bluuebunny/crossref_metadata_2025 huggingface dataset:
Dye laser photocoagulation through experimentally induced retinal hemorrhage
Authors: Obana Akira , Miki Tokuhiko
Published: March 2007

The histological effects of photocoagulation obtained by using each of 4 wavelengths of the dye laser (577, 590, 610, and 630 nm) on experimentally induced retinal hemorrhage in cat eyes were examined. Energy from 577, 590, and 610 nm laser was directly absorbed by red blood cells in the retinal hemorrhage and destroyed the inner layers of the retina. Red blood cells were not directly coagulated with the use of 630 nm laser, and the retinal pigment epithelial cells (RPE cells) and choroidal melanocytes were coagulated. These results suggest that the use of yellow or orange dye lasers for photocoagulative therapy in a retinal hemorrhage is dangerous, because of the risk for destruction of the inner layers of the retina. A 630 nm dye laser is useful for photocoagulation of a retinal hemorrhage, while the laser energy is unable to reach the RPE cells and the choroid with the use of other wavelengths.
Mechanism of CW Nd:YAG laser recanalization with modified fiber tips: Influence of temperature and axial force on tissue penetration in vitro
Authors: Verdaasdonk Rudolf M. , Jansen E. Duco , Holstege Frank C. , Borst Cornelius
Published: March 2007

Modified fiber tips are used for laser angioplasty of totally occluded peripheral arteries. It has not been established, however, to what extent the mechanism of action of various laser probes is optical, thermal, or mechanical. We examined transparant contact probes (hemispherical contact probes and ball‐shaped fibers) and metal laser probes, coupled to a continuous‐wave NdYAG laser. By using homogeneous thick porcine fatty tissue samples submerged in blood plasma, tissue penetration was measured in relation to the temperature of the probe and the axial force exerted on the tissue. By using 15 W, 1 s laser pulses, the surface of transparent contact probes had to be first contaminated by carbonized tissue particles to achieve tissue penetration. Penetration increased from 1 to 10 mm per pulse when axial force increased from 20 to 100 g. Metal probes had to be sufficiently insulated from the liquid environment by water vapour entrapped in a denatured protein layer to exceed the threshold temperature of 225°C for tissue penetration. When axial force increased from 20 to 80 g at 10 W continuous exposure, the velocity of tissue penetration increased in the range from 1 to 4 mm/s. Tissue penetration by modified fiber tips is attributed to both remodeling and vaporization of tissue. With transparant contact probes, tissue is heated partly by direct light absorption and partly by a hot probe surface. Axially directed force is necessary to displace lateral non‐ablated tissue and to overcome mechanical resistance. We conclude that mechanical dilation due to axial catherization force (Dotter effect) contributes substantially to tissue penetration by transparent contact probes.
Temperature along the surface of modified fiber tips for Nd:YAG laser angioplasty
Authors: Verdaasdonk Rudolf M. , Holstege Frank C. , Jansen E. Duco , Borst Cornelius
Published: March 2007

For laser angioplasty probes, the thermal properties of the probes will primarily determine their mechanism of action. We examined the absorption, temperature increase, and probe degradation of transparent contact probes (hemispherical contact probe and ball‐shaped fibers) and metal laser probes coupled to a continuous‐wave Nd‐YAG laser. Temperature was recorded by means of thermocouples and the measurements were corrected for direct light absorption by the thermocouple. During 15 W, 1 s exposure, the peak temperature rise of the hemispherical contact probe in contact with tissue dropped from approximately 1,000°C at the front end to below 45°C (95% drop) at the lateral side. In contrast, during continuous exposure the peak temperature rise of metal laser probes in contact with tissue dropped from 560°C at the front end to near 400°C (30%drop) at the 5.5 mm proximal rear end. During exposure in blood or tissue, the transparent contact probes became contaminated. Their absorption increased from 5 to 33% and the probe deteriorated. Repeated use of metal laser probes in blood resulted in a higher temperature at the rear than at the front end due to backburing of the fiber. Owing to the large temperature drop along the surface of transparent contact probes, the area of thermal destruction is limited to the tissue in front of the probe, whereas along the entire surface of metal laser probes the tissue will be affected. The large difference between these temperature distributions should be respected during clinical application of the transparant contact probe and the metal laser probe.
Fluorescence localization of early colonic cancer in the rat by hematoporphyrin derivative
Authors: Bjorkman David J. , Samowitz Wade S. , Brigham Earl J. , Peterson Brian J. , Straight Richard C.
Published: March 2007

Laser excitation of hematoporphyrin derivatives (HPD) localizing in tumors of the tracheobronchial tree and bladder is useful in the identification and treatment of those tumors. A comparable utility for HPD in the endoscopic localization of colonic tumors may be possible. In this study the ability of HPD to identify 1,2 dimethylhydrazine (DMH) induced colon cancer in rats is evaluated.

A total of 111 rats were studied with HPD. Sixty‐nine rats received weekly injections of DMH (20 mg/kg) and 42 received injections of the vehicle alone. Twenty‐four hours after the intravenous injection of 5 mg/kg of HPD, 18 DMH‐induced tumors were identified by visual fluorescence using excitation by either a blue light (390–436 nm) or an argon laser (488 and 514 nm). This represented 100% of the visually or microscopically detected tumors. Seventy‐five fluorescent areas were noted that did not contain evidence of cancer. The majority (63) of false positive areas contained lymphoid follicles. All but 2 false positive areas (73/75, 97%, p < .001) were seen in DMH‐treated animals, suggesting that they were an artifact of DMH treatment. HPD fluorescence did not identify microscopic dysplasia.

