bluuebunny/crossref_metadata_2025 huggingface dataset:
Keratinocyte protein expression in rapidly regenerating epidermis following laser‐induced thermal injury
Authors: Smoller Bruce R. , Dover Jeffrey S. , Hsu Amy
Published: March 2007

We examined 20 punch biopsies taken from five patients at varying intervals following CO2 laser‐induced thermal injury. The regenerating epidermis was studied with monoclonal antibodies AE1 and AE3 (directed against low and high molecular weight keratins), and involucrin, a protein found within the cellular envelope of the most mature keratinocytes. Twenty‐four hours following thermal damage, there was extensive spillage of keratins and involucrin into the papillary dermis and disarray of all constituents of the necrotic keratinocytes. Early ingrowth of basaloid keratinocytes weakly expressed AE1. By 1 week, keratinocytes expressed AE1 in varying intensities throughout the epidermis. AE3 was present in its normal distribution, staining all but the most basaloid keratinocytes. Involucrin stained cells deep within the epidermis. Six weeks following the initial injury, the staining pattern within the epidermis had returned to normal. Thus, it appears that the regenerating epidermis produces low molecular weight keratins in cells at all levels and forms premature cellular envelopes, perhaps as a protective measure, before expression of these constituents reverts to the normal pattern. These findings suggest that keratinocyte differentiation in wound‐healing following laser‐induced thermal injury is similar to that seen in other types of injury. Observed clinical differences may be attributable to differences in keratinocyte proliferative or migratory capabilities.
Suppressed tuberculin reaction in guinea pigs following laser irradiation
Authors: Inoue Koji , Nishioka Junichi , Hukuda Sinsuke
Published: March 2007

Tuberculin reactions were tested at the bilateral sites of the backs of sensitized guinea pigs. Laser irradiation at an energy fluence of 3.6 J at one site of reaction suppressed the reaction not only at the irradiated site but also at the contralateral nonirradiated site. These phenomena were observed when mononuclear cells were dominant in the perivascular cellular infiltration. The results indicate that local irradiation with a low‐power laser has systemic inhibitory effects on delayed hypersensitivity reactions.
Laser recanalization of pyloric stenosis: A guidewire‐directed contact probe technique
Authors: Lambert Michele , Faintuch Jack S.
Published: March 2007

A variety of techniques has been used to relieve the obstructive symptoms of pyloric stenosis. Endoscopic dilatation using hydrostatic balloon dilators, multiple‐diameter bougies, and electrocautery with a sphincterotome have been described. The neodymium yttrium aluminum garnet laser also has been used, with both noncontact and contact probes. We describe a new technique using a guidewire‐directed contact probe for laser recanalization of pyloric stenosisin a patient with radiation‐induced gastric outlet obstruction.
In vitro production of viable bacteriophage in a laser plume
Authors: Ediger M. N. , Matchette L. S.
Published: March 2007

Bacteriophage ϕX 174, present at high concentrations in an agar overlay in vitro system, were used as a target for pulsed 2.94 μm (Er:YAG) laser ablation. In this preliminary experiment, the potential for transport of viable viruses in the photoablation plume was investigated for laser energy densities of approximately 3.5 J/cm2 per pulse in exposures of 75–600 laser pulses. Transport of relatively few numbers of viable viruses from the ablation site to the plate assay detector, a distance of approximately 2 cm, was observed.
Mid‐infrared erbium:YAG laser ablation of bone: The effect of laser osteotomy on bone healing
Authors: Nelson J. Stuart , Orenstein Arie , Liaw Lih‐Huei L. , Berns Michael W.
Published: March 2007

A comparative study was undertaken in rabbit tibiae to assess the healing of bone in response to osteotomies by a mid‐infrared erbium:YAG (2.94 μm) laser or a mechanical saw. Laser parameters necessary for osteotomy were shown to produce deep cuts with sharp edges and no gross charring or burning of adjacent bone. However, it was noted histologically that there was a delay in healing of the laser osteotomies as compared to saw osteotomies. This delay was caused by a microscopic zone of damage to bone adjacent to the laser cuts. It is concluded that, although the erbium:YAG laser may be a useful tool in orthopaedic surgery to ablate bone, under the conditions used in this study, there will be a delay in the healing process after laser osteotomy.
Diagnosis of gastric cancers with fluorescein‐labeled monoclonal antibodies to carcinoembryonic antigen
Authors: Tatsuta Masaharu , Iishi Hiroyasu , Ichii Makoto , Baba Miyako , Yamamoto Reiko , Okuda Shigeru , Kikuchi Katsuya
Published: March 2007

Forty gastric adenocarcinomas in 30 resected stomachs were examined by an endoscopic immunofluorescent technique using fluorescein isothiocyanate (FITC)‐labeled antibodies to carcino‐embryonic antigen (CEA). Fluorescence images of the tumors were obtained with a newly developed endoscopic television system for detecting faint fluorescence. Computer‐assisted processing was used to enhance the detection and localization of the tumors visualized by the immunofluorescent technique. Twenty seven (90%) of 30 tumors showed positive fluorescence after treatment with FITC‐labeled antibodies for 60 minutes, whereas only two (40%) of five cancers could be detected by the immunofluorescent technique after treatment with antibodies for less than 60 minutes. There was no significant relationship between positive fluorescence and the gross and histological types or the stages of the tumors. In contrast, no positive fluorescence could be demonstrated in cases of benign gastric lesions or after pretreatment with FITC‐labeled alpha‐fetoprotein. This study therefore suggests that the immunofluorescent technique using FITC‐labeled anti‐CEA antibodies can be useful in detecting the early stages of gastric cancer.
Effect of pulse duration on microsecond‐domain laser lithotripsy
Authors: Bhatta Krishna M. , Nishioka Norman S.
Published: March 2007

