bluuebunny/crossref_metadata_2025_split huggingface dataset:
Limits of radial time constants to approximate thermal response of tissue
Authors: Meijering Laurens J. T. , van Gemert Martin J. C. , Gijsbers Geert H. M. , Welch Ashley J. 
Published: March 2007

AbstractThe time constant model, as an approximation to the bio‐heat equation, was tested for non‐ablating, deep penetrating (argon) laser beams in absorbing tissue phantoms (polyacrylamide) in air. Temperature responses were measured with a thermal camera, both during laser irradiation as well as after the laser beam was switched off. The radial time constant model was found to give a reasonable prediction (within 5%) of temperature rise for irradiation times of up to the order of one time constant. The cooling behavior of tissue could not be described by one single time constant. The time constant model was found to fit the early cooling rate (cooling time about equal to irradiation time) for laser pulse durations of up to one time constant. The late cooling rate turned out to be much slower than predicted by the radial time constant model, yet it was faster than the cooling rate predicted by the one‐dimensional instantaneous hot cylinder surface model. © 1993 Wiley‐Liss, Inc.
Healing process of laser–welded intestinal anastomosis
Authors: Rabau Micha Y. , Wasserman Iian , Shoshan Shmuel 
Published: March 2007

AbstractIntestinal welding by means of low‐power laser has been reported as an efficient method for intestinal anastomosis. We designed an experimental model in rats to investigate collagen and DNA concentrations in CO2 laser–welded anastomoses as compared with those in sutured anastomoses on the 4th, 7th, and 10th postoperative days. The results revealed that DNA, total collagen, and insoluble collagen concentrations were significantly lower in the lased anastomoses than in the sutured anastomoses on the 4th postanastomotic day. On the 7th and 10th postanasto‐motic days, collagen concentrations increased in the laser‐treated group attaining significantly higher levels than in the sutured group at that time. These findings are compatible with other studies demostrating that laser–welded intestinal anastomoses are more prone to dehiscence during the first 4 postanastomotic days, but become at least as effective as the sutured ones with passage of time. © 1994 Wiley‐Liss, Inc.
Hemostasis and healing of superficial splenic injuries using Nd:YAG laser and nonsuture techniques: Preliminary report
Authors: Vanterpool Clyde C. , Alrashedy Farhad H. , Gurchumelidze Teimuraz , Gales Morris E. , Silva Yvan J. , Libcke John , Schork M. Anthony 
Published: March 2007

AbstractThis study was designed to compare Nd:YAG laser to fibrin glue, electrocautery, and avitene in the management of superficial splenic injury. Six dogs were submitted to laparotomy. A #11 blade scalpel was used to sharply excise the splenic capsule inflicting four 1″ × 1″ superficial injuries on each spleen. The lesions were treated. All animals had a second laparotomy (“first relaparotomy”); 2 dogs each were reexplored on postop days 3, 7, and 14. Morphologic and histologic observations were made. A third and final relaparotomy was performed on all dogs at 21 days with repeated morphologic and histologic assessments. Hemostatic times, grades of adhesions, and microscopic changes were not significantly different among the various treatments (P > 0.25). Capsular plaque formations were significantly different at the first relaparotomy (P < 0.01) and at final relaparotomy (P < 0.05). Both adhesions and capsular plaque formation were least at fibrin glue‐treated sites, whereas Nd:YAG (1.06 μm) was most effective for average hemostatic time (mean = 109.67 s). Electrocautery produced the greatest necrosis at treatment sites. We conclude that all modalities are effective in controlling hemorrhage. © 1994 Wiley‐Liss, Inc.
Microarterial anastomosis using a noncontact diode laser versus a control study
Authors: Tang Jing , Godlewski Guilhem , Rouy Simone , Dauzat Michel , Juan Jean‐Marie , Chambettaz FrançOis , Salathe Rene 
Published: March 2007

