Browsing by Author "Samarasinghe, D."

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Arsenic and hardness in ground water from Chronic Kidney Disease of Unknown Etiology (CKDU) prevalent areas and non-CKDU prevalent areas in Sri Lanka
(Postgraduate Institute of Science, University of Peradeniya, 2012) Fonseka, S.; Jayasumana, C.; Jayalath, K.; Amarasinghe, M.; Senanayake, K.; Wijewardhane, C.; Samarasinghe, D.; Dahanayake, K.; Mahamithawa, P.; Paranagama, P.A.
Increasing hardness and deteriorating quality of groundwater, the primary source of potable water, has been the general observation of inhabitants of areas where chronic kidney disease of unknown etiology (CKDu) is prevalent. Present study was conducted during 2011, to determine the groundwater hardness and presence of arsenic in Padavi- Sripura, Polpithigama, Moneragala, Thanamalwila in the dry climatic zone and in Pasagoda in the wet zone. Total hardness of the water samples collected from dug wells and tube wells was measured using EDTA titration (EPA 130.2) and arsenic content was measured using GF-AAS after filtration and acid digestion (EPA 7060A). Highest average groundwater hardness (466+34 mg l-1) was observed at Padavi-Sripura (n= 28) and the values ranged from 270+54 – 820+62 mg l-1). Arsenic content in water ranged from 21.07+3.54 to more than 100.91+12.31 !" #-1. The second most hardwater was found from Polpithigama area (n= 16) which ranged 90+8 – 615+47 mg l-1. Arsenic content in water ranged 2.49+0.61 – 60.55+7.21 !" #-1. The lowest hardness in groundwater among the test sites was observed at Moneragala (n=38), where the hardness ranged 10+2 – 340+31. The arsenic content ranged 2.14+0.84 – 52.47+6.71 !"#-1. Groundwater at Thanamalwila (n=19) recorded hardness value, i.e. 279+26 mg l- 1-with a range 170+8 - 500+24 mg l-1 and the arsenic content in water ranged 39.37+5.21- >100.42+9.45 !" #-1. Groundwater at Pasgoda, the control site of this study, was not hard (60+5 mg l-1) and arsenic was not detected. Statistical analyses reveal that a positive correlation exists between total hardness of groundwater and the arsenic content in it.
Arterial tortuosity syndrome: A rare inherited form of connective tissue disorder with SLR2A10 gene mutation
(Sri Lanka College of Paediatricians, 2022) Wijesinghe, S.; de Silva, D.; Samarasinghe, D.; Irugalbandara, S.
No abstract available
Determination of Arsenic Content in Synthetic and Organic Manure Based Fertilizers Available in Sri Lanka
(International Conference on Chemical Sciences, 2012) Fernando, A.; Paranagama, P.A.; Jayalath, K.; Fonseka, S.; Amarasinghe, M.D.; Senanayake, K.; Jayasumana, C.; Mahamithawa, P.; Wijewardhane, C.; Samarasinghe, D.; Dahanayake, K.S.
Development of a low cost semiquantitative polymerase chain reaction assay for molecular diagnosis of williams syndrome
(Clinical Laboratory Publications, 2024) Ranaweera, D.M.; de Silva, D.C.; Samarasinghe, D.; Perera, S.; Kugalingam, N.; Samarasinghe, S.R.; Madushani, W.Y.; Jayaweera, H.H.E.; Gunewardene, S.; Muneeswaran, K.; Gnanam, V.S.; Chandrasekharan, N.V.
BACKGROUND: Williams Beuren Syndrome (WBS) is a well-recognized and common genetic cause of congenital heart defects, developmental delay, hypercalcemia, and characteristic facial features. It is caused by a 1.5 - 1.8 Mb heterozygous deletion of chromosome 7q11.23 with loss of around 28 coding genes. The aim of this study was to develop a low-cost, semi-quantitative PCR (sqPCR) method to detect the chromosome 7q11.23 deletion. METHODS: Twenty-four suspected WBS cases were recruited following ethical clearance and informed consent. Blood was obtained, DNA extracted and spectrophotometrically quantified using standard methods. To detect the deletion by dosage analysis, a target region within a gene located in the WBS commonly deleted region of 7q11.23 was amplified together with a control region in a duplex sqPCR assay. The control region was telomeric to the WBS commonly deleted region and was located in chromosome 7q31.2. The two target regions within the deleted region namely a locus within ELN and a marker in the intergenic region between FZD9 and FKBP6 and designated IFF, were amplified in separate duplex sqPCR assays. The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene was used as the control for normalization. Included in the assay were a non-deleted and deleted individuals' samples. RESULTS: Nineteen patients were identified to have the deletion while five did not. All 24 patients' results were confirmed by whole exome sequencing and 11 also by fluorescence in-situ hybridization (FISH). CONCLUSIONS: The data obtained indicates the sqPCR assay developed in this study to be an accurate and reliable diagnostic test for WBS. Most Sri Lankan patients with WBS are diagnosed clinically, as many parents of affected WBS children are unable to afford currently available molecular diagnostic testing. This low cost sqPCR test is therefore likely to benefit Sri Lankan WBS patients, by enabling genetic testing for confirming or refuting a clinical diagnosis of WBS and may be of use in other low and middle income countries.
