Multiple Optical Elastography Techniques Reveal the Regulation of Corneal Stiffness by Collagen XII

9 pags., 5 figs., 1 tab.PURPOSE. Collagen XII plays a role in regulating the structure and mechanical properties of the cornea. In this work, several optical elastography techniques were used to investigate the effect of collagen XII deficiency on the stiffness of the murine cornea. METHODS. A three-prong optical elastography approach was used to investigate the mechanical properties of the cornea. Brillouin microscopy, air-coupled ultrasonic optical coherence elastography (OCE) and heartbeat OCE were used to assess the mechanical properties of wild type (WT) and collagen XII¿deficient (Col12a1¿/¿) murine corneas. The Brillouin frequency shift, elastic wave speed, and compressive strain were all measured as a function of intraocular pressure (IOP). RESULTS. All three optical elastography modalities measured a significantly decreased stiffness in the Col12a1¿/¿ compared to the WT (P < 0.01 for all three modalities). The optical coherence elastography techniques showed that mean stiffness increased as a function of IOP; however, Brillouin microscopy showed no discernable trend in Brillouin frequency shift as a function of IOP. CONCLUSIONS. Our approach suggests that the absence of collagen XII significantly softens the cornea. Although both optical coherence elastography techniques showed an expected increase in corneal stiffness as a function of IOP, Brillouin microscopy did not show such a relationship, suggesting that the Brillouin longitudinal modulus may not be affected by changes in IOP. Future work will focus on multimodal biomechanical models, evaluating the effects of other collagen types on corneal stiffness, and in vivo measurements.Supported by the National Institutes of Health, grant numbers R01EY022362, R01EY030063, R01EY029395, R01EY028666, and P30EY007551

ОПЫТ ЛАПАРОСКОПИЧЕСКОЙ ХИРУРГИИ ПРИ ЛЕЧЕНИИ ПОЧЕЧНО-КЛЕТОЧНОГО РАКА НА БАЗЕ РЕСПУБЛИКАНСКОГО КЛИНИЧЕСКОГО ОНКОЛОГИЧЕСКОГО ДИСПАНСЕРА

Purpose of the study. Study of the nearest results of laparoscopic operations in patients with localized renal cell carcinoma.Materials and methods. The results of treatment of 92 patients who underwent operative treatment in the period from 2015 to 2017 with the help of laparoscopic technique for kidney carcinoma were analyzed and evaluated. Of these, 57 men (62%) and 35 women (38%), the average age is 50.5 ± 2.25 years (min. 26 and not more than 75 years). Results. The duration of the operation was influenced by various factors, such as the features of the vascular anatomy of the kidneys, the presence of the adhesive process of the abdominal cavity, the state of paranephalic fat. When improving the technique of performing laparoscopic interventions, the operation time was reduced. In the period of mastering the technique of laparoscopic interventions on the kidney, the operation time averaged 210.0 ± 20.2 min (min 120 and max 300 min); subsequently it decreased on average to 130.00 ± 10.5 min (min 70 and max 190 min). After accumulation of experience, the technique of laparoscopic resection of the kidney without total ischemia with selective clamping of segmental arteries, or without compression of the renal artery was mastered.The conclusion. An analysis of the immediate results of laparoscopic interventions in patients with renal cell carcinoma showed their high efficacy and safety. The results of laparoscopic nephrectomies and kidney resections significantly improve with the improvement of technology and the accumulation of surgical experience. Введение. Цель исследования - изучение ближайших результатов лапароскопических операций у пациентов с локализованным почечно-клеточным раком.Материалы и методы. Проанализированы и оценены результаты лечения 92 пациентов, прооперированных с 2015 по 2017 гг. с помощью лапароскопической техники по поводу почечно-клеточного рака. Из них 57 мужчин (62%) и 35 женщин (38%), средний возраст 50,5±2,25 года (min 26 и max 75 лет).Результаты. На продолжительность операции влияли различные факторы, такие как особенности сосудистой анатомии почек, наличие спаечного процесса брюшной полости, состояние паранефральной жировой клетчатки. При совершенствовании техники выполнения лапароскопических вмешательств время операции значительно сократилось. В период освоения методики лапароскопических вмешательств на почке время операции в среднем составляло 210,0±20,2 мин (min 120 и max 300 мин), в последующем оно уменьшалось в среднем до 130,00±10,5 мин (min 70 и max 190 мин). После накопления опыта была освоена методика лапароскопической резекции почки без тотальной ишемии с селективным пережатием сегментарных артерий или без компрессии почечной артерии.Заключение. Анализ ближайших результатов лапароскопических вмешательств у пациентов с почечно-клеточным раком показал их высокую эффективность и безопасность. Результаты лапароскопических нефрэктомий и резекций почки существенно улучшаются с совершенствованием технологий и накоплением хирургического опыта.

