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Optically deviated focusing method based high-speed SD-OCT for in vivo retinal clinical applications
Wijesinghe, R. E.,Park, K.,Kim, P.,Oh, J.,Kim, S. W.,Kim, K.,Kim, B. M.,Jeon, M.,Kim, J. Springer Science + Business Media 2016 Optical review Vol.23 No.2
<P>The aim of this study is to provide accurately focused, high-resolution in vivo human retinal depth images using an optically deviated focusing method with spectral-domain optical coherence tomography (SD-OCT) system. The proposed method was applied to increase the retinal diagnosing speed of patients with various values of retinal distances (i.e., the distance between the crystalline eye lens and the retina). The increased diagnosing speed was facilitated through an optical modification in the OCT sample arm configuration. Moreover, the optical path length matching process was compensated using the proposed optically deviated focusing method. The developed system was mounted on a bench-top cradle to overcome the motion artifacts. Further, we demonstrated the capability of the system by carrying out in vivo retinal imaging experiments. The clinical trials confirmed that the system was effective in diagnosing normal and abnormal retinal layers as several retinal abnormalities were identified using non-averaged single-shot OCT images, which demonstrate the feasibility of the method for clinical applications.</P>
Wijesinghe, W.A.J.P.,Kang, Min-Cheol,Lee, Won-Woo,Lee, Hyi-Seung,Kamada, Takashi,Vairappan, Charles S.,Jeon, You-Jin The Korean Society of Phycology 2014 ALGAE Vol.29 No.4
In this study, four compounds isolated from the red alga Laurencia snackeyi were evaluated for their potential anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. These compounds were tested for their inhibitory effects on nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells. Since $5{\beta}$-hydroxypalisadin B showed the best activity it was further tested for the production of prostaglandin-$E_2$ ($PGE_2$), expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the release of pro-inflammatory cytokines tumor necrotic factor-alpha (TNF-${\alpha}$), interleukin-$1{\beta}$ (IL-$1{\beta}$), and interleukin-6 (IL-6). $5{\beta}$-Hydroxypalisadin B significantly reduced the $PGE_2$ release and suppressed the iNOS and COX-2 expression in LPS-stimulated RAW 264.7 cells. It also significantly reduced the release of pro-inflammatory cytokines TNF-${\alpha}$, IL-$1{\beta}$, and IL-6. These findings provide the first evidence of anti-inflammatory potential of $5{\beta}$-hydroxypalisadin B isolated from the red alga L. snackeyi and hence, it could be exploited as an active ingredient in pharmaceutical, nutraceutical and functional food applications.
Wijesinghe, W.A.J.P.,Senevirathne, Mahinda,Oh, Myung-Cheol,Jeon, You-Jin The Korean Nutrition Society 2011 Nutrition Research and Practice Vol. No.
In the present study, a suitable drying method was developed for citrus press cakes (CPCs), which are produced as a by-product in citrus juice plants, and the protective effect of methanol extract of CPCs prepared by far-infrared radiation (FIR) drying against $H_2O_2$-induced DNA damage was evaluated versus that of freeze-dried CPCs. Methanol extract of FIR-dried CPCs exhibited comparatively good ROS scavenging activity versus the freeze-dried CPCs at the concentration of 100 ${\mu}g$/mL. The extract strongly enhanced the cell viability against $H_2O_2$-induced oxidative damage in Vero cells. Lipid peroxidation inhibitory activity of the extract from FIR-dried CPCs was comparable to that of the extract from freeze-dried CPCs. This sample also exhibited good protective effects against $H_2O_2$-mediated cell apoptosis as demonstrated by decreased apoptotic body formation in the nuclear staining with Hoechst 33342. In the comet assay, the CPC extracts exhibited strong inhibitory effects against $H_2O_2$-mediated DNA damage in a dose-dependent manner. Thus, this study demonstrated that FIR drying effectively preserves CPC as a functionally important natural antioxidant source and the FIR drying can be adapted for drying CPCs and is more economical for massive production than freeze drying.
Wijesinghe, W.A.J.P.,Ko, Seok-Chun,Jeon, You-Jin The Korean Nutrition Society 2011 Nutrition Research and Practice Vol. No.
Inhibition of angiotensin I-converting enzyme (ACE) activity is the most common mechanism underlying the lowering of blood pressure. In the present study, five organic extracts of a marine brown seaweed Ecklonia cava were prepared by using ethanol, ethyl acetate, chloroform, hexane, and diethyl ether as solvents, which were then tested for their potential ACE inhibitory activities. Ethanol extract showed the strongest ACE inhibitory activity with an $IC_{50}$ value of 0.96 mg/ml. Five kinds of phlorotannins, phloroglucinol, triphlorethol-A, eckol, dieckol, and eckstolonol, were isolated from ethanol extract of E. cava, which exhibited potential ACE inhibition. Dieckol was the most potent ACE inhibitor and was found to be a non-competitive inhibitor against ACE according to Lineweaver-Burk plots. Dieckol had an inducible effect on the production of NO in EAhy926 cells without having cytotoxic effect. The results of this study indicate that E. cava could be a potential source of phlorotalnnins with ACE inhibitory activity for utilization in production of functional foods.
