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Nm Laser (nm + laser)
Terms modified by Nm Laser Selected AbstractsTreatment of Pigmented Hypertrophic Scars with the 585 nm Pulsed Dye Laser and the 532 nm Frequency-Doubled Nd:YAG Laser in the Q-Switched and Variable Pulse Modes: A Comparative StudyDERMATOLOGIC SURGERY, Issue 8 2002Leyda Elizabeth Bowes MD background. Pigmented hypertrophic scars are a difficult condition to treat. They may result from traumatic injuries or from surgical and cosmetic procedures. The 585 nm flashlamp-pumped pulsed dye laser (FLPDL) has been used to treat this condition, with significant improvement of varying degrees. It remains to be determined whether other laser modalities may have a similar or even greater success in the treatment of pigmented hypertrophic scars. objective. To determine the efficacy of the 532 nm frequency-doubled Nd:YAG laser in the treatment of pigmented hypertrophic scars as compared to the 585 nm FLPDL. methods. Six patients with pigmented hypertrophic scars and skin phototypes II,IV were chosen. A scar was selected for treatment in each patient and divided into four equal 2 cm segments. Three segments were each treated with a different laser modality and one was left untreated to serve as the control. A 585 nm FLPDL was used with an energy of 3.5 J, a pulse duration of 450 ,sec, and a 10 mm spot size. A 532 nm Q-switched frequency-doubled Nd:YAG laser was set to an energy of 2.8 J, a 10-nsec pulse, and a 3 mm spot size. The same 532 nm laser was set to the variable pulse mode to treat a 2 cm scar segment, with an energy of 9.5 J, a 10-msec pulse, and a 4 mm spot size. An average of 3.3 treatments were performed on each scar segment, at intervals of 4,6 weeks and long-term follow-up at 22 weeks. Treatment outcome was graded by a blind observer using the Vancouver General Hospital (VGH) Burn Scar Assessment Scale. A SigmaStat t -test was used to determine the statistical significance of the values obtained. results. Treatment of pigmented hypertrophic scars with the 532 nm Q-switched Nd:YAG laser led to a significant improvement of 38% in the VGH scores when compared to baseline (P = .005). The 585 nm FLPDL also had a favorable effect on the scars, with an average improvement of 36.1% in the VGH scores. There was no significant difference noted between the outcome of treatment with either of these two lasers. Treatment with the 532 nm variable pulse Nd:YAG laser led to a 19% improvement in the VGH scores of scars, which did not differ significantly from the 16.1% improvement observed in control scars on the last follow-up visit. No side effects or complications from treatment were noted or reported during the course of the study. At the conclusion of the study, five of six patients chose the segment treated with the 532 nm Q-switched Nd:YAG laser as the best segment overall. conclusion. The 532 nm Q-switched Nd:YAG laser and the 585 nm FLPDL offer comparable favorable results in the treatment of pigmented hypertrophic scars. The 532 nm Q-switched Nd:YAG laser may be preferred by patients particularly distressed by the dark color of their scars. [source] Dual-Mode Luminescent Colloidal Spheres from Monodisperse Rare-Earth Fluoride NanocrystalsADVANCED MATERIALS, Issue 19 2009Peng Li Monodisperse rare-earth fluoride nanocrystals are synthesized and used as building blocks to fabricate dual-mode luminescent colloidal spheres, which are composed of two distinct units, one offering down-converting luminescence under UV excitation and the other providing up-converting luminescent emission when excited with a 980,nm laser, and have potential applications in multiplexed and highly sensitive bioassays. [source] Broadband Near-IR Emission in Tm/Er-Codoped GeS2,In2S3 -Based Chalcohalide GlassesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2009Yinsheng Xu The near IR emission spectra of Tm/Er-codoped GeS2,In2S3 -based chalcohalide glasses are studied with an 808 nm laser as excitation source. A broad emission with a full-width at half-maximum of ,170 nm is recorded in a 0.5Tm2S3,0.1Er2S3 -codoped 70GeS2,20In2S3,10CsBr (in mol%) glass. The luminescence mechanisms are discussed with different CsI concentration, different halogen atoms, and different In content. These results suggest that both halogen (X) atoms and [InSxX4,x] structural units can enhance the emission intensity located at 