Spectro-Temporal Autofluorescence Contrast–Based Imaging for Brain Tumor Margin Detection and Biobanking
Yu Chen, Babak Kateb in Neurophotonics and Brain Mapping, 2017
Ultraviolet (UV) radiation is part of the electromagnetic spectrum, between the visible and x-ray regions, that spans from extreme UV at 10 nm (nanometers, 10−9 m) to visible violet at 400 nm. Most of the UV spectra, extreme to middle UV (10–300 nm), is absorbed by the atmosphere and does not propagate to long distances. UV radiation is used in many applications in black-light activated technologies and serves different purposes at various wavelength bands; near UV 300–400 nm is used in security measures and counterfeit detection, middle UV 200–300 nm used in disinfection devices, and far UV 100–200 nm that is absorbed by oxygen and does not propagate well in air. The middle UV has more potential in damaging tissue and can cause severe damage to DNA (Sinha and Hader 2002). Devices that use this wavelength band exhibit harmful radiation levels and use it to denature proteins to effectively kill bacteria. Excimer lasers often operate in the far UV and are used in the semiconductor industry for photolithography and in medicine for eye surgeries (LASIK), ablating material without heating the tissue.
Basic science, investigations and lasers
Mostafa Khalil, Omar Kouli in The Duke Elder Exam of Ophthalmology, 2019
These work by breaking chemical bonds that hold tissue together using ultraviolet light, in a process called photoablation. An excimer laser is a laser that causes photoablation and has important uses in refractive surgery: Photorefractive keratectomy (PRK): Corneal epithelium is first removed, then laser ablation is used to reshape the cornea.Laser-assisted in situ keratomileusis (LASIK): A corneal flap is created; the stroma is then ablated (to reshape the cornea) and the flap is replaced.Laser epithelial keratomileusis (LASEK): The corneal epithelium is peeled using 20% ethanol, laser ablation is performed and the epithelium is replaced.
The Art and Practice of UVB Phototherapy and Laser
John Y. M. Koo, Ethan C. Levin, Argentina Leon, Jashin J. Wu, Alice B. Gottlieb in Moderate to Severe Psoriasis, 2014
One of the newest advances in phototherapy is targeted UVB excimer laser therapy. The excimer laser device is a major technical achievement and is manufactured by multiple companies. The authors are most familiar with the manufacturer PhotoMedex and use the PhotoMedex XTRAC® Ultra and newer XTRAC® Velocity laser machines. Targeted UVB laser therapy is one of the newest and most efficacious treatments for psoriasis. This laser is based on a xenon-chloride lasing medium, which produces UV light at a wavelength of 308 nm. At high fluences, 308 nm light can be used to ablate tissue, such as cornea or atherosclerotic plaque, or other materials [87,88]. At the relatively low fluences used to treat psoriatic plaques, the laser does not destroy tissue but rather acts as a form of localized UVB phototherapy. The excimer laser is 308 nm (0.1 angstroms wide), and this narrowband is near the optimal peak of the psoriasis action spectrum. Excimer laser phototherapy is narrower than NB-UVB, which ranges from 308 to 313 nm in wavelength. Perhaps due to the coherence of laser light, this may provide some benefit over traditional forms of UV phototherapy [89].
Meta-analysis of 308-nm excimer laser therapy for alopecia areata
Published in Journal of Dermatological Treatment, 2021
In addition to lasers, the 308-nm excimer lamp was also investigated for AA treatment. The excimer lamp is similar to the excimer laser device differing in that the lamp emits incoherent light and may require a longer duration but like the laser maintains the ability to target specific lesions. In practice, the 308-nm excimer lamp and laser have demonstrated similar efficacy in treating other autoimmune diseases such as vitiligo (18) and psoriasis (19). Therefore, four uncontrolled trials/case studies tested 308-nm light for efficacy (20–23). All studies recommended the use of 308-nm light therapy for AA, including recalcitrant AA and AU. In a trial of 11 patients with resistant AU, four were considered to have a good response (20). Regrowth did not correlate with disease duration or history of atopic dermatitis. In a second trial, three out of eight patients observed regrowth, including one case of AU and two AA (21). In a third trial, 14 out of 16 patients had regrowth with 10 being more than 50% (23). In a case series of three patients with AA resistant to conventional treatment, all resulted in clinical improvement (22). Adverse events included erythema, hyperpigmentation and mild itching.
Evaluation of the Difference between Predicted and Measured Central Corneal Thickness Reduction after SMILE and Femtosecond Laser-assisted LASIK for Myopia
Published in Current Eye Research, 2021
Currently, there are many types of excimer lasers in clinical practice. Clinicians performing excimer laser surgery on different lasers should understand the relationship between expected and measured ablation depth for different machines to increase the refractive predictability of the laser. In our study, the Aspheric Smart Ablation profile of MEL 80 platform tends to systematically overestimate the measured CCT reduction, which can be subtracted when calculating the residual stromal thickness. For SMILE surgery, the presence of the cap may lead to different biomechanical distributions, which may affect the achieved lenticule thickness and thus affect refractive correction. Further studies with larger population are still needed to confirm the difference between the estimated and measured CCT reduction of SMILE with different cap thickness.
The 308-nm excimer laser stimulates melanogenesis via the wnt/β-Catenin signaling pathway in B16 cells
Published in Journal of Dermatological Treatment, 2019
Lili Li, Yanping Liang, Donghong Zhang, Chen Wang, Nannan Pan, Jiqiong Hong, Hewei Xiao, Zhi Xie
Several signaling pathways have been proposed to be involved in the specific mechanism that controls melanin biosynthesis via the tyrosinase family (16). Nevertheless, the mechanism of the 308-nm excimer laser has not yet been elucidated. Therefore, we further explored the signaling pathway that mediates the effects of the 308-nm excimer laser in the treatment of vitiligo. MITF, a master regulator of melanogenesis that is involved in these pathways, upregulates the melanogenesis enzymes TYR, tyrosinase-related protein 1 (TRP-1) and TRP-2, which catalyze the conversion of tyrosine into melanin pigments (12,17,18), via binding to the M-box motif in their promoter regions. Our studies demonstrated that 308-nm excimer laser irradiation induced a significant increase in the expression of MITF and TYR, thereby promoting melanin synthesis.
Related Knowledge Centers
- Dimerization
- Halide
- Molecular Orbital
- Molecule
- Monomer
- Pyrene
- Molecularity
- Xenon Monochloride
- Excimer Lamp
- Biophysics