bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser recanalization in high risk patients
Authors: Seeger James M. , Kaelin Lawrence D. , Barbeau Gerald , Abela George S. 
Published: March 2007

AbstractLaser recanalization was attempted in 13 patients in whom the risk of surgical therapy was increased by severe angina, infection, absent venous conduit, or recent deep venous thrombosis, and in 4 patients at high risk for limb loss due to severe infrapopliteal arterial occlusive disease. Total occlusions of the superficial femoral, tibial, or peroneal arteries were treated. Recanalization was accomplished using Argon laser power and a Spectraprobe‐PLRm. Two patients also required common femoral artery endar‐terectomy to improve inflow. Laser recanalization was successful in 9 patients (53%), and 8 (47%) had relief of symptoms. None of the 4 patients with tibial and peroneal artery occlusion had successful recanalization or limb salvage. Restenosis or reocclusion developed in 4 patients during the first year after successful recanalization, but only 1 had recurrent symptoms. Limb salvage was initially achieved in 5 of 8 recanalization failures by surgical reconstruction but 3 developed graft infections requiring graft removal in 2 and amputation in 1. Thus, laser recanalization can accomplish limb salvage in selected patients whose medical or surgical risks complicate arterial bypass surgery.
Photodynamic therapy: Tumor volume limitation and tumor response for murine fibrosarcoma
Authors: Al‐Watban Farouk A. H. 
Published: March 2007

AbstractThe clonogenic survival rates and tumor growths following photodynamic therapy (PDT) were studied as a function of tumor volume for RIF‐1 using C3H mice as an animal model. The clonogenic survival rates showed a saturation level approaching a 99.8% survival rate for large volumes (above 1,900 mm3), possibly indicating poor light utilization of 630 nm because of the limited tissue penetration and/or tumor hypoxia. With a small tumor volume [<150 mm3], the survival rate (<0.3%) showed an exponential increase with volume. The survival rates (<0.03%) corresponding to a volume lower than 50 mm3 gave complete tumor eradication. On the other hand, partial response and recurrence were noticed with volumes larger than 90 mm3, which had more than ∼0.1% survival rates. After PDT, all tumors responded with immediate swelling and skin discoloration, followed by necrosis, tumor delay, and regrowth. Regrowth rate and tumor cell doubling time were slower than the control growths and decreased further following superficial irradiation with a second interstitial illumination. The regrowth rates were slow for small initial tumor volumes and fast for large initial tumor volumes. Also, the delay period was longer for the small initial tumor volumes in comparison to a shorter period for the medium tumor volumes and very low probability of delay for the large volumes.
Sutureless End‐to‐End bowel anastomosis using Nd:YAG and water‐soluble intralurninal stent
Authors: Costello Anthony J. , Johnson Douglas E. , Cromeens Douglas M. , Wishnow Kenneth I. , Von Eschenbach Andrew C. , Ro Jae Y. 
Published: March 2007

AbstractSutureless end‐to‐end intestinal anastomoses were successfully constructed in 20 rabbits. A water‐soluble intraluminal stent was used to approximate the tissue edges, and the anastomotic seam was lased with 1.06 μm neodymium:YAG (Nd:YAG) laser energy supplied through a hand‐held 600‐μm gas‐cooled noncontact optical fiber. A continuous 5‐watt wave of power was applied over periods ranging from 46 to 92 seconds to produce the tissue blanching and shrinkage that indicated a satisfactory tissue weld. Integrity, degree of tissue reaction, and bursting pressures of the anastomoses were compared to those of anastomoses constructed using standard sutured techniques.The results of the two methods were equivalent at 1 to 3 days, but the laser‐fused enteric anastomoses showed less inflammatory reaction and greater bursting pressures at 7 and 14 days. Application of a variety of proteinaceous solutions including extracellular matrix materials and epidermal growth factors prior to lasing failed to augment wound healing. We conclude that lasers show promise as reconstructive, in addition to ablative, surgical instruments.
Laser photobioactivation mechanisms: In vitro studies using ascorbic acid uptake and hydroxyproline formation as biochemical markers of irradiation response
Authors: Labbe Robert F. , Skogerboe Kristen J. , Davis Holly A. , Rettmer Rebecca L. 
Published: March 2007

