Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Annotated checklist of chigger mites (Trombidiformes: Leeuwenhoekiidae, Trombiculidae and Walchiidae) in Sri Lanka(Elsevier, 2022) Ashani, M.L.S.; Gunathilaka, P.A.D.H.N.; Premaratna, B.A.H.R.; Chandrasena, T.G.A.N.; Jacinavicius, F.C.; Silva, R.B.Chigger mites (Leeuwenhoekiidae, Trombiculidae, and Walchiidae) are parasites of any terrestrial vertebrate. The present study updates the list of chigger mite (Trombiculidae, Leeuwenhoekiidae, and Walchiidae) species recorded from Sri Lanka along with taxonomic classification based on previous investigations since 1946 to date and our observations in western and southern parts of the country. This checklist listed 15 species in 9 genera within the three chigger families. For now, murid species were the host most sampledparasitized by chiggers in Sri Lanka. However, further studies are required to increase the diversity of chigger mites in Sri Lanka and probably the description of new species, which will be possible with morphological and molecular characterization.Item A determination of air pollution in Colombo and Kurunegala, Sri Lanka, using energy dispersive X-ray fluorescence spectrometry on Heterodermia speciosa(The Scientific and Technological Research Council of Turkey, 2011) Gunathilaka, P.A.D.H.N.; Ranundeniya, R.M.N.S.; Najim, M.M.M.; Seneviratne, S.ABSTRACT: Sri Lanka is facing severe environmental problems such as air and water pollution due to rapid industrialisation and urbanisation. Because there have not been many studies on heavy metal pollution in Sri Lanka, the present study attempts to contribute to the literature a determination of metal pollution using indicators found in lichen specimens. Our study utilised energy dispersive X-ray fluorescence spectrometry to determine element concentrations resulting from air pollution in the lichen species Heterodermia speciosa Wulfen. These samples, collected from Colombo and Kurunegala, Sri Lanka, were analysed using the energy dispersive X-ray fluorescence (EDXRF) method in order to determine the concentrations of 13 different elements. A radioisotope excited X-ray fluorescence analysis was applied to the elemental analysis of lichens using the method of multiple standard addition. Our qualitative analysis of spectral peaks showed that the samples contained potassium, calcium, titanium, iron, manganese, copper, zinc, lead, bromine, rubidium, strontium, yttrium, and gallium. Samples from the environment around Colombo, which is a highly congested urban area with much industrial development, were found to be more polluted when compared with Kurunegala, a city that is less congested and without industries. Concentrations of K, Ca, Ti, and Fe were always higher than other elemental concentrations in the lichens we analysed, a fact attributed to the proximity to the sea or exposed earth crustal sources. From the elements reported from the 2 cities, K, Ca, Ti, Fe, Mn, Zn, and Pb were reported at concentrations higher than background levels. Levels of Pb and Zn in samples from Colombo were higher than those from Kurunegala, reflecting the increased vehicular traffic. This study reveals that the common lichen species Heterodermia speciosa can be used as an indicator lichen to analyse the pollution level and other elements in the atmosphere. © TÜBITAK. AUTHOR KEYWORDS: Air; EDXRF; Heterodermia; Lichens; Metal pollution. INDEX KEYWORDS: atmospheric pollution; concentration (composition); fungus; heavy metal; lichen; radionuclide; spectrometry; urban area; X-ray fluorescence, Colombo; Sri Lanka; Western Province [Sri Lanka], Heterodermia; Heterodermia speciosaItem Determination of the efficiency of diets for larval development in mass rearing Aedes aegypti (Diptera: Culicidae)(CABI Publishing, 2018) Gunathilaka, P.A.D.H.N.; Uduwawala, U.M.H.U.; Udayanga, N.W.B.A.L.; Ranathunge, R.M.T.B.; Amarasinghe, L.D.; Abeyewickreme, W.Larval diet quality and rearing conditions have a direct and irreversible effect on adult traits. Therefore, the current study was carried out to optimize the larval diet for mass rearing of Aedes aegypti, for Sterile Insect Technique (SIT)-based applications in Sri Lanka. Five batches of 750 first instar larvae (L 1) of Ae. aegypti were exposed to five different concentrations (2-10%) of International Atomic Energy Agency (IAEA) recommended the larval diet. Morphological development parameters of larva, pupa, and adult were detected at 24 h intervals along with selected growth parameters. Each experiment was replicated five times. General Linear Modeling along with Pearson's correlation analysis were used for statistical treatments. Significant differences (P < 0.05) among the larvae treated with different concentrations were found using General Linear Modeling in all the stages namely: total body length and the thoracic length of larvae; cephalothoracic length and width of pupae; thoracic length, thoracic width, abdominal length and the wing length of adults; along with pupation rate and success, sex ratio, adult success, fecundity and hatching rate of Ae. aegypti. The best quality adults can be