AbstractA series of direct carotid end‐to‐end laser anastomosis vs. direct manual suture was carried out on a series of 70 Wistar rats (mean weight 260 g). Both common carotids (0.8–1.2 mm) were sectioned and repaired. The left side (n = 70) was submitted to laser‐assisted microvascular anastomosis (LAMA) performed by means of a diode laser device (wavelength 830 nm and power output 3 W in continuous wave) without chromophore. The right side (n = 70) underwent a control manual suture (CMA). The diode laser energy was delivered into a micromanipulator coupled to a Zeiss operating microscope with a focused spot of 300 μm in diameter. After placement of three 10.0 stitches for edge coaptation, the LAMA was achieved using laser shots (average 3) of 500 mW power, 4.5 s duration, and 700 W/cm2 irradiance each. The CMA was performed by means of six 10.0 stitches. The good vascular flow was confirmed by Doppler spectral analysis (n = 466) carried out from day 0 to day 90. Light and scanning electron microscopy (n = 82) showed that re‐endothelialization after LAMA was gaining ground on day 3, whereas collagenous network developed in the media scar by day 10. In contrast, after CMA the arterial repair was delayed on day 20, inducing a media fibrotic scar. The patency rate was 93% in both anastomoses. The shorter operating time (13 min for LAMA vs. 22 min for CMA) and the noncontact laser technique are the main intraoperative advantages. The technical benefits of the diode laser are pointed out. © 1994 Wiley‐Liss, Inc.
Autofluorescence spectroscopy using a XeCl excimer laser system for simultaneous plaque ablation and fluorescence excitation
Authors: Morguet Andreas J. , Körber Beate , Abel Bernd , Hippler Horst , Wiegand Volker , Kreuzer Heinrich 
Published: March 2007

AbstractLaser–induced fluorescence may be used to guide laser ablation of atherosclerotic lesions. This study was performed to evaluate arterial autofluorescence spectroscopy in vitro using a single XeCl excimer laser (308 nm) for simultaneous tissue ablation and fluorescence excitation. The laser beam was coupled to a 600‐μm silica fiber transmitting 40–50 mJ/mm2 per pulse. The fluorescence radiation emanating retrogradely from the fiber was collected by a concave mirror for spectroscopic analysis over a range of 321–657 nm. The arterial media (n = 26), lipid plaques (n = 26), and calcified lesions (n = 27) of aortic specimens from ten human cadavers were investigated in air, saline, and blood. Whereas the spectrum of calcified lesions changed with the surrounding optical medium, the other spectra remained constant. In air and blood, the spectra of arterial media, lipid plaques, and calcified lesions could be differentiated qualitatively and quantitatively (P < 0.0001). In saline, there was no clearcut spectroscopic difference between lipid plaques and calcified lesions. However, normal arterial media and atherosclerotic lesions (lipid plaques plus calcified lesions) could still be discriminated. Thus spectroscopy and plaque ablation can be combined using a single XeCl excimer laser. These encouraging results should stimulate further studies to determine the potential use of this approach to guide laser angioplasty in humans. © 1994 Wiley‐Liss, Inc.
Temperature dependence of the absorption coefficient of water for midinfrared laser radiation
Authors: Jansen E. Duco , van Leeuwen Ton G. , Motamedi Massoud , Borst Cornelius , Welch Ashley J. 
Published: March 2007

AbstractThe dynamics of the water absorption peak around 1.94 μm was examined. This peak is important for the absorption of holmium and thulium laser radiation. To examine the effect of temperature on the absorption coefficient, the transmission of pulsed Ho: YAG, Ho:YSGG, and Tm:YAG laser radiation through water of 22°C, 49°C, and 70°C was measured as a function of the thickness of the water layer. From these data the absorption coefficients were determined at the three wavelengths. We found that at all three wavelengths, the absorption coefficients decreased when increasing the temperature. Second, the absorption spectrum of water was measured from 1,850–2,150 nm with a spectrophotom‐eter. It was found that the absorption peak at 1.94 p,m (at 22°C) shifts to shorter wavelengths with increasing temperatures, to 1.92 μm at 70°C.A model was developed to predict the temperature distribution incorporating the dynamic change in absorption coefficient. The temperature distributions are compared to the predictions of a model assuming constant optical properties. It is shown in this study that the dynamics of the absorption coefficient has a significant influence on the expected zone of damage and ablation parameters in the 2‐μm wavelength range. © 1994 Wiley‐Liss, Inc.
Silver halide fiber optic radiometric temperature measurement and control of CO2 laser‐irradiated tissues and application to tissue welding
Authors: Shenfeld Ofer , Ophir Eyal , Goldwasser Benad , Katzir Abraham 
Published: March 2007