We conclude that HPD fluorescence is an effective method of identifying early colonic cancer and may have a potential clinical role in patients at high risk for colorectal cancer.
In situ testing of CO2 laser on dental pulp function: Effects on microcirculation
Authors: Friedman Shimon , Liu Mintsai , Dörscher‐Kim Jutta , Kim Syngcuk
Published: March 2007

The effect of CO2 laser irradiation on pulpal microcirculation was studied in cat canines. The enamel surfaces of 4 teeth were exposed with energy densities of 304‐1440J/cm2, using either a handpiece or a microslad, with a focal spot of 0.21mm and 0.33mm respectively. Pulpal blood flow (PBF) before and following lasing was recorded through the intact tooth surface by a laser Doppler flowmeter. CO2 laser irradiation caused an increase in PBF, which was immediate and transient. The PBF increase was higher in a large pulp than in a small pulp, and it was inversely related to the focal spot size. These findings confirm that the dental pulp is thermally affected by CO2 lasing of the tooth surface, however, without extensive pulp coagulation. It is concluded that the effects of laser irradiation on the pulpal microcirculation may be studied in situ by means of the presented methodology.
Contact diode laser application through a fiberoptic cutting tip
Authors: Peyman Gholam A. , Cruz Sergio A. , Ruiz‐Lapuente Carlos
Published: March 2007

We applied diode laser energy through a fiberoptic probe to cut ocular structures. The diameter of the probe's tip was 100 μm. The amount of energy used for cutting the lid, the cornea, or for perforation of the globe was 2.5 watts in the continuous mode. The incised border demonstrated coagulation into the healthy tissue ranging from 10 to 50 μm.
Nd:YAG laser‐induced hyperthermia treatment of spontaneously occurring veterinary head and neck tumors
Authors: Panjehpour Masoud , Overholt Bergein F. , Frazier Donita L. , Klebanow Edward R.
Published: March 2007

Conventional hyperthermia treatment of superficial tumors in the oral cavity is troublesome due to difficulty in accessing the lesion. A new hyperthermia technique employing near‐infrared radiation delivered through a flexible silica optical fiber is described. The system consisted of an Nd:YAG laser for tissue heating, a He–Ne laser for aiming beam, a computer‐controlled optical shutter, an interstitial thermometer, computer, and a printer. A 3‐m‐long 600‐μm silica fiber delivered laser energy to the tumor via surface illumination. Using the aiming beam, the spot size was adjusted to include 5 mm of surrounding normal tissue. A thermocouple implanted in the tumor base provided temperature feedback to maintain desired hyperthermic temperature within the lesion.

Three spontaneously occurring canine (two squamous cell carcinomas on the gum, one pigmented melanoma on the hard palate) and one feline tumor (squamous cell carcinoma on the nose) have been treated with Nd:YAG laser hyperthermia. Hyperthermia was delivered at 43.5°C for 1 h. All animals received standard radiation treatment prior to hyperthermia. Nd:YAG laser hyperthermia allowed effective and efficient delivery of heat to veterinary nasal and oral lesions otherwise not treatable with conventional heating techniques.
Nd:YAG laser hyperthermia treatment of rat mammary adenocarcinoma in conjunction with surface cooling
Authors: Panjehpour Masoud , Wilke August V. , Frazier Donita L. , Overholt Bergein F.
Published: March 2007

Electromagnetic radiation ranging from radiofrequency to microwave has classically been used to induce hyperthermia for treatment of cancer. This paper presents a new technique using near infrared radiation from an Nd:YAG laser in conjunction with surface cooling to induce hyperthermia in a rat tumor model.

A CW Nd:YAG laser hyperthermia system was used to induce hyperthermic temperatures in chemically (DMBA) induced rat mammary adenocarcinomas. The laser was interfaced to a computer and a thermometry unit that provided feedback to control the tumor temperature between 43.2–43.5°C. A thermocouple was placed at the base of the tumor and its temperature was used to control laser exposure. All tumors were 10 to 20 mm in diameter.

Surface cooling methods investigated included forced air flow from a fan, forced oxygen flow plus an IV drip, and forced moist oxygen flow from a nebulizer. Twelve rat mammary adenocarcinomas have been treated with Nd:YAG laser hyperthermia. In 4 treatments, no surface cooling was employed. In one treatment the surface was cooled using oxygen flow plus IV drip. In 7 treatments the skin was cooled using the nebulizer technique. The nebulization provided the most effective and reproducible surface cooling.

Nd:YAG laser hyperthermia delivered in conjunction with nebulizer surface cooling produced efficient heating of rat mammary adenocarcinomas. A mean temperature of 42.1 °C was obtained at the base of the tumors while the mean surface temperature was 37.0 °C.
Presence of blood significantly decreases transmission of 630 nm laser light
Authors: Vincent G. Michael , Fox Jolene , Charlton Gerald , Hill J. Stan , McClane Robert , Spikes John D.
Published: March 2007

Application of 630 nm light in the presence of blood is often necessary during photodynamic therapy, particularly for proposed intravascular applications. The effect of blood on transmission of 630 nm light was studied using a three dimensional irradiation model and an integrating sphere for measuring light transmitted in any direction through blood layers of different hematocrit (25 to 75) and thickness (.15 to .98 mm). There was an inverse relationship between transmission and hematocrit and transmission and blood thickness, p=.000 for both. At a physiologic hematocrit of 46, transmission through blood layers of .98, .41, .28, and .15 mm were 21%, 33%, 29%, and 58% respectively. These blood thicknesses or more are likely in the clinical environment, and can be expected to result in significant transmission losses. The marked absorption of 630 nm light by blood indicates that removal of the blood or correction for power loss should be employed when 630 nm light is applied in a blood containing environment.
Effect of low level laser therapy on wound healing after palatal surgery in Beagle dogs
Authors: de Braekt Marcel M. H. In , van Alphen Frank A. M. , Kuijpers‐Jagtman Anne M. , Maltha Jaap C.
Published: March 2007

