CO2 lasers in the management of potentially malignant and malignant oral disorders

The CO2 laser was invented in 1963 by Kumar Patel. Since the early 1970s, CO2 laser has proved to be an effective method of treatment for patients with several types of oral lesions, including early squamous cell carcinoma. Laser surgery of oral premalignant disorders is an effective tool in a complete management strategy which includes careful clinical follow-up, patient education to eliminate risk factors, reporting and biopsying of suspicious lesions and any other significant lesions. However, in a number of patients, recurrence and progression to malignancy remains a risk. CO2 laser resection has become the preferred treatment for small oral and oropharyngeal carcinomas. Laser resection does not require reconstructive surgery. There is minimal scarring and thus, optimum functional results can be expected. New and improved applications of laser surgery in the treatment of oral and maxillofacial/head and neck disorders are being explored. As more surgeons become experienced in the use of lasers and as our knowledge of the capabilities and advantages of this tool expands, lasers may play a significant role in the management of different pathologies

Structural validation of oral mucosal tissue using optical coherence tomography

Background: Optical coherence tomography (OCT) is a non-invasive optical technology using near-infrared light to produce cross-sectional tissue images with lateral resolution. Objectives: The overall aims of this study was to generate a bank of normative and pathological OCT data of the oral tissues to allow identification of cellular structures of normal and pathological processes with the aim to create a diagnostic algorithm which can be used in the early detection of oral disorders. Material and methods: Seventy-three patients with 78 suspicious oral lesions were referred for further management to the UCLH Head and Neck Centre, London. The entire cohort had their lesions surgically biopsied (incisional or excisional). The immediate ex vivo phase involved scanning the specimens using optical coherence tomography. The specimens were then processed by a histopathologist. Five tissue structures were evaluated as part of this study, including: keratin cell layer, epithelial layer, basement membrane, lamina propria and other microanatomical structures. Two independent assessors (clinician and pathologist trained to use OCT) assessed the OCT images and were asked to comment on the cellular structures and changes involving the five tissue structures in non-blind fashion. Results: Correct identification of the keratin cell layer and its structural changes was achieved in 87% of the cohort; for the epithelial layer it reached 93.5%, and 94% for the basement membrane. Microanatomical structures identification was 64% for blood vessels, 58% for salivary gland ducts and 89% for rete pegs. The agreement was “good” between the clinician and the pathologist. OCT was able to differential normal from pathological tissue and pathological tissue of different entities in this immediate ex vivo study. Unfortunately, OCT provided inadequate cellular and subcellular information to enable the grading of oral premalignant disorders. Conclusion: This study enabled the creation of OCT bank of normal and pathological oral tissues. The pathological changes identified using OCT enabled differentiation between normal and pathological tissues, and identification of different tissue pathologies. Further studies are required to assess the accuracy of OCT in identification of various pathological processes involving the oral tissues

Spin-Dependent Quantum Emission in Hexagonal Boron Nitride at Room Temperature

Optically addressable spins associated with defects in wide-bandgap semiconductors are versatile platforms for quantum information processing and nanoscale sensing, where spin-dependent inter-system crossing (ISC) transitions facilitate optical spin initialization and readout. Recently, the van der Waals material hexagonal boron nitride (h-BN) has emerged as a robust host for quantum emitters (QEs), but spin-related effects have yet to be observed. Here, we report room-temperature observations of strongly anisotropic photoluminescence (PL) patterns as a function of applied magnetic field for select QEs in h-BN. Field-dependent variations in the steady-state PL and photon emission statistics are consistent with an electronic model featuring a spin-dependent ISC between triplet and singlet manifolds, indicating that optically-addressable spin defects are present in h-BN $-$ a versatile two-dimensional material promising efficient photon extraction, atom-scale engineering, and the realization of spin-based quantum technologies using van der Waals heterostructures.Comment: 38 pages, 34 figure

Engineering model 8-cm thruster subsystem

An Engineering Model (EM) 8 cm Ion Thruster Propulsion Subsystem was developed for operation at a thrust level 5 mN (1.1 mlb) at a specific impulse 1 sub sp = 2667 sec with a total system input power P sub in = 165 W. The system dry mass is 15 kg with a mercury-propellant-reservoir capacity of 8.75 kg permitting uninterrupted operation for about 12,500 hr. The subsystem can be started from a dormant condition in a time less than or equal to 15 min. The thruster has a design lifetime of 20,000 hr with 10,000 startup cycles. A gimbal unit is included to provide a thrust vector deflection capability of + or - 10 degrees in any direction from the zero position. The EM subsystem development program included thruster optimization, power-supply circuit optimization and flight packaging, subsystem integration, and subsystem acceptance testing including a cyclic test of the total propulsion package

Non-metastatic cutaneous squamous cell carcinoma treated with photodynamic therapy using intravenous mTHPC