The pulsed dye laser (wavelength 504 nm, pulse duration 1 μs) is widely used for fragmenting urinary and biliary calculi. In this study, the performance of this laser was compared with pulsed dye lasers producing pulse durations of 8 and 20 μs. Fragmentation thresholds and fragmentation rates were measured using a variety of urinary and biliary calculi. Effective fragmentation of urinary and biliary calculi was obtained with 1‐μs and 8‐μs pulse durations, but satisfactory fragmentation could not be achieved at 20 μs.
Transscleral cyclophotocoagulation using a contact laser probe: A histologic and clinical study in rabbits
Authors: Latina M. A. , Patel S. , de Kater A. W. , Goode S. , Nishioka N. S. , Puliafito C. A.
Published: March 2007

Transscleral photocoagulation of the ciliary body was achieved in pigmented rabbits using a sapphire probe delivery system coupled to a commercial surgical continuous‐wave Nd:YAG laser. This contact technique was found to be effective in reducing intraocular pressure (IOP); greater treatment energies were associated with a more prolonged reduction in IOP, and also correlated with a greater degree of histologic damage to the ciliary body. Treatment energies of 0.8–1.0 Joules produced substantial disruption of the ciliary body. This technique is easy to learn and offers ease in control and placement of the coagulation spots.
Dye‐enhanced laser tissue welding
Authors: Chuck Roy S. , Oz Mehmet C. , Delohery Thomas M. , Johnson Jeffrey P. , Bass Lawrence S. , Nowygrod Roman , Treat Michael R.
Published: March 2007

For vascular anastomosis, use of topical photosensitizing dye enhances selective delivery of laser energy to target tissue, thus reducing the amount of collateral thermal injury and threshold power required for welding. For fluorescein isothiocyanate (FITC)—stained rabbit aorta in vitro, the threshold for tissue blanching was 15 seconds of 100 mW exposure of cw argon ion laser compared with 15 seconds at 300 mW for unstained tissue. The threshold power density needed for argon laser welding of abdominal aortotomies in rabbits in vivo was 3.8 W/cm2 with FITC and 7.6 W/cm2 without the dye. However, bursting pressures for the two groups (164 mm Hg with FITC, 147 mm Hg without FITC) were not significantly different. Histology revealed decreased collateral thermal damage in FITC‐enhanced welds. Use of photosensitizing dyes for tissue welding is feasible and may allow arterial welding with lower power laser systems and cause less thermal trauma by lowering threshold power levels.
Laser photoirradiation of the canine ureteral orifice: Comparison between contact and noncontact techniques
Authors: Wishnow Kenneth I. , Johnson Douglas E. , Cromeens Douglas M. , Ro Jae Y.
Published: March 2007

We studied the long‐term effects of Nd:YAG laser photoirradiation in 17 canine ureteral orifices, comparing results of the contact and noncontact (free‐fiber) techniques. The noncontact technique damaged four of eight ureters, causing ureteral obstruction with significant hydronephrosis in three and reflux in one. The amount of energy used correlated with the subsequent appearance of ureteral obstruction; obstruction developed in both cases when 3,000 and 3,300 joules were used but in only one of five cases when less than 2,300 joules were used. In contrast, the contact technique, using 350–800 joules, caused no hydronephrosis and only one case of reflux. Since these animal studies clearly document that the Nd:YAG laser may significantly damage the ureter, particularly when the noncontact technique is used, we recommend that the surgeon consider the contact technique to reduce the risk of ureteral damage and use the smallest amount of energy required for adequate tumor eradication when treating tumors in or near the ureteral orifice.
Characteristics of 308 nm excimer laser activated arterial tissue photoemission under ablative and non‐ablative conditions
Authors: Laufer Günther , Wollenek Gregor , Rüeckle Benno , Buchelt Martin , Kuckla Christian , Ruatti Helmut , Buxbaum Peter , Fasol Roland , Zilla Peter
Published: March 2007

The present study was designed to assess the characteristics of tissue photoemission obtained from normal and atherosclerotic segments of human postmortem femoral arteries by 308 nm excimer laser irradiation of 60 ns pulsewidth. Three ablative (20, 30, and 40 mJ/pulse) and three non‐ablative (2.5, 5, and 10 mJ/pulse) energy fluences were employed. Both the activating laser pulses and the induced photoemission were guided simultaneously over one and the same 1,000 μm core optical fiber that was positioned in direct tissue contact perpendicular to the vascular surface. The spectral lineshape of normal arterial and noncalcified atherosclerotic structures was characterized by a broad‐continuum, double‐peak emission of relevant intensity between wavelengths of 360 and 500 nm, with the most prominent emission in the range of 400–415 (407 nm peak) and 430–445 nm (437 nm peak). Fibrous and lipid atherosclerotic lesions, however, exhibited a significantly reduced intensity at 437 nm compared to normal artery layers (P < 0.001), expressed as a 407/437 nm ratio of 1.321 ± 0.075 for fibrous and 1.392 ± 0.104 for lipid lesions. Normal artery components presented with approximately equal intensity at both emission peaks (407/437 nm ratio: intima, 1.054 ± 0.033; media, 1.024 ± 0.019; adventitia, 0.976 ± 0.021). Comparison of spectral lineshape obtained under various energy fluences within a group of noncalcified tissues disclosed no substantial difference using the 407/437 nm ratio (P > 0.05). In contrast, calcified lesions revealed high‐intensity multiple‐line (397, 442, 461, and 528 nm) emission spectra under ablative energy fluences, whereas a low‐intensity broad‐continuum, single‐peak spectrum resulted from irradiation beyond the ablation threshold. Thus, these findings suggest fluorescence phenomena for broad‐continuum spectra, and plasma emission for multiple‐line spectra as an underlying photodynamic process. Regardless of the activating energy fluence, spectral analysis of 308 nm activated photoemission provides accurate information about the laser target under standardized in vitro conditions. It is demonstrated that direct contact ablation and simultaneous spectral imaging of the target tissue via the same optical fiber is feasible.
Electron spin resonance investigation of laser and heated metal‐tip–induced free radical formation in various tissues
Authors: Jain Sandeep , Shi Xianglin , Billie Mike , Jain Abnash C. , Dalal Nar S.
Published: March 2007