The effect of low level laser therapy on wound healing and wound contraction after palatal surgery in Beagle dogs of 12 weeks of age was investigated. A total of 30 Beagle dogs was used and assigned to a control group (Group C; n=6) and two experimental groups (Group L; n=12 and group LL; n=12). In both experimental groups, Von Langenbeck's palatal repair was simulated. Then in the LL group the denuded bony areas were treated with low level laser therapy using a continuous Ga‐As‐Al laser beam (830 nm) and energy output set at 30 mW. Per treatment a dosage of 1 J/cm2 wound surface area was used. Therapy was carried out three times a week with a total of ten treatments.

Wound healing was observed clinically until wound healing was completed at 4 weeks p.o. and wound areas were measured at regular intervals on standardized intra‐oral photographs. Wound contraction was measured as the increments of the distances between tattoo points on the opposite wound margins. No significant differences were found in the quality and rate of wound healing between the two experimental groups. The same held true for the increments of the distances between opposite tattoo points. It was concluded that macroscopically low level laser therapy under conditions used in this study did not have an influence on wound closure or wound contraction.
Healing of infected wounds following Iodine scrub or CO2 laser treatment
Authors: Reid A. Bruce , Stranc Miroslaw F.
Published: March 2007

This study compares CO2 laser sterilization with iodine surgical scrub in infected pseudomonas wounds in the rabbit, and on frequency of wound breakdown secondary to sepsis. Thirty‐three New Zealand rabbits underwent bilateral flank incisions and infection with a standard solution of pseudomonas aeruginosa. After 4 days of incubation, the wounds were randomized to receive laser sterilization and routine iodine surgical scrub respectively. Following sterilization, excision of the wound, and suturing was carried out. After 12 days, the wounds were assessed for evidence of residual infection as well as wound breakdown in a double blind fashion. Clinical observation, qualitative microbiology, and in some cases histology, were used to document the presence of infection. Statistical analysis of wound breakdown secondary to infection revealed a significant difference in breakdown rates. Three laser and 12 iodine treated wounds displayed breakdown secondary to sepsis. We conclude that the CO2 laser sterilization technique is more effective than routine iodine surgical scrub.
Application of the argon laser to dentistry
Authors: Kelsey William P. , Blankenau Richard J. , Powell G. Lynn
Published: March 2007

A review was conducted to determine specific areas of application of the argon laser to dentistry. When appropriate, comparisons between the argon laser and other treatment methods were made. It was concluded that the argon laser has applicability in composite resin placement, in enamel and dentin bonding procedures, in preventive dental therapies, and in endodontic procedures.
Contact Nd: YAG tonsillectomy: Effects on weight loss and recovery
Authors: Maloney Richard W.
Published: March 2007

Contact Nd: YAG tonsillectomy using synthetic sapphire blades appears to meet or exceed standards established by spot monopolar cautery. Subjects' percentage of weight loss and return to work/social activities was measured and the laser group displayed less percentage of weight loss, faster return to pre‐operative weight, and less recovery time than the comparative cautery group. Because of the unique nature of Nd: YAG laser light combined with sapphire blades, special consideration should be given to these accessories by physicians before attempting tissue cutting and vessel coagulation. The author believes that the extent of physician training and proficiency may be key to the success of soft tissue head and neck applications, such as tonsillectomy, which will have an effect on the outcome of clinical data.
Laser‐induced fluorescence emission: I. The spectroscopic identification of fibrotic endocardium and myocardium
Authors: Perk Masis , Flynn Gregory J. , Smith Carolyn , Bathgate Ben , Tulip John , Yue Wen , Lucas Alexandra
Published: March 2007

Laser‐induced fluorescence has been developed as a guidance system for laser angioplasty. Laser ablation has been used for resection of arrhythmogenic ventricular scar. We have investigated the use of laser‐induced fluorescence for the detection of fibrotic and ischemic changes in endocardium and myocardium. Fluorescence emission spectra from human necropsy specimens were correlated with histologic examination. Normalized fluorescence intensity detected from both the endocardial and the myocardial surfaces of the fibrotic ventricular specimens was significantly higher than that of corresponding normal specimens at 440 to 475 nm. Fibrotic endocardium could be identified by a fluorescence emission intensity ratio less than 1.5 for wavelength ratio 375/450nm. Acutely infarcted endocardium was recognizable by a ratio of 1.5 to 2.0. The specificity and sensitivity of detection of scarred endocardium was 70 and 100%, respectively. Fibrotic myocardium was also consistently identified by fluorescence spectroscopy.

Conclusion: Fluorescence emission spectroscopy can differentiate normal and fibrotic endocardium and myocardium, in vitro. This technique may be useful for guidance during laser ablation of arrhythmogenic ventricular scar.
Solid state ultraviolet laser (213 nm) ablation of the cornea and synthetic collagen lenticules
Authors: Gailitis Ray P. , Ren Qiushi , Thompson Keith P. , Lin J. T. , Waring George O.
Published: March 2007

We used a Q‐switched Nd:YAG laser with non‐linear optical crystals to produce the 5th (213 nm) and the 4th (266 nm) harmonic frequencies. Using these two wavelengths, we ablated fresh porcine corneas and type I collagen synthetic epikeratoplasty lenticules. For the 213‐nm ablation, radiant exposure was 1.3 J/cm2. The ablation rate was 0.23 μm per pulse for the epikeratoplasty lenticules. We examined all tissues with light microscopy, transmission electron microscopy, and scanning electron microscopy. Histology for the 213‐nm ablation showed a clean ablation crater with minimal collagen lamellae disruption and a damage zone less than 1μm. In comparison, the 266 nm radiation showed more charring at the edges with a damage zone approximately 25 μm deep with disruption of the stromal lamella.

