Glass pipettes were drawn to an outer tip diameter of 50 μm and a thermocouple was vapor deposited at the tip of the pipette. Direct absorption of light by the thermocouple produced near step changes in temperature proportional to the fluence rate of the light. © 1995 Wiley‐Liss, Inc.
Lasers in ophthalmology
Authors: Krauss Joel M. , Puliafito Carmen A.
Published: March 2007

This article reviews the principle uses of ophthalmic lasers, providing historical background with an emphasis on new applications and areas of investigation. Ophthalmic photocoagulation was the first medical laser application and has restored or maintained vision in millions of people. More recently, photodisruption and, increasingly, ablation have gained prominence for treating a wide range of ocular pathology. The unique properties of lasers have also been harnessed for diagnostic purposes, with optical coherence tomography representing a significant improvement over existing imaging methods. Many ophthalmic applications of lasers have been developed, but the field is a dynamic one which continues to evolve along with laser technology itself. © 1995 Wiley‐Liss, Inc.
An anterolateral thigh flap based on the superior cutaneous perforator artery: An anatomic study and case reports
Authors: Chen Zhong , Zhang Chun , Lao Jie , Xing Jin‐Jun , Zhu Min‐Xing , Wu Yang , Ma An‐Jun
Published: March 2007

This study was performed to observe the patterns of the superior perforator artery as a pedicle for an anterolateral thigh flap and report the results of clinical application. The perforator arteries at the anterolateral part of the thigh were observed on 50 lower limbs from embalmed cadavers and the results of 65 clinical cases who received transfer of the anterolateral thigh flap, which adopted the superior perforator artery as the pedicle. This study found that 34 superior perforator arteries presented in 29 of the 50 cadaveric limbs (58%), which might arise from the ascending branch, the transverse branch, and the descending branch of the lateral circumflex femoral artery. All flaps of the 65 clinical cases survived postoperatively. Our results showed that the superior perforator artery has a high occurrence and a relative constant location. We thought that it could be adopted as a complement of the conventional perforator artery. © 2007 Wiley‐Liss, Inc. Microsurgery, 2007.
The dependence of sustained bladder contractions provoked by filling or by subcutaneous bethanechol upon sacral afferent pathways
Authors: El‐Salmy S. , Downie J. W. , Awad S. A.
Published: March 2007

The dependence of the detrusor response to sc bethanechol chloride on afferent nerves was studied in 20 cats by selective dorsal rhizotomy L7‐S3 in different combinations. Combined S1 and S2 dorsal rhizotomy abolished both the micturition reflex and the sustained bladder contraction in response to sc bethanechol administration. However in six of 13 experiments selective S2 dorsal rhizotomy abolished the bethanechol response while leaving the mictu rition reflex intact, albeit with a higher threshold volume. On the other hand, the bethane chol response was always lost if the micturition reflex was lost. We conclude that the sustained bladder response to sc bethanechol requires a complete reflex pathway involving sacral dorsal roots.
Normative bladder diary measurements: Night versus day
Authors: Parsons Matthew , Tissot William , Cardozo Linda , Diokno Ananias , Amundsen Cindy L. , Coats Alfred C. ,   on behalf of the Bladder Diary Research Team
Published: March 2007

Aims

To investigate bladder diary measurements from asymptomatic subjects in separate night and day periods, including their relationships to age and total volume voided. A major objective of this study was to generate age‐adjusted reference values against which clinical measurements of nocturia can be compared.

Materials and Methods

Three‐day bladder diaries were collected from 161 females and 92 males (age: median = 46.5 years; range = 19.6–84.6 years). We studied: average volume voided (“Vavg”), voiding frequency, and four urine production measures (volume, production rate, and their ratios to 24‐hr values)

Results

Both day and night Vavg and frequency increase with increasing volume. The night increase is much steeper than the day increase. With aging, frequency increases, Vavg decreases, day production decreases and night production increases. These age effects are steeper for males than females. Adjusting for age by regression analysis reduces the night production measure's variability by about 40%, and expressing production rate as a percent of the 24‐hr value reduces the variability by an additional 20%.

Conclusions

We present regression equations that can be used to adjust night and day Vavg frequency and production rate reference values for the influences of age and total volume. Using these equations, we calculated a table of 95% confidence limits of night urine production and night frequency. The least variable night urine volume measurement studied was night/24‐hr production rate; hence this may prove to be the most efficacious measurement to use in detecting nocturnal polyuria. Neurourol. Urodynam. 26:465–473, 2007. © 2007 Wiley‐Liss, Inc.
Glutamate measurement in Parkinson's disease using MRS at 3 T field strength
Authors: Kickler Nils , Krack Paul , Fraix Valérie , Lebas Jean‐François , Lamalle Laurent , Durif Franck , Krainik Alexandre , Rémy Chantal , Segebarth Christoph , Pollak Pierre
Published: March 2007

Loss of nigral dopamine neurons in Parkinson's disease induces abnormal activation of glutamate systems in the basal ganglia. The purpose of this study was to assess these changes in the lentiform nucleus using MRS with optimized glutamate sensitivity (TE‐averaged method). Ten patients with Parkinson's disease and 10 healthy controls were examined. Compared with healthy controls, no significant differences in glutamate were measured in patients, but a trend to lower total creatine was observed. Copyright © 2007 John Wiley & Sons, Ltd.
Discontinuous Galerkin finite element methods for dynamic linear solid viscoelasticity problems
Authors: Rivière Béatrice , Shaw Simon , Whiteman J.R.
Published: March 2007

We consider the usual linear elastodynamics equations augmented with evolution equations for viscoelastic internal stresses. A fully discrete approximation is defined, based on a spatially symmetric or non‐symmetric interior penalty discontinuous Galerkin finite element method, and a displacement‐velocity centred difference time discretisation. An a priori error estimate is given but only the main ideas in the proof of the error estimate are reported here due to the large number of (mostly technical) estimates that are required. The full details are referenced to a technical report. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Combined finite difference and spectral methods for the numerical solution of hyperbolic equation with an integral condition
Authors: Ramezani Mehdi , Dehghan Mehdi , Razzaghi Mohsen
Published: March 2007

In this work the combined finite difference and spectral methods have been proposed for the numerical solution of the one‐dimensional wave equation with an integral condition. The time variable is approximated using a finite difference scheme. But the spectral method is employed for discretizing the space variable. The main idea behind this approach is that we can get high‐order results. The new method is used for two test problems and the numerical results are obtained to support our theoretical expectations. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
On the stability of alternating‐direction explicit methods for advection‐diffusion equations
Authors: Campbell L.J. , Yin B.
Published: March 2007

Alternating‐Direction Explicit (A.D.E.) finite‐difference methods make use of two approximations that are implemented for computations proceeding in alternating directions, e.g., from left to right and from right to left, with each approximation being explicit in its respective direction of computation. Stable A.D.E. schemes for solving the linear parabolic partial differential equations that model heat diffusion are well‐known, as are stable A.D.E. schemes for solving the first‐order equations of fluid advection. Several of these are combined here to derive A.D.E. schemes for solving time‐dependent advection‐diffusion equations, and their stability characteristics are discussed. In each case, it is found that it is the advection term that limits the stability of the scheme. The most stable of the combinations presented comprises an unconditionally stable approximation for computations carried out in the direction of advection of the system, from left to right in this case, and a conditionally stable approximation for computations proceeding in the opposite direction. To illustrate the application of the methods and verify the stability conditions, they are applied to some quasi‐linear one‐dimensional advection‐diffusion problems. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007