1460 nm. [source] Hypertrophic scarring of the neck following ablative fractional carbon dioxide laser resurfacingLASERS IN SURGERY AND MEDICINE, Issue 3 2009Mathew M. Avram MD Abstract Background Ablative fractional carbon dioxide (CO2) laser treatments have gained popularity due to their efficacy, shortened downtime, and decreased potential for scarring in comparison to traditional ablative CO2 resurfacing. To date, scarring with fractional CO2 lasers has not been reported. Objective Five patients treated with the same fractional CO2 laser technology for photodamage of the neck were referred to our practices 1,3 months after treatment. Each patient developed scarring. Of the five cases, two are discussed in detail. The first was treated under general anesthesia on the face and anterior neck at a pulse energy of 30 mJ (859 µm depth) with 25% coverage. Eleven days after treatment, three non-healing areas along the horizontal skin folds of the anterior neck were noted. At 2 weeks after CO2 ablative fractional resurfacing, these areas had become thickened. These raised areas were treated with a non-ablative fractionated 1,550 nm laser to modify the wound healing milieu. One week later, distinct firm pale papules in linear arrays with mild hypopigmentation had developed along involved neck skin folds. Skin biopsy was performed. For the second patient, the neck was treated at a pulse energy of 20 mJ (630 µm depth) with 30% coverage of the exposed skin, with a total treatment energy of 5.0 kJ. Minimal crusting was noted on the neck throughout the initial healing phase of 2 weeks. She then experienced tightness on her neck. Approximately 3 weeks after treatment, she developed multiple vertical and horizontal hypertrophic scars (HS). Results Histopathology for the first case confirmed the presence of a hypertrophic scar. The papules in this case completely resolved with mild residual hypopigmentation after treatment with topical corticosteroids. HS failed to resolve in the second case to date after 1 month. Conclusion As with traditional ablative CO2 laser resurfacing, HS is a potential complication of ablative fractional CO2 laser resurfacing, particularly on the neck. With early diagnosis and appropriate treatment HS of neck skin may be reversible. We urge caution when treating the neck with this device and close attention to wound care in the post-operative period. Lasers Surg. Med. 41:185,188, 2009. © 2009 Wiley-Liss, Inc. [source] Effect of fluence on efficacy using the 1440 nm laser with CAP technology for the treatment of rhytids,LASERS IN SURGERY AND MEDICINE, Issue 6 2008Jenifer R. Lloyd D.O. Abstract Background and Objective The objective of this study was to evaluate the effect of fluence on the treatment of rhytids using a 1440 nm laser with CAPSM technology and the T350 tip. Study Design/Materials and Methods Twelve subjects with rhytids were enrolled in an IRB approved study. The AffirmÔ laser with CAP technology (Cynosure, Inc., Westford, MA) 1440 nm, 10 mm T350, 2 milliseconds, 1.5 Hz was used at fluences ranging from 3.0 to 5.5 J/cm2 in a split face study. At each treatment visit, fluences on the right side of the face were held constant at 3.0 J/cm2, while the left side of the face started at 3.0 J/cm2 and increased 0.5 J/cm2 with each treatment to a maximum of 5.5 J/cm2. Five treatments were given at 2-week intervals using the SmartCoolÔ (Cynosure, Inc.). Photographic comparisons at baseline and 3 months were used to compare fluence results as well as to evaluate for efficacy in the treatment of rhytids. The following standard scale was employed: Poor (0,25%), Fair (26,50%), Good (51,75%), and Excellent (76,100%). In addition, following the study, a few subjects received a series of laser pulses at increasing fluences on their buttocks to further evaluate the effect of fluence on tissue reaction. Results Comparing the right and left photographic results, no clinically observable differences were noted. Both sides received the same grade in all cases. Five subjects (42%) were noted to have Good results, three (25%) were given a rating of Fair, and four (33%) were given a Poor result with little or no improvement observed. The follow-up buttock fluence study demonstrated an effect threshold at 3.0 J/cm2. Conclusion The 1440 nm laser with CAP technology can provide overall improvement in patients with rhytids at moderate fluences. Increasing