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At least 613 records · Page 34Linked to original sources
PubMed1988

Partial nephrectomy using the Nd:YAG laser: a comparison of the 1.06 mu and 1.32 mu lasers employing different delivery systems.

A comparative study of the 1.06 mu and the 1.32 mu Nd:YAG laser using a variety of delivery systems (focusing handpiece, freehand GI quartz fiber, or frosted laser scalpel) was undertaken to determine the usefulness of these modalities in performing partial nephrectomies in dogs. Variables evaluated included total operative time, total joules expended, estimated amount of blood loss, and extent of renal tissue damage. The contact laser scalpel provided the greatest precision and speed, but no hemostasis, and is therefore inappropriate for parenchymal renal surgery. Evaluation of the other delivery systems showed no discernible differences in the extent of renal damage that could be attributed to either wavelength or wattage used. The usual depth of acute renal damage ranged from 1.0 mm to 1.8 mm when the tissue was fixed immediately after completing the polar nephrectomy, but the damage had extended to 3.0 mm when tissue was examined after 6 weeks. No consistent differences in extent of cellular damage could be demonstrated between the renal cortex and medulla. The lens system inherent in the focusing handpiece limited the total power (60 watts) that could be employed and surgery proceeded at a slower pace and required a greater expenditure of energy. Likewise, the maximal power that could be applied using the 1.32 mu laser was 25 watts and surgery also proceeded at a slower pace.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Silicates↗
PubMed1989

Laser dentistry: a new application of excimer laser in root canal therapy.

We report the first study of the application of excimer lasers in dentistry for the treatment of dental root canals. High-energy ultraviolet (UV) radiation emitted by an XeCl excimer laser (308 nm) and delivered through suitable optical fibers can be used to remove residual organic tissue from the canals. To this aim, UV ablation thresholds of dental tissues have been measured, showing a preferential etching of infiltrated dentin in respect to healthy dentin, at laser fluences of 0.5-1.5 J/cm2. This technique has been tested on extracted tooth samples, simulating a clinical procedure. Fibers of decreasing core diameters have been used to treat different sections of the root canal down to its apical portion, resulting in an effective, easy, and fast cleaning action. Possible advantages of excimer laser clinical applications in respect to usual procedures are also discussed.

Fiber Optic Technology↗
PubMed1990

Combination treatment for massive cavernous hemangioma of the face: YAG laser photocoagulation plus direct steroid injection followed by YAG laser resection with sapphire scalpel tips, aided by superselective embolization.

A massive cavernous hemangioma of the face in an 11 month old child has been successfully resected utilizing a combination of laser and non-laser techniques. The hemangioma was initially treated twice with YAG laser photocoagulation plus direct injection of steroids. This treatment promptly stopped the rapid growth and induced blanching as well as a 25% shrinkage with each treatment. Arteriogram with superselective embolization produced a further shrinkage of the hemangioma. Finally, the contact YAG laser with sapphire scalpel tips was utilized for complete and cosmetically satisfactory hemangioma resection. The treatment of a massive cavernous hemangioma by a combination of modalities is discussed.

Combined Modality Therapy↗
PubMed1990

Histologic comparison of the pulsed dye laser and copper vapor laser effects on pig skin.

Albino pig skin was exposed to the copper vapor (CVL) and flash-lamp pulsed dye (PDL) lasers at 578 nm with a 3 mm diameter spotsize over a range of fluences until purpura and whitening were first established. The total irradiation time was the parameter that was varied in order for the CVL to reach the desired fluence. The lowest fluence producing each clinical endpoint was designated the threshold fluence: 34 J/cm2 was required to produce purpura using the CVL compared to 7.5 J/cm2 with the PDL laser. Histologically, skin exposed to purpura fluences from the CVL revealed the presence of constricted, disrupted papillary dermal blood vessels with trapped RBC's within them which were unlike those exposed to PDL where the irradiated vessels were dilated and packed with masses of intravascular agglutinated RBC's. The whitening threshold fluences for the CVL and PDL lasers were 67 J/cm2 and 29 J/cm2, respectively. Streaming of epidermal cells and dermal collagen denaturation were observed in CVL irradiated skin, compared to occasional dyskeratotic epidermal cells and focal dermal collagen denaturation following PDL exposure. The mechanisms responsible for the clinical and histologic changes produced by the two laser systems are discussed.

Animals↗
PubMed1991

Laser-assisted microvascular anastomosis using CO2 and KTP/532 lasers.