AbstractClinical investigations of laser photobioactivation, or biostimu‐lation, might be differently designed and more fruitful if knowledge of basic biochemical mechanisms were better understood. In this investigation, biochemical events identified as responses to 904 nm irradiation included increased ascorbic acid uptake by fibroblasts. These cells also showed increased hydroxyproline formation, and this was increased several‐fold by the addition of proline to the medium. Maximum biochemical responses were observed at a pulse frequency of 67 Hz and a pulse width of 150 nsec with an energy density of approximately 7 mJ/cm2 per exposure. Elements in the mitochondrial cytochrome system are proposed as the radiation absorbing chromophore(s). Hypothet‐ically, the energy generated is linked to ascorbic acid uptake, which in turn stimulates collagen synthesis.
Study of the mechanisms of laser‐induced release of liposome‐encapsulated dye
Authors: Khoobehi Bahram , Char Clifford A. , Peyman Gholam A. , Schuele Kathleen M. 
Published: March 2007

AbstractTo differentiate the contributing factors (blood or encapsulated dye) leading to the release of encapsulated dyes from liposomes after laser exposure, we initiated an in vitro experimental study. The release of encapsulated calcein was quantified under various experimental conditions in whole blood and in buffered solution containing high‐density lipoprotein. Generally, the amount of dye release improved with an increase in laser power, with a maximum release of approximately 80% of encapsulated dye. Because the laser exposure was not continuous, only 80% of each sample was actually exposed. Therefore, 80% release may be thought of as total release. In a lipoprotein/buffer mixture, the 488 nm wavelength caused greater dye release than the 577 nm wavelength, because the maximum absorption of calcein is near 488 nm. The laser wavelength at 577 nm, however, caused greater release in the blood mixture, reflecting the peak absorption of hemoglobin at near 577 nm. At a 3x higher liposome concentration, the differences in the effects of wavelengths on the release of dye from liposomes were insignificant. Although the 577 nm wavelength is an optimum wavelength for dye and drug delivery in the presence of blood, the 488 nm wavelength might also be suitable for the release of dye from the liposomes.
Strength of laser vascular fusion: Preliminary observations on the role of thrombus
Authors: Oz Mehmet C. , Bass Lawrence S. , Chuck Roy S. , Johnson Jeffrey P. , Parangi Sareh , Nowygrod Roman , Treat Michael R. 
Published: March 2007

AbstractWe hypothesized that autologous clot deposited on the luminal surface of laser vascular welds immediately after creation would produce higher time zero bursting pressures than could be achieved in welds perfused with saline alone. To test this hypothesis, we compared bursting pressures of welds created in isolated rabbit aortic segments (1) with saline perfusion only, (2) with blood perfusion, and (3) with blood perfusion followed by infusion of urokinase. Tissue welds with saline perfusion had a mean bursting pressure of 159 ± 45 mm Hg; tissue welds following blood perfusion had a mean pressure of 262 ± 29 mm Hg; tissue welds with blood perfusion followed by urokinase infusion had a mean bursting pressure of 187 ± 35 mm Hg. The saline and urokinase groups were not significantly different. However, the blood‐perfused group was significantly higher than both the saline group and the urokinase group. Thus, the addition of urokinase eliminates the beneficial effects noted after blood reperfusion. These observations suggest that the enhancement of weld strength following exposure to blood is due predominantly to the adherence of fibrin‐platelet aggregates at the site of the weld.
Laser in situ keratomileusis
Authors: Pallikaris Loannis G. , Papatzanaki Maria E. , Stathi Evdoxia Z. , Frenschock Oliver , Georgiadis Anthimos 
Published: March 2007

AbstractA new laser refractive procedure is being developed in a rabbit model. With a modified microkeratome, central corneal flaps were created. An ArF excimer laser was used to produce 3‐mm‐diameter circular ablations on the central part of the exposed stromal bed. One group of animals was sacrificed immediately postoperatively, and both the dissected and ablated areas were studied using scanning electron microscopy. A second group of animals was sacrificed 4 weeks postoperatively. In this group, the subsequent healing of the corneas was studied using light microscopy. At 3 days, the wounded stromal areas showed some degree of haze. Haze was progressively reduced over 1 month, but it could be still discerned biomicroscopically. A hemicircular opacification corresponding to the flap edges was also apparent on slit‐lamp examination. Microscopic observation showed that the epithelium was normal, except at the flap margins, where it was thickened. An increased number of keratocytes was observed in the interface between the flap stroma and the ablated area. The procedure might induce stable corneal changes because of the preservation of the anterior layers of the cornea.
Determination of retinal blood velocity with respect to the cardiac cycle using laser‐Triggered release of liposome‐Encapsulated dye
Authors: Khoobehi Bahram , Aly Omar M. , Schuele Kathleen M. , Stradtmann Manrique Ortiz , Peyman Gholam A. 
Published: March 2007