Our results show that this solid state UV laser is a potential alternative to the excimer laser for cornea surgery.
Technique for cellular microsurgery using the 193‐nm excimer laser
Authors: Palanker Daniel , Ohad Shoshanit , Lewis Aaron , Simon Alex , Shenkar Joseph , Penchas Shmuel , Laufer Neri
Published: March 2007

A new cell surgery technique has been developed to produce well‐defined alterations in cells and tissue without detectable heating and/or other structural damage in the surroundings. The technique involves the use of an argon fluoride excimer laser, in the deep ultraviolet (UV) region of the spectrum at 193 nm, which is guided through a glass pipette filled with a positive air pressure. To demonstrate the method, holes were drilled in the zona pellucida of mouse oocytes. The diameter of the drilled hole was determined by the pipette tip size, and its depth by an energy emitted per pulse and number of pulses. Scanning electron microscopy of the drilled mouse oocytes showed uniform, round, well‐circumscribed holes with sharp edges. Oocytes that had their zona pellucida drilled with this new method fertilized in vitro and developed to the blastocyst stage in a rate similar to that of control group. These results demonstrate the nonperturbing nature of this cold laser microsurgical procedure. In addition to the extension of our results for clinical in vitro fertilization purposes, such as enhancement of fertilization and embryo biopsy, there are wide‐ranging possible uses of our method in fundamental and applied investigations that require submicron accuracy in cellular alteration.
Glucose administration combined with photodynamic therapy of cancer improves therapeutic efficacy
Authors: Nelson J. Stuart , Kimel Sol , Brown Lisa , Berns Michael W.
Published: March 2007

Both the scope and the levels of activity in basic research and in the clinical applications of PDT, have grown enormously during the past few years. Several studies have examined the synergism of hyperthermia and chemotherapeutic agents in combination with PDT to enhance tumor eradication. The present study investigates the synergism of glucose administration combined with phototherapy.

The results of this study suggest that glucose administration is simple and well tolerated, and combined with PDT produces a larger percentage of animals cured than using PDT alone. Furthermore, the results indicate that this approach requires lower amounts of light and might enable dosage reduction of photosensitizer for optimal response, with minimal side effects, to the treatment of cancer. © 1992 Wiley‐Liss, Inc.
Effect of helium–neon laser irradiation on serum lipid peroxide concentrations in burnt mice
Authors: Zhang Dahong , Chen Tingren , Wang Channian , Wu Shimin , Fu Chengli
Published: March 2007

The effect of helium–neon irradiation on serum lipid peroxide concentrations in mice following 6–7% body surface area burns was investigated in a controlled study. Immediately following injury by an 8‐sec 100°C scalding, 25 mice were irradiated by a helium‐neon laser at 0.05 J/cm2. A control group of the same size underwent identical treatment but received only sham irradiation. Serum lipid peroxide concentrations increased markedly in the control group at 0.5–4 h (P<0.0001, two sample t‐test). In the laser treated group, the lipid peroxide concentrations remained relatively constant and were significantly depressed relative to the control group 4 h following burning (P < 0.0001, two‐sample t‐test). © 1992 Wiley‐Liss, Inc.
Laser and suture anastomosis: Passive compliance and active force production
Authors: Dalsing Michael C. , Packer C. Subah , Kueppers Peter , Griffith Steven L. , Davis Thomas E.
Published: March 2007

One carotid from each dog underwent a laser anastomosis and the other carotid an interrupted suture repair. One or eight weeks later (n ≥ 4 dogs/time period); four rings (1 mm in length) containing the laser or suture anastomosis or the normal artery (two/dog) were removed. Using a photoelectric force transducer and lever system, the ring was stretched in increments and passive force measured. At each length, the arterial muscle was stimulated and active force measured.

The mean laser and control passive length/tension (L/T) curves were not different (P > 0.05), but the suture curve was shifted downward (P<0.05). The mean laser and suture active L/T curves were similar at 1 week ( > 0.05) and lower than the control curve (P < 0.04). At 8 weeks, the laser‐repaired vessels produced an active force similar to control muscle (P > 0.05) but the suture repairs could not generate this active force (P<0.05).

These data suggest that the laser repair and normal artery are more mechanically compatible than the suture repair as studied by this method. © 1992 Wiley‐Liss, Inc.
A special irrigation liquid to increase the reliability of laser‐induced shockwave lithotripsy
Authors: Reichel Erich , Paltauf Günther , Schmidt‐Kloiber Heinz , Groke Karl
Published: March 2007

For the laser‐induced Shockwave lithotripsy (LISL) the laser‐pulses of a Q‐switched Nd:YAG laser produce an optical breakdown in the irrigation liquid surrounding the urinary stone. Subsequently high‐pressure Shockwaves are emitted causing stone fragmentation. Since the LISL is an endoscopic technique, problems arise from the transmission of the laser pulses through optical fibers. The intensity threshold for an optical breakdown in commonly used saline solution amounts to 21 GW/cm2, in optical silica fibers, to about 3 GW/cm2. Therefore bare fibers cannot be used without being destroyed by a breakdown. So we have developed an irrigation liquid by adding small quantities of metal ions to saline solution to lower the threshold intensity. The most suitable ion was Fe3+ in a concentration of 0.02 mmol/1, which shows a lowering to 5 GW/cm2. In combination with a spherically shaped fiber exit the intensities that have to be transmitted are below the threshold of the fiber material. Using this irrigation liquid the overall reliability of the method could be significantly increased and several stone fragmentations can be performed with a single optical fiber. © 1992 Wiley‐Liss, Inc.
Effect of coolant flow on the performance of round sapphire tips in a saline field
Authors: Royston David D. , Waynant Ronald W. , Elliott Ariann M. , Oshry Stacy
Published: March 2007