The short‐lived free radical formation accompanying laser irradiation and laser‐heated metal tip contact was examined using electron spin resonance (ESR) spin‐trap methodology. Various tissues (canine myocardium, human aorta, liver, and spleen) were irradiated by argon‐ion (continuous wave [CW] and pulse) and YAG (CW) lasers employing both naked fiber and a laser‐heated metal tip. All showed the formation of primarily carbon‐centered, not oxygenated, free radicals, together with some minor unidentified species. This implies that the backbones of amino acids, lipids, or other biological building blocks are cleaved during the irradiation or thermal treatment. Different tissues produce similar radicals but with different amounts when irradiated by argon‐ion, YAG, and laser‐heated metal tip sources. The amount of the free radicals formed depends on the laser power (within 5–15 W). Compared to the naked fiber, the laser‐heated metal tip shows the generation of at least twice the amount of free radicals. The possible relationship of the free radical formation to tissue injury is briefly discussed.
Enhancement of physical properties of resin restorative materials by laser polymerization
Authors: Kelsey William P. , Blankenau Richard J. , Powell G. Lynn , Barkmeier Wayne W. , Cavel W. Thomas , Whisenant Brian K.
Published: March 2007

A study was conducted to compare the compressive strength, diametral tensile strength, transverse flexural strength, and flexural modulus of a microfilled and a small particle composite resin restorative material following argon laser and conventional visible light polymerization techniques. All physical properties examined in this study were enhanced by laser polymerization. The diametral tensile strength of both types of restorative materials was significantly greater following laser polymerization, as were the transverse flexural strength and the flexural modulus of the microfilled resin restorative material. Additionally, these results were obtained with a laser polymerization time that was one‐fourth that used for visible light activation. It was concluded that the argon laser is a potentially advantageous means of initiating the polymerization of dental composite resin restorations.
Nd:YAG laser‐Induced interstitial hyperthermia using a long frosted contact probe
Authors: Panjehpour Masoud , Overholt Bergein F. , Milligan Andrew J. , Swaggerty Michael W. , Wilkinson J. Erby , Klebanow Edward R.
Published: March 2007

The heating potential of a closed loop interstitial hyperthermia system employing 1,064 nm laser light in conjunction with a long frosted contact probe was investigated in hind limb muscle of anesthetized dogs. The laser system was an Nd:YAG surgical laser modified with a single channel thermometry unit, a computer, a printer, and a computer‐controlled laser exposure shutter. The long frosted laser probe was implanted into the muscle, and 3.12–5.00 Watts of laser power was delivered interstitially. Temperature distribution was measured in three dimensions around the frosted probe. The temperature distributions generated by this technique were satisfactory for producin desired hyperthermia temperatures in an approximately 3.5 cm3 cylindrical tissue volume. A multiple laser delivery system is needed to induce interstitial hyperthermia in large tumors.

A significant potential for the long frosted contact probe may be its use in combining interstitial hyperthermia and interstitial photodynamic therapy. Using this technique, both modalities may be delivered while employing the same treatment setup.
Endoscopic laser coagulation through an optical laser balloon
Authors: Shimamura Yoshiyuki , Gunvén Peter , Ishii Masanori , Kitai Shouzou , Ono Masato , Okajima Kazuo , Shima Yasou , Ikuta Shigeo , Takahashi Akira , Kitaya Tomoki , Matsuyama Tomoji
Published: March 2007

An endoscope was equipped with a saline‐filled latex rubber balloon at its tip to displace contaminating blood, bile, or gastric contents during operative portoscopy, biliary endoscopy, or upper gastrointestinal endoscopy. A fiber with its tip inside the balloon transmitted energy from an Nd:YAG laser for coagulation of tumors in one bile duct cancer, in six portal vein growths from primary liver cancers, and in a superficially growing stomach cancer. The balloon increased the precision of irradiation by making lesions easier to identify through displacement of bile or blood and by keeping the fiber tip at a fixed position relative to the lesion. The technique, basic experimental studies, and clinical experiences are reported.
Thermally induced optical property changes in myocardium at 1.06 μm
Authors: Derbyshire Garrett J. , Bogen Daniel K. , Unger Michael
Published: March 2007

