Browsing by Author "Samarakoon, S."

Now showing 1 - 8 of 8

Establishment of human endometriai stromal cell cultures as in-vitro models to test the effects of metalloestrogens in women with or without endometriosis
(Sri Lanka Medical Association, 2012) Silva, N.; Tennekoon, K.; Senanayake, H.; Samarakoon, S.; Fernando, S.; Wickremasinghe, A.R.; John, R.P.
INTRODUCTION: Effects of metalloestrogens like cadmium (Cd), lead (PbJ and nickel (Ni) are difficult to demonstrate in-vivo due to toxicity and therefore requires suitable in-vitro models. AIMS: To establish endometriai stromal cell (ESC) cultures as in-vitro models to demonstrate the effects of metalloestrogens in women with and without endometriosis. METHODS: Stromal cells were isolated from eutopic endometriai samples from five women with endometriosis (patients) and five women without endometriosis (controlsj. ESC cultures were established and maintained in RPMI medium. Cultures were treated with Cd, Pb and Ni at concentrations of 10-6M, 10-9M and 10-9M respectively. At 24 h and 48 h, cell number was counted using the Neubauer haemocytometer. Sulphorhodamine(SRB) cytotoxicity assay was used to test the effect of different concentrations of metals on ESC cultures. After 24 h of treatment, caspase levels in ESC cultures were evaluated with a commercially available ELISA kit Relative cell proliferation, SRB assay results and caspase levels were analyzed with ANOVA. RESULTS: ESC cultures were maintained up to 30 days. In both patients and controls Cd, but not Pb or Ni increased the relative proliferation in ESC cultures (p<0.05). At 48 h, Cd induced ESC proliferation was higher in patients than in controls (p=0.02). SRB assay results and caspase levels were similar in the two groups. CONCLUSIONS: Established ESC cultures served as stable in-vitro models. Cd induced the proliferation of ESC from women with endometriosis which appears to be independent of reduced apoptosis. Similar effects of Pb and Ni could not be demonstrated in this in vitro model.
Learner Beliefs on Learning English as A Second Language: A Study of Undergraduates in The University of the Visual and Performing Arts
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Samarakoon, S.; Gunarathne, D.
A large body of research has been conducted in the area of language learning beliefs, across the world. Beliefs inevitably matters in the pragmatic aspect of language learning. If learners are driven by misconceptions of language learning, the performance in class might be really low. Teachers’ consciousness about English language teaching is also reflected in the methods utilized in class. Research indicates that individual students differ considerably in their use of learning strategies. Elaine Horwit, who developed the Beliefs About Language Learning Inventory (BALLI) was the first to conduct a systematic research into the nature of language learning beliefs. The theoretical framework of BALLI is based on five major components pertaining to language learning; foreign language aptitude, the difficulty in language learning, nature of (English) language learning, learning and communication strategies and motivation. In order to collect data, a questionnaire survey was conducted with a group of 30 ESL learners in the University of the Visual and Performing Arts. The sample group is little exposed to English since their medium of instruction is Sinhala and most of them come from rural backgrounds. The gathered data was statistically analyzed and several significant findings were revealed. According to the survey, it was found out the subjects believe that it is easy to learn a foreign language at a young age. The majority agreed that they have the ability to achieve proficiency in English. All the female participants believe that women are better than men at learning. Most of the subjects maintain a neutral opinion on learning English grammar. All the participants agreed that they want to learn English and believe that they will have better job opportunities if they learn English well. However, all the participants agreed that it is not necessary to be able to speak in English to live in Sri Lanka. It appears that this questionnaire is a valid instrument that can be applied to the Sri Lankan context to a great extent, despite its limitations. In order to make it more applicable to the Sri Lankan context, slight modifications should be done to make sure that the questions mirror the role played by culture, social background, discipline of study and field of work, in shaping beliefs of English language learners in Sri Lanka.
Neurophysiological findings in patients 1 year after snake bite induced neurotoxicity in Sri Lanka
(Oxford University Press, 2010) Bell, D.J.; Wijegunasinghe, D.; Samarakoon, S.; Palipana, H.; Gunasekera, S.; de Silva, H.A.; Lalloo, D.G.; Ranawaka, U.K.; de Silva, H.J.
