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目的:探讨Q开关Nd:YAG激光多次低能量祛除文身的临床疗效观察。方法:临床选取21例文身患者,治疗采用自身对比:A区为试验区,使用Q开关1064nm波长激光,光斑直径4~6mm,能量密度为2.0~4.0J/cm2,平行均匀照射1遍,术后即刻反应皮损变白霜,无皮肤出血点,每天治疗1次,连续治疗3~4次;B区为对照区,使用Q开关1064nm波长激光,光斑直径3~4mm,能量密度为5.0~8.0J/cm2,均匀照射1遍,即刻反应皮损灰白或皮肤出血。两组病例均于术后6个月观察疗效。结果:术后6个月观察,试验区:治愈9例(42.8%),显效12例(57.2%),无瘢痕形成;对照区:治愈3例(14%),显效5例(24%),好转13例(62%),2例(9.5%)出现轻度增生性瘢痕。结论:采用Q开关Nd:YAG激光多次低能量治疗文身的方法可加快文身消退病程,减少文身治疗中能量密度过大形成瘢痕或色素脱失的风险,为文身治疗提供一种新的治疗方法。  相似文献   

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The effects of laser energy on articular cartilage were studied utilizing the neodymium YAG laser. Partial-thickness cartilage defects were surgically attempted in the femoral condyles of knee joints in guinea pigs. The defects were exposed to laser energy of varying intensities [group I, 25 J (5 W X 5 sec); group II, 75 J (15 W X 5 sec); group III, 125 J (25 W X 5 sec)]. A fourth group was studied, in which the defect was not lased. Animals were killed at weekly intervals from 1 to 6 weeks and the knee joints were subjected to histological analysis. At 5 weeks, the knees exposed to 25 and 75 J demonstrated a reparative process with chondral proliferation. The knees exposed to 125 J demonstrated fibrotic tissue and tissue necrosis that resulted in fibrosis. In the knees not exposed to laser energy, numerous foci of granulation tissue were present at all stages with the end point of healing being one of fibrosis with disorganized patchy cartilage islands.  相似文献   

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BACKGROUND AND OBJECTIVE: In skin grafting, evaluation of graft adhesion to the recipient site in the early postgrafting period is important. However, conventional diagnoses such as visual observation and thermography required about 1 week to obtain results and these methods cannot give quantitative information on the adhesion of a skin graft. We proposed a new method for monitoring adhesion of grafted skin that is based on measurement of photoacoustic signals. To investigate the validity of the method, we performed experiments using rat autografts models. STUDY DESIGN/MATERIALS AND METHODS: Grafted skin in a rat was irradiated with 200 microJ, 532-nm nanosecond laser pulses, and photoacoustic signals were detected with a piezoelectric transducer placed on the skin at various postgrafting time. Temporal profiles of the signals were converted to depth profiles using an assumed sound velocity of 1,500 m/second. Histological analysis was performed to observe neovascularities formed in the grafts. RESULTS: At 6 hours postgrafting, a photoacoustic signal peak appeared in the depth region corresponding to the graft. The results of histological analysis also showed formation of neovascularities in the graft after 6 hours postgrafting, indicating that photoacoustic signal peaks observed in the graft originated from the neovascularities, which are an indication of graft adhesion. For up to 24 hours postgrafting, no significant difference was observed between the results of visual observation and laser Doppler imaging of the same grafted skins. CONCLUSION: We have demonstrated that photoacoustic signals originating from neovascularities in grafts can be sensitively detected in the early postgrafting period, suggesting the validity of photoacoustic measurement for adhesion monitoring of skin grafts.  相似文献   

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BACKGROUND AND OBJECTIVES: Much interest has been shown in the use of lasers for nonviral targeted gene transfer, since the spatial characteristics of laser light are quite well defined. The aim of this study was to demonstrate in vivo gene transfer by the use of laser-induced stress waves (LISWs). STUDY DESIGN/MATERIALS AND METHODS: After reporter genes had been intradermally injected to rat skin in vivo, a laser target was placed on the gene-injected skin. LISWs were generated by the irradiation of an elastic laser target with 532-nm nanosecond laser pulses of a Q-switched Nd:YAG laser. RESULTS: Levels of luciferase activities for the skin exposed to LISWs were two orders of magnitude higher than those for the skin injected with naked DNA. Expressions of enhanced green fluorescent protein (EGFP) and beta-galactosidase were observed only in the area that was exposed to LISWs, and in addition, epidermal cells were selectively transfected. No major side effects were observed, and luciferase activity levels as high as 10(5) RLU per mg of protein were sustained even 5 days after gene transfer. CONCLUSION: Highly efficient and site-specific gene transfer can be achieved by applying a few pulses of nanosecond pulsed LISWs to rat skin in vivo.  相似文献   