The Effect of Perceived Risk on the Purchase Intention of Alternative Fuel Vehicles
(Sri Lankan Journal of Management, 2018) Karunanayake, T.; Samarasinghe, D.
The diffusion of AFV’s is comparatively high in Sri Lanka, even though the uncertainties and negative consequences of owning them are perceived to be high. This contradicts the theory of perceived risk which postulates that when customers perceive the negative consequences of purchasing, goal driven purchase intention should weaken. Hence, the purpose of this paper is to examine the effect of perceived risk on the relationships between key purchasing determinants and purchase intention of alternative fuel vehicles in Sri Lanka. This study examines this unexpected local consumer behaviour through the lens of the Theory of Perceived Risk and the study employed structured questionnaires to gather primary data from the sample utilizing a convenience sampling technique. It employed two- step Partial Least Squares (PLS)-Structural Equation Modeling (SEM) to analyze the data, and the analysis revealed that performance expectancy facilitating conditions (FC) are the key determinants of the purchase intention of AFV customers in Sri Lanka. Furthermore, perceived risk was found to moderate the relationships between these determinants and the purchase intention of customers who plan to invest in AFVs.
Green Stimuli Characteristics and Green Self-Identity Towards Ethically Minded Consumption Behavior with Special Reference to Mediating Effect of Positive and Negative Emotions
(Asian Social Science, 2019) Gayathree, P.K.; Samarasinghe, D.
Research studies related to ethical consumerism has been gaining increasing attention in the last decade due to growing importance with environmental pollution. Research studies pointed out a gap between ethical consumers’ behavior and intention which is common in Sri Lanka as well. Hence the study used emotions and self-identity as two key drivers which assist in exploring the intention-behavior gap that has not been researched so far. Therefore the research problem addressed is “whether the positive and negative emotions aroused as a result of consumer subjective evaluation to stimuli, impact on the ethically minded consumption behavior?”. The study focused only on environmental friendly electrical household appliances and the population is the academics and professionals who reside Gampaha and Colombo suburbs and who bought environmental friendly electrical household appliances within the last one year of duration. The unit of analysis is individual consumers and the convenience sampling method used. 200 individual respondents contributed to the study and the data collection was done through a self-administered questionnaire. The study has used Smart PLS 3.2 software and the results showed that the green stimuli characteristics and green self-identity significantly influence ethically minded consumer behavior and only positive emotions act as a significant mediator. Most importantly if the consumer’s perceived effectiveness is high, despite the presence of emotions ethically minded consumer behavior will be triggered more. In conclusion, marketers have to use positive emotions when creating the stimuli and should give more priority for assuring the individuals small step for protecting the environment.
Meckel Gruber syndrome: a single gene cause of recurrent neural tube defects
(Sri Lanka Medical Association, 2001) de Silva, D.; Suriyawansa, D.; Mangalika, M.; Samarasinghe, D.
Meckel Gruber syndrome (MGS), an autosomal recessive disorder characterised by posterior encephalocoele, multicystic kidneys and post-axial polydactyly should be recognised by obstetricians and paediatricians to counsel parents regarding the 25% recurrence risk. We report a consanguineous family with MGS affecting three infants.
Molecular diagnosis of velo-cardio-facial syndrome among sri lankan patients with congenital cardiac defects
(Sri Lanka College of Paediatricians, 2015) Tevarajan, I.; Ranaweera, D. M.; Perera, S.; Samarasinghe, D.; Morawakkorala, R.; Silva, R. L.; de Silva, D.; Chandrasekharan, N.V.