AbstractTissue heating by laser irradiation has attained importance in many clinical applications. Accurate temperature measurements of laser‐irradiated tissues are difficult to achieve, and experiments have produced conflicting results. Fiber optic radiometry allows temperature measurement of laser‐irradiated tissues by remote sensing of the emitted infra red (IR) radiation. We have developed an IR fiber optic radiometer capable of accurate tissue temperature measurements (± 0.2°C) and utilized it to monitor and control the heating of tissues by CO2 laser irradiation. Tissue temperature control of ± 2.5°C was achieved. This system was used to control tissue temperature during CO2 laser‐assisted welding of urinary bladders in rats. The strength of the welds was recorded for different welding temperatures. A temperature of 55°C was found to be optimal. © 1994 Wiley‐Liss, Inc.
Effects of thermal exposure on binding of heparin in vitro to the arterial wall and to clot and on the chronic angiographic luminal response to local application of a heparin film during angioplasty in an in vivo rabbit model
Authors: Spears J. Richard , Yellayi Subrahmanya S. , Makkar Raj , Nallamothu Nasaraiah , Rizvi Mohammad A. D. , Sheriff Mohammad U. , Khetpal Vikram , Zhan Hong , Jang Jie , Kundu Sourav K. , Zaidan Jonathan T. , McMath Linda P. , Wang Tao , Mammen Eberhard F. , Khan Muhammad A. , Sathavorn Charn S. , Fromm Barbara 
Published: March 2007

AbstractExperimentally, heparin inhibits mechanisms that promote fibrosis, neointimal cellular proliferation, and thombin bound to fibrin at the surface of intraluminal thrombus, but only in relatively high concentrations. A preliminary hypothesis was tested and confirmed in vitro that initial binding of 3H‐heparin to mechanically injured porcine aorta is concentration‐dependent over a 1,000–50,000 units/ml range (r = 0.9). The hypothesis was then tested in vitro that thermal exposure during contact of heparin to arterial tissue and to clot would enhance binding of the drug. 3H‐heparin binding to clot, whole blood particulates, and washed erythrocytes was markedly enhanced by exposure to temperatures > 70°C. Thermal exposure (80°C × 40 s) also enhanced tissue persistence of the drug within porcine aorta subjected to a shear rate of 1,100−1in an annular Baumgartner chamber perfused with normal saline at 37°C for 48 h. Heparin in vitro anticoagulant activity persisted after thermal exposure and binding to tissues.A new method was developed for local application of a heparin film that provides a maximum concentration with a tolerable systemic dose during an angioplasty procedure. In an in vivo rabbit model of mural fibrosis after iliac artery angioplasty, the 1‐month mean angiographic luminal diameter loss (23% compared to the acute postangioplasty result by computer image analysis) in response to conventional balloon angioplasty (BA) and laser balloon angioplasty (LBA) was the same (P > 0.05). Local application of a heparin film (3,000 units at a concentration > 100,000 units/g), however, reduced the mean % loss in diameter 1 month after LBA (12 %), but not after BA (29%), compared to arteries subjected to angioplasty without local heparin (P < .05). The results are consistent with the hypothesis that thermal energy enhances heparin binding to tissues and that local application of a heparin film favorably modulates arterial luminal responses to LBA, but not to BA, in this animal model. © 1994 Wiley‐Liss, Inc.
Effect of low level diode laser irradiation of human oral mucosa fibroblasts in vitro
Authors: Loevschall Henrik , Arenholt‐Bindslev Dorthe 
Published: March 2007

AbstractThe effects of low level laser (LLL) irradiation on the proliferation of human buccal fibroblasts were studied. A standardized LLL set‐up was developed (812 nm, 4.5 ± 0.5 mW/cm2). Cultures in petridishes were divided into eight groups (1 group served as control). On day 6 after seeding, routine growth medium was replaced with PBS for 1/2 hour. At the beginning of this period, LLL irradiation was performed for 0, 1, 3, 10, 32, 100, 316, or 1,000 seconds, respectively—corresponding to the radiant exposures 0, 4.5, 13.5, 45, 144, 450, 1,422, 4,500 mJ/cm2. Subsequently the cells received 3H‐dT in fresh medium for 16 hours DNA‐incorporation. Scintillations from tritium and total protein concentration per culture dish were determined. The individual 3H‐cpm/protein‐concentration ratios were calculated in % of control. Three experiments were performed (N = 151). Following LLL exposure the H‐cpm/protein ratio was increased with maximum cpm/protein ratio (132.5% ± 10.6% SEM) in the group receiving 450 mJ/cm2 (P < 0.03 nonparametric Kruskal Wallis one‐way ANOVA‐test). This study demonstrated an increased incorporation on tritiated thymidine in cultured human oral fibroblasts following LLL exposure and suggests that LLL irradiation can induce increased DNA Synthesis. © 1994 Wiley‐Liss, Inc.
Attenuation of the process of muscle regeneration in the toad gastrocnemius muscle by low energy laser irradiation
Authors: Bibikova A. , Oron U. 
Published: March 2007

