Browsing by Author "Dissanayaka, P."

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Anthropometric knee profile measurements on articulator surface of femur among Sri Lankan population.
(Sri Lanka Medical Association, 2023) Fernando, G.K.S.; Ranaweera, L.; Cabral, L.L.E.; Dissanayaka, P.; Bandara, I.D.M.R.N.; Sovis, W.F.U.N.
INTRODUCTION: In Sri Lankan context there are no published data for articulator surface measurements for knee joints. Forensic, Anatomical, Archaeological, Bio-medical engineering, development of knee S145 prosthesis beneficial with anthropometrics. Digital Vernier Caliper (measuring range 0-140mm, resolution 0.02mm, accuracy ±0.01mm) used to obtain measurements. OBJECTIVES: The aim of this study, was to provide standard anthropometrics for the distal femur in Sri Lankan context. METHODS: Dried adult Femurs (42 male and 28 female) were analysed for the measurements of Medial condyle Antero-Postero Length (MAP), Anteroposterior length of intercondylar area (AP), Medial-Lateral Length (ML), Aspect Ratio (ML/AP) and Epi Condylar breadth (EB). Sex Dimorphism Ratio (SDR) were calculated for dry femurs. RESULTS: The mean values for male; MAP 24.95(±2.22), AP 25.47(±2.27), ML 20.82(±2.56), Aspect Ratio 0.82(±0.11) and EB 7.68(±0.43). The mean values for female; MAP 24.95(±3.08), AP 25.47(±3.16), ML 20.82(±2.28), Aspect Ratio 0.82(±0.18) and EB 7.68(±0.37). SDR values are MAP 107.74, AP 107.12, ML 99.04, and EB 106.55. CONCLUSIONS: The majority of SDR values lie above 100. Therefore, a difference between male and female values can be observed. Findings offer assistance to develop knee joint prostheses with culture-particular values, fitting for the Sri Lankan setting and pave the pathway to the studies on the above-mentioned fields in the local and international context. Sex determination is a crucial element in the creation of a biological profile since it offers information for identities.
Changes in erythrocyte glucose-6-phosphate dehydrogenase (G6PD) and reduced glutathione (GSH) activities in the development of senile and diabetic cataracts
(SEAMEO Regional Tropical Medicine and Public Health Project, 2008) Chandrasena, L.G.; de Silva, L.D.R.; de Silva, K.I.; Dissanayaka, P.; Peiris, H.
Oxidative and osmotic stress have been implicated in the pathogenesis of cataracts. Reactive oxygen intermediates (ROI) mediate peroxidation of membrane lipids and cause irreversible damage to lens proteins. The purpose of this study was to assess the changes in erythrocyte glucose- 6-phosphate dehydrogenase enzyme (G6PD) and reduced glutathione (GSH) levels in the development of senile and diabetic cataracts. The activity of erythrocyte G6PD and the concentration of GSH were measured to assess changes in oxidation-reduction status. The oxidation-reduction status of 26 non-diabetic non-cataract (control) subjects were compared with 24 diabetic non-cataract, 30 diabetic cataract and 28 non-diabetic cataract subjects. The results revealed that the GSH and G6PD levels of the subjects with senile cataracts were significantly lower than the subjects without cataracts. The present study reveals the risk of developing senile cataracts is associated with decreased levels of erythrocyte G6PD and GSH. In the formation of diabetic cataracts an adequate supply of NADPH (G6PD activity) is essential to produce osmotically active sorbitol in the lens
Statistical Analysis of Eye Movement Trajectories
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Dissanayaka, P.; Su, J.; Ghosh, B.K.
Eye movement refers to the voluntary or involuntary movement of the eyes. Eye trajectories explain human search behavior. It has been revealed that variations of these trajectories reflect the dynamics of the oculomotor system. Eye movement trajectories under free exploration contain a lot of noise with saccades and fixations. As a result eye movement trajectories cannot be treated as any other trajectory. It has been a challenge to analyze gaze during free exploration, preserving spatial and temporal characteristics of eye movements. Therefore, most of the experiments are carried in laboratories under restrictions. Here we address the problem of analyzing the binocular eye movement trajectory under free exploration, to understand the underlying patterns in the movement. First eye movement trajectory is mapped onto the unit sphere as a set of time indexed points. The obtained eye movement trajectories on the sphere are not simple curves and with repeated movements. Therefore, the whole trajectory was segmented using the speed at each time instance in order to obtain simple trajectories. For each segment, we have estimated a smoothed curve given by a set of time-indexed points on the sphere so that the estimated curve would approximate the data points best at given time instants while being regular as possible. These smoothed curves as cubic splines can be used to analyze patterns in the whole trajectory. Furthermore, the estimated curves as a set of time indexed points were used in interpolation and clustering. Distances between different curves are calculated using the geodesic distance on the unit sphere. Using the distance matrix of the segmented smoothed curves and the software called cystoscope, curves are grouped to obtain four different clusters. Each cluster from the binocular eye movement was analyzed for both left and right eye movement to obtain curves overlapped where both eyes move together in the same direction. These overlapped curves can be analyzed further to compare eye movement patterns in different individuals.