Age-related changes in the viscoelasticity of rabbit lens characterised by surface wave dispersion analysis

6 pags., 5 figs., 1 tab.The viscoelastic properties of the young and mature rabbit lenses in situ are evaluated using wave-based optical coherence elastography (OCE). Surface waves in the crystalline lens are generated using acoustic radiation force (ARF) focused inside the eyeball. Surface-wave dispersion is measured with a phase-stabilised optical coherence tomography (OCT) system. The Young's modulus and shear viscosity coefficient are quantified based on a Scholte wave model. The results show that both elasticity and viscosity are significantly different between the young and mature lenses. The Young's modulus of the lenses increased with age from 7.74 ± 1.56 kPa (young) to 15.15 ± 4.52 kPa (mature), and the shear viscosity coefficient increased from 0.55 ± 0.04 Pa s (young) and 0.86 ± 0.13 Pa s (mature). It is shown that the combination of ARF excitation, OCE imaging, and dispersion analysis enables nondestructive quantification of lenticular viscoelasticity in situ and shows promise for in vivo applications.This research was funded by the National Institutes of Health (Grant Nos R01EY022362 and R01EY030063)

Growth, spectroscopy and continuous-wave laser performance of Nd³⁺:LiLu<inf>0.65</inf>Y<inf>0.35</inf>F<inf>4</inf> crystal

© 2018 Astro Ltd. A mixed fluoride crystal of LiLu0.65Y0.35F4 doped with Nd3+ ions was grown by the Bridgman-Stockbarger method. Polarized absorption and luminescence spectra as well as luminescence lifetime were measured at room temperature. Emission probabilities, branching ratios and radiative lifetime were studied within the Judd-Ofelt theory and the emission cross section spectra were calculated. Efficient continuous wave laser operation was demonstrated with the crystal. A maximum output power of 7.7 W and slope efficiency of 60% were achieved at 1047 nm for the TEM00 mode

Growth, spectroscopy and continuous-wave laser performance of Nd³⁺:LiLu<inf>0.65</inf>Y<inf>0.35</inf>F<inf>4</inf> crystal

© 2018 Astro Ltd. A mixed fluoride crystal of LiLu0.65Y0.35F4 doped with Nd3+ ions was grown by the Bridgman-Stockbarger method. Polarized absorption and luminescence spectra as well as luminescence lifetime were measured at room temperature. Emission probabilities, branching ratios and radiative lifetime were studied within the Judd-Ofelt theory and the emission cross section spectra were calculated. Efficient continuous wave laser operation was demonstrated with the crystal. A maximum output power of 7.7 W and slope efficiency of 60% were achieved at 1047 nm for the TEM00 mode

Assessing Age-Related Changes in the Biomechanical Properties of Rabbit Lens Using a Coaligned Ultrasound and Optical Coherence Elastography System

PURPOSE. To evaluate the capability of a novel, coaligned focused ultrasound and phase-sensitive optical coherence elastography (US-OCE) system to assess age-related changes in biomechanical properties of the crystalline lens in situ. METHODS. Low-amplitude elastic deformations in young and mature rabbit lenses were measured by an US-OCE system consisting of a spectral-domain optical coherence tomography (OCT) system coaligned with a focused ultrasound system used to produce a transient force on the lens surface. Uniaxial compressional tests were used to validate the OCE data. RESULTS. The OCE measurements showed that the maximum displacements of the young rabbit lenses were significantly larger than those of the mature lenses, indicating a gradual increase of the lens stiffness with age. Temporal analyses of the displacements also demonstrate a similar trend of elastic properties in these lenses. The stress-strain measurements using uniaxial mechanical tests confirmed the results obtained by the US-OCE system. CONCLUSIONS. The results demonstrate that the US-OCE system can be used for noninvasive analysis and quantification of lens biomechanical properties in situ and possibly in vivo