AbstractThe effect of number, frequency, and timing of HeNe (6.0 mW; 31.2J/cm2) and Ga‐As‐diode (average power at 2.82 Hz‐0.005 mW) laser irradiations on the process of muscle regeneration at 14 days following cold injury to the toad gastrocnemius muscle was investigated using histomorphometric methods. The volume fraction (percent of total injured area) of mononucleated cells, myotubes and degenerated fibers was 10 ± 1%, 0%, and 4 ± 1%, respectively, in the HeNe laser irradiated muscles (5 irradiations every alternate day, beginning on the 4th day after injury), whereas in the control nonirradiated muscles, these values were significantly higher comprising 57 ± 2% (P < 0.01), 11 ± 1% and 10 ± 2% (P < 0.05), respectively. The volume fraction of young myofibers in injured areas that were subjected to the same laser irradiation regime was 8.6‐fold significantly higher (P < 0.01) than their volume fraction in control muscles. The histomorphometric results were the same for injured zones of muscles that were laser irradiated only once, on the 9th day postinjury, and for those that received five consecutive irradiations every alternate day. Muscle regeneration was equally promoted by single Ga‐As‐diode laser or HeNe irradiation. Multiple irradiations of Ga‐As‐diode laser caused some pathological changes in the newly formed muscular structures. It is concluded that the process of skeletal muscle regeneration is markedly promoted by low energy laser irradiations, but that the effect depends on the number, timing, and frequency of irradiations and the type of laser used. © 1994 Wiley‐Liss, inc.
Interferometric surface monitoring of biological tissue to study inertially confined ablation
Authors: Albagli Douglas , Banish Bryan , Dark Marta , Janes G. Sargent , von Rosenberg Charles , Perelman Lev , Itzkan Irving , Feld Michael S. 
Published: March 2007

AbstractWe present results from the application of laser interferometry to the study of short‐pulsed laser ablation of biological tissue. The mechanical response of tissue to laser–induced stress is examined under subthreshold conditions to determine its role in initiating the ablation process. A theoretical model is developed to relate this surface displacement to the pressure within the tissue and the mechanical properties of the tissue. In the experiment, a 7.5 ns pulse of 355 nm light was used to irradiate bovine shank bone, human meniscus, and an aqueous dye solution. Interferometric monitoring of the tissue surface was used to determine its motion after laser irradiation. The surface movement of bone was qualitatively consistent with the theoretical predictions of the model. The movement of meniscus and an aqueous dye solution showed additional features that are consistent with the growth and collapse of cavitation bubbles. © 1994 Wiley‐Liss, inc.
Effects of surface irrigation on the thermal response of tissue during laser irradiation
Authors: Anvari Bahman , Motamedi Massoud , Torres Jorge H. , Rastegar Sohi , Orihuela Eduardo 
Published: March 2007

AbstractEffects of surface irrigation on the thermal response of tissue during laser irradiation are investigated. In particular, influence of temperature and flow rate of the irrigation fluid on the resulting temperature distributions and coagulation depths are studied. Intraluminal Nd:YAG laser irradiation of bovine muscle is performed in vitro for a fixed value of the irrigation flow rate while the irrigation temperature is varied, and for a fixed irrigation temperature while the irrigation flow rate is kept constant. Thermocouples are used to measure the temperatures within the tissue for various irradiation and irrigation conditions. Higher temperatures and deeper coagulation depths are achieved as the temperature of the irrigation fluid is increased. For sufficiently low values of irradiance and exposure time, the use of cold irrigation is shown to prevent or delay tissue carbonization. Beyond a critical irradiance and an exposure time, use of cold irrigation does not prevent tissue carbonization. Coagulation depths and temperature distributions are not affected by a change in the flow rate of laminar irrigation. Application of stagnant irrigation, however, results in an increase in coagulation depth. Results of this study suggest that the dominating mechanism of heat transfer during application of laminar irrigation is thermal diffusion as compared to the bulk motion of the fluid. © 1994 wiley‐Liss, Inc.
Light distribution of ocular endophotocoagulator probes and its surgical implications
Authors: Whitacre Marc M. , Timberlake George T. , Stein Richard A. , Stanley Adrienne M. , Van Vleck S. , Dominick Kurt E. 
Published: March 2007

