bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser‐induced experimental vascular occlusion using liposome‐encapsulated ADP
Authors: Khoobehi Bahrain , Peyman Gholam A. , Bhatt Nitul , Moshfeghi Darius
Published: March 2007

The therapeutic occlusion of retinal vessels is often helpful in treating various pathological conditions. We compared the combined effects of argon laser photocoagulation and adenosine diphosphate (ADP) released from temperature‐sensitive liposomes with argon laser photocoagulation alone on occlusion of retinal vessels in pigmented rats.

In Group A, 8 eyes were treated with liposome‐encapsulated ADP and laser photocoagulation. In Group B, 8 eyes were treated with laser photocoagulation alone. The laser parameters (power, spot size, exposure time) were maintained at the same levels for both groups. The laser was focused on the retinal vessels at the optic nerve head. The treated retinal vessels were observed at time zero, day 1, day 4, and weekly for a period of 3 months.

At time zero, 6 of 8 eyes were totally occluded in Group A, with best results obtained at 80 mW. Only 1 of 8 eyes in Group B achieved total occlusion. After 3 months, 4 of 8 eyes in Group A remained totally occluded; no eyes in Group B were occluded. Complete and permanent occlusion of retinal vessels can be achieved by using ADP and laser photocoagulation of lower power density than traditional laser photocoagulation alone. © 1992 Wiley‐Liss, Inc.
CO2 laser urethroplasty in the rabbit: A preclinical model
Authors: Choma Theodore J. , Poppas Dix P. , Presberg Harry J. , Cundiff Maria , Schlossberg Steven M.
Published: March 2007

Our previous work has shown that the CO2 laser can be successfully used in urethral reconstruction in a rat model. This new experiment investigates the use of the CO2 laser to perform a patch graft urethroplasty in the rabbit, as a preclinical model to its use in the repair of hypospadias in humans. Using sterile technique, a patch graft of preputial skin was welded in the repair of a standardized urethral defect in 10 rabbits. In another cohort, the same urethral defect was repaired using standard microsuture technique. In a control group the patch graft was placed with microsuture in a nonwatertight fashion. All animals were followed for 3 weeks. Histologic and radiologic analyses were done in a blinded fashion. Our study showed that CO2 laser repair, when compared to microsuture in urethral reconstruction, required 40% less operative time and produced better graft healing and less intraluminal scarring. © 1992 Wiley‐Liss, Inc.
Quantification of phthalocyanine concentration in rat tissue using laser–induced fluorescence spectroscopy
Authors: Panjehpour Masoud , Sneed Rick E. , Frazier Donita L. , Barnhill Mary Ann , O'Brien Sherrie F. , Harb William , Overholt Bergein F.
Published: March 2007

Quantification of photosensitizer concentration in tissue should improve planning and outcome of photodynamic therapy. laser–induced fluorescence (LIF) can be used to measure in vivo fluorescence of photosensitizers in tissue. This study was designed to determine if in vivo fluorescence intensity of chloroaluminum phthalocyanine tetrasulfonate correlates with its concentration in different rat tissues. Following LIF measurements, the animals were humanely euthanized and the concentration of phthalocyanine in different tissues was determined using chemical extraction technique. The correlation of phthalocyanine fluorescence intensity and its concentration was determined for each tissue using Pearson product‐moment correlation analysis. A strong correlation between in vivo phthalocyanine fluorescence intensity and its concentration was found for spleen, kidney, liver, and chemically induced mammary adenocarcinoma. Low correlation was found for thigh skin and planum of nose. No correlation was found for thigh muscle and tongue. © 1993 Wiley‐Liss, Inc.
Comparison of magnetic resonance images and the histopathological findings of lesions induced by interstitial laser photocoagulation in the brain
Authors: Tracz Robert A. , Wyman Douglas R. , Little Peter B. , Towner Rheal A. , Stewart Wendy A. , Schatz Stanley W. , Wilson Brian C. , Pennock Paul W. , Janzen Edward G.
Published: March 2007