the fluence does not appear to increase efficacy. Lesers Surg. Med. 40:387,389, 2008. © 2008 Wiley-Liss, Inc. [source] Mechanistic comparison of blood undergoing laser photocoagulation at 532 and 1,064 nmLASERS IN SURGERY AND MEDICINE, Issue 2 2005John F. Black PhD Abstract Background and Objectives We seek to compare and contrast the mechanisms of blood photocoagulation under 532 and 1,064 nm laser irradiation in vitro in order to better understand the in vivo observations. We also seek to validate a finite element model (FEM) developed to study the thermodynamics of coagulation. Study Design/Materials and Methods We study the photocoagulation of whole blood in vitro at 532 and 1,064 nm using time-domain spectroscopic and optical coherence tomography (OCT)-based imaging techniques. We model the coagulation using an FEM program that includes the latent heat of vaporization (LHV) of water, consideration of the pulse shape of the laser, and the bathochromic shift in the hemoglobin absorption spectrum. Results We find significant similarities in the spectroscopic, chemical, and structural changes occurring in hemoglobin and in the blood matrix during photocoagulation despite the very large difference in the absorption coefficients. The more uniform temperature profile developed by the deeper-penetrating 1,064 nm laser allows us to resolve the structural phase transition in the red blood cells (going from biconcave disc to spherocyte) and the chemical transition creating met-hemoglobin. We find that the RBC morphology transition happens first, and that the met-Hb transition happens at a much higher temperature (,>,90°C) than is found in slow bath heating. The FEM analysis with the LHV constraint and bathochromic shift predicts accurately the imaging results in both cases, and can be used to show that at 1,064 nm there is the potential for a runaway increase in absorption during the laser pulse. Conclusions Photothermally mediated processes dominate the in vitro coagulation dynamics in both regimes despite the difference in absorption coefficients. There is a significant risk under 1,064 nm irradiation of vascular lesions in vivo that the dynamic optical properties of blood will cause runaway absorption and heating. This may in turn explain some recent results at this wavelength where full-thickness burns resulted from laser treatment. Lasers Surg. Med. 36:155,165, 2005. © 2005 Wiley-Liss, Inc. [source] Study of Laser-Induced Photopolymerizations by Optical PyrometryMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2004Patrick Lin Abstract Summary: Studies of the 355 nm laser induced free radical and cationic photopolymerization reactions of mono- and multifunctional monomers were conducted. These investigations were carried out with the aid of a specially constructed optical pyrometry instrument that provides rapid, reproducible temperature versus time profiles for these fast photopolymerization reactions. Using this technique, the effects of various reaction parameters and monomer structures on the rate and extent of the photopolymerization reactions were examined. Optical pyrometry instrument for the monitoring of laser-induced photopolymerizations. [source] Enhancement of Laser Cancer Treatment by a Chitosan-derived Immunoadjuvant,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2005Wei R. Chen ABSTRACT A chitosan derivative, glycated chitosan (GC), has been used as an immunostimulant for cancer treatment in laser immunotherapy. The function of GC is to enhance the host immune response after direct cancer cell destruction by a selective laser photothermal interaction. To further test its effects, laser immunotherapy was extended to include several different adjuvants for immunological stimulation and to include photodynamic therapy (PDT) as a different tumor-destruction mechanism. Complete Freund (CF) adjuvant, incomplete Freund (IF) adjuvant and Corynebacterium parvum (CP) were selected for treatment of metastatic mammary tumors in rats, in combination with a selective photothermal interaction. The solution of the immunoadjuvants admixed with indocyanine green (ICG), a light-absorbing dye, was injected directly into the tumors, followed by noninvasive irradiation of an 805 nm laser. Combined with PDT, in the treatment of tumors in mice, GC was administered peritumorally immediately after laser irradiation. The survivals of