AbstractOphthalmic endophotocoagulator probe cone angle affects the spot size, working distance, laser output power requirement, tissue exposure time, and uniformity of tissue irradiance, which all affect ease and safety of clinical use. The cone angle and irradiance distribution of several ophthalmic endophotocoagulator delivery systems were studied by directing the laser energy emitted by them on a CCD video sensor at several angles of incidence. The irradiances followed a Gaussian distribution. The measured irradiances were compared to a mathematical model of tissue irradiance that adjusted for the cone angle, probe‐tissue distance, and angle of incidence. Using this model, laser irradiances produced by endophotocoagulator probes can be estimated under a wide variety of conditions. At highly oblique angles of incidence, wide‐angle probes produce unexpectedly higher and uneven tissue irradiance. When numerous characteristics are considered, probes with a cone angle in the range of 10© have many advantages over narrower or wider angle probes. © 1994 Wiley‐Liss, Inc.
Application of the potassium‐titanyl‐phosphate laser during extraocular muscle surgery: Technique and histopathology
Authors: Hertle Richard W. , Mollet Linda , Prayer William C. 
Published: March 2007

AbstractWe determined laser parameters and delivery system requirements for successful use of the potassium‐titanyl‐phosphate (KTP) laser for strabismus surgery and its histopathologic effect on extraocular muscle, tendon, sclera, and cornea of human and rabbit eyes. Enucleated cadaver eyes and exenterated rabbit orbital contents were used. Using a 200‐μm fiberoptic tip delivery system, varying laser energies were used to perform muscle insertion site and corneal damage, tenotomies, and myotomies. Pulse durations of 0.5 second and energies above 0.8 watt were needed for tenotomy or myotomy. No damage to the surrounding tissues or sclera was observed with laser tenotomy or myotomy performed 0.5 mm from the insertion site. Energy above 0.8 watt applied directly caused full thickness disruption. In comparison to scissor myotomy, the laser provided charring of the superficial tissues. This study shows that the KTP laser can be safely and accurately used for extraocular muscle tenotomy or myotomy. © 1994 Wiley‐Liss, Inc.
Rate‐dependent, nonlinear photoablation of ocular tissue at 308 nm
Authors: Schallen Eric H. , Awh Carl C. , De Juan Eugene 
Published: March 2007

AbstractTo quantify the dependence on pulse repetition rate of 308 nm laser ablation in ocular tissue and elucidate the photoablation mechanisms involved, 85 full‐thickness ab interno sclerostomies were created in six human donor eyes using an 800‐μm‐diameter quartz optical fiber. A laser pulse duration of 135 ns, fluence of 31 mJ/mm2, and a fixed repetition rate between 5 and 40 Hz were used for 38 sclerostomies; the remaining 47 sclerostomies were completed at various laser settings during initial experimentation. Surprisingly, the numbers of pulses required for complete penetration of the optical fiber through the fixed tissue thickness were not constant as expected but decreased nonlinearly with increasing repetition rate. This demonstrates that the 308 nm excimer laser cuts ocular tissue significantly more rapidly per pulse at higher repetition rates. To explain this nonlinearity, we propose a composite ablation mechanism composed of photochemical, thermal, mechanical, and optical effects in varying proportions. © 1994 Wiley‐Liss, Inc.
Lasers in neurosurgery
Authors: Krishnamurthy Satish , Powers Stephen K. 
Published: March 2007

AbstractLasers have been used in neurosurgery for the past 25 years, undergoing modifications to suit the specific needs of this medical discipline. The present report reviews the current use of lasers in neurosurgical practice and examines the pros and cons of lasers in specific neurosurgical applications. In spite of their advantages, laser use is still not widespread in neurosurgery. One reason is the continued lack of complete control over real‐time laser interactions with neural tissue. A greater acceptance and use of lasers by neurosurgeons will depend upon automated control over defined specific parameters for laser applications based upon the type of tissue, the desired effect on tissue, and application to the clinical situation without loss of precision and a lot of expense. This will require the integration of newer lasers, computers, robotics, stereotaxy, and concepts of minimally invasive surgery into the routine management of neurosurgical problems. © 1994 Wiley‐Liss, Inc.