Interest has developed in using magnetic resonance (MR) imaging to monitor the volume of tissue destroyed by interstitial laser photocoagulation (ILP). In these experiments, ILP was induced in the normal brains of 9 anesthetized cats by delivering 1.5 W of continuous‐wave Nd:YAG laser energy (1,064 nm) from a single 400‐μm core optical fiber for 1,000 s. The irradiations were monitored using proton spin‐echo MR imaging during and immediately after ILP and at postirradiation survival times of 2, 5, and 14 days. At 2 days postirradiation, the necrotic thermal lesion consisted of a central cavity surrounded by 2 concentric zones of coagulative necrosis, one dense and the other dispersed. The lesion shrank and the zonal appearance became less obvious over the 14 day survival period. An enhancing halo on contrast‐enhanced T1‐weighted images acquired immediately postirradiation best approximated the total lesion diameter at 2 days. These images also indicated that the volume of tissue destroyed during ILP corresponded better to the necrotic volume determined at 2 days than at 5 days and 14 days postirradiation. T2‐weighted images acquired during and immediately after ILP consistently underestimated the total lesion diameter at 2 days. © 1993 Wiley‐Liss, Inc.
Rationale for automatic scanners in laser treatment of port wine stains
Authors: Mordon Serge , Rotteleur Guy , Brunetaud Jean Marc , Apfelberg David B.
Published: March 2007

Laser therapy of port wine stains (PWS) is well established. However, the application of lasers to PWS treatment over the last decade has resulted in the use of many laser systems. The goal of this study is to describe the different laser parameters, treatment techniques, and delivery systems. Two methods, coagulation and microvaporization, are used to destroy the abnormal blood vessels. The coagulation method results in excellent treatment, but it requires careful control of laser parameters during the treatment process. Scanning devices can be utilized for this purpose. The microvaporization method, obtained with a pulsed dye laser, is restricted to PWS composed of small vessels since it is difficult to obtain a pulse longer than 450 microseconds. In addition, numerous retreatments are needed with the pulsed dye method. The initial assessment of the patient should contribute to an improvement in the choice of laser parameters and the outcome of treatment. © 1993 Wiley‐Liss, Inc.
Assessing Photofrin® uptake in atherosclerosis with a fluorescent probe: Comparison with photography and tissue measurements
Authors: Hsiang York , Stonefield Michael , Bower Robert D. , Fragoso Miguel , Tsang Vincent , Crespo M. Teresa , Lundkvist Anna
Published: March 2007

The purpose of this study was to assess Photofrin® porfimer sodium (P*) concentration in atherosclerotic plaque (ASP) using a fluorescence detector (Fluoroprobe) compared with fluorescent photography and chemical extraction of P*. ASP was created in the aortoiliac segments of Yucatan miniswine by a combination of balloon endothelial injury and 2% cholesterol and 15% lard diet for 7 weeks. At that time, swine were given P* I.V. in one of the following single dosages: Group I, 2.5; Group II, 1.0; or Group III, 0.5 mg/kg. Swine were sacrificed 24 hours later and aortoiliac and control carotid artery segments removed. Fluorescence was determined from these segments using photographic techniques, the Fluoroprobe, and a spectrofluorometer after chemical extraction. ASP were identified in all swine using photography and the Fluoroprobe. The intensity of fluorescence measured with the Fluoroprobe for Groups I to III was 1,098 ± 524, 471 ± 337, and 295 ± 173 units, respectively (P < 0.01). The tissue concentration of P* in ASP from each group was 130.4 ± 82.7, 10.0 ± 1.2, and 9.1 ± 0.6 ng/g, respectively (P < 0.01). There was a linear correlation between the fluorescence intensity measured with the Fluoroprobe and the extracted tissue concentration (r = 0.88, P < 0.0001). This study showed that a fluorescent detector such as the Fluoroprobe accurately detects the uptake of P* into atherosclerotic plaque. © 1993 Wiley‐Liss, Inc.
Evaluation of changes in oxygen tension as indicators of RIF‐1 tumor response to Nd:YAG laser heating
Authors: Fahy Alice K. , Waldow Stephen M.
Published: March 2007