AbstractA system of selective angiography has been developed for measuring blood velocity in retinal arteries and veins. It uses a lipo‐some‐encapsulated fluorescent dye that is released by application of laser energy in a specific retinal vessel. The method is shown to be able to distinguish between peak systolic velocity and minimum diastolic velocity. In the cynomolgus monkey, the two values were found to differ by approximately a factor of three. It is known that many ocular and systemic diseases affect retinal circulation, and therefore a method of blood velocity measurement with such sensitivity may prove highly valuable in the practice of ophthalmology. As an example, the velocity in a retinal vein was measured before and after partial occlusion by pho‐tocoagulation. The two values obtained were significantly different, and the blood velocity was found to return to the value prior to occlusion when measured at 18 days.
Transscleral application of a semiconductor diode laser
Authors: Peyman Gholam A. , Naguib Khaled S. , Gaasterland Douglas 
Published: March 2007

AbstractWe used a diode laser with an output power of 1 W through a fiberoptic light pipe (200 μm diameter) to deliver laser energy through the sclera of pigmented rabbits. Ciliary body destruction occurred with energy levels of 300–400 mW and exposure time of 0.5 sec. Retinal photocoagulation was achieved with energy levels of 200–500 mW in 0.5 sec. Histologic examination of acute lesions demonstrated thermal destruction of ciliary body processes and retina. Chorioretinal scar formation was observed clinically and histologically within 2–3 weeks. Our data indicate that the transscleral diode laser may be used for destruction of the ciliary body processes or peripheral retinal coagulation in pigmented eyes.
Comparative bactericidai exposures for selected oral bacteria using carbon dioxide laser radiation
Authors: Dederich Douglas N. , Pickard Michael A. , Vaughn Allison S. , Tulip John , Zakariasen Kenneth L. 
Published: March 2007

AbstractAlthough relatively high CO2 laser energies have been shown to sterilize root canals, the response of several bacterial strains to decreasing exposures of CO2 laser energy remains unknown. Freshly grown bacterial cells were irradiated on glass microscope coverslips. A comparison of equivalent energy exposures with differing parameters was made on the bacterial viability. No statistically significant difference was found in the energy required to kill closely related bacterial species. However, the energy density required to kill greater than 99.5% of the bacteria is less than 200 J/cm2, much less than that shown to sterilize in a previous study.
Bladder perforation resulting from the use of the neodymium: YAG laser
Authors: Greskovich Frank J. , von Eschenbach Andrew C. 
Published: March 2007

AbstractComplications resulting from the use of the neodymium:YAG (Nd:YAG) laser to treat superficial bladder cancer are uncommon and are usually associated with abnormally high laser power outputs. We report a case of bladder perforation in a human attributed to the Nd:YAG laser used at a low power setting and comment on those factors that contributed to this complication.
Endoscopic thoracic sympathectomy: Evaluation of pulsatile laser, non‐pulsatile laser, and radiofrequency‐generated thermocoagulation
Authors: Massad Malek , LoCicero Joseph , Matano Jun , Oba Junichi , Greene Rodney , Gilbert Jeremy , Hartz Reneé 
Published: March 2007