Wijesinghe, Ruchire Eranga,Lee, Seung-Yeol,Kim, Pilun,Jung, Hee-Young,Jeon, Mansik,Kim, Jeehyun SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS 2017 JOURNAL OF BIOMEDICAL OPTICS Vol.22 No.9
<P>Seed germination rate differs based on chemical treatments, and nondestructive measurements of germination rate have become an essential requirement in the field of agriculture. Seed scientists and other biologists are interested in optical sensing technologies-based biological discoveries due to nondestructive detection capability. Optical coherence tomography (OCT) has recently emerged as a powerful method for biological and plant material discoveries. We report an extended application of OCT by monitoring the germination rate acceleration of chemically primed seeds. To validate the versatility of the method, Capsicum annum seeds were primed using three chemical compounds: sterile distilled water (SDW), butandiol, and 1-hexadecene. Monitoring was performed using a 1310-nm swept source OCT system. The results confirmed more rapid morphological variations in the seeds treated with 1-hexadecene medium than the seeds treated with SDW and butandiol within 8 consecutive days. In addition, fresh weight measurements (gold standard) of seeds were monitored for 15 days, and the obtained results were correlated with the OCT results. Thus, such a method can be used in various agricultural fields, and OCT shows potential as a rigorous sensing method for selecting the optimal plant growth-promoting chemical compounds rapidly, when compared with the gold standard methods. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)</P>
Reference Standard for Harmonics and Nonsinusoidal Power Measurements
Wijesinghe, W M S,Young Tae Park IEEE 2011 IEEE transactions on instrumentation and measureme Vol.60 No.7
<P>In this paper, a method for the measuring the harmonic amplitude and power of nonsinusoidal signals, which utilizes two synchronized high-precision digital voltmeters, is described. The harmonics of voltage and current waveforms were computed from digital samples and compared with the values obtained from thermal converters. The software developed, which is based on the fast Fourier transform algorithm, computes current and voltage harmonics with uncertainties of less than 10 × 10<SUP>-6</SUP> of fundamental. The uncertainty of the power harmonics is 17 μW/VA . The system can be used as a reference system for calibrating harmonic analyzers at power frequencies.</P>
Wijesinghe, R. E.,Lee, S. Y.,Ravichandran, N. K.,Shirazi, M. F.,Moon, B.,Jung, H. Y.,Jeon, M.,Kim, J. Springer Science + Business Media 2017 Optical review Vol.24 No.2
<P>The pathological and physiological defects in various types of fruits lead to large amounts of economical waste. It is well recognized that internal fruit defects due to pathological infections and physiological disorders can be effectively visualized at an initial stage of the disease using a well-known bio-photonic detection method called optical coherence tomography (OCT). This work investigates the use of OCT for identifying the morphological variations of anthracnose (bitter rot) disease infected and physiologically disordered Diospyros kaki (Asian Persimmon) fruits. An experiment was conducted using fruit samples that were carefully selected from persimmon orchards. Depthresolved images with a high axial resolution were acquired using 850-nm-based spectral-domain OCT (SD-OCT) system. The obtained exemplary high-resolution two-dimensional and volumetric three-dimensional images revealed complementary morphological differences between healthy and defected samples. Moreover, the obtained depth-profile analysis results confirmed the disappearance of the healthy cell layers among the healthyinfected boundary regions. Thus, the proposed method has the potential to increase the diagnostic accuracy of the OCT technique used in agricultural plantations.</P>
Wijesinghe, Ruchire Eranga,Lee, Seung-Yeol,Ravichandran, Naresh Kumar,Han, Sangyeop,Jeong, Hyosang,Han, Youngmin,Jung, Hee-Young,Kim, Pilun,Jeon, Mansik,Kim, Jeehyun The Optical Society 2017 Applied Optics Vol.56 No.9
<P>We developed a compact, wearable diagnostic imaging modality employing optical coherence tomography for in situ plant leaf quality assessments. This system is capable of diagnosing infected leaves at the initial disease stages. Our system is a versatile backpack-type imaging modality with a compact spectrometer, miniature computer, rechargeable power source, and handheld inspection probe. This method enhances real-time in situ specimen inspection through direct implementation of the imaging modality in a plantation. To evaluate the initial performance, field experiments were conducted in apple, pear, and persimmon plantations. Based on the obtained results, we can conclude that the developed imaging modality can be considered as a promising, efficient, convenient, and fast in situ inspection technique for various agricultural fields, which minimizes the limitations of complex tabletop inspection modalities. (C) 2017 Optical Society of America.</P>