Light in the visible and near‐infrared region is diffusely scattered in tissues by macromolecules. It was therefore hypothesized that tissue coagulation caused by high‐power continuous wave laser irradiation might significantly alter tissue optical properties, resulting in a redistribution of laser energy during the laser ablation process. Infrared transmittance studies confirmed the hypothesis by demonstrating an irreversible decrease in light transmittance (45%) during heating of a 0.75 mm thick slice of tissue. Absorption and scattering coefficients were then determined from transmittance and reflectance measurements on thin slices of raw and coagulated myocardium irradiated with a Nd:YAG laser (1.06 μm). The scattering coefficient was found to increase fourfold (0.427 mm−1 → 1.74 mm−1) during tissue coagulation, while the absorption coefficient remained relatively unchanged (0.044 mm−1 → 0.051 mm−1). Calculations indicate that the coagulation–induced changes in tissue optical properties substantially increase surface back‐scattering and reduce tissue penetration.
Helium‐Neon laser irradiation inhibits the growth of kidney epithelial cells in culture
Authors: Gross Andreas J. , Jelkmann Wolfgang
Published: March 2007

We have investigated the in vitro action of helium‐neon (He‐Ne) laser light on the cell cycle and the growth of rat kidney epithelial cell cultures. Dose‐response studies showed that repeated He‐Ne irradiation (dose rate 40 mW/cm2) once a day in a dose range between 11.9 and 142 J/cm2 significantly inhibited cell growth, while daily irradiation with 4.7 J/cm2 had no effect. Microscopic examination of nuclear spreads revealed an increased number of cells in mitosis after a single irradiation with 142 J/cm2. These results support previous observations suggesting that laser light of low thermal energy interferes with cell cycling and may inhibit cell growth when irradiation is performed at doses of 11.9 J/cm2 or more.
Multifiber gradient‐index lens laser angioplasty probe
Authors: Decker‐Dunn Diana , Christensen Douglas A. , Vincent G. Michael
Published: March 2007

A novel laser angioplasty probe fabricated with a gradient‐index (GRIN) lens positioned at the tip of a seven‐fiber bundle is presented. The combination of the GRIN lens and the fiberoptic bundle provides selectable optical directionality in either the axial direction or one of six off‐axis directions for illumination of the arterial wall. The probe diameter (1 mm) is small enough for use in coronary laser angioplasty, and the probe is shown to transmit laser light and receive fluorescent signals simultaneously. In a 2 mm diameter lumen, the spot width in a plane normal to the axis of the lens is about 2 mm and the lateral spot size is approximately 10 mm long. The ability to direct the probe's beam pattern angularly should provide flexibility in both diagnosis and treatment.
Percutaneous transcatheter laser balloon ablation from the canine coronary sinus: Implications for the Wolff‐Parkinson‐White syndrome
Authors: Schuger Claudio D. , Steinman Russell T. , Lehmann Michael H. , Schuger Lucia , Boldea Deborah , McMath Linda , Spears J. Richard
Published: March 2007

Transcatheter direct current electrical shocks for ablation of left‐sided accessory pathways in Wolff‐Parkinson‐White patients have led to serious complications. We report the feasibility of percutaneous transcatheter laser balloon ablation of left‐sided accessory pathways from the coronary sinus using a 1,064‐nm, continuous wave Nd:YAG laser triple lumen catheter with an optical fiber terminating in a cylindrical diffusing tip within a 2‐cm‐long, 3‐mm‐diameter balloon transparent to Nd:YAG laser radiation. In eight mongrel dogs (18 to 31 kg), the laser balloon catheter was positioned via an 8 French guide catheter in the distal and proximal coronary sinus. During balloon inflation, two to three consecutive laser doses of 30 W × 20 sec were applied to each site (cumulative energy, 1,200 to 1,800 J). Coronary angiog‐raphy, left ventriculography, and coronary sinus injection were performed before and after laser exposure. After percutaneous transcatheter laser balloon ablation, there was no evidence of mitral regurgitation, left circumflex artery, coronary sinus obstruction, or perforation. Coagulation necrosis and/or polymor‐phonuclear infiltrates involving the atrioventricular groove and left atrial wall over a mean length of 17 mm were present in all eight dogs sacrificed 6 ± 1 hr postablation. In conclusion, percutaneous transcatheter laser balloon ablation from the coronary sinus is free of immediate major complications and may be feasible for potential interruption of left‐sided accessory pathways.
Disparate absorption of argon laser radiation by fibrous versus fatty plaque: Implications for laser angioplasty
Authors: Torres Jorge H. , Motamedi Massoud , Welch Ashley J.
Published: March 2007

The thermal response of white fibrous atheromatous plaque to argon laser irradiation was compared with the thermal response of yellow fatty plaque and normal aortic wall to the same type of radiation. Samples of normal aorta, fibrous, and fatty plaque were irradiated in air with 3.5 Watts of laser power on a 2 mm spot for 5 and 10 seconds. Heterogeneous foci, each covering normal aorta and either fibrous or fatty plaque, were additionally irradiated with 7 Watts on a 1 cm spot for 30 seconds to 2.5 minutes. Tissue surface temperature was monitored during laser irradiation via a 3‐5 μm infrared camera. For the 2 mm spot and 5 second exposure time, argon laser irradiation of normal aorta produced popping and surface tearing at a peak temperature of 145 ± 10°C. Irradiation of fatty plaque produced popping and crater formation at a peak temperature of 200 ± 10°C. However, fibrous plaque was nonablatively discolored by the same dose of laser radiation with a peak temperature of only 85 ± 10°C. Irradiation for 10 seconds caused crater formation and carbonization in the fatty plaque but failed to produce ablation in the fibrous plaque. Irradiation of the heterogeneous foci confirmed the disparity in the temperature attained by these two types of plaque and their degree of damage. Therefore, this study suggests that the ablation threshold for soft atheroma is strongly dependent on the optical properties of the particular type of tissue. Yellow fatty plaque preferentially absorbs argon laser radiation, but white fibrous plaque absorbs this radiation less readily than normal aortic wall.
Traumatic tattoo removal: Comparison of four treatment methods in an animal model with correlation to clinical experience
Authors: Sunde Douglas , Apfelberg David B. , Sergott Thomas
Published: March 2007