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BACKGROUND AND OBJECTIVE: Conventional methods of residual composite removal after the debonding of orthodontic brackets involve the use of abrasives that damage the underlying enamel. The objective of this study was to demonstrate that 355-nm laser pulses with a pulse width of 10 ns are well suited for the removal of composite through selective laser ablation. STUDY DESIGN/MATERIALS AND METHODS: The residual composite remaining on the surface of extracted human third molars and bovine incisors was removed using multiple laser pulses from the third harmonic (355-nm) of a Q-switched Nd:YAG laser. RESULTS: There is selective ablation of composite from the enamel surface without any discernable damage to the underlying enamel. CONCLUSION: This study demonstrates that 355-nm, 10 ns laser pulses can be used for the selective ablation of dental composite without thermal or mechanical damage to the underlying enamel.  相似文献   

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BACKGROUND AND OBJECTIVE: A large number of clinical trials of transmyocardial laser revascularization (TMLR) have been conducted to treat severe ischemic heart diseases. A variety of laser sources have been used or tested for this treatment, however, no comprehensive study has been performed to reveal the mechanism and the optimum laser irradiation condition for the myocardium tissue ablation. There have been reported limited experimental data of the high-intensity pulsed laser ablation of myocardium tissues. STUDY DESIGN/MATERIALS AND METHODS: A 1064-nm Q-switched Nd:YAG laser and its 2nd (532 nm), 3rd (355 nm), and 4th (266 nm) harmonics were used for ablation experiments. At each wavelength, 25 laser pulses irradiated the porcine myocardium tissue samples at a constant laser intensity (peak laser power divided by laser spot area) of approximately 2 GW/cm(2) and the ablation depths were measured. During ablation, laser-induced optical and acoustic emissions were measured to investigate the ablation mechanism at each laser wavelength. For the ablated tissues, histological observation was made with a polarization optical microscope. RESULTS: It was shown that the ablation efficiency did not directly depend on the linear absorption coefficient of the tissue; the ablation depth was maximized at 355 and 1064 nm, and minimized at 532 nm. Strong laser-induced optical and acoustic emissions were observed for the 266- and 1064-nm laser irradiations. The histology showed that thermal denaturation of the tissue near the ablation walls decreased with decreasing wavelength for 266, 355, and 532 nm, but it was limited for 1064 nm. CONCLUSION: At the laser intensity of approximately 2 GW/cm(2), ablation characteristics were drastically changed for the different laser wavelengths. The results indicated that for 266, 355, and 532 nm, the tissue removal was achieved mainly through a photothermal process, but for 266 nm the intense laser-induced plasma formation would result in a reduced laser energy coupling to the tissue. For 1064 nm, a photodisruption was most probable as a dominant tissue removal process. Because of the high ablation rate and limited thermal denaturation, the 355- and 1064-nm lasers could be potential laser sources for TMLR, although further investigation is needed to discuss the clinical issues.  相似文献   

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BACKGROUND AND OBJECTIVES: We investigated the mechanism and characteristics of porcine myocardium tissue ablation in vitro with nanosecond 1,064- and 532-nm pulsed lasers at laser intensities up to approximately 5.0 GW/cm(2). Particular attention was paid to study the influence of the laser-induced plasma on the ablation characteristics. The applicability of these two lasers to transmyocardial laser revascularization (TMLR) was discussed. STUDY DESIGN/MATERIALS AND METHODS: Porcine myocardium tissue samples were irradiated with 1,064- and 532-nm, Q-switched Nd:YAG laser pulses, and the ablation depths were measured. The temporal profiles of the laser-induced optical emissions were measured with a biplanar phototube. For the ablated tissue samples, histological analysis was performed with an optical microscope and a polarization microscope. RESULTS: The ablation efficiency at 1,064 nm was higher than that at 532 nm. The ablation threshold at 1,064 nm (approximately 0.8 GW/cm(2)) was lower than that at 532 nm (approximately 1.6 GW/cm(2)), in spite of the lower absorption coefficient being expected at 1,064 nm. For the 1,064-nm laser-ablated tissues, thermal damage was very limited, while damage presumably caused by the mechanical effect was observed in most of the cases. For the 1,064-nm laser ablation, the ablation threshold was equal to the threshold of the laser-induced optical emission (approximately 0.8 GW/cm(2)), while for the 532-nm laser ablation, the optical emission threshold ( approximately 2.4 GW/cm(2)) was higher than the ablation threshold. CONCLUSIONS: We considered that for the 1,064-nm laser ablation, the tissue removal was achieved through a photodisruption process at laser intensities of > approximately 0.8 GW/cm(2). At laser intensities of > 3.0 GW/cm(2), however, the ablation efficiency decreased; this can be attributed to the absorption of incoming laser pulses by the plasma. For the 532-nm laser ablation, the tissue removal was achieved through a photothermal process at laser intensities of > approximately 1.6 GW/cm(2). At laser intensities of > 2.4 GW/cm(2), a photodisruption process may also contribute to the tissue removal, in addition to a photothermal process. With regard to the ablation rates, the 1,064-nm laser was more suitable for TMLR than the 532-nm laser. We concluded that the 1,064-nm Q-switched Nd:YAG laser would be a potential candidate for a laser source for TMLR because of possible fiber-based beam delivery, its compact structure, cost effectiveness, and easy maintenance. Animal trials, however, have to be carried out to evaluate the influence of the tissue damage.  相似文献   

