Lead Probe Research Articles

Therapeutic Outcomes of Photobiomodulation in Cancer Treatment-induced Oral Mucositis: A Systematic Review.

This systematic review was performed to analyze the therapeutic efficacy of photobiomodulation (PBM) in managing oral mucositis (OM) that appears in this context. The search strategy of the systematic review was conducted according to PRISMA guidelines. The eligibility criteria according to PICO process has been defined as follows: Population (P): adult patients with head and neck cancer; Intervention (I): PBM; Comparison (C): placebo group; Outcome (O): pain, oral quality of life (QoL), evolution of the grade OM and pain. The set criteria for inclusion were peer-reviewed articles. The following database were searched from November 2021 to February 2022, for clinical trials: Pubmed, Scopus and Cochrane. From 296 records, 10 studies were included involving in the systematic review. Data from 759 patients who received chemoradiotherapy were analyzed. These studies used different classifications for oral mucositis (WHO, NCI, RTOF/EORTC), pain (VAS) and quality of life (EORTC QLQ-C30, UW-QOL (v4), FACT-HN). PBM therapy protocol used five different lasers (GaAlAs, InGaAlP, He-Ne, diode laser, red and near-IR LED probe) with wavelengths ranging from 632,8nm to 850nm. Pain evaluation in was based on the visual analogue scale (VAS) mainly. Prophylactic PBM was effective as it reduced the incidence of grades 3-4 and reduced the overall mean grade of OM during the chemoradiotherapy course compared to the control group. On the other hand, when PBM was used for treatment purposes, it decreased the mean duration of OM compared to the placebo arm. PBM reduced the incidence of more severe grade of OM induced by chemoradiotherapy. Also, PBM therapy reduced the mean duration of severe OM, mean pain scores and subsequently improved QoL. Key words:Oral mucositis, photobiomodulation, low-level laser therapy, chemotherapy, radiotherapy.

Feasibility of using an led-probe in third-space endoscopy: a clinical study

BackgroundThird-space endoscopy is a novel, safe, and effective method for treating different gastrointestinal conditions. However, several failed endoscopic procedures are attributed to incomplete myotomy. Lighting devices are used to prevent organic injuries. We aimed to investigate the feasibility of using a hand-made LED-probe (LP) in third-space procedures.MethodsThis prospective study was conducted in a tertiary-care center in Mexico between December 2016 and January 2019. We included peroral endoscopic myotomy (POEM) and gastric peroral endoscopic myotomy(G-POEM) procedures. Pseudoachalasia, peptic ulcer, normal gastric emptying scintigraphy (GES) and prepyloric tumors were excluded. LP was used to guide or confirm procedures. Clinical and procedural characteristics were recorded and analyzed.ResultsSeventy third-space procedures were included (42POEM,28G-POEM), with an average patient age of 46.7 ± 14.3 and 43.7 ± 10.1 years, respectively. For the POEM and G-POEM groups, respectively, 18/42(42.9%) and 13/28(46.7%) patients were males; median procedure times were 50 (interquartile range [IQR]: 38–71) and 60(IQR: 48–77) min, median LP placement times were 5(IQR: 4-6) and 6(IQR: 5-7) min, mild adverse events occurred in 4(9.4%) and 4(14.2%) of cases, and clinical success at 6 months occurred in 100 and 85.7% of cases. Integrated relaxation pressure (IRP) improved from 27.3 ± 10.8 to 9.5 ± 4.1 mmHg (p < 0.001); retention percentage at 4 h also improved. LP was successfully placed and adequate myotomy confirmed including 14.2 and 17.8% of POEM and G-POEM difficult patients.ConclusionsUsing an LP is promising and allows guiding during third-space procedures either for submucosal tunnel creation or myotomy confirmation, with excellent safety and efficacy in clinical practice.

Optogenetic activation of neocortical neurons in vivo with a sapphire-based micro-scale LED probe.