The acute or emergency treatment of traumatic tattoos has been based on the principles of immediate and thorough removal of all particles. The delayed treatment of traumatic tattoos has classically been with overgrafting or dermabrasion. We developed an animal model for traumatic tattoos. Two levels of wounds were made (shallow and deep). Each group consisted of five guinea pigs with one consistent level of wounding. Four treatment methods were applied carbon dioxide laser, argon laser, overgrafting, and dermabrasion. The results were evaluated by trained observers on a gross basis. Although no statistically significant differences were found within these small groups, clinical experience in a small group of patients suggests that carbon dioxide laser may prove to be useful in the delayed treatment of traumatic tattoos. Eight patients have been treated over a 4‐year period. Satisfactory total or subtotal foreign body removal of various agents (road tar, cement, cooper particles) has been achieved.
Epilation of hair‐Bearing urethral grafts utilizing the neodymium: YAG surgical laser
Authors: Finkelstein Leonard H. , Blatstein Lee M.
Published: March 2007

Non‐hair‐bearing skin should be utilized when grafting is necessary in carrying out urethroplasty for stricture or hypospadius repair. Occasionally this is not possible, or hair‐bearing skin is used inadvertently. Traditionally electrocoagulation has been the method used for epilation when intraluminal hair has become a problem, such as interfering with flow, being foci for recurring urinary tract infection, or acting as a nidus for calculus formation. Electrocautery is also used at the time of grafting in an attempt to prevent the growth of hair when hair‐bearing skin is utilized. Unfortunately, because of lack of penetration, the hair follicles are not destroyed and the epilating procedure fails or is only partially successful. The neodymium: YAG (Nd:YAG) surgical laser can photocoagulate tissue to a depth up to 5.0 mm and thus has the ability to destroy hair follicles. We report three cases presenting with clinical problems directly related to hair‐bearing urethral grafts successfully treated by Nd:YAG epilation.
Factors affecting emission collection by surgical smoke evacuators
Authors: Smith Jerome P. , Topmiller Jennifer L. , Shulman Stanley
Published: March 2007

Gaseous and particulate emissions from laser surgery are often controlled by the use of smoke evacuators. Thus it is important that factors affecting the performance of these evacuators be understood. In this study, a tracer gas technique was used to examine a number of factors affecting the performance of smoke evacuators, including evacuator flow rate, distance from the evacuator nozzle to the surgical site, and direction and speed of external air flow in relation to nozzle flow. The tracer gas technique allowed the release of emissions to be visualized with infrared imaging and also allowed the collection efficiency to be assessed quantitatively. The results were demonstrated with the use of a surgical laser system. It was found that the collection efficiency of the smoke evacuator was affected by all the factors studied. Increasing the evacuator flow rate allowed the collection of emissions under conditions in which lower evacuator flow rates had less efficient collection. The speed and direction of external air flow affected collection of emissions greatly. If the air flow was in the same direction as the nozzle flow, efficient collection of emissions at a distance from the emission release point was observed. However, at other angles relative to nozzle flow, the efficiency degraded rapidly with distance from the emission release site.

With the use of the surgical laser system, at laser powers of 30 W, the tracer system predicted the collection of emissions. At 60 and 100 W of laser power, higher external air flows and greater attention to nozzle positioning were necessary. Based on the results of this study, conclusions are drawn on how to improve the collection efficiency of smoke evacuators used in laser surgery.
Thermal characteristics of sapphire contact probe delivery systems for laser angioplasty
Authors: Ashley S. , Brooks S. G. , Gehani A. A. , Kester R. C. , Rees M. R.
Published: March 2007

Contact probes made from synthetic sapphire crystal, designed for general laser surgery, are currently being evaluated for use in laser angioplasty. Their mode of action and safety in the context of arterial recanalisation is unknown, particularly with respect to the degree of probe and catheter heating. Infrared thermal imaging was used to investigate the surface temperature rise of various rounded sapphire probes during emission of continuous wave Nd‐YAG (1,064 nm) laser energy. Catheter safety was addressed by analyzing the temperature of the metal interface between the optical fiber and sapphire, as well as the catheter proximal to this junction. Transmission of Nd‐YAG energy through each probe was also measured.

Five rounded probes of 1.8–3.0 mm diameter (three supplied by Surgical Laser Technologies [SLT], two by Living Technology [LT]), along with their respective optical catheters, were compared. There was a large temperature gradient between the front and rim of the probes. The maximum surface temperature rise of the sapphire (at 20 W, 5‐second exposure) was 314–339°C (SLT) and 90–108°C (LT) [P < 0.00l, 3‐way ANOVA]. The reason for this difference may be related to “crazing” of the front surface of the SLT sapphires. At all energy levels sapphire temperatures were considerably lower than attained by metal laser thermal angioplasty probes. Forward transmission was slightly higher in the SLT probes (75–85%) than the LT sapphires (54‐69%). With fiber perfusion at 2 ml/minute, a minor degree of heating of the metal sapphire holders was recorded (maximum rise 35°C), but heating of the catheter proximal to this was negligible. Therefore, it would appear that the risk of tip detachment or arterial injury due to heating of the connecting metal interface is extremely low. Without perfusion, however, there was a greater degree of interface heating in the LT delivery system suggestive of more laser backscattering by these sapphires compared with the SLT probes [P < 0.00l, one‐way ANOVA]. The SLT system is, therefore, potentially safer in this respect. These results suggest that some degree of surface heating of contact probes due to energy absorption within the sapphire does occur, but is localised to the front of the probe. This effect may contribute to the process of arterial recanalisation with this device. However, variation in the thermal and optical properties of sapphires from different sourceshas been demonstrated. The influence of these properties on plaque ablation, and ultimately the clinical performance of different contact probe systems, requires further investigation.
Laser induced fluorescence spectroscopy of normal and atherosclerotic human aorta using 306–310 nm excitation
Authors: Baraga Joseph J. , Rava Richard P. , Taroni Paola , Kittrell Carter , Fitzmaurice Maryann , Feld Michael S.
Published: March 2007