Round sapphire and silica tips have been studied as surgical probes for focusing Nd:YAG laser radiation during various surgical indications. Since most of these data have been obtained with silica tips from Surgical Laser Technology, there are limited data on the physical performance of round sapphire tips. An investigation of round sapphire tip performance during tissue ablation was undertaken. Nd:YAG laser power was delivered in repetitive 2‐sec exposures to a round sapphire tip placed on fresh skinned chicken breast. Total exposures of 1,000 J were performed at different saline perfusion rates. The tip's performance in terms of tissue perforation rate, blanched tissue area, tissue heating rate, and forward transmission was measured. Best tip performance occurred at the lowest cooling rates and was independent of the tip's forward transmission value. No physical deterioration of the tip's optical surface was observed. Round sapphire tip performance in a saline field is primarily determined by the tip's temperature. © 1992 Wiley‐Liss, Inc.
Intravascular ultrasound guided Holmium:YAG laser recanalization of occluded arteries
Authors: White Rodney A. , Kopchok George E. , Tabbara Marwan R. , Cavaye Douglas M. , Cormier Francois
Published: March 2007

Current angioplasty devices are limited by arterial wall dissection and perforation, and by early recurrence from inadequate debulking of lesions. This study evaluated intravascular ultrasound (IVUS) as guidance for concentric laser recanalization of arterial occlusions. Twelve, 2–4‐cm‐long canine iliac artery occlusions were treated at 2 weeks (organizing thrombus) to 12 weeks (firm fibrous lesions) using a Holmium:YAG laser (2,100 nm wavelength) in free running mode, FRM, (250 μsec pulse, 5 Hz), n = 9; and Q‐switched mode, QSM (200 ns pulse, 6 Hz), n = 3. A 200 μm (n = 2) or 600 μm (n=10) optic fiber was centered in the artery coaxial to a 5Fr rotating A scan IVUS probe. The fiber was positioned in the center of the artery distal to the lesion and slowly advanced through the obstruction. In 8 occlusions the same fiber was used as a guide wire for passage of either a 1.6‐mm‐(n=2) and/or 3.0‐mm (n=6) diameter multifiber catheter (19 × 100 and 19 × 200 μm fibers, respectively) using FRM energy to further debulk the lesion. In all cases, IVUS guidance enabled concentric initial recanalization of occlusions, although 3 vessel perforations resulted from fiber deviation off the center of the lumen at a distance of 2 to 4 cm from the IVUS imaging element. Both QSM and FRM modes ablated tissue, with FRM modes producing more tissue fragmentation and thermal effect. IVUS images accurately diagnosed the location of lesions compared to angioscopic views and pathologic analysis of the specimens. This study suggests that IVUS guided laser energy may enable initial concentric re‐canalization of arterial occlusions if adequate tissue removal can be accomplished to provide continuous IVUS imaging as the re‐canalization proceeds. © 1992 Wiley‐Liss, Inc.
Laser treatment of premalignant and malignant squamous cell lesions of the penis
Authors: Malek Reza S.
Published: March 2007

Thirty men with biopsy‐proven premalignant or malignant squamous cell lesions of the penis were treated. All had subclinical aceto‐white lesions with histologic evidence for human papilloma virus infection. Nineteen patients had penile intraepithelial neoplasia (PIN I and II) and 11 had squamous cell carcinoma. Of these 11 patients, 6 had noninvasive penile intraepithelial neoplasia—carcinoma in situ (PIN III/Tis)—and 5 had invasive squamous cell carcinoma (4 stage T2 and 1 T3). All were treated with laser: CO2 was used for low‐stage lesions, Nd:YAG was used alone or in combination with CO2 laser for more histologically advanced lesions, and KTP/532 was used in one patient with squamous cell carcinoma (Tis). Follow‐up in 23 patients for up to 2 years showed that all but 1 (stage T3) remained free from penile malignancy. Appropriate laser therapy for all but deeply invasive (T3) tumors controls local disease, producing results that are clinically equal and cosmetically and functionally far superior to partial penectomy. © 1992 Wiley‐Liss, Inc.
Prevention of X‐ray‐induced late dermal necrosis in the pig by treatment with multi‐wavelength light
Authors: Rezvani Mohiaddin , Nissan Moshe , Hopewell John W. , van den Aardweg Gerard J. M. J. , Robbins Mike E. C. , Whitehouse Elizabeth M.
Published: March 2007