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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.  相似文献   

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Objectives

Quality‐switched (QS) lasers are known to be an effective treatment for removing solar lentigines, however, high incidence of post‐inflammatory hyperpigmentation (PIH) is a concern in darker skin types. The objective of this study was to evaluate the efficacy and safety of a dual‐wavelength and dual‐pulse width picosecond Nd:YAG laser for removing solar lentigines in Asians.

Methods

This was a prospective, IRB‐approved study. Twenty cases with solar lentigines on the face were enrolled for treatment and evaluated at 1‐ and 3‐month after the final treatment. Results were assessed by blinded evaluators using a 5‐grade percentage improvement scale and Melanin index (MI) measured by a reflectance spectrophotometer. A patient self‐assessment questionnaire was also administered using a 5‐grade improvement scale. Additional treatment was performed if the improvement was less than 75% or the lentigo partially remained after 4 weeks. Histological evaluation was performed to compare the differences between the current picosecond laser and a QS Nd:YAG laser 532‐nm using light and electron microscopy.

Results

Forty‐three lesions in 20 females, skin type III or IV, age 53.7 ± 9.75 were treated and evaluated. The laser setting was: 532‐nm, 750 picoseconds, average fluence of 0.35 ± 0.06 J/cm [2] using a spot size of 3 or 4 mm. Forty lesions (93.02%) achieved over 75% clearance with a single treatment and the other three lesions (6.98%) needed two treatments. PIH occurred only in 4.65% of lesions. The average score of the blinded evaluators’ assessment was 4.77 and 4.58 on a 5‐grade percentage improvement scale. The patients’ self‐assessment rating was 4.76 and 4.67 on a 5‐grade scale at 1‐ and 3‐month follow‐up, respectively. The improvement rate of relative MI (MI in the lesion minus that of the normal area) was 77.60 ± 36.27% and 76.93 ± 20.95% at 1‐and 3‐month follow‐up. Histology showed vacuolar formation by both lasers in the epidermis that were different sizes between lasers. Electron microscopy showed destruction of melanosomes with surrounding tissue damage with the QS laser and without particular damage with the picosecond laser.

Conclusions

To the best of our knowledge, this is the first study using a picosecond Nd:YAG laser 532‐nm for removing solar lentigines in darker skin types that includes histological evaluation. Although there are many options to treat solar lentigines, our results suggest that picosecond laser with preferable endpoint determination can be a safer and more effective treatment over conventional treatments in Asian patients. Lasers Surg. Med. 50:851–858, 2018. © 2018 Wiley Periodicals, Inc.  相似文献   

