International Research Symposium on Pure and Applied Sciences (IRSPAS)

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Author: search.filters.author.Rajapakse, R.P.V.J.Has files: Yes

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    Influence of humidity and temperature variation of natural breeding sites on abundance of Leishmaniasis vector Phlebotomus argentipes population in Anuradhapura District
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Nayakarathna, N.M.N.G.; Ganehiarachchi, G.A.S.M.; Rajapakse, R.P.V.J.; Jayanetti, S.R.
    Cutaneous leishmaniasis (CL) is an endemic public health problem in Sri Lanka. Leishmania donovani is the suspected causative agent of the disease and this parasite is transmitted by a dipteran fly species; Phlebotomus argentipes. Studies on vector behavioral and ecological aspects, although important for better understanding of disease transmission, are still limited. The present study is an attempt to uncover the vector ecological aspects focusing on the successful vector control interventions. This study is being carried out in Anuradhapura district, Sri Lanka; where there is a high disease prevalence of CL. Three sampling sites; Thalawa, Wijayapura and Padawiya were selected. Adult sand flies were collected monthly over a six months duration using CDC light traps (5) and yellow sticky traps (30). In the meantime, relative humidity and air temperature were measured using hygrometer and thermometer in each site. The collected sand flies were identified up to the species level using standard keys. Percentage composition of each of the species was calculated. Temporal variations of primary vector, Phlebotomus argentipes along with the dynamics of temperature and relative humidity was determined using regression analysis. Phlebotomus argentipes was the dominant sand fly species found in the study sites. The percentage composition of the primary vector exhibited a variation during the study period and maximum percentage composition was recorded during May and June, 2016. The relationship between percentage composition of Ph.argentipes versus mean temperature was significant (P = 0.000, R2 = 97.7%) and elevated percentage composition were recorded under lower temperature. Further, percentage composition of Ph.argentipes exhibited an increasing trend with higher humidity levels (P = 0.000, R2= 98.4%). In conclusion, the primary vector populations of leishmaniasis are increased with lower temperature and higher humidity. As such, this relationship will helpful to predict the variation of vector population with the changes of ecological parameters and finally a successful vector management strategy can be implemented with the thorough knowledge of its life history parameters and behavioral pattern.
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    In-vitro anti-cancer and cytotoxic properties of aqueous seaweed extracts on BHK and HeLa cell lines
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ranahewa, T.H.; Premarathna, A.D.; Jayasooriya, L.J.P.A.P.; Wijesundara, R.R.M.K.K.; Rajapakse, R.P.V.J.
    Cancer is a major health problem all over the world. Seaweeds and its active compounds have shown their potent cytotoxicity against cancer cells opening new sights for the production of new therapeutics. This study was performed to determine the cytotoxic effect and anti-cancer activity of aqueous extracts of selected Sri Lankan seaweed species on cancer (HeLa) and normal (Baby Hamster Kidney fibroblasts, BHK) cell lines. In addition, seaweed species with potent anticancer effect against cancer cell line was investigated. Samples of Ulva faciata (SW 01), Caulerpa racemosa (SW 02), Gracilaria corticata (SW 03), Sargassum illicifolium (SW 15) and Jania adhaereus (SW 26) were collected from Northern, Southern and North Western coastal sites of Sri Lanka. Aqueous extracts of seaweeds were prepared by soaking dried, powdered seaweed samples in distilled water through a modified method. Cells were cultured in a 96-well plate in Roswell Park Memorial Institute (RPMI 1640) medium and after 24-hour incubation, cells were treated with different seaweed extracts. Tetrazolium (MTT) colorimetric assay (in-vitro) was carried out after 24-hour incubation to determine cytotoxicity and anticancer effects. Viability percentages and growth inhibition rates for both cell types and with controls were compared. It was found that the seaweed extracts from different species showed significantly variable responses against cancer and normal cell lines. All seaweed extracts showed significant cytotoxic effect on cancer (HeLa) cells.