Low‐level light from a multi‐wavelength array of light sources has been used to prevent late X‐ray‐induced dermal necrosis in the pig. Skin fields, measuring 4 × 4 cm on the flank, were irradiated with a single dose of 23.4 Gy of X‐rays. This X‐ray dose was associated with the development of a 100% incidence of dermal necrosis, 10–16 weeks after irradiation. These irradiated skin sites were subsequently exposed to light of 660, 820, 880, and 950 nm wavelengths from a gallium aluminium arsenide multiple wavelength multidiode cluster probe (Biotherapy Medical Laser, 3ML), three times a week, from 4 to 16 weeks or 6 to 16 weeks after X‐irradiation. The skin fields were exposed to the light pulsating at either 2.5 Hz or 5 kHz. With light pulsating at 5 kHz, energy densities of 0.22, 0.54, 1.08 2.16, 4.32, and 10.8 J/cm2 were used. Treatment with light pulsating at 2.5 Hz, 6–16 weeks after X‐irradiation, or treatment with light pulsating at 5 kHz, 4–16 weeks after X‐irradiation, did not have a significant effect on the incidence or the latency for the development of ischemia dermal necrosis irrespective of the exposure time to light at each treatment. With light pulsating at 5 kHz, no effect of light dose was observed. However, the overall incidence of dermal necrosis was significantly reduced (P = 0.001) to 52% in the X‐irradiated fields receiving treatment with 5 kHz light, 6–16 weeks after X‐irradiation. Treatment with light for only three days immediately after X‐irradiation with 5 kHz light had no beneficial effect. These findings suggest that light when applied appropriately may be useful in the prevention of late X‐ray‐induced damage to the dermis provided that it is given for the most appropriate time after X‐irradiation. © 1992 Wiley‐Liss, Inc.
Exogenous chromophores for the argon and Nd:YAG lasers: A potential application to laser‐tissue interactions
Authors: Brooks Stephen G. , Ashley Simon , Fisher John , Davies Gwilym A. , Griffiths John , Kester Ralph C. , Rees Michael R.
Published: March 2007

Chromophore dyes can be employed to modify laser‐tissue interaction. A number of dyes have been investigated for their effect on the absorption and transmission of argon and Nd:YAG laser energy by vascular tissue in vitro. Three histological dyes have been assessed as potential chromophores for the argon laser and four infrared dyes for the Nd:YAG. Segments of porcine coronary artery to which dye had been applied were lased (1,064 nm, 2.5 W, 83 W/cm2, 60 s and 488/514 nm, 400 mW, 10.5 W/cm2, 60s) and the tissue temperature measured remotely using an infrared thermometer. In addition, energy transmission was measured with a photodiode and tissue morphological changes assessed histologically.

All three argon dyes significantly increased energy absorption (typically 60°C v. 20°C at 60 s, P < 0.001, 2‐way ANOVA). Three of the four infrared dyes behaved similarly (40–70°C v. 20°C, P < 0.001). All dyes significantly increased the initial rate of rise in tissue temperature during lasing. A reduction in energy transmission was observed for each of the Argon dyes but not for the Nd:YAG dyes. Histological evidence of thermal damage in control tissue first occurred for the argon and Nd:YAG lasers at 800 mW and 7.5 W without chromophore and at 400 mW and 2.5 W with the chromophore, respectively.

A number of effective chromophores have therefore been identified at each wavelength. © 1992 Wiley‐Liss, Inc.
Use of the holmium:YAG laser in urology
Authors: Johnson Douglas E. , Cromeens Douglas M. , Price Roger E.
Published: March 2007

The tissue effects of a holmium:YAG (Ho:YAG) laser operating at a wavelength of 2.1μ with a maximum power of 15 watts (W) and 10 different energy‐pulse settings was systematically evaluated on kidney, bladder, prostate, ureteral, and vasal tissue in the dog. In addition, various urologic surgical procedures (partial nephrectomy, transurethral laser incision of the prostate, and laser‐assisted vasovasostomy) were performed in the dog, and a laparoscopic pelvic lymph node dissection was carried out in a pig. Although the Ho:YAG laser has a strong affinity for water, precise tissue ablation was achieved in both the contact and non‐contact mode when used endoscopically in a fluid medium to ablate prostatic and vesical tissue. Using the usual parameters for tissue destruction (blanching without charring), the depth of thermal injury in the bladder and ureter was kept superficial. In performing partial nephrectomies, a 2‐fold reduction in the zone of coagulative necrosis was demonstrated compared to the use of the continuous wave Neodymium:YAG laser (Nd:YAG). When used through the laparoscope, the Ho:YAG laser provided precise cutting and, combined with electrocautery, allowed the dissection to proceed quickly and smoothly. Hemostatic control was adequate in all surgical procedures. Although the results of these investigations are preliminary, our initial experience with the Ho:YAG laser has been favorable and warrants further investigations. © 1992 Wiley‐Liss, Inc.
Transurethral incision of the prostate using the holmium:YAG laser
Authors: Johnson Douglas E. , Cromeens Douglas M. , Price Roger E.
Published: March 2007

Transurethral incisions of the prostate were made endoscopically in 5 dogs under a fluid medium using a holmium:YAG (Ho: YAG) laser operating at a wavelength of 2.1 μm and with delivery of 1.0 J/pulse in 15 Hz (15 W). Histopathologic examination of tissues collected immediately after surgery revealed irregular crevices outlined by a narrow zone of coagulative necrosis. Ulcerated fissures persisted at 5 and 7 days with the initial stages of epithelial regeneration partially re‐epithelializing the ulcerated surfaces. A modest inflammatory response characterized by edema, hemorrhage, and a mixed inflammatory cell infiltrate was also associated with the laser incision sites at 5 and 7 days. Three weeks postlasing, the ulcerated surfaces of the fissures were completely re‐epithelialized. At 5 weeks only a slight indentation persisted at the incision sites with minimal changes in the subjacent submucosa and prostatic glandular architecture. Although the results of these investigations are preliminary, we believe that the Ho:YAG laser warrants further clinical evaluation for treating patients with benign prostatic hyperplasia (BPH), urethral strictures, bladder neck contractures, and constrictions of the upper urinary tracts. © 1992 Wiley‐Liss, Inc.
Erb:YAG and Hol:YAG laser ablation of meniscus and intervertebral discs
Authors: Buchelt Martin , Kutschera Hans‐Paul , Katterschafka Thomas , Kiss Harald , Schneider Barbara , Ullrich Robert
Published: March 2007