The milliwatt carbon dioxide (CO2) laser has been shown to be an effective device for performing laser-assisted microvascular anastomosis (LAMA) with consistently high patency rates, minimal tissue disruption, and rapid surgical time as well as the potential for reduced inflammation due to fewer foreign bodies (sutures) in the wound. The purpose of this investigation was to determine the feasibility of using the potassium titanyl phosphate (KTP) laser to perform LAMA and to compare it to CO2 LAMA in both arteries and veins. Patency rates, inflammatory response, and course of healing were evaluated through histological analysis. Twenty-eight rats were divided into two groups, which underwent either CO2 or KTP LAMA and then were sacrificed at 3 days, and 1, 2, 4, 8, and 12 weeks postoperatively. Patency rates for arteries and veins were comparable for both wavelengths (CO2: 100% for arteries, 93% for veins; KTP: 93% for arteries, 93% for veins). Histological grading of inflammation and fibrosis showed no significant difference between the two groups. This study demonstrated the efficacy of using the KTP/532 laser in performing LAMA. We found the KTP and CO2 LAMA to have comparable patterns of tissue damage and course of healing. Although this experiment did not investigate the mechanism(s) of tissue welding, our results suggest that successful LAMA may be independent of wavelength.

Anastomosis, Surgical↗
PubMed1992

Microbeam laser-injured neurons increase in vitro astrocytic gap junctional communication as measured by fluorescence recovery after laser photobleaching.

An important aspect of the neuronal-astrocyte relationship is the interaction of reactive astrocytes with injured and/or dying neurons. Few studies have focused on the signaling of astrocytes by injured neurons or on the possibility that neurons can alter astrocytic gap junctional communication. The purpose of this study was to determine whether the presence of injured neurons could alter astrocytic gap junctional coupling by establishing an in vitro method of microbeam laser neuronal injury and coculturing these neurons with astrocytes. Neurons from two rat neuronal clonal cell lines were injured using a 20-W argon laser operating on the ultraviolet (UV) multiline (351-361 nm) directed through a X40 objective of an inverted microscope. After laser injury, the glass slide with the injured neurons was sandwiched with a slide on which primary rat astrocytes were grown. Although the neurons and astrocytes were bathed in the same medium, they were not in direct contact during the coculture period (24, 48, or 72 hr). Astrocytic gap junctional dye coupling was examined using the fluorescence recovery after laser photobleaching (gap-FRAP) analysis technique. Astrocytes cocultured with the injured neurons for 24 to 48 hr did not show a significant difference in fluorescence recovery when compared to control values. After 72 hr of coculture, there was a significant increase in the gap junctional dye coupling. These results indicate that injured neurons influence in vitro astrocytic gap junctional conductance after 72 hr of coculture as measured by dye coupling.

Animals↗
PubMed1992

Exogenous chromophores for the argon and Nd:YAG lasers: a potential application to laser-tissue interactions.

Chromophore dyes can be employed to modify laser-tissue interaction. A number of dyes have been investigated for their effect on the absorption and transmission of argon and Nd:YAG laser energy by vascular tissue in vitro. Three histological dyes have been assessed as potential chromophores for the argon laser and four infrared dyes for the Nd:YAG. Segments of porcine coronary artery to which dye had been applied were lased (1,064 nm, 2.5 W, 83 W/cm2, 60 s and 488/514 nm, 400 mW, 10.5 W/cm2, 60s) and the tissue temperature measured remotely using an infrared thermometer. In addition, energy transmission was measured with a photodiode and tissue morphological changes assessed histologically. All three argon dyes significantly increased energy absorption (typically 60 degrees C v. 20 degrees C at 60 s, P less than 0.001, 2-way ANOVA). Three of the four infrared dyes behaved similarly (40-70 degrees C v. 20 degrees C, P less than 0.001). All dyes significantly increased the initial rate of rise in tissue temperature during lasing. A reduction in energy transmission was observed for each of the Argon dyes but not for the Nd:YAG dyes. Histological evidence of thermal damage in control tissue first occurred for the argon and Nd:YAG lasers at 800 mW and 7.5 W without chromophore and at 400 mW and 2.5 W with the chromophore, respectively. A number of effective chromophores have therefore been identified at each wavelength.

Absorption↗
PubMed1992

Percutaneous laser discectomy with the Ho:YAG laser.