Heat‐induced oxygen tension changes in RIF‐1 tumors in C3H male mice were analyzed in an attempt to correlate these changes with tumor response to Nd:YAG laser heating. A low power, microprocessor‐controlled Nd:YAG laser was used to superficially heat 250–300 mm3 tumors to base temperatures of 44, 45, 46, or 48°C for 30 minutes via a flexible 600 μm quartz fiberoptic with a terminating microlens. A glass, Clark‐style microelectrode was inserted into the center of each tumor allowing real time measurement of the tumor's oxygenation status before, during, and after heating. Results showed that heating at 44°C caused a greater than 2‐fold increase in oxygen tension during heating, while a temperature of 48°C caused a brief initial increase in oxygen tension followed by a decrease to below pretreatment values. There was a significant correlation (P<0.05) between relative tumor oxygen tension during and post‐heating and tumor growth delay. A significant correlation (P<0.05) was also seen between tumor base temperature during heating and tumor growth delay. It appears from our initial data that single point oxygen tension measurements in small RIF‐1 tumors may be useful indicators of this model's response to Nd:YAG laser heating. This result may allow for modification of heating parameters (temperature/time) during treatment to optimize thermal response. © 1993 Wiley‐Liss, Inc.
Fluorospectral study of the rat brain and glioma in vivo
Authors: Tsai Jui‐Chang , Kao Ming‐Chien , Hsiao Yi‐Yun
Published: March 2007

An animal model of cerebral glioma was utilized by implanting C6 glioma cells into the brains of adult Wistar rats. Once tumors developed to 7–12 mm in diameter, we conducted continuous fluorimetry monitoring of glioma up to 24 hours using a fibre‐optic system connected to an intensified multichannel photodetector after an intravenous injection of hematoporphyrin derivative (HPD) into the rats. The intensity of the fluorescence in normal brain reached a plateau 6 hours after intravenous injection of HPD while that in glioma reached a plateau 80 minutes after injection. These fluorescence intensities of glioma, brain adjacent to tumor (BAT), and surrounding normal brain were measured in vivo 24 hours after intravenous administration of 5 mg/kg of HPD. The ratio of fluorescence intensities between glioma and brain was 6.1 while the ratio between BAT and brain was 3.9. There were no obvious differences in shapes between the spectra of the natural fluorescence (autofluorescence) of rat glioma and brain but the intensity of autofluorescence was much weaker in glioma. There are many problems in spectroscopic studies of biological tissues in vivo. It cannot be overemphasized that very strict criteria must be applied in order to get accurate data. Fluorescence from HPD administration may be used to discriminate tumor tissue from surrounding normal brain tissue during operation if the measuring conditions could be kept constant. It is important to understand the photospectral properties of glioma and brain tissue in order to get the most benefits in clinical application of light‐induced fluorescence or photoradiation therapy. © 1993 Wiley‐Liss, Inc.
Water‐jet‐cooled Nd:YAG laser coagulation of experimental liver metastases: Correlation between ultrasonography and histology
Authors: van Hillegersberg Richard , de Witte Marcel T. , Kort Will J. , Terpstra Onno T.
Published: March 2007

To establish the value of ultrasonography in imaging laser coagulation of tumor and surrounding tissue, the relation between measurements on ultrasound and histology was determined in a rat tumor model. A piece of colon carcinoma CC531 was implanted in the liver of 21 Wag/Rij rats; 20 days later, tumors (mean diameter 5.3 mm) were treated with a water‐jet‐cooled Nd:YAG laser at 10 W and either 150 J, 300 J, 600 J, 1,200 J, 1,700 J, or 2,400 J. Ultrasonography was done just pre‐ and immediately post‐laser treatment. The animals were sacrificed and livers removed for light microscopical evaluation. Depth and width of coagulation were measured directly on ultrasound, and on histological samples by computer‐assisted image analysis. Laser treatment did not change the echogenic aspect of the tumor on ultrasound. However, liver damage appeared hypoechoic compared to normal liver. A significant correlation was found between the total size of the lesion on ultrasound and histology (P = 0.015, r = 0.57 for depth; P = 0.012, r = 0.58 for width), suggesting that laser induced tumor destruction may be derived from the amount of surrounding hepatic damage on ultrasound. © 1993 Wiley‐Liss, Inc.
Comparison of the flashlamp pulsed dye laser with the argon tunable dye laser with robotized handpiece for facial telangiectasia
Authors: Ross Maria , Watcher Melissa A. , Goodman Matthew M.
Published: March 2007