Erb:YAG and Hol:YAG laser ablation rates of fibrocartilage and nucleus pulposus were measured in vitro simulating clinical conditions. After ablation macroscopic and microscopic appearance of the ablation site was investigated. Hol:YAG and Erb:YAG laser mean ablation rates increased almost linearly with rising energies, showing higher total ablation rates for the Hol:YAG laser due to its higher achievable energy density. At comparable energy densities the Erb:YAG laser appears to be more effective with respect to the corresponding ablation rates. Consequently, the ablational threshold proved to be lower for the Erb:YAG laser. Whereas during Hol:YAG laser ablation, some smoke formation and considerable tissue shrinking occurred, these effects could not be observed during Erb:YAG laser ablation. Consequently macroscopic and microscopic inspection showed some thermal damage after Hol:YAG and only minimal alterations after Erb:YAG laser ablation. Adjacent thermal damage was determined and proved to be lower for the Erb:YAG laser. In our opinion the characteristics of each laser system provide certain advantages for special clinical indications. © 1992 Wiley‐Liss, Inc.
Feasibility of skin deepithelialization using the contact Neodymium‐Yttrium‐Aluminum‐Garnet laser
Authors: Hallock Geoffrey G. , Rice David C.
Published: March 2007

In a manner similar to laserbrasion, the carbon dioxide (CO2) laser has a proven role for expediting skin deepithelialization, which is an essential component of many reconstructive procedures. However, the contact Neodymium‐Yttrium‐Aluminum‐Garnet (Nd:YAG) laser has many additional attributes such as tactile feedback and less plume that theoretically offer an advantage over the CO2 laser for this adjunctive maneuver. In rat experimental models and clinical applications, removal of the epidermis necessary for skin deepithelialization may indeed be achieved using a rounded probe for vaporization with the contact Nd:YAG laser. Unfortunately, the length of tune necessary for skin deepithelialization with the Nd:YAG laser exceeded even conventional methods, such that this role with the present technology, although possible, is inefficient and impractical. © 1992 Wiley‐Liss, Inc.
In vitro laser recanalization of chronically occluded prosthetic grafts
Authors: Kaelin Lawrence D. , Klingman Nina , Normann Sigurd J. , Seeger James M.
Published: March 2007

Polytetrafluoroethylene (PTFE) and Dacron grafts were implanted in canine femoral and carotid arteries using PTFE and Prolene suture, respectively. Arteries containing occluded grafts were explanted and laser recanalization was attempted in vitro.

Laser recanalization was successful in 78% of PTFE grafts compared to 30% of Dacron grafts. Recanalization was complete (residual stenosis < 5%) in opened PTFE grafts, whereas residual stenosis averaged 60% in recanalized Dacron grafts. PTFE graft/ PTFE suture anastomotic tensile strength was unchanged after recanalization, while Dacron graft/Prolene suture anastomotic tensile strength decreased significantly. In addition, anastomotic bursting pressure was significantly higher for lased PTFE grafts with PTFE sutures (300 mg Hg) compared to lased Dacron grafts with Prolene sutures (70 mm Hg).

Chronically occluded PTFE grafts with PTFE suture can be safely and effectively opened by laser recanalization. In contrast, attempted laser recanalization of Dacron grafts sutured with Prolene suture is seldom successful, significantly weakens the graft artery anastomosis, and should be avoided.
Interstitial photoradiation injury of normal brain
Authors: Ji Ying , Walstad Diana , Brown J. Tony , Powers Stephen K.
Published: March 2007

The effect on normal brain of continuous interstitial laser irradiation at 630 nm through an implanted cylindrical‐shape, diffusion‐tipped optical fiber was studied in the rat. Brain water content in the laser irradiation area (LIA) and Evans blue (EB) dye content in selected areas of the brain were measured for different laser power outputs from 0 to 250 mW after 5 minutes of photo‐radiation. The degree and nature of tissue damage was examined histologically and correlated with the laser power level.

There is significant brain damage, blood brain barrier (BBB) disruption, and brain edema in LIA for laser power outputs in excess of 100 mW from the diffusion tip (p < 0.001). Brain edema in the LIA is strongly correlated with BBB disruption indicated by the presence of EB. Histologically, the cortical surface was more susceptible than deeper white matter regions to interstitial laser irradiation. Possible indirect mechanisms of brain injury from interstitial laser irradiation are discussed. © 1992 Wiley‐Liss, Inc.
Therapeutic effect of Ga‐Al‐As diode laser irradiation on experimentally induced inflammation in rats
Authors: Honmura Akie , Yanase Masahiro , Obata Junichi , Haruki Eiichi
Published: March 2007

We produced experimental inflammation models in rats by carrageenin and studied the effect of Ga‐Al‐As diode laser irradiation (780 nm, continuous wave, 31.8 j/sec/cm2, spot size of 0.2 mm) on inflamed regions compared with those of indomethacin, a potent anti‐inflammatory agent. We found that a low‐power infrared laser has an anti‐inflammatory effect on carrageenin inflammation. A low‐power laser inhibits: (1) the increase of vascular permeability during the occurrence of an acute inflammation in the carrageenin‐air‐pouch model, (2) edema in the acute stage in the carrageenin‐paw‐edema model, and (3) the granuloma formation in the carrageenin‐granuloma model after receiving laser irradiation once daily. In all cases, irradiation for less than 10 min was sufficient to inhibit the inflammation by 20–30%. The inhibitory effect of laser irradiation was not comparable to that of indomethacin (4 mg/kg, i.o.) in the air‐pouch model and the paw‐edema model, whereas laser irradiation was more potent than that of daily administration of indomethacin (1 mg/kg, i.o.) in the granuloma model.

