Wound healing process in beagles after vaporization of the prostate with a novel 200W 450-nm laser.

In comparison to other commercially used lasers, the coagulation layer of the novel 450-nm laser is thinner, and this coagulation layer's thickness is a key factor influencing wound healing. In this study, we investigated whether the novel 200W 450-nm laser system (BR6800, Blueray Medical Ltd., Shaanxi, China) is superior to classic transurethral resection of the prostate (TURP) for wound healing in beagles. Twenty-two 6-to 8-year-old male beagles were treated with TURP or blue laser vaporization of the prostate (BLVP). Prostate wounds were observed via cystoscopy at 3 h and at 1, 2, 3, and 5 weeks post-operation (two beagles per group). Additionally, two elderly beagles without surgery served as normal controls. After cystoscopy examination, prostate samples were collected and fixed for hematoxylin and eosin (H&E) and immunofluorescence staining to observe wound healing progression under microscopy. The urethras of prostates under cystoscopy in BLVP groups were healed three weeks after surgery, while in the TURP group, they were healed five weeks after surgery. H&E staining confirmed that the coagulation necrosis layer in the TURP group was thicker than that in the BLVP group and it took longer to remove coagulation necrosis after surgery. Macrophage polarity transformation was also earlier in the BLVP group. The new 200W 450-nm laser was superior to TURP for wound healing. The thinner coagulation layer of the 450-nm laser was the primary reason for this process.

450-nm blue diode laser: a novel medical apparatus for upper tract urothelial lesions.

OBJECTIVE: To explore the feasibility, safety and effectiveness of the 450-nm blue diode laser (BL), novel blue laser in the treatment of upper tract urothelial carcinomas (UTUCs) and other lesions in a porcine model. MATERIAL AND METHODS: For in vitro experiment, the ureter tissue was vaporised and coagulated with BL, green-light laser (GL) and Ho:YAG laser (Ho). The efficiency, width and depth of vaporisation, and depth of coagulation were recorded and compared. For in vivo experiments, four swines weighing 70 kg were used. In the acute group, different modes of operations were performed to evaluate the thermal damage, perforation and bleeding. In the chronic group, the overall appearance of the ureter and laser wound healing were observed by the naked eyes and H&E staining 3 weeks after surgery. RESULTS: In in vitro study, the BL showed a higher efficiency of tissue vaporisation and less tissue coagulation for fresh ureter compared to GL and Ho. In the in vivo study, the power of BL set at 7 W was better, and the thickness of thermal damage varied with different surgery types in the range of 74-306 µm. After 3 weeks, the wound healed well static in vaporisation (SV), moving vaporisation (MV) and H&E staining indicated mucosal healing rather than scar healing. CONCLUSION: 5-10W blue diode laser achieved a higher efficiency of tissue vaporisation and less tissue coagulation in a porcine model, indicating its potential application in the endoscopic surgery of UTUC as an optional device with high performance and safety.

Generation of 13.9-mJ Terahertz Radiation from Lithium Niobate Materials.

Extremely strong-field terahertz (THz) radiation in free space has compelling applications in nonequilibrium condensed matter state regulation, all-optical THz electron acceleration and manipulation, THz biological effects, etc. However, these practical applications are constrained by the absence of high-intensity, high-efficiency, high-beam-quality, and stable solid-state THz light sources. Here, the generation of single-cycle 13.9-mJ extreme THz pulses from cryogenically cooled lithium niobate crystals and a 1.2% energy conversion efficiency from 800 nm to THz are demonstrated experimentally using the tilted pulse-front technique driven by a home-built 30-fs, 1.2-Joule Ti:sapphire laser amplifier. The focused peak electric field strength is estimated to be 7.5 MV cm-1 . A record of 1.1-mJ THz single-pulse energy at a 450 mJ pump at room temperature is produced and observed that the self-phase modulation of the optical pump can induce THz saturation behavior from the crystals in the substantially nonlinear pump regime. This study lays the foundation for the generation of sub-Joule THz radiation from lithium niobate crystals and will inspire more innovations in extreme THz science and applications.

High-power 450 nm blue diode laser for endoscopic mucosal resection/endoscopic submucosal dissection in the stomach: Preliminary results on a porcine model with a modified flexible endoscope.

BACKGROUND: Due to the precise vaporization of the novel 450 nm blue diode laser in soft tissues (i.e., bladder and colon) in our previous studies, porcine stomach tissues were applied here to certify its efficacy in endoscopic mucosal resection (ESR)/endoscopic submucosal dissection (ESD) for hypothetical lesions ex vivo and in vivo. MATERIALS AND METHODS: In an ex vivo study of ESR, 20 pieces of tissues (8 cm × 6 cm) from 7 fresh stomachs after spraying saline were vaporized with a three-dimensional scanning system using the blue diode laser at a maximum of 30 W, a different treatment speed and working distance (WD). In ex vivo ESD, 18 pieces of tissues from 6 fresh stomachs were used and the same laser parameters were used to perform the procedure. The depth, width, and coagulation of the laser vaporization were measured. Furthermore, the large scales (2.0 cm × 1.5 cm) for 18 hypothetical lesions of the gastric mucosa and submucosa of the 6 fresh stomachs were also resected with a modified flexible endoscope. In vivo, six hypothetical lesions of six porcine were vaporized by the novel blue laser, and the resultant lesions at the acute and chronic stages were assessed by the naked eye and hematoxylin and eosin staining. RESULTS: In the contact mode, more tissue was vaporized, and the thickness of the coagulation was stable when the WD was 0-2 mm, whose value varied from 0.33 to 1.73 mm. In the gastroscopy model, the mean thickness of coagulation from the mucosa was 0.67 mm, and a significant carbonization zone was not observed. In vivo, the laser beam could accurately act on the hypothetical target. No bleeding and clear vision were present in the procedure. After 3 weeks, tissue healing was well recovered after laser coagulation, resection, and submucosal dissection. CONCLUSIONS: In the present study, the novel 450 nm blue diode laser exhibited ideal vaporization and thinner coagulation thickness in the porcine stomach, which indicated that it could be alternately used as a new device for stomach lesions.