produced at larval diet concentration of 10%. However, the 8% larval diet concentration was most suitable for adult male survival.Item Composition of malaria vectors and diversity of anopheline breeding habitats in the district of Mannar, Sri Lanka(Central Environmental Authority (CEA), 2016) Gunathilaka, P.A.D.H.N.; Hapugoda, M.D.; Wickremasinghe, A.R.; Abeyewickreme, W.In the malaria elimination phase in Sri Lanka, investigation on biological and ecological factors of malaria vectors are important in planning appropriate vector controlling strategies. Lack of sufficient biological and ecological information on malaria vectors in the Northern Province of the country, a malaria endemic region, is a major constrain in successful implementation of malaria control programmes. Therefore, the objective of this study was to explore the diversity of breeding habitats and species composition of malaria vector mosquitoes in the District of Mannar, Sri Lanka. Potential habitats for Anopheles mosquito larvae were surveyed from June, 2010 to July 20 J2 on a monthly basis in selected sampling sites in the Mannar District: Mannar Town, Vankalai and Silawathiura, within a radius about 20 km. In each site, 4 sub sites were selected A total of 37,788 Anopheles representing ten species was recorded from 12 breeding habitat categories. Built wells and waste water collections were conducive for anopheline breeding. Anopheles subpictus (96.2%, n= 36,351) was the dominant species followed by An. peditaeniatus (1.47%, n= 557), An. barbirostris (1.23%, n= 463), An. nigerriums (0.75%,n = 285), An. varuna (0.19%, n= 74), An. barbumbrosus (0.1%, n= 38), An. vagus' (0.03%, n= 12), An. pallidus (0.01%, n= 4), An.jamesii (0.05%, n= 2) and An. pseudojamesi (0.05%, n= 2). Use of wells and waste water drains as breeding places by potential malaria vectors indicates that both of these habitats act as larval reservoirs during the dry season. Presence of theses habitats in close proximity to human habitats create a potential risk of malaria transmission among humans. Therefore, health authorities need to be vigilant on these new habitats in vector control programmes.Item Awareness on dengue and solid waste management among selected school students in Gampaha District of Sri Lanka(Moleclar Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Radhika, N.M.L.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.; Kasturiratne, K.T.A.A.BACKGROUND: Community mobilization is often respected as a powerful tool in ensuring the effective controlling of dengue via promoting effective and sustainable dengue vector control strategies. The current study attempts to investigate the level of awareness on dengue and solid waste management, among selected school students in Gampaha District which is the second highest dengue reported district in Sri Lanka. METHODOLOGY: Awareness programmes on dengue (transmission, vector ecology and preventive measures) and solid waste management were conducted in 10 schools belong to Kelaniya Medical Officer of Health (MOH) area selecting a minimum group of 200 students from each school within the age of 13 - 15 years. Tools such audio-visual presentations, leaflets and videos were used for the awareness programmes. A questionnaire was given to each student prior to the awareness and after the awareness programs as pre and post evaluations respectively in order to assess the general awareness on dengue and solid waste management before and after the awareness programme. One-Way ANOVA, paired t-test and multiple regression techniques were utilized in evaluation of the degree of awareness and key factors affecting the level of awareness, prior and after the conducting the awareness programmes. RESULTS: The degree of initial awareness on dengue and solid waste management of the target school community was recognized to be significantly characterized by the grade of the students and the Education Zonal Category [EZU] (into which their school belongs to) in accordance with One-Way ANOVA (p < 0.05). A significant increment in post awareness of the target school community was recognized due to the conducting of awareness programmes in accordance with the statistics of paired t-test (p < 0.05). Furthermore, based on the multiple linear regression modelling, the post awareness was significantly influenced by the grade of the students and the initial awareness (p < 0.05), regardless of the EZU (p > 0.05). CONCLUSIONS: The awareness of school students on dengue and solid waste management is significantly affected by the grade of the students and EZCs. Awareness programmes are an effective media of raising the awareness of school communities on dengue and solid waste management, while motivating them to actively contribute for the controlling of dengue, via establishing a strong inter sectorial network among schools and other relevant institutions within the Gampaha District.Item Encapsulation of essential oil blend in β-CD nanoparticles as a repellent for slow release(Moleclar Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Jayaweera, V.; Eliyapura, A.; Gunasekara, D.; Weerasinghe, L.