AbstractWe describe a modified technique for percutaneous denervation of the thoracic sympathetic chain by laser to treat selected cases of sympathetic causalgia of the upper extremities. The technique involves transpleural ablation with laser under thoracoscopic guidance through the second or third intercostal space‐anterior axillary line. We also compare four different modalities of endoscopic denervation: A xenon chloride excimer laser (308 nm, 35 mJ/pulse, 20 pulses/sec, 2.2 mm catheter tip), CO2, laser (14 W, CW, 2 mm spot size), Nd:YAG laser (88 W, CW, 3 mm spot size), and radiofrequency‐generated thermocoagulation (3 W, CW, 2.1 mm catheter tip) by performing bilateral thoracic sympathectomy on 12 mongrel dogs (three dogs each). Criteria analyzed included duration of exposure, power density, total energy output, laser penetration and spread, gross morphology, and scanning electron microscopy (SEM) of the destroyed neural tissue. Total ablation of the inferior segment of the stellate ganglion and the T1‐T2, nerve roots by excimer laser required 83±1 Joules over an exposure period of 118 seconds. Ablation by CO2, and Nd:YAG laser required 153±13 Joules and 554±47 Joules delivered over 11 and 6 seconds respectively. In contrast, ablation of the same volume of nerve tissue by RF required 810±50 Joules over 270 seconds. SEM evaluation revealed that excimer and CO2, laser lesions were narrower in configuration compared to RF and Nd:YAG lesions which showed more lateral spread. The actual depth of penetration per 1 second exposure was similar for Excimer and CO2, (1.5 mm) and RF (1.3 mm), but deeper for Nd:YAG (3 mm). Our data shows that excimer and CO2, laser produce discrete lesions with minimal damage to surrounding structures. It also demonstrates the safety and reliability of endoscopic denervation, particularly for bilateral denervation which can be performed in one sitting without the added morbidity of a thoracotomy incision.
Gross and microscopic changes in the viscera induced by photodynamic therapy applied to the lower abdomen of intact rats
Authors: Chazen Mark D. , Baggs Raymond B. , Gibson Scott L. , Albert Michael S. , Hilf Russell 
Published: March 2007

AbstractPhotodynamic therapy (PDT) is a promising approach to the treatment of cancer. Preferential retention of the photosensitizer by malignant tissue has been considered a hallmark of this treatment modality. However, photosensitivity can be observed in normal, non‐neoplastic tissues, and the present study investigated the effects of PDT treatment on the abdomen of intact rats. A circular region (1 cm diameter) on the shaved abdomen of Fischer rats, pretreated 24 h prior with Photofrin II, was irradiated for 30 min at 632 nm. Control animals received either photoradiation or Photofrin II administration. Subsequent lesions were observed in the irradiated skin, its associated abdominal wall, and the underlying gut in rats receiving Photofrin II and laser irradiation. All tissues were not equally sensitive to PDT treatment. Gut lesions were consistently more severe than were skin and abdominal wall injuries. By 24 hr after treatment, the gut manifested a transmural hemorrhagic necrosis, while the irradiated skin and abdominal wall were edematous, with an inflammatory infiltrate in the dermis and around occasional swollen myocytes. These results indicate that superficial lesions induced by PDT may not be reliable indicators of the extent of deeper PDT tissue damage. Further, it may be possible to take advantage of this discrepancy in tissue sensitivity and treat deep tissues through less sensitive superficial tissues.
Optical properties of normal, diseased, and laser photocoagulated myocardium at the Nd:YAG wavelength
Authors: Splinter Robert , Svenson Robert H. , Littmann Laszlo , Tuntelder Jan R. , Chuang Chi Hui , Tatsis George P. , Thompson Michelle 
Published: March 2007

AbstractLaser photocoagulation of the myocardium effectively destroys arrhythmogenic foci. The purpose of this study was 1) to compare the optical properties of canine myocardium before and after photocoagulation, 2) to compare the canine model with clinical cases by measuring the optical properties of human myocardium, and 3) to assess the optical properties of human myocardial scar and epicardial fat tissue. Measured optical properties were the absorption coefficent, μa; scattering coefficient, μs; and scattering anisotropy factor, g. Optical measurements were performed at 1064 nm wavelength on thin plane parallel tissue slices using the integrating sphere method with glass hemispheres on either side of the sample. The study showed 1) an increase of the scattering coefficient by 40% and a two‐ to threefold increase in reduced scattering coefficient as a result of photocoagulation; 2) that the μa (0.035 ± 0.024 mm−1) and μs (17.9 ± 3.8 mm−1) of human myocardium were not significantly different from μa (0.043 ± 0.021 mm−1) and μs (17.3 ± 2.2 mm−1) of canine myocardium, whereas the human g (0.964 ± 0.005) was slightly different from the canine g (0.974 ± 0.008); and 3) that the μa (0.021 ± 0.016 mm−1) of epicardial fat and μs (13.8 ± 1.1 mm−1) of myocardial scar were significantly lower than those of normal myocardium. A dynamic model of laser‐tissue interaction incorporating these changes and inhomogeneities is necessary to better describe light distribution during laser photocoagulation.
Analysis of photoproducts, free radicals, and particulate debris generated during in vivo argon laser myoplasty
Authors: Gal Dov , Fonger James D. , Rastegar Hassan , DeJesus Stephen T. , Clarke Richard H. , Isner Jeffrey M. 
Published: March 2007