Ultraviolet excited laser induced fluorescence (LIF) was studied in normal and atherosclerotic human arterial wall in vitro. Using excitation wavelengths from 306 to 310 nm, two distinct emission bands were observed in the LIF of both normal and pathologic aorta: a short wavelength band, peaking at 340 nm emission, which was attributed to tryptophan; and a long wavelength band, peaking at 380 nm emission, which was assigned to a combination of collagen and elastin. The intensity of the short wavelength band was quite sensitive to the choice of excitation wavelength, while the long wavelength band was not, so that the relative contributions of the bands could be controlled by the precise choice of excitation wavelength. A valley in the spectra at 418 nm was attributed to fluorescence reabsorption by oxy‐hemoglobin.

By using 308 nm excitation to observe emission simultaneously from both the short and long wavelength bands, normal and atherosclerotic aorta were spectrally distinct. Two LIF emission intensity ratios were defined to characterize both the relative tryptophan fluorescence content as well as the ratio of elastin to collagen fluorescence in each spectrum. The differences in these two emission ratios among the various histologic tissue types correlated qualitatively with the histologic and biochemical compositions of these tissues. By combining these parameters in a binary classification scheme, normal and atherosclerotic aorta were correctly distinguished in 56 of 60 total cases. Furthermore, atherosclerotic plaques, atheromatous plaques, and exposed calcifications could be classified individually with sensitivitieslpredictive values of 90%/90%, 100%/75%, and 82%/82%, respectively.
Lateral thermal damage along pulsed laser incisions
Authors: Zweig Adrian D. , Meierhofer Brigitte , Müller Otfried M. , Mischler Charlotte , Romano Valerio , Frenz Martin , Weber Heinz P.
Published: March 2007

The damage adjacent to incisions created in dorsal mouse skin by overlapping Er3+ and CO2 laser pulses of a duration of 250 μs is investigated histologically. It is compared to injuries induced by long‐term heating. We demonstrate how the lateral thermal damage near the laser cuts can be explained by heat conduction. We show that it is necessary to introduce as a heat reservoir a layer of tissue that has been liquefied during the cutting process. The width of the thermally damaged region depends mainly on the extension of the liquid material that remains in the cut after the laser‐tissue interaction.
Intraoperative phototherapy (PDT) and surgical resection in a mouse neuroblastoma model
Authors: Davis R. Kim , Smith Lane F. , Thurgood Randy F. , Kereszti Zsolt , Straight Richard C.
Published: March 2007

This study evaluates the effect of intraoperative photodynamic therapy (PDT) using the multiline argon laser (488–514 nm) or the argon‐dye laser (630 nm) combined with surgical resection compared with surgical resection alone in reducing the incidence of C1300 neuroblastoma recurrence in mice. In the control groups, surgical resection alone resulted in 86% ± 12% tumor recurrence. Surgical resection and intraoperative lasing without photosensitizer resulted in 75% ± 27% tumor recurrence with the argon‐dye laser and 55% ± 18% recurrence with the multiline argon laser. In the treatment groups, surgical resection and intraoperative PDT at 630 nm resulted in 56% ± 19% tumor recurrence whereas surgical resection and intraoperative PDT at 488–514 nm resulted in 21% ± 7% tumor recurrence. The cause for the decrease in local recurrence in the control group using the multiline argon laser is unknown, but could it be due in part to hyperthermic effects. Intraoperative PDT was an effective adjunct to surgical resection in preventing local recurrence in this tumor model.
Laser‐Induced hyperthermia in the treatment of liver tumors
Authors: Hahl Juha , Haapiainen Reijo , Ovaska Jari , Puolakkainen Pauli , Schröder Tom
Published: March 2007

Seven patients with malignant liver tumors were treated with Nd:YAG laser induced hyperthermia. The laserthermia was performed during laparotomy using Nd:YAG laser with contact sapphire probes with power settings of 6 W. The contact tip was placed into the middle of the tumor and the temperature in 1.5‐2.0cm from the middle of the tumor was raised and held between 41C and 45C for ten minutes. One fatal complication appeared caused by an air embolism. In the postoperative fine needle biopsies on third and fifth postoperative day the sytologic finding in the tumor was necrosis. However, in 30% of the samples there was also a suspicion of cancer cells. In the computer tomography four weeks after the treatment there were also signs of necrosis. It seems that selective destruction of malignant liver tumors is possible with contact Nd:YAG laser induced hyperthemia.
Acute and chronic effects of bone ablation with a pulsed holmium laser
Authors: Stein Eric , Sedlacek Thomas , Fabian Richard L. , Nishioka Norman S.
Published: March 2007