A prototype Ho:YAG (2.15 microns) laser operating at 2-J/pulse, 3 Hz through a 600-microns fiber was employed to perform laser discectomies at the L3-4 disc through an 18G needle in five juvenile pigs. No temperature elevations were recorded in the posterior longitudinal ligament at the disc level and all animals recovered fully with no adverse sequelae, even immediately upon awakening from anesthesia. Pathologic examination demonstrated a wide swath of coagulation necrosis confined to the disc space. The Ho:YAG laser, owing to its close approximation to the intense 2.0 microns absorption band of water, appears to be a viable candidate for clinical trials of laser discectomy.

Adult↗
PubMed1995

Photodynamic laser cyclodestruction with chloroaluminum sulfonated phthalocyanine (CASPc) or Photofrin (PII) vs. Nd:YAG laser cyclodestruction in a pigmented rabbit model.

BACKGROUND AND OBJECTIVE: To investigate Photofrin (PII) and CASPc for photodynamic therapy (PDT) of the ciliary body in rabbits. STUDY DESIGN/MATERIALS AND METHODS: PII (10 mg/kg) or CASPc (1 mg/kg) was given by ear vein. Pharmacokinetics were studied in frozen sections by fluorescence microscopy (CCD camera based low light detection system with digital image processing) at 1 and 24 h (8 rabbits; 16 eyes). Laser light was delivered (argon pumped dye laser; 630 and 675 nm; 8 rabbits; 16 eyes) by contact fiberoptic. To compensate for iris attenuation, irradiance was 125 mW/cm2 (20, 40, 80, or 160 J/cm2). Controls (4 rabbits; 8 eyes) received laser light without photochemicals (OD) and for comparison, continuous wave Nd:YAG laser by fiberoptic (0.8-1.2J; OS). RESULTS: Localization studies showed intravascular distribution with some selective ciliary body distribution at 24 h (PII > CASPc). Rabbits treated with PII or CASPc exhibited variable amounts of gross ciliary body edema, infarction, and necrosis by 24-48 h. This response was not seen in PDT control tissues; damage was seen in the iris and ciliary body, with partial vacuolization of the pigment epithelium. CONCLUSION: PDT may offer a more selective approach to ciliary body destruction. A small but significant thermal effect was seen during PDT from melanin photon uptake with damage to iris and ciliary body. Thermal damage and potential interaction with ocular visual pigments may limit use of these photochemicals and wavelengths for PDT of the ciliary body.

Animals↗
PubMed2004

Treatment of alopecia areata with the 308-nm xenon chloride excimer laser: case report of two successful treatments with the excimer laser.

BACKGROUND AND OBJECTIVES: Alopecia areata is a common disease of unknown etiology; it causes significant cosmetic and psycho-social distress for most of the people it affects. We report on an innovative form of treatment in two patients with typical alopecia areata on the capillitium. STUDY DESIGN/PATIENTS AND METHODS: We successfully treated two patients whose alopecia areata had worsened progressively for 3 and 14 weeks. The treatment involved the use of a 308 nm xenon chloride excimer laser (dosage 300-2,300 mJ/cm(2) per session). RESULTS: After 11 and 12 sessions within a 9-week and 11-week period, the entire affected focus showed homogenous and thick regrowth. No relapse was observed during the follow-up period of 5 and 18 months. CONCLUSIONS: The use of the excimer laser is an effective, elegant, and safe means of treatment and has good tolerability. Analogous to topical treatment of alopecia areata, the immunosuppressive mechanism of the excimer laser can be interpreted as an induction of T-cell apoptosis. This new means of treatment has yet to be discussed in medical literature. Further studies with greater numbers are needed to assess its potential more precisely and evaluate the excimer laser in treating alopecia areata.

Adult↗
PubMed2004

The vascular response induced by transmyocardial laser revascularization is determined by the size of the channel scar: Results of CO2, holmium and excimer lasers.

BACKGROUND AND OBJECTIVES: To investigate the angiogenic effect of CO2, Ho:YSGG, and XeCl excimer TMLR in a rat model with morphologic characteristics of chronic myocardial ischemia. STUDY DESIGN/MATERIALS AND METHODS: Two channels (200-320 microm) were created per rat heart. After 14 days, vessel numbers and densities in and around laser scars were assessed. RESULTS: Capillary densities in the laser scars were equal between the three lasers ( approximately 130 vessels/mm2) but much lower than in control areas ( approximately 2,100 vessels/mm2). Vessel densities excluding capillaries were significantly higher in Ho:YSGG and CO2 scars compared to excimer scars, while only Ho:YSGG scars contained significantly more large vessels (diameter > or = 20 microm) than control areas. Only rarely, extension of vascular growth into adjacent myocardium was observed in any of the three groups. CONCLUSIONS: These results indicate that the angiogenic response following TMLR is limited to the channel scar and related to the scar size rather than the specific laser type.