This prospective study compares the efficacy, side effects, and patient acceptance of the flashlamp pulsed dye laser (FPDL) with the argon tunable dye laser with robotized handpiece (ATDL/H) for facial telangiectasias. Seventeen adult patients with bilaterally symmetric facial telangiectasias were enrolled. The right cheek on each patient was treated in one session with the FPDL at a fluence of 6.0–6.75 J/cm2 and a spot size of 5 mm. The left cheek was treated at the same session with the ATDL/H at a power of 1 W, a fluence of 26–27 J/cm2, and a hexagonal treatment area of 13 mm (127 individual 1 mm spots grouped mechanically by the handpiece). Patients were evaluated subjectively and by the investigators at 2, 4, and 6 weeks for blistering, swelling, bruising, changes in pigment, scarring, overall efficacy, and patient preference. Average treatment times were 5.4 minutes for FPDL and 9.4 minutes for ATDL/H. Blistering, crusting, and discomfort were completely resolved on both sides by week 2 in all patients. Bruising occurred in all patients with FPDL but had resolved in 62.5% of patients at 2 weeks and 100% at 4 weeks. There was no bruising with ATDL/H. Postinflammatory hyper‐pigmentation was much more prominent with FPDL but had resolved in 88% of cases by week 6. As rated by the investigators 100% of the FPDL treated areas showed excellent clearing of telangiectasias, compared with 47% of ATDL/H treated areas. Despite better efficacy of the FPDL in clearing facial telangiectasias in one treatment, of the 15 patients with a preference 47% preferred the ATDL/H due to the marked bruising experienced with the FPDL. In conclusion, although the FPDL showed greater objective efficacy, the acceptable efficacy combined with the lack of bruising led almost half of the patients to prefer treatment with the ATDL/H. © 1993 Wiley‐Liss, Inc.
β‐Carotene enhances plaque detection by fluorescence attenuation in an atherosclerotic rabbit model
Authors: Ye Biqing , Abela George S.
Published: March 2007

Improved detection of plaque during cardiovascular procedures could enhance the outcome of diagnosis and therapy. We evaluated a new method to stain plaque using a special intravenous preparation of β‐carotene (β‐C) in an in vivo model. β‐C was used to enhance the absorption coefficient of plaque and decrease the laser–induced fluorescence emission. Using this approach the difference in fluorescence emission was accentuated between normal artery and atherosclerotic plaque. Twenty‐nine NZW rabbits were divided into five groups, each receiving a different intervention. This included the administration of β‐C to rabbits on a normal or a high cholesterol diet, with or without endothelial debridement. Aortae were examined grossly, by histology, and relative total fluorescence was detected at 886 sites using 488 nm or 514 nm laser excitation. At 488 nm excitation, unstained plaque attenuated total fluorescence twice as much as normal controls (7.55± 1.46 vs. 15.06 ± 3.12; P<0.0001); β‐C stained plaque attenuated total fluorescence 17 times more than normal controls (0.89 ± 0.29 vs. 15.06 ± 3.12; P<0.0001). Total fluorescence from unstained plaque was eight times greater than plaque stained with β‐C (7.55 ± 1.46 vs. 0.89 ± 0.29; P<0.0001). Results obtained using 514 nm excitation were similar. The attenuation effect persisted up to 8 weeks following β‐C administration. Thus, β‐C stained plaque displayed fluorescence attenuation, which suggests that pretreatment with β‐C may greatly enhance plaque detection. This may be useful as a guide during‐plaque removal procedures. © 1993 Wiley‐Liss, Inc.
Acute response of the arterial wall to pulsed laser irradiation
Authors: Nakamura Fumitaka , Kvasnicka Jan , Levame Micheline , Lange Françoise , Bousbaa Hassan , Geschwind Herbert J.
Published: March 2007