Snake bite causes significant morbidity and mortality in Sri Lanka. Snake venoms contain neurotoxins that block neuromuscular junction transmission. Presynaptic neurotoxicity most commonly causes destruction of nerve terminals with recovery by regrowth, whilst postsynaptic neurotoxicity usually involves competition at the acetylcholine receptor. The aim of this study was to investigate whether there were long-term clinical or neurophysiological changes in snake bite survivors 1 year after their envenoming. Detailed neurophysiological tests and clinical examinations were performed on 26 snake bite victims who had presented with neurotoxicity 12 months previously, and their results were compared with controls recruited from the same communities. Significant differences were observed in some nerve conduction parameters in some snake bite victims compared with controls, predominantly in those thought to have elapid bites, including prolongation of sensory, motor and F-wave latencies and reduction of conduction velocities. There was no evidence of any residual deficits in neuromuscular junction transmission. These results suggest a possible demyelinating type polyneuropathy. None of the cases or controls had abnormalities on clinical examination. This is one of the few studies to report possible long-term neurological damage following systemic neurotoxicity after snake bite. The clinical significance of these neurophysiological abnormalities is uncertain and further studies are required to investigate whether the abnormalities persist and to see whether clinical consequences develop
A Novel Cytotoxic Compound From the Endolichenic Fungus, Xylaria psidii Inhabiting the Lichen, Amandinea medusulina
(Natural Product Communications, 2020) Santhirasegaram, S.; Wickramarachchi, S. R.; Attanayake, R. N.; Weerakoon, G.; Samarakoon, S.; Wijeratne, K.; Paranagama, P. A.
The lichen host, Amandinea medusulina, collected from mangrove habitats in Sri Lanka, and its associated endolichenic fungi were isolated and identified by rDNA-ITS sequence analysis and morphological features. One of the fungal strains frequently isolated from the lichen thalli was identified as Xylaria psidii. This study aimed at the isolation and identification of the cytotoxic compounds present in this fungus. Secondary metabolites of X. psidii were first extracted into ethyl acetate and subsequently subjected to bioassay-guided fractionation to isolate the bioactive compounds. Sulforhodamine B assay against a lung cancer (NCI-H292) cell line was used to determine the differential cytotoxic activity. Bioassay-guided fractionation led to the isolation of an active compound, SS/02/29/08, showing moderate cytotoxicity (IC50 = 27.2 μg/mL). Its structure was elucidated by IR, 1D- and 2D-NMR, and 13C-NMR spectrophotometry and MS, in combination with HRMS, 13C NMR, HSQC, HMBC, and DQF-COSY. The structure of SS/02/29/08 was determined as (Z)-3-{(3-acetyl- 2-hydroxyphenyl) diazenyl}-2,4-dihydroxybenzaldehyde and identified as a new compound. This novel compound has promising differential cytotoxic activity against human lung cancer cell line (NCI-H292).
A Novel Cytotoxic Compound From the Endolichenic Fungus, Xylaria psidii Inhabiting the Lichen, Amandinea medusulina
(Natural Product Communication, 2020) Santhirasegaram, S.; Wickramarachchi, P.A.S.R.; Attanayake, R.N.; Weerakoon, G.; Samarakoon, S.; Wijeratne, K.; Paranagama, P.A.
The lichen host, Amandinea medusulina, collected from mangrove habitats in Sri Lanka, and its associated endolichenic fungi were isolated and identified by rDNA-ITS sequence analysis and morphological features. One of the fungal strains frequently isolated from the lichen thalli was identified as Xylaria psidii. This study aimed at the isolation and identification of the cytotoxic compounds present in this fungus. Secondary metabolites of X. psidii were first extracted into ethyl acetate and subsequently subjected to bioassay-guided fractionation to isolate the bioactive compounds. Sulforhodamine B assay against a lung cancer (NCI-H292) cell line was used to determine the differential cytotoxic activity. Bioassay-guided fractionation led to the isolation of an active compound, SS/02/29/08, showing moderate cytotoxicity (IC50 = 27.2 µg/mL). Its structure was elucidated by IR, 1D- and 2D-NMR, and 13C-NMR spectrophotometry and MS, in combination with HRMS, 13C NMR, HSQC, HMBC, and DQF-COSY. The structure of SS/02/29/08 was determined as (Z)-3-{(3-acetyl-2-hydroxyphenyl)diazenyl}-2,4-dihydroxybenzaldehyde and identified as a new compound. This novel compound has promising differential cytotoxic activity against human lung cancer cell line (NCI-H292).
Psidium guajava L. (Common Guava) Peel, Pulp and Leaves as Natural Sources of Antioxidants, Antimicrobials and Photoprotective Agents for Development of Sun Protection Cosmeceuticals
(Asian Journal of Chemistry, 2022) Dewage, D.; Samarakoon, S.; Karunaratne, S.; Rajapakse, N.