Animals↗
PubMed2006

Laser resection technique and results of multiple lung metastasectomies using a new 1,318 nm Nd:YAG laser system.

BACKGROUND AND OBJECTIVES: Advantages of a new 1,318 nm Nd:YAG laser based on multiple lung metastasectomies are shown. STUDY DESIGN/MATERIALS AND METHODS: Ninety-three percent of 328 patients with metastases (8/patient, range 1-124) had precision laser resections (lobectomy-rate reduced to 7%); this laser delivers 20 kW/cm(2) 1,318 nm power densities with 400 microm fibers, and a focussing handpiece. Absorption in water is tenfold higher. RESULTS AND CONCLUSIONS: Between 1/1996 and 12/2003 in 328 patients (164 males/females, 61 years) 3,267 nodules were removed. Pathologic examination revealed 2,546 metastases (range 3-80 mm) from kidney (n = 112), colorectal (n = 91), and breast cancers (n = 35). In 85% of patients where the complete resection was achieved the 5-year survival was 41%. For remaining 15% (incomplete resection) the 5-year survival was 7%. Five-year survival for patients with 10 (and more) metastases was 28%, for patients with 20 (and more) was 26%. No 30-day mortality was observed. CONCLUSION: This new laser system facilitates any kind of parenchymal lung resection in lobe-sparing manner and in case of complete resection improves significantly the survival.

Adult↗
PubMed1996

Retinal damage and laser-induced breakdown produced by ultrashort-pulse lasers.

BACKGROUND: In vivo retinal injury studies using ultra-short-pulse lasers at visible wavelengths for both rabbit and primate eyes have shown that the degree of injury to the retina is not proportional to the pulse energy, especially at suprathreshold levels. In this paper we present results of calculations and measurements for laser-induced breakdown (LIB), bubble generation, and self-focusing within the eye. METHODS: We recorded on video and measured the first in vivo LIB and bubble generation thresholds within the vitreous in rabbit and primate eyes, using external optics and femtosecond pulses. These thresholds were then compared with calculations from our LIB model, and calculations were made for self-focusing effects within the vitreous for the high peak power pulses. RESULTS: Results of our nonlinear modeling and calculations for self-focusing and LIB within the eye were compared with experimental results. The LIB ED50 bubble threshold for the monkey eye was measured and found to be 0.56 microJ at 120 fs, compared with the minimum visible lesion (MVL) threshold of 0.43 microJ at 90 fs. Self-focusing effects were found to be possible for pulsewidths below 1 ps and are probably a contributing factor in femtosecond-pulse LIB in the eye. CONCLUSIONS: Based on our measurements for the MVL thresholds and LIB bubble generation thresholds in the monkey eye, we conclude that in the femtosecond pulsewidth regime for visible laser pulses, LIB and self-focusing are contributing factors in the lesion thresholds measured. Our results may also explain why it is so difficult to produce hemorrhagic lesions in either the rabbit or primate eye with visible 100-fs laser pulses even at 100 microJ of energy.

Animals↗
PubMed1995

Laser treatment in urology: our experience with neodymium:YAG and carbon dioxide lasers.

Laser surgery is currently considered as an effective alternative in the treatment of several urological diseases. We report on our three-year experience treating recurrent superficial low grade bladder carcinoma in 80 patients using Neodymium: YAG (Nd:YAG) laser. A decrease in local tumour recurrence rate (11%) was observed, but the overall not treated area recurrence was 45%. No complications were noted when the procedure was carried out on outpatient basis. Furthermore, we have been treating successfully urogenital condylomata using Nd:YAG and carbon dioxide (CO2) lasers in 364 patients. In addition we describe the use of Nd:YAG laser in the percutaneous treatment of a patient with bilateral transitional cell carcinoma of the renal pelvis.

Adult↗
PubMed2003

Analysis of serotonin release from single neuron soma using capillary electrophoresis and laser-induced fluorescence with a pulsed deep-UV NeCu laser.

The use of capillary electrophoresis (CE) with laser-induced fluorescence excited by ultraviolet (UV) lasers in the range 200-300 nm has been restricted by the available wavelengths and expense of UV lasers. The integration of a NeCu deep UV laser operating at 248.6 nm with a single channel CE system with post-column sheath flow detection allows detection limits for serotonin and tryptophan of 3.9x10(-8) M and 4.5x10(-8) M respectively. Single cell analysis of serotonergic metacerebral cells from the sea slug Aplysia californica yields a value of 800+/-85 fmol of serotonin in each cell soma. For the first time, serotonin is directly detected in electrically stimulated release from single metacerebral cell soma, with approximately 4% of the serotonin contained in the soma released from a semi-intact preparation with a 2 min electrical stimulation.