This study was designed to examine the acute response of normal arterial wall to pulsed laser irradiation. Irradiation with an Excimer or a Holmium YAG laser was performed in 15 normal iliac sites of 8 male New Zealand white rabbits. The excimer laser was operated at 308 nm, 25 Hz, 50 mj/mm2/pulse, and 135 nsec/pulse and the Ho:YAG laser was operated at 2.1 μm, 3.5 Hz, 400 mj/ pulse, 250 μsec/pulse. The excimer and Ho:YAG laser were coupled into a multifiber wire‐guided catheter of 1.4 and 1.5 mm diameter, respectively. The mean luminal diameter increased similarly from 2.01 ± 0.29 to 2.46 ± 0.27 mm (P < 0.0005) and from 2.09 ± 0.53 to 2.45 ± 0.30 mm (P < 0.005) after excimer and Ho:YAG laser irradiation, respectively. Perforation occurred in 3 of 15 Ho:YAG irradiated sites and 0 of 15 excimer laser irradiated sites. The sites irradiated with excimer or Ho:YAG laser had similar histologic features, consisting of shedding of the endothelium, disorganization of internal elastic lamina, localized necrosis of vascular smooth muscle cells, and fissures in the medial layer. However, the sites irradiated with excimer laser had lower grading scores than those irradiated with the Ho:YAG laser (P<0.05). Irradiation with excimer or Ho:YAG laser of normal arteries results in: (1) vasodilation of the irradiated artery; (2) localized mechanical vascular injury, and (3) Ho:YAG laser induces more severe damage to the arterial wall than excimer. © 1993 Wiley‐Liss, Inc.
Tumor specific response to photodynamic therapy
Authors: Stern Scott J. , Craig Jock , Flock Stephen , Montague Donna , Waner Milton , Jacques Steven
Published: March 2007

The exact mechanism by which photodynamic therapy (PDT) causes tumor destruction has not been elucidated. Early reports indicated that PDT causes direct cellular effects probably mediated by unstable oxygen species, resulting in cellular oxidation and death. More recently, PDT effects on tumor blood flow have been implicated, and there are questions as to whether the PDT response is specific to tumor tissue.

Rats were implanted with a window chamber containing either a mammary adenocarcinoma or a piece of inert surgical sponge. After growth of the tumor was ascertained, all rats were given 5 mg/kg Photofrin intraperitoneally, and then were irradiated with 630 nm light 24 hours post‐injection. Caliper thickness and reflectance measurements were performed before and after irradiation; all animals were sacrificed 72 hours post‐PDT and the chambers submitted for histologic analysis.

Animals implanted with tumors demonstrated marked edema of the chamber with an associated decrease in reflectance. No edema response was noted in the chambers containing inert sponge, or in any controls. Nonselective PDT effects (characterized by a marked foreign body response) in chambers containing sponge was not seen. Histologic analysis of treated specimens corroborate the above data. © 1993 Wiley‐Liss, Inc.
Effects of pulse width on erbium: YAG laser photothermal trabecular ablation (LTA)
Authors: Hill Richard A. , Stern David , Lesiecki Michael L. , Hsia James , Berns Michael W.
Published: March 2007