A pulsed holmium laser transmitted through a quartz fiber was used to create osteotomies in the facial bones and sinuses of rabbits. The ablation process was quantified and residual thermal injury was assessed by light microscopy. Adjacent thermal damage was determined to vary between 130 and 220 pm and was independent of radiant exposure and pulse repetition rate. In other studies, large osteotomies were made to examine the biological response and to assess the technical feasibility of using fiber‐delivered laser pulses in an operative setting. The animals tolerated the procedure without obvious problems and postoperative follow‐up revealed a vigorous healing response. Because it can ablate both bone and soft tissue and can be transmitted through readily available, flexible quartz fibers, the holmium laser may prove to be a useful adjunct to endoscopic sinus surgical procedures.
Thermal laser probe angioplasty: Influence of constant tip temperature, plaque composition, and probe/vessei diameter ratio
Authors: Vincent G. Michael , Fox Jolene , Johnson Michael D. , Strickland Richard , Garry Stacey L. , Hammond Elizabeth
Published: March 2007

Thermal laser angioplasty uses constant laser power, producing widely variable tip temperatures in vivo. Results have been sub‐optimal. We studied the effect of 50–400°C tip temperatures on depth of ablation at 192 sites on plaqued and normal human aorta in vitro, and the angiographic and histologic response in vivo of 300–400°C at probe/vessel ratios of 0.5–1.0, in 40 normal canine femoral artery segments. In vitro, there was a direct relationship between tip temperature and depth of ablation, r = 0.71 (all segments), r = 0.74 for fibrous plaque, but a poor correlation in fatty plaque r = 0.35. In fibrous plaque, there was proportionately more ablation at tip temperatures >300°C, mean depth 0.62 mm, than at 150–300°C, mean 0.37 mm, (P <.001). Ablation was similar in plaqued and normal aorta. In vivo, 300°C, 350°C, and 400°C produced similar effects. At probe/vessel ratios <0.8, only disruption of internal elastic lamina was observed. At ratios ⩾0.8, spasm occurred in 39% (7/18), transmural damage in 28% (5/18), and perforation in one of 18. Ablation is not selective for plaque and is highly variable in fatty plaque. Tip temperatures above 300°C produce greater ablation than at lower temperatures. In clinical applications, probehessel rations ⩽0.7 may be most appropriate, and it appears that thermal remodeling may contribute more to outcome than plaque ablation.
Carbon dioxide gas as a perfusion medium for the sapphire probe in laser ablation of human atheromatous plaques: Comparison study with saline
Authors: Yang Xiaoming , Manninen Hannu , Kankkunen Jussi P. , Ji Hongxiu , Naukkarinen Anita , Suhonen Matti , Soimakallio Seppo
Published: March 2007

The effectiveness of CO, gas as a perfusion medium was compared to that of saline in laser ablation of human atheromatous plaque. In an experimental circulation–occlusion model using flowing whole blood, human cadaveric arterial samples were irradiated by a sapphire probe with the Nd‐YAG laser. The following experiments were performed: (1) lasing without perfusion, (2) lasing with saline perfusion of the probe, and (3) lasing with CO2 perfusion. Different perfusion flow rates of saline and CO2 were used. Results showed that the mean ablation area was 1.6‐fold larger with CO2 than with saline perfusion (P < 0.05, Student's t test). The mean lateral injury at the site adjacent to the ablation crater and at the area directly facing the probe was not significantly different with either perfusion medium. The larger ablation area with CO2 was probably due to the fact that CO2 is a good insulator for maintaining a higher probe temperature and keeps the probe free of blood debris. In conclusion, our results show that CO2 perfusion facilitates more effective laser ablation of atheromatous plaque than saline perfusion by the sapphire probe with the continuous wave Nd‐YAG laser.
Vasovasostomy in dogs using the carbon dioxide milliwatt laser: Part II
Authors: Seidmon E. James , Krisch Evan B. , Baer Harry M. , Phillips Steven J. , Tang Chik‐Kwun , Shea Francis J.
Published: March 2007

This is the second study of a two‐prong investigation conducted to learn two different aspects of vasovasostomy in dog vas defe‐rens by using the carbon dioxide milliwatt laser. This investigation involves the evaluation of patency and analysis of sperm.

Six dogs underwent vasectomy, followed by vasovasostomies performed between 4 and 12 weeks later, utilizing two approximating sutures and welding with the carbon dioxide milliwatt laser. Metal clips were used both for x‐ray analysis and localization of the vasovasostomy site.

All dogs had pre‐vasectomy semen analysis. Following vasectomy each dog underwent ejaculation until azoospermia was obtained. Vasovasostomy was performed and semen was examined. Prior to harvesting, vasography was also obtained. All ejaculates had active sperm noted and 12 of 12 vasograms (100%) revealed patency. The dogs were sacrificed at 4 weeks, 6 weeks, and 8 weeks post‐vasovasostomy. The vasovasostomy specimens were studied with electron microscopy and by histological evaluation.