INTRODUCTION Photodynamic therapy (PDT) is a method of treating various pathologies. In this retrospective study with prospective intent, a total of 22 patients with T1/T2 N0 cutaneous squamous cell carcinoma (SCC) were treated with intravenous mTHPC (meta-tetrahydroxyphenylchlorin) and surface illumination PDT. Comparisons with the clinical features, rate of recurrence and overall outcome were made. MATERIALS AND METHODS Surface illumination PDT was offered under local anaesthesia. 0.05 mg/kg mTHPC was administered intravenously into the midcubital vein 48 h prior to tissue illumination. A single-channel 652 nm diode laser was used for illumination and light was delivered at 20 J/cm2 per site. Lesion response evaluation was carried out according to Response Evaluation Criteria In Solid Tumors (RECIST). RESULTS Clinical assessment revealed that 16 patients had lesions of <2 cm in size (T1), while the rest were T2. No nodal involvement was identified in any of the patients. None of the patients had a locally recurrent lesion. During the 3-year follow-up, 20/22 patients had complete response (CR) and this was after one round of treatment. Two patients suffered from recurrent disease within 3 years of the follow-up, and they underwent surgical resection. CONCLUSION PDT achieved high efficacy in the treatment of T1N0 cutaneous squamous cell carcinoma with greatly reduced morbidity and disfigurement. The technique is simple, can commonly be carried out in outpatient clinics, and is highly acceptable to patients

Apparent Complete Response of a Treatment Refractory and Recurrent Squamous Cell Carcinoma Lesion to Photochemical Internalization: A Clinical Case Study

Photochemical internalisation (PCI) depends on the delivery of sub‐lethal photodynamic reaction to facilitate the work of a chemotherapeutic agent. We discuss our experience in managing a patient with extensive squamous cell carcinoma of the right face and scalp under the TPCS2a‐based bleomycin PCI treatment protocol. In this case, an 84‐year‐old Caucasian received 0.25mg/kg of TPCS2a (Amphinex®). Surface illumination photochemical internalisation was carried out after 4 days, which was preceded by the chemotherapeutic agent infusion (Bleomycin). After one week from the illumination time, tissue necrosis was evident and tumour shrinkage was most noticeable at day 14 post‐illumination. Follow‐up at 6 weeks continued to show tissue healing and regeneration with no clinical evidence of recurrence. Multiple surgical biopsies were taken at 1 and 3 months post‐illumination and found to be tumour free. PCI’s depth of effect has been very significant with negligible damage to the collateral tissues. This technology has a role in interventional oncology especially when managing challenging cases

Epithelial tissue thickness improves optical coherence tomography's ability in detecting oral cancer

BACKGROUND OCT is a non-invasive imaging technique that enables the measurement of epithelial thickness and architectural changes, which can help in the diagnosis of pre-cancerous and cancerous lesions. The purpose of the study was to assess whether epithelial tissue thickness improves optical coherence tomography’s ability in detecting oral cancer. PATIENTS AND METHODS Surgically resected oral margins from 60 patients diagnosed with oral squamous cell carcinoma were subjected to OCT. Three OCT measurements (immediate, 1 h and 24 h post-resection) were conducted per resected tissue specimen to look at the effect of saline and formalin on the specimen and its effect on the reproducibility of the OCT. OCT was, then, used to measure the epithelial tissue thickness in cancer-free and cancer-involved margins in eight oral anatomical locations. This data was, then, combined with architectural changes data to calculate the sensitivity and specificity. RESULTS An overall of 189 cancer-free margins and 51 cancer-involved margins had their epithelial thickness measured using OCT and compared to histopathology. With regards to the validity of the OCT and histopathological measurements, epithelial thickness showed good correlation between different readings at all oral sites. With regards to the reproducibility of the OCT measurements, the mean epithelial thickness for all measurements at first (immediate) and second (1 h post-resection – saline preserved) measurements was not significantly different. Underestimation of the epithelial depth in cancer-free margins was 20 μm, while in the cancer-involved margins was 10 μm. Combining data from architectural changes and epithelial thickness, a sensitivity of 92% and a specificity of 94% was achieved. CONCLUSION Oral epithelium measurements using OCT were valid compared to those made with gold standard pathology. Measurements made using OCT was also reproducible with minor underestimation. Epithelial thickness, combined with architectural changes, led to high accuracy in differentiating between cancer-free and cancer-involved margins

On the Gold Standard for Security of Universal Steganography

While symmetric-key steganography is quite well understood both in the information-theoretic and in the computational setting, many fundamental questions about its public-key counterpart resist persistent attempts to solve them. The computational model for public-key steganography was proposed by von Ahn and Hopper in EUROCRYPT 2004. At TCC 2005, Backes and Cachin gave the first universal public-key stegosystem - i.e. one that works on all channels - achieving security against replayable chosen-covertext attacks (SS-RCCA) and asked whether security against non-replayable chosen-covertext attacks (SS-CCA) is achievable. Later, Hopper (ICALP 2005) provided such a stegosystem for every efficiently sampleable channel, but did not achieve universality. He posed the question whether universality and SS-CCA-security can be achieved simultaneously. No progress on this question has been achieved since more than a decade. In our work we solve Hopper's problem in a somehow complete manner: As our main positive result we design an SS-CCA-secure stegosystem that works for every memoryless channel. On the other hand, we prove that this result is the best possible in the context of universal steganography. We provide a family of 0-memoryless channels - where the already sent documents have only marginal influence on the current distribution - and prove that no SS-CCA-secure steganography for this family exists in the standard non-look-ahead model.Comment: EUROCRYPT 2018, llncs styl

Photodynamic therapy in the management of potentially malignant and malignant oral disorders

Photodynamic therapy (PDT) is a minimally-invasive surgical tool successfully targeting premalignant and malignant disorders in the head and neck, gastrointestinal tract, lungs and skin with greatly reduced morbidity and disfigurement. The technique is simple, can commonly be carried out in outpatient clinics, and is highly acceptable to patients. The role of photodynamic therapy in the management of oral potentially malignant disorders and early oral cancer is being discussed