Sunscreens with natural ingredients for skin care become a new trend in cosmetology as it protects skin against photo-aging and dermatologic disorders. Therefore, the goal of this study was to evaluate the antioxidant, antimicrobial and photoprotective properties of methanolic extracts of leaves, peel and pulp of Psidium guajava L. to investigate their potentials to be used as sources of cosmeceutical ingredients for sun protection. Chemical constituents of the plant parts were extracted into methanol by maceration. Among the extracts, leaf extract exhibited higher DPPH free radical scavenging activity (IC 50 = 89.56 ± 0.97 μg/mL), than that of peel and pulp extracts. The highest total phenolic content (TPC) and total flavonoid content (TFC) were found to be in the leaf extract. All extracts demonstrated antibacterial activity against the examined potential pathogens in cosmetic products. Among the extracts, leaf extract showed the highest photoprotective property with the sun protection factor (SPF) of 30.38 ± 0.22 at 2 mg/mL indicating its potential to be used in the development of sunscreen formulations.
Symptoms and signs of β thalassaemia trait: results of the first comparative study
(Sri Lanka Medical Association, 2007) Premawardhena, A.P.; Weerasinghe, M.; Kottachchi, D.; Arambepola, M.; Katugaha, N.; Samarakoon, S.; Otivieri, N.F.; Weatherall, D.J.
OBJECTIVE: Thalassaemia trait is considered a mild and asymptomatic condition. However patients with this disease may be symptomatic. Should these be attributed to the disease? Does pre-knowledge about the diagnosis affect patients' symptoms? Previous studies were affected by the lack of a control arm. This is the first controlled study which compares symptoms of (3 thalassaemia trait with matched controls and also looks at how prior knowledge of the disease affects symptoms. DESIGN, SETTING AND METHODS: We administered a questionnaire to 146 individuals who knew that they had thalasseamia trait (Group 1} and to 248 "normal" volunteers who did not know their "thalassaemic status". Eleven symptoms were assessed. All individuals were examined by the same investigator and had a full blood count from an automated analyzer and a thalassaemia screening with High Performance Liquid Chromatography (HPLC- Bio Rad). RESULTS: The FBC and HPLC data showed that of the 248 "normal" controls , 63 had p thalassaemia trait (Group 2), and a further 96 had MCV< 80 and MCH <27 without thalassaemia (Group 3), presumably due to iron deficiency. 89 had normal red cell indices and normal HPLC (Group 4). Comparison of the four groups showed that "anaemic symptoms" like headache, exercise intolerance and lethargy occurred in significantly higher numbers in Groups 1 and 2 compared to Group 4. Comparison of Group 1 and Group 3 did not show any significant difference suggesting a similar mechanism for symptoms. Group 2 did not differ significantly from Group 1 in anyway. CONCLUSIONS: The p thalasseamia trait can be a symptomatic disorder and the symptoms arc those of anaemia. Symptoms are not affected or caused by being aware of the diagnosis.
Using red cell indices as a screening test for the detection of haemoglobin E trait in population screening for haemoglobin disorders
(Sri Lanka Medical Association, 2005) Premawardhena, A.; Samarakoon, S.; Perera, U.; Samaranayake, R.; Arambepola, M.
INTRODUCTION: When screening populations for haemoglobin E trait, which is found in up to 5% in some regions in Sri Lanka, some believe that the full blood count with red cell indices, demonstrating hypochromasia and microcytosis (MCV<80fl and MCH< 27pg), is not sensitive enough, as up to 5% may be missed. If this is true, more complicated and expensive tests will be necessary to detect Hb E trait. There are no studies which have attempted to test the efficacy of red cell indices as a screening test for Hb E trait in Sri Lanka AIMS: To test the sensitivity of the full blood count with red cell indices as a screening test for the detection of haemoglobin E trait MATERIALS AND METHODS: Individuals diagnosed to have Hb E trait by the usage of high performance liquid chromatography (HPLC) - (Bio Rad) had their red cell indices measured using an automated cell counter (Coulter, Act Diff III) RESULTS: 47 Individuals with Hb E trait were identified using HPLC analysis. 28 were females (59%). The haemoglobin levels ranged from 10.5 to 15.4 g/dl. (Mean 12.6). There was only one individual with an MCV of 80, whilst the rest had values below that. MCV values ranged from 58-80fl. There were 3 individuals with an MCH over 27 (27.4, 28.8 and 27.4). The individual with an MCV of 80 had an MCH of 27.4. CONCLUSIONS: In this ongoing study we found that by using a cutoff point for MCV at 80ft up to 2% of individuals with Hb E trait will be missed. As the screening test needs to be more sensitive than this, we suggest that by using a slightly higher cutoff point for the MCV (eg. 81 fl) we would still be able to detect individuals with Hb E trait using red cell indices, thus minimizing cost.