The vasovasostomy was completed in under 90 minutes by using this laser‐assisted technique. This procedure offers to the urologist a more simplified and reproducible operation that can be performed easily and with a potential decrease in hospital costs.
Application of pulsed and continuous wave 1.32 and 1.06 μm wavelengths of the Nd:YAG laser in the canine tracheobronchial tree: A comparative study
Authors: Rebeiz Elie E. , Aretz H. Thomas , Shapshay Stanley M. , Pankratov Michail M.
Published: March 2007

Previous investigations have shown good clinical potential for the use of the 1.32 μm wavelength Nd:YAG laser because its soft tissue absorption is better than that of the 1.06 μm wavelength NdYAG laser. The 1.32 μm wavelength Nd:YAG laser has an absorption coefficient in water that is 10 times higher than the 1.06 μm wavelength Nd:YAG laser. A comparative in vivo study of laser soft tissue effects was performed by using the 1.32 μm wavelength and the 1.06 μm wavelength Nd:YAG lasers in a pulsed wave (PW) mode and continuous wave (CW) mode using a noncontact endoscopic delivery system. A standard 5 mm mucosal lesion was made in the canine tracheobronchial tree down to the level of the perichondrium. Soft tissue and cartilage effects were examined by light and scanning electron microscopy, acutely, 1 week and 2 weeks after operation, and a comparison was made between the different laser modalities. To create similar lesions, higher energy was required when using the 1.06 μm wavelength Nd:YAG laser. Soft tissue injury was greater with the 1.06 μm wavelength in CW mode, and no cartilage damage occurred in the PW mode. Soft tissue and cartilage repair after 1 and 2 weeks was better with the 1.32 μm wavelength laser. In comparison, the CO2laser and the contact Nd:YAG laser proved to be more precise cutting tools than the 1.32 μm wavelength or the 1.06 μm wavelength Nd:YAG lasers. Both Nd:Yag laser wavelengths were useful for coagulation and vaporization of tissues and blood vessels. More studies are needed to determine the effect of the new 1.32 μm wavelengths on endotracheal tumors.
Preliminary experience with the pulsed dye laser for treatment of urolithiasis
Authors: Loughlin Kevin R. , Sharpe John F.
Published: March 2007

We report our initial experience using the pulsed dye laser in 26 patients with urolithiasis. The patients ranged in age from 27 to 82 years; 11 patients were female and 15 were male. Of the 26 patients, 4 stones were in the kidney, 21 were in the ureter, and one was in the bladder. Surgical time ranged from 32 to 130 minutes. All patients were treated under spinal or general anesthesia. The size of ureteral stones ranged from 0.2 to 1.5 cm, and the renal stones 3.0 to 4.0 cm. Chemical analysis of the stones was not available on all patients, but when available, chemical analysis revealed the stones to be calcium monohydrate, calcium dihydrate, or struvite. The use of the Candela miniscope in 11 patients permitted access without ureteral dilation. In 19 patients, ureteral stents were placed. One patient suffered a ureteral perforation. Success was defined as adequate disintegration of the stone for passage of the fragments without the necessity of a secondary procedure. Using this criterion, 22 of 26 patients were successfully treated for an overall success rate of 85%.
Noncontact tissue ablation by Holmium: YSGG laser pulses in blood
Authors: van Leeuwen Ton G. , van der Veen Maurits J. , Verdaasdonk Rudolf M. , Borst Cornelius
Published: March 2007

To assess the feasibility of intra‐arterial tissue ablation by Holmium:YSGG laser pulses (2.1 μm) in a noncontact mode, the transmission of the laser pulses through saline and blood was measured. The temporal interaction between the 500 μs laser pulse and saline at the fiber tip was investigated with time‐resolved flash photography. The penetration depth in blood and saline depended on the fiber output energy. In blood at 37°C, the penetration depth varied from 1.2 to 2.1 mm for intensities of 3.1 to 12.4 J/mm2 per pulse, respectively, whereas its theoretical value for water is 0.33 mm, which is based on the measured absorption coefficient of 3.0 ± 0.1/mm. The large penetration depth was due to the development of a transparent vapour cavity around the fiber tip. In saline, its maximum length was 4.7 mm. Its maximum width was 2.8 mm. The lifetime of the cavity was 450 μs. In blood, ablation of porcine aorta was feasible at a distance of 3 mm. Large fissures observed in adjacent tissue are likely to be caused by the expansion of the vapour cavity. We conclude that, due to a “Moses effect in the microsecond region,” Holmium: YSGG tissue ablation is possible through at least 2.7 mm of blood.
Effects of CO2 laser beam on cortical bone
Authors: Rayan Ghazi M. , Pitha Jan V. , Edwards Janet S. , Everett Royce B.
Published: March 2007

Sixteen bone blocks from two freshly amputated legs were used to study the effect of CO2 laser on cortical bone. They were divided into two groups. In Group I, the blocks were treated with CO2 laser using 1 mm spot (focused mode). In Group II, they were treated with CO2 laser using 3 mm spot (defocused mode). Two other variables were investigated: the power and time of exposure. Three histologic zones were observed: a superficial zone with black particle deposits (carbonization), an intermediate zone with fibrillations and enlarged empty lacunae, and a deep zone with normal appearing bone. The bony changes in the first two zones combined were superficial in all specimens and did not exceed 200 microns. Increased energy, a focused beam, and time of exposure were all associated with increased matrix changes. CO2 laser can be applied to cortical bone in vitro with minimal residual thermal damage.
Comparison of three lasers for dental instrument sterilization
Authors: Powell G. Lynn , Whisenant Brian K.
Published: March 2007

The sterilization of dental instruments is an area of great interest and recent concern in the field of dentistry. The purpose of this study was to compare the ability of three lasers (argon, CO2, and NdYAG) to sterilize dental instruments. Endodontic reamers were contaminated with microorganisms, lased at various levels of energy, placed in Trypticase soy broth, incubated, and read for growth or no growth to determine sterility. Results indicated that the argon laser is capable of sterilizing selected dental instruments at the lowest energy level (1 watt for 120 seconds) of the three lasers tested. The other two lasers were able to sterilize the instruments also, but at higher energy levels.

Results indicated all three lasers capable of sterilizing selected dental instruments; however, the argon laser was able to do so consistently at the lowest energy level of 1 watt for 120 seconds.