An erbium (Er):YAG laser can remove trabecular meshwork (TM) by photothermal ablation with minimal contiguous thermal damage. A variable pulse width Er:YAG laser was used to investigate the effect of varying pulse width on ablation of human TM. Trabecular photothermal ablation was performed on tissue obtained from eye bank eyes at pulse widths of 50, 150, and 250μs, with energy held constant at 4 mJ. At this energy, a single laser pulse was sufficient for full‐thickness ablation of TM. Laser energy was delivered through a 200‐μm diameter optical fiber held in apposition to the tissue sample, which was immersed in physiologic saline. High‐speed photography of the resultant steam bubbles also was performed. Light microscopy and scanning electron microscopy of TM ablated at 50 μs revealed the greatest variability in size (0–140 μm) of the full‐thickness ablated areas and demonstrated blast effects, tissue shredding and ⩽10 μm thermal damage. At 150 μs, the full‐thickness ablated areas were more consistent in size (115–120 μm), showed no blast effects and 10 to 20 μm thermal damage. At 250 μs, the largest ablations were found (180–220 μm) and showed no blast damage; however, a significant amount of thermal damage (⩽50 μm) was evident. The steam bubbles produced by the laser energy were largest at 50 μs and did not begin to collapse until well over twice the original pulse interval. At 150 and 250 μs, the steam bubbles were successively smaller and dissipated at the end of the laser pulse. In single pulse Er:YAG photothermal laser trabecular ablation, a pulse width (total energy of 4 mJ) around 150 μs appears to be optimal. The resultant acoustic shock wave from steam bubble formation is smaller, its duration does not exceed the laser pulse width and tissue thermal damage is minimal. © 1993 Wiley‐Liss, Inc.
Slit lamp laser doppler interferometer
Authors: Fercher Adolf F. , Li Hai C. , Hitzenberger Christoph K.
Published: March 2007

A slit lamp laser interferometer is described for clinical in vivo eye length measurements. The basic components are a laser Doppler interferometer, a slit lamp attachment, and a commercial slit lamp. First measurements of the axial length of the eye yielded a standard deviation of 0.04 mm and less. © 1993 Wiley‐Liss, Inc.
Low‐level CO2 laser–induced release of 51chromium from canine 2C5 gliosarcoma cells
Authors: Van Kooten David W. , Maciunas Robert J. , Carver Robert S.
Published: March 2007

Recently, interest has grown in the area of low‐power laser effects upon tissues. We used a 51Cr cell labeling technique with glioma tissue to better understand these effects. Canine 2C5 gliosarcoma cells with intracellular 51Cr were exposed to CO2 laser in the range of 0.2 to 3.0 J/cm2. Correlative analysis of the data indicated that there is a strong direct relationship between laser fluence and the percent of total intracellular 51Cr released from the glioma cells with a coefficient of correlation (r) of +0.93. The calculated standard error of the correlation coefficient was ± 0.06 and the coefficient of determination (r2) was 0.86. These results indicate that the 51Cr cell labeling technique is a useful method for quantifying the low‐power laser effects on the integrity of the cell membrane of gliosarcoma cells in vitro. However, further investigation is needed to clarify the specific mechanisms by which the CO2 laser induces changes upon these cells. © 1993 Wiley‐Liss, Inc. © 1993 Wiley‐Liss, Inc.
Clinical exacerbation of systemic lupus erythematosus after photodynamic therapy of laryngotracheal papillomatosis
Authors: Abramson Allan L. , Alvi Aijaz , Mullooly Virginia M.
Published: March 2007

Photodynamic therapy was used to treat a patient with recurrent laryngotracheal papillomatosis who had a history of systemic lupus erythematosus (SLE). At the time of photoactivation, the patient's SLE was in remission for 2 years. Postoperatively, the patient was not compliant in avoiding sunlight exposure and developed photosensitive skin reactions of his face and hands. In addition, he had clinical activation of his SLE following that exposure. © 1993 Wiley‐Liss, Inc.
Fundus laser coagulation using a video system of scanning laser ophthalmoscope
Authors: Peyman Gholam A. , Khoobehi Bahram , Shamsnia Saeed , Navarro Greta C.
Published: March 2007

We modified a scanning laser ophthalmoscope for simultaneous photocoagulation of the retina and video recording. Using a diode laser (810 nm wavelength), we produced fundus lesions that scarred within 14 days. © 1993 Wiley‐Liss, Inc.
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

The 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

Intestinal 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

This 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

A 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

Laser–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

The 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

Tissue 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

Experimentally, 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

The 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

The 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

We 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

Effects 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

Ophthalmic 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

We 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

To 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

Lasers 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.