Velo cardio facial Syndrome (VCFS) is caused by a 3 Mb deletion of chromosome 22qll.2. Its multiple clinical features include orofacial clefting, congenital cardiac defects (especially conotruncal),developmental delay and learning difficulties. Hypoparathyroidism and thymic hypoplasia are associated. Dysmorphic features include expressionless face, prominent nose, narrow eyes and long fingers/ toes. Clinical diagnosis is difficult due to its variability making molecular diagnosis essential but this is often too expensive for widespread use. We have developed a less expensive semi-quantitative PCR method for diagnosing VCFS and report preliminary results in congenital cardiac defect patients.OBJECTIVE: • Identify the 22qll.2 deletion syndrome among a selected group of children with typical cardiac defects • Describe clinical features of affected cases DESIGN, SETTING AND METHOD: TweIve children (6 males, mean age 3y lmo) with conotruncal congenital cardiac anomalies or cardiac defects associated with other clinical feature of VCFS were .recruited following informed consent from parents. Ethical approval had been granted for this study. A blood sample was obtained for DNA extraction and the clinical data recorded. Molecular diagnosis was performed using semi-quantitative PCR. RESULTS: Three cases were positive for the deletion. Their cardiac anomalies were an interrupted aortic arch,tetralogy of Fallot and right sided aortic arch. None had palatal anomalies and two (67%) had learning difficulties. None had a positive family history. Only one had facies that were typical. The negative cases included six with aortic arch anomalies, none with clefting and 4 with learning difficulties(44). Two had a family history suggestive of VCFS and two had typical facial features. CONCLUSIONS: Three out of the 12 children were positive for the 22qll.2 deletion.
Molecular diagnosis of Williams Buren syndrome in a cohort of Sri Lankan patients
(Sri Lanka Medical Association, 2012) Ranaweera, D.M.; de Silva, D.; Samarasinghe, D.; Perera, S.; Rajapaksha, N.; Chandrasekharan, N.V.
INTRODUCTION: Williams Bueren Syndrome (WBS) is a common genetic cause of congenital heart defects associated with developmental delay, hypercalcaemia and characteristic facial dysmorphism. It is caused by a 1.5 to 1.8 Mb deletion of chromosome 7qll.23 involving the loss of around 23 genes including the elastin (ELN) gene. This study reports the development of a semi quantitative PCR method to diagnose WBS. AIMS: To establish a molecular diagnostic test for WBS and determine the frequency of ELN deletions among clinically suspected cases. METHODS: Sixteen suspected WBS cases identified by two paediatric cardiologists were recruited following ethical clearance and informed consent. DNA was extracted and dosage analysis was carried out using semi-quantitative PCR. In a multiplex PCR reaction normal (N), positive control (with a confirmed deletion) and patients' (PJ DNA was amplified using 2 primer pairs which amplified regions within the ELN gene and the CFTR gene on chromosome 7 but outside the deleted region. Following agarose gel electrophoresis, the amplified products were quantified. A ratio of P:N of 0.5 indicated the presence of a deletion while a ratio of 1 indicated the absence of a deletion. RESULTS: Among sixteen suspected cases, 12 (75%) had an ELN gene deletion while 4 cases did not. CONCLUSIONS: This semi-quantitative PCR method was able to distinguish ELN deleted cases from the non deleted ones. The preliminary data supports this as a useful diagnostic test for WBS but validation is required before its clinical use.
Molecular diagnosis of Williams syndrome using quantitative polymerase chain reaction (qPCR) in a cohort of Sri Lankan patients.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Ranaweera, D.M.; De Silva, D.; Panchananthan, N.; Samarasinghe, D.; Perera, S.; Morawakkorala, R.; Gunewardene, S.; Chandrasekharan, N.V.
Williams Beuren Syndrome (WBS) is a genetic cause of congenital heart defects associated with developmental delay, hypercalcaemia and characteristic facial features. Its cause is a 1.5 to 1.8 Mb hemizygous deletion of chromosome 7q11.23 involving the loss of around 23 genes including the elastin (ELN) gene. The deletion results in copy number alterations. The aim of this study was to identify whether a group of Sri Lankan children with a clinical diagnosis of WBS could have their diagnosis confirmed or refuted by the use of genetic testing using a validated low cost method. A quantitative PCR method was evaluated for use in deletion screening. Twenty four suspected WBS cases were recruited following ethical clearance and informed consent. DNA was extracted, spectrophotometrically quantified and qPCR performed. The target used for deletion screening was the ELN gene and TES was used as the reference gene for normalization. In all assays, a 10 fold dilution series of standards, a no template control (NTC) and a negative control (NC) were included. The fold copy number change (ΔKCt) was determined and the mean for normals (n=6) was -0.087 ± 0.11 representing no loss while the mean for previously clinically diagnosed WS patients and confirmed by either Fluorescent in situ hybridization (FISH) or microarray analysis (n=6) was -1.39 ± 0.086 representing the loss of one copy (deletion). Among twenty four suspected cases, 19 (79%) had an ELN gene deletion while 5 cases did not and the findings correlated strongly with the clinical suspicions. This qPCR method was able to distinguish ELN deleted cases from the non-deleted ones. The preliminary data supports this as a useful diagnostic test for WBS. Validation of this test using FISH has been performed for five patient’s samples and the microarray confirmed positive which correlated with the qPCR results.