Optogenetics has proven to be a revolutionary technology in neuroscience and has advanced continuously over the past decade. However, optical stimulation technologies for in vivo need to be developed to match the advances in genetics and biochemistry that have driven this field. In particular, conventional approaches for in vivo optical illumination have a limitation on the achievable spatio-temporal resolution. Here we utilize a sapphire-based microscale gallium nitride light-emitting diode (μLED) probe to activate neocortical neurons in vivo. The probes were designed to contain independently controllable multiple μLEDs, emitting at 450 nm wavelength with an irradiance of up to 2 W/mm2. Monte-Carlo stimulations predicted that optical stimulation using a μLED can modulate neural activity within a localized region. To validate this prediction, we tested this probe in the mouse neocortex that expressed channelrhodopsin-2 (ChR2) and compared the results with optical stimulation through a fiber at the cortical surface. We confirmed that both approaches reliably induced action potentials in cortical neurons and that the μLED probe evoked strong responses in deep neurons. Due to the possibility to integrate many optical stimulation sites onto a single shank, the μLED probe is thus a promising approach to control neurons locally in vivo.

Thermal and optical characterization of micro-LED probes for in vivo optogenetic neural stimulation

Within optogenetics there is a need for compact light sources that are capable of delivering light with excellent spatial, temporal, and spectral resolution to deep brain structures. Here, we demonstrate a custom GaN-based LED probe for such applications and the electrical, optical, and thermal properties are analyzed. The output power density and emission spectrum were found to be suitable for stimulating channelrhodopsin-2, one of the most common light-sensitive proteins currently used in optogenetics. The LED device produced high light intensities, far in excess of those required to stimulate the light-sensitive proteins within the neurons. Thermal performance was also investigated, illustrating that a broad range of operating regimes in pulsed mode are accessible while keeping a minimum increase in temperature for the brain (0.5°C). This type of custom device represents a significant step forward for the optogenetics community, allowing multiple bright excitation sites along the length of a minimally invasive neural probe.

WE-E-J-6B-03: Endoscopic Laser Projection for Image-Guided Surgery

Purpose: The goal of this work is development of an endoscopic system for three-dimensional localization of tissue surfaces during image-guided surgery. The system has the potential to track tissue movement in real time and to measure the shape of organ surfaces within the endoscopes' fields of view via localization of thousands of surface points. The system is intended to provide real-time localization of surface points as a means to guide coregistration with preoperative anatomic image sets and to provide the constraints required by deformable tissue models. Method and Materials: A benchtop prototype of the system consisting of a pair of conventional endoscopes, a computer-controlled laser scanner, a high-speed CCD camera, and a commercial optical tracking system has been constructed in Creare's laboratory. Calibration of the prototype has been performed by verifying the accuracy of the optical tracking system used to measure the position of the endoscopes, measuring the repeatability of the laser scanner when projecting the laser through an endoscope, characterization of the distortion present in the endoscope optics, and the measurement of the maximum usable field-of-view. The accuracy of the system has been determined based on the difference between three-dimensional coordinates measured by our system with those measured by the commercial optical tracking system. Results: The repeatability of the system to consistently localize a fixed point was determined by measuring the location of 25 points while maintaining fixed positions of the endoscopes and laser mirrors. The mean three-dimensional repeatability of the localizations was 0.08 mm with a standard deviation of 0.05 mm. The accuracy of the system was ascertained relative to measurements made with the optical tracking system and a standard six LED probe, known to have an accuracy on the order of 0.1 mm. Using a planar test phantom with machined semicircular holes, the projecting endoscope laser was steered to the center of each hole, and the position of the illuminated spot determined using the system. The position of each hole was also measured with the six LED probe, and the resulting three-dimensional error found to be 1.9 mm with a standard deviation of 0.3 mm. The system can localize approximately 400 points per second. Conclusion: The use of a scanning laser endoscope has the potential to provide cost-effective, real-time localization of any point within the surgical field that can be simultaneously observed by two endoscopes. The initial results of our work show that points can be localized accurately and rapidly. Educational Objectives: 1. Calibration techniques for endoscopic laser projection. 2. Discussion of endoscopic localization as a means of assisting image- guided surgery.

Operating characteristics of the vaginal photoplethysmograph: some implications for its use.

Two operating characteristics of the vaginal photoplethysmograph were examined in an attempt to explain some of the methodological variance in the data produced by this device. Both the original Sintchak and Geer (1975) vaginal probe and a modified LED probe were examined for response consistency and temperature sensitivity. The results reveal that, for both types of probes, there is a considerable drift over time when the device is operated on DC in a temperature and light-controlled environment. This drift was not consistent across devices or trials, thus eliminating the possibility of experimentally or statistically controlling for it. In addition, both types of device were found to be extremely temperature sensitive when operated on DC in a light-controlled environment. Implications for continued use of the vaginal photoplethysmograph in research and clinical settings are discussed and recommendations are made regarding alternative genital measures of sexual arousal in women.