Animals↗
PubMedDate not supplied

Asian blepharoplasty with a short-pulsed contact Nd-Yag laser: limited-incision resectable laser double fold with internal medial and lateral functional epicanthoplasty.

The double-fold operation is the most common aesthetic procedure in Asia, but complications such as gross asymmetry, loss of folds, and scars on the medial canthal region and upper eyelid are relatively common. To prevent these complications, caused by displacement of fixation sutures secondary to excessive edema or hematoma, we use fine fiber-delivered contact surgical Nd-Yag (Japan SLT) laser for incision, excision, coagulation, dissection, ablation, and fusion of the soft tissue. Comparing this laser treatment to conventional electrocautery techniques or to CO2 laser blepharoplasty, this contact short-pulsed Nd-Yag laser gives us a tactile sensation, providing a more precise, controlled surgical procedure without lateral thermal damage, and it is possible to operate through a small incision. A long-term follow-up study shows that there was no gross asymmetry, loss of folds, or visible or hypertrophic scars on the upper eyelid and medial canthal regions.

Adolescent↗
PubMed2000

CT-guided percutaneous laser disc decompression with Ceralas D, a diode laser with 980-nm wavelength and 200-microm fiber optics.

The aim of this study was to evaluate the compact, portable Ceralas-D diode laser (CeramOptec; 980 + 30 nm wavelength, 200-microm optical fiber) concerning clinical usefulness, handling, and clinical results in the CT-guided treatment of herniated lumbar discs. The positioning of the canula in intradiscal space, the placement of the laser fiber into the disc through the lying canula, and the vaporization itself were carried out under CT-guidance. Due to the thin fiber optic, it was possible to use a thin 23-gauge canula. The laser procedure was performed in 0.1- to 1-s shots with 1-s pulse pause and 4-W power output. A total of 1650-2300 J was applied on each percutaneous laser disc decompression (PLDD). Results in 26 patients were established with a visual-analogue scale (VAS). On the follow-up examinations, 46% of the patients were absolutely pain free ( > 85 % VAS) and fully active in everyday life after 4 postoperative weeks. Thirty-one percent of patients were relieved of the leg pain but had occasional back pain without sensorimotor impairment. Fifteen percent sensed a slight alleviation ( > 50% VAS) of the radiate pain. Eight percent did not experience radicular or pseudo-radicular pain alleviation (< 25% VAS). Cerales-D proves to be an efficient tool for CT-guided PLDD on non-sequestered herniated lumbar discs.

Adult↗
PubMed1991

Enhancement of pulsed-dye laser ablation of arterial tissues with blood medium: effects of laser-induced shock waves.

The influence of blood medium on tissue ablation by a pulsed dye laser and its selectivity for atheroma were investigated. The role of shock waves on tissue ablation was also evaluated. Normal and atherosclerotic human aortas were irradiated by a 480 nm pulsed dye laser activated at 5 Hz. The laser was coupled with a single 0.2 mm fiber (Uni-guide) (40 mjoules/pulse) or a multifiber catheter (14 x 150 microns) (100 mjoules/pulse). Shock waves were measured using a fluid-filled catheter connected to a strain gauge manometer. With the Uni-guide, pulse-dye lasing resulted in greater ablation of atheroma in blood (11.6 x 10(-3) mm3/joule, p less than 0.001 versus atheroma measured in saline and normal tissue in blood) followed by normal tissue in blood (2.5 x 10(-3)mm3/joule), atheroma in saline (1.71 x 10(-3)mm3/joule, p less than 0.05 versus normal tissue in saline), and normal tissue in saline (0.54 x 10(-3) mm3/joule). With the multifiber catheter, laser ablation was the greatest in atheroma in blood (0.55 +/- 0.26 mm3/joule p less than 0.001 versus atheroma in saline and normal tissue in blood), followed by normal tissue in blood (0.27 +/- 0.12 mm3/joule), atheroma in saline (0.14 +/- 0.15 mm3/joule, p less than 0.001 versus normal tissue in saline), and normal tissue in saline (0 mm3/joule). The ablation efficiency of the multifiber catheter was greater than that of the Uni-guide (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Laser↗