AbstractCatheter‐guided laser myoplasty in a closed ventricle has been advocated for the treatment of hypertrophic cardiomyopathy, ablation of arrythmogenic foci, and transmyocardial laser revascularization of ungraftable regions of ischemic myocardium. The purpose of this study was to evaluate the nature of particulate debris and photoproducts generated in vivo. Accordingly, cardiopulmonary bypass was established in four dogs without active cooling and an apical left ventricular vent was placed. In two dogs, a laser catheter was inserted into the cardioplegia‐arrested left ventricle through the left atrial appendage and across the mitral valve. In the other two dogs the laser catheter was inserted into a perfused, fibrillating left ventricle retrograde across the aortic valve. Myocardial ablation of the ventricular septum was performed using continuous argon‐ion laser irradiation (8–10 watts, 4–11 minutes) and blood samples were drawn through the ventricular vent. The final ablation in each dog was done during a separate ventricular flush with a chemical “spin trap” capable of detecting free radicals. Analysis of ventricular effluent revealed levels of carboxyhemoglobin and hydrogen cyanide which were well below accepted clinical toxic limits. Microparticulate debris (2‐300 femtoliter) was not detected. Evidence of trace free radical generation was suggested in one of four dogs.In conclusion, closed ventricular argon laser myoplasty did not generate clinically significant levels of the toxic photoproducts we measured, or microparticulate debris. These in vivo findings suggest that the clinical application of catheter‐based laser myoplasty will not be limited by the generation of these toxic photoproducts or microembolic debris.
Co:MgF2 laser ablation of tissue: Effect of wavelength on ablation threshold and thermal damage
Authors: Schomacker Kevin T. , Domankevitz Yacov , Flotte Thomas J. , Deutsch Thomas F. 
Published: March 2007

AbstractThe wavelength dependence of the ablation threshold of a variety of tissues has been studied by using a tunable pulsed Co:MgF2 laser to determine how closely it tracks the optical absorption length of water. The Co:MgF2 laser was tuned between 1.81 and 2.14 μm, a wavelength region in which the absorption length varies by a decade. For soft tissues the ablation threshold tracks the optical absorption length; for bone there is little wavelength dependence, consistent with the low water content of bone. Thermal damage vs. wavelength was also studied for cornea and bone. Thermal damage to cornea has a weak wavelength dependence, while that to bone shows little wavelength dependence. Framing‐camera pictures of the ablation of both cornea and liver show explosive removal of material, but differ as to the nature of the explosion.
Photodynamic therapy for rat pituitary tumor in vitro and in vivo using pheophorbide‐a and white light
Authors: Yano Takashi , Uozumi Tohru , Kawamoto Keiichi , Mukada Kazutoshi , Onda Jun , Ito Akihiro , Fujimoto Nariaki 
Published: March 2007

AbstractThis is the first report on the use of photodynamic therapy (PDT) for rat pituitary tumor in vivo. Rat pituitary tumor (GH3) cells were cultured, GH3 tumor was subcutaneously implanted in nude mice, and pheophorbide‐a (Ph‐a) and white light were prepared. Photocytotoxicity proportional to Ph‐a concentration, intensity of irradiation, and incubation time was observed in vitro. Despite the delay in the disappearance of Ph‐a from the tumor, Ph‐a in the pituitary gland rapidly decreased after intravenous administration in vivo. Through PDT, the tumor grossly disappeared, the plasma levels of rat growth hormone secreted from the tumor also remarkably decreased, and the development of giantism was inhibited. These results indicate that PDT is effective against rat pituitary tumor.
Interspersion of fragmented fiber's splinters into tissue during pulsed alexandrite laser lithotripsy
Authors: Strunge Christian , Brinkmann Ralf , Flemming Gabriela , Engelhardt Ralf 
Published: March 2007

AbstractLaser induced shockwave lithotripsy (LISL) on artificially inserted human renal calculi was realized in explanted pig ureters. A pulse stretched Alexandrite solid state laser was used at 750nm. Pulses of 350ns and 1μs duration were transmitted through a 250μm all silica fiber onto a stone surface, keeping the fiber tip in contact with a stone close to the ureter wall. The high power density of the 350ns pulses lead to an optical breakdown inside the distal fiber tip causing fiber fragmentation of about 28mm/100 pulses. Deep penetration of the fiber fragments into the ureter wall was proven histologically. Fiber fragmentation was avoided by increasing the pulse duration up to 1μs. Risks for patient treatment caused by short pulse lithotripsy are discussed.