treated animals were compared with untreated control animals. In the treatment of rat tumors, CF, IF and CP raised the cure rates from 0% to 18%, 7% and 9%, respectively. In comparison, GC resulted in a 29% long-term survival. In the treatment of EMT6 mammary sarcoma in mice, GC of 0.5% and 1.5% concentrations increased the cure rates of Photofrin-based PDT treatment from 38% to 63% and 75%, respectively. In the treatment of Line 1 lung adenocarcinoma in mice, a 1.67% GC solution enabled a noncurative meso -substituted tetra(meta -hydroxy-phenyl)chlorin,based PDT to cure 37% of the tumor-bearing mice. The experimental results of this study confirmed our previous studies, showing that immunoadjuvants played an active role in laser-related cancer treatment and that GC significantly enhanced the efficacy of laser cancer treatment. [source] Photoluminescence properties of erbium-doped amorphous gallium-germanium-selenium films fabricated by RF sputteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S1 2009Takahiko Imai Abstract Chalcogenide glasses have various useful features for optical devices such as a high refractive index, low-loss transmission in the mid-IR, and low phonon energies. The fabrication of thin films is important for use in waveguide applications and integrated photonics. In this work, we report the properties of vacuum deposited films of gallium-germanium-selenium glasses onto fused silica substrates by an RF magnetron sputtering technique (RF electric power of 40-250 W and growth rate of 0.01-2.1 ,m/min). The concentration of Er3+ ions is controlled by the number of sintered Er2S3 small plates on a target. Samples are shown to be in an amorphous-like state as measured by X-ray diffraction experiments. Film thicknesses are proportional to the RF sputtering power and sputtering time. The compositions of films obtained from energy dispersive X-ray (EDX) analysis. There are much dependent on the condition of the sputtering target, for example whether the target is in the bulk or powder-state. Photoluminescence (PL) spectrum, intensity, and lifetime at 1550 nm band are measured by excitation from a 973 nm laser. The PL band of the films has a similar shape to those of bulk glasses. The PL intensity increased with the RF electric power. The PL lifetime at the 1550 nm band of the film is about 1.8-2.6 ms; the latter values are similar to those of bulk samples. The results show that the RF sputtering is a potential method of fabrication for Er-doped GeGaSe thin films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] In vitro study examining the effect of sub-lethal QS 755 nm lasers on the expression of p16INK4a on melanoma cell linesLASERS IN SURGERY AND MEDICINE, Issue 2 2003Henry H.L. Chan Abstract Background and Objectives Q-switched lasers had been used in the treatment of lentigo maligna but their role remains controversial. While previous studies have addressed the change in adhesion molecule expression after sub-lethal laser damage, no study has addressed the impact of sub-lethal laser damage at a molecular level. The p16 gene has been proposed as the candidate gene for melanoma. Our objective is to examine the effect of sub-lethal laser damage on p16 expression in melanoma cell lines. Study Design/Materials and Methods Three human melanoma cell lines,HTB 66, Sk-mel-24 (HTB 71), and G361,were irradiated by a Q-switched 755 nm Alexandrite laser at fluencies that ranged from 0.85 to 2.0 J/cm2. HTB 66 was the only cell line with significant expression of p16INK4a while the other two cells lines were p16INK4a negative and served as negative control. Protein and mRNA expression for p16 were assessed by flow cytometry and RT-PCR, respectively. Results The level of p16INK4a protein in cell line HTB 66 increased significantly after laser irradiation as compared with non-irradiated cells. The level of p16INK4a protein did not change in p16INK4a-negative cell lines (Sk-mel-24 and G361). However, there was only a slight increase in the percentage of G0/G1 phase cells. Conclusions Sub-lethal laser damage could increase DNA damage leading to an increase in p16 expression, and such effect would be particularly undesirable for patients with p16 mutation. Further studies are warranted to examine the role of sub-lethal laser damage in inducing p16 mutation. Lasers Surg. Med. 32:88,93, 2003. © 2003 Wiley-Liss, Inc. [source] | |||||||||||||