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.; Karunaratne, V.BACKGROUND: Malaria, dengue, and other tropical diseases carried by arthropods such as mosquitoes, ticks and fleas have greatly affected life expectancy, infant mortality, quality of life and work productivity. Essential oils such as citronella, lemon eucalyptus, peppermint, lemon, eucalyptus, lemongrass, geranium, and lavender are known for their mosquito repellency. Due to high volatility of essential oils, these are needed to be reapplied to the skin every 30–60 minutes. Therefore, development of a long lasting mosquito repellent is needed for effective repellent activity. The aim of this experiment is to develop a new blend which encompasses citronella, lemon eucalyptus, lemon and lavender. This oil blend is encapsulated using β-Cyclodextrin (β-CD) to decrease the volatility of the oil blend and increases the long-lasting repellency. METHODS: Citronella, lemon eucalyptus, lemon and lavender were obtained in 15% v/v, 15% v/v, 1% v/v and 1% v/v respectively for a total volume of 100 ml. These oils were mixed with 0.2% w/v of β-Cyclodextrin for encapsulation. The blend was sonicated for 20 min and dissolved in ethanol. This final encapsulated mixture was subjected to bioassays using 110 adult Aedes albopictus mosquitoes against the control. Sitting and biting mosquito behavior patterns were studied against the releasing time. RESULTS: The bioassay results indicated that the encapsulated repellent product is effective against the mosquitos up to 6 hours with zero sitting and biting comparatively to the control. In the 7th hour showed single mosquito sitting with zero biting. CONCLUSION: The encapsulated repellent is effective against the Ae, albopictus mosquitoes for 6 hour time period. Therefore, it is a long-lasting repellent that protect against dengue fever caused by mosquitoes.Item Synthesis of Fe2O3 nanoparticles for the development of a rapid diagnostic test kit for dengue detection(Moleclar Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Jayarathna, I.P.L.; Gunathilaka, P.A.D.H.N.; Athapaththu, A.M.M.H.; Abeyewickreme, W.BACKGROUND: Hybrid nanoparticles have great potential for biotechnological and biomedical applications. It was recently proposed that biopolymer/co-shell nano-materials could be easily obtained by adapting traditional routes used in pharmaceutical science to design drug delivery system. Most of the case, super-paramagnetic nanoparticles of iron oxides, magnetite (Fe3O4) and maghemite (ᵧ -Fe2O3) have been employed and these interesting magnetic properties are due to finite-size effects and high surface/volume ratio. METHOD: Iron oxide was synthesized by using modified co-precipitation method and resulting particles were characterized using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Diffused Reflectance Fourier Transform-Infrared Spectroscopy (DRIFT-IR). RESULTS: The XRD pattern matches well that of ᵧ -Fe2O3. Six characteristic peaks for ᵧ -Fe2O3 (2θ = 31.7°, 36.7°, 41.1°, 53.4°, 57.0° and 62.6°) marked by their Miller indices [(220), (311), (400), (422), (511) and (440)] were observed for sample. The TEM images reveal that the particles are in 5 – 20 nm range, and well fitted with spaniel cubic structure, but when particles are dry it prefer to agglomerate with neighboring particles to reduce their surface charges. The spectrum of ᵧ -Fe2O3 nanoparticles shows a characteristic broad band at 3410 cm-1 is due to the stretching vibration of H2O molecules. The band corresponding to the bending vibrations of H2O molecules is positioned at 1633 cm-1. Two intense IR bands at 627 and 451 cm-1 are typical for ferrihydrite or ᵧ -Fe2O3 nanoparticles. The spectrum of this sample showed the presence of carbonate groups on the basis of IR bands at 1508, 1340 and 1069 cm-1. The presence of carbonate groups is due to the adsorption of atmospheric carbon dioxide by ᵧ -Fe2O3 nanoparticles. The bands of Fe–O stretching vibrations of ᵧ -Fe2O3 appeared at 627 and 451 cm-1 and the bands at 892 and 796 cm-1 can be assigned to Fe-OH···H bending vibrations. CONCLUSION: Magnetic ᵧ -Fe2O3 nanoparticles were synthesized by the co-precipitation method and this work confirmed that magnetic ᵧ -Fe2O3 nanoparticles are in nano-scale and well matches with spaniel cubic structureItem Designing of immunogenic peptides from Dengue Virus NS1 region for production of monoclonal antibodies as diagnostic intermediates(Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Munasinghe, M.M.E.; Chandrasekharan, N.V.; Korbakis, D.; Soosaipillai, A.; Diamandis, E.P.; Athapaththu, A.M.M.H.