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BACKGROUND AND OBJECTIVE: Short-pulse solid-state lasers have recently received much attention as new coherent light sources for medical applications, but steady transmission of their high-energy output pulses through a solid quartz fiber is difficult because of the onset of laser-induced breakdown. We previously demonstrated that hollow waveguides could be used to deliver nanosecond laser pulses for tissue ablation. The aim of this study was to determine the optimum laser pulse energy and range of defocused distance for obtaining a deep and sharp ablation channel in myocardial tissue with laser pulses transmitted through a hollow waveguide. STUDY DESIGN/MATERIALS AND METHODS: Cyclic-olefin-polymer-coated silver hollow waveguides of 1 mm in inner diameter and 1 m in length were used. A vacuum-cored scheme was applied to the waveguides to suppress laser-induced air breakdown. Porcine myocardial tissue was irradiated with 300 laser pulses that were delivered through the waveguide in vitro at various laser energy levels and defocused distances, and depths and diameters of channels were measured. Histological analysis of the ablated tissues was also performed. RESULTS: At an ablation energy of approximately 60 mJ/pulse, deep (>4.5 mm) and sharp (depth-to-diameter ratio of > 6) channels were created in tissue in the range of defocused distances of -4 approximately + 0.5 mm. Under these conditions, waveguide bending did not cause a remarkable change in ablation characteristics. Histological analysis of ablated tissue showed limited thermal damage but suggested a certain extent of mechanical effects in the tissue. CONCLUSION: With near-infrared, nanosecond laser pulses delivered through a cyclic-olefin-polymer-coated silver hollow waveguide, efficient and sharp ablation of myocardial tissue can be achieved, suggesting the usefulness of the hollow waveguide as a new flexible delivery system for high-intensity laser pulses.  相似文献   

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Background and Objective: The purpose of this study was to determine the geometrical development of a coagulated zone in the canine prostate during free beam side fire Nd: YAG laser coagulation. Study Design/Materials and Methods: A series of 10 male dogs underwent endoscopic prostatic Nd: YAG fixed position laser coagulation through a suprapubic cystotomy using a right-angle deflecting delivery catheter (Microvasive, Boston, MA) at times varying from 10 to 120 seconds at 30 watts. In addition, two dogs underwent lasing by pulling the catheter at 1 mm/s in four quadrants. Acute gross and microscopic pathology specimens were prepared and the lesion shape and volume determined. Results: Analysis of the coagulated volume showed that during the initial 15 seconds of lasing, the zone of coagulation approximates a sphere centered on the urothelium opposite the laser fiber. However, as lasing progressed, the lesion changed from a sphere to an expanding ellipse. This changing geometry can be explained by the absorption and scatter characteristics of the laser and the temperature equilibrium that is established within the prostate. Conclusion: An understanding of this time-dependent geometrical shift from a sphere to an ellipse allows the surgeon to supplement the fixed protocols for lasing at certain positions for given amounts of time. Specific plans can then be established for tissue at the bladder neck, apex, anterior stroma, floor, and irregular prostatic regrowth. © 1995 Wiley-Liss, Inc.  相似文献   

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BACKGROUND AND OBJECTIVE: Cartilage has a limited regenerative capacity, and there are a lack of reliable techniques and methods to stimulate growth of new tissue to treat degenerative diseases and trauma. This study focused on identifying chondrocyte cell proliferation in ex vivo cartilage tissue following heating Nd:YAG laser using whole-mount analysis and flow cytometry, and compared findings with results produced by contact, and water bath heating methods, mechanical injury, and the addition of transforming growth factor-beta (TGF-beta). STUDY DESIGN/MATERIALS AND METHODS: Ex vivo rabbit nasal septal cartilages were either irradiated with an Nd:YAG laser (lambda = 1.32 microm, 2-16 seconds, 6 W/cm(2)), heated by immersion in a warm saline bath, heated by direct contact with a metal rod, or mechanically damaged by scoring with a scalpel or crushing. After treatment, specimens were incubated for 7 or 14 days in growth media containing 10 microM bromodeoxyuridine (BrdU). Additional specimens were cultured with both BrdU and TGF-beta. Both whole-mount BrdU-double-antibody detection techniques and flow cytometry were used to determine the presence of DNA replication as a marker of proliferation. RESULT: An annular region of regenerating chondrocytes was identified surrounding the laser irradiation zone in whole-mount tissue specimens, and the diameter of this region increased with irradiation time. Using whole-mount analysis, no evidence of chondrocyte DNA replication was observed in tissues heated using non-laser methods, grown in TGF-beta, or mechanically traumatized. In contrast, flow cytometry identified the presence of BrdU-positive cells in the S-phase of the cell cycle (synthesis of DNA) for all protocols, indicating chondrocyte proliferation. The percentage of cells that are in S-phase increased with irradiation time. CONCLUSION: These data provide evidence that laser irradiation, along with other thermal and mechanical treatments, causes a proliferative response in chondrocytes, and this is observed ex vivo in the absence of cellular and humoral repair mechanisms. The advantage of using optical methods to generate heat in cartilage is that microspot injuries could be created in tissue and scanned across surfaces in clinical applications.  相似文献   

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