In future studies of the mechanism of laser effect, it should be noted that irradiating a rat twice, before and after the provocation of inflammation, was essential in order to achieve an effective inhibition of paw‐edema. © 1992 Wiley‐Liss, Inc.
Effect of the ArF excimer laser on human enamel
Authors: Feuerstein Osnat , Palanker Daniel , Fuxbrunner Amihay , Lewis Aaron , Deutsch Dan
Published: March 2007

Human enamel surface was irradiated with ArF excimer laser and examined under light microscopy and scanning electron microscopy (SEM). Enamel surface was irradiated at three different areas with different energy fluences. It is demonstrated that the ArF excimer laser causes ablation of the calcified hard enamel tissue. Ablation curves were measured. There was no significant difference found in the etch depth between the three different areas of enamal surface. The morphology of the irradiated areas seen under the SEM was found to be dependent on energy flu‐ence. It changed with increase in energy fluence from being etched to forming a smooth, fused, glaze‐like surface and then at very high energy fluences producing a rough surface. The influence of the laser irradiation was confined to the irradiated area only, with no visible heat damage to the surroundings. These results suggest that excimer laser could be applied in a controlled and defined manner for tooth enamel treatments in dentistry. © 1992 Wiley‐Liss, Inc.
Preliminary evaluation of a new high power diode laser
Authors: Wyman Andrew , Duffy Sean , Sweetland Helen M. , Sharp Frank , Rogers Kenneth
Published: March 2007

A high‐powered semiconductor diode laser (805 nm) has recently been developed for medical use. The laser‐tissue interactions of this wavelength have been compared with Nd:YAG (1064 nm). When used in the contact mode, the extent of tissue vaporization and zones of thermal necrosis produced by these two lasers were similar. The diode laser was also an effective and haemostatic laser scalpel. This compact laser unit has potential advantages over existing Nd:YAG lasers. © 1992 Wiley‐Liss, Inc.
Power density and exposure time of He‐Ne laser irradiation are more important than total energy dose in photo‐biomodulation of human fibroblasts in vitro
Authors: van Breugel Hans H. F. I. , Bär P. R. Dop
Published: March 2007

The absorption spectrum of human fibroblast monolayers showed several absorption peaks, among them one at a wavelength of 630 nm. Cultures of these fibroblasts were subjected to He‐Ne laser (632.8 nm) irradiation of various energy doses by varying power density and exposure time. On three consecutive days the cell monolayers were irradiated for periods between 0.5 and 10 min. Laser power varied from 0.55 to 5.98 mW. Both cell number and collagen type I production were determined for each irradiation condition within one experiment. Results show that laser power below 2.91 mW could enhance cell proliferation (as determined by cell counting), whereas higher laser power (5.98 mW) had no effect. Stimulatory effects were most pronounced at irradiation times between 0.5 and 2 min. Collagen type I production (as determined by an ELISA) was affected in the opposite direction to cell proliferation: when the cell proliferation was increased, collagen type I production was decreased. From these experiments it is clear that exposure time and power density determine the effects of laser irradiation. Both stimulation and inhibition of the observed cell properties can be obtained with the same laser on the same cells. © 1992 Wiley‐Liss, Inc.
EMLA for laser treatment of portwine stains in children
Authors: Tan O. T. , Stafford T. J.
Published: March 2007

Vascular‐specific lasers with pulse durations of between 300 and 500 microseconds are the treatment of choice for portwine stains (PWS), particularly in children. Although the discomfort felt following laser irradiation from a single pulse is transient, these sensations are intensified when multiple pulses are delivered over a confined area of skin. Because 75–80% of PWS are located in the head and neck regions, laser treatment of these sites tends to be more painful than those located in most other parts of the body. A prospective double blind randomized study, assessing pain during laser irradiation on PWS skin occluded with either EMLA, placebo, or no cream (control) was performed in 73 PWS subjects between 5 and 16 years of age. Analysis of the data showed that the pain scores for EMLA‐treated sites were the smallest, the control scores tended to be the highest, with the placebo scores in the middle. The differences between the treatments were significant (P < 0.0001). © 1992 Wiley‐Liss, Inc.
Initial results of endothelial cell seeding following argon laser carotid endarterectomy
Authors: Sawchuk Alan P. , Herring Malcolm B. , Dalsing Michael C.
Published: March 2007

This study evaluates the initial results of endothelial cell (EC) seeding following argon laser carotid endarterectomy. Venous endothelial cells were harvested from 12 dogs and cultured. A laser endarterectomy was performed on both carotids of each dog. One side was seeded with endothelial cells. Six dogs had both carotids harvested 1 hour after restoring blood flow. The others were harvested in 24 hours. The percentage of lumen covered with EC was evaluated by scanning electron microscopy. At 1 hour, the seeded arteries demonstrated 35 ± 3 percent EC coverage, whereas the unseeded arteries had no EC coverage (P = 0.0002). At 24 hours, the seeded arteries had 58 ± 15 percent EC coverage, whereas the unseeded arteries had no coverage (P = 0.01). Significant gross thrombus developed only in unseeded arteries (P = 0.047), two of which were occluded at 24 hours. EC seeding is beneficial following argon laser carotid endarterectomy resulting in improved patency and less surface thrombogenicty. © 1992 Wiley‐Liss, Inc.