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.BACKGROUND: Small peptide antigens have become an essential tool for antibody production in the recent life science research applications. The immunogenicity of peptide antigens is a critical factor to induce the immune response in order to produce desired antibodies. METHODS: In the current study, we have previously determined four Dengue (DEN) serotype specific peptides, containing 28 Amino Acid (AA) residues were re-designed. The peptides were re-designed considering many factors, for instance, sequence of the Sri Lankan isolates, abundance of Cysteine residues, solubility and the length of the peptide, carrier protein to be used and several other factors such as the N-terminal and C- terminal AAs and multiple AA residues. The peptide sequences were analysed using Antigen Profiler Peptide Tool (Thermo-scientific), Peptide Property Calculator (Genscript) and Swiss-Model (Biozentrum). RESULTS: The protein sequence of the peptides were changed according to the Sri Lankan isolates (AEB98757.1, ACS32038.1, AHG23239.1 and AHN50410.1). Oxidation of Cysteine residues results in significant conformational changes. Replacement of Cysteine with Serine prevents such oxidation reactions and it often retains full biological activity. Generally, peptides with a high number of hydrophobic AA (>50%) may result insoluble peptides. Similarly, to obtain a soluble peptide, it is important to contain at least one charged AA in every five AAs. Hence, the number of hydrophobic residues in the peptides were maintained below 50% and ensured that one out of every five amino acids is charged. The length of the peptide is an important factor as long peptide increases immunogenicity, but also increases the chance for cross-reactivity while a short peptide improves the specificity, but may not be immunogenic. In order to obtain both highly conserved and variable regions among four serotypes, the peptide length was determined as 29 residues. A terminal Cysteine was added to allow peptide conjugation with carrier protein. Keyhole Limpet Hemocyanin was selected as the carrier protein due to its higher immunogenicity. N-terminal Glutamine or Aspargine and C-terminal Proline or Glycine in the sequences were avoided. Finally, the peptides sequences were determined as: DEN1; CPESSDDQRA WNIWEVEDYGFGIFTTNIW,DEN2; CAESPN TNRA WNSLEVEDYGFGVFTTNIW, DEN3;CPESPSASRAWNVWEVEDYGFGVFTTNIW and .DEN4;CSESPNERRAWNSLEVEDYGFGMFTTNIW. CONCLUSION: These peptides have a high potential to be used as peptide antigens for Monoclonal Antibody production.Item Laboratory studies on larvivorous potential of five fish species against Aedes ageypti (Linnaeus) and Ae. albopictus (Skuse)(Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Gunathilaka, P.A.D.H.N.; Hapugoda, M.; Abeyewickreme, W.BACKGROUND: The dengue vectors, namely, Aedes aegypti (Linnaeus) and Ae. albopictus (Skuse) are container breeders, thus, container management is a key element for elimination of vector breeding sites. Use of predator fish is a potential tool for dengue vector control in some container habitats. However, in order to select suitable fish species, larvivorous potential of different fish species needs to be determined. Therefore, the objective of the study was to determine the larvivorous potential of some fresh water fish species against the dengue vectors. METHODOLOGY: Five fish species, namely: Poecilia reticulata, Aplocheilus dayi, Oreochromis niloticus, Rasbora daniconius and Puntius bimaculatus were collected from their natural breeding places during the field surveillance conducted from January-October, 2015. Each fish species was placed in separate fish stock cement tanks at the Regional Office of the Anti- Malaria Campaign in Kandy until they were used for the study. In order to determine the larvivorous potential of the fish, each species was placed in separate enamel trays containing de-chlorinated water and allowed to acclimatize for 30 minutes. A batch of 25 Ae. aegypti and Ae. albopictus larvae was introduced to each tray superlatively and the number of larvae remaining was counted after 24 hours of observation period. Once all the batch of larvae consumes by the fish species, another batch of 25 larvae from respective species was introduced during the observation period. The whole experiment was repeated for 6 times. RESULTS: The mean values of Ae. aegypti larvae consumed by one fish of O. niloticus, P. reticulata, A. dayi, R. daniconius and P. bimaculatus were 97.6, 66.9, 49.3, 62.5 and 47.5 respectively while, one fish of O. niloticus, P. reticulata, A. dayi, R. daniconius and P. bimaculatus consumed 98.4, 62.3, 51.2, 62.5 and 45.4 of mean Ae. albopictus larvae respectively. CONCLUSIONS: All five fish species showed larvivorous activity. However, O. niloticus showed the highest larvivorous potential followed by P. reticulata. Therefore, these two fish species may be considered as a supplementary method to control immature stages of dengue vectors.Item Effects of socio-economic and socio-cultural risk factors on low malaria transmission in Mannar and Trincomalee Districts of Sri Lanka(University of Kelaniya, 2014) Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.; Ranathunge, R.M.T.B.; Hapugoda, M.D.; Wickremasinghe, A.R.The socio-economic and socio-cultural practices of the people differ between communities and play an important role in malaria control operations. The present study was conducted to assess the influence of household socio-economic and socio-cultural status on reduction of malaria transmission in the Districts of Mannar and Trincomalee, which are endemic regions for malaria in Sri Lanka.