Browsing by Author "de Silva, P."

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    Assessing Potential Genotoxic Effects of Nano-Titanium Dioxide on Nile Tilapia (Oreochromis Niloticus)
    (Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) de Silva, P.; Pathiratne, A.
    Due to widespread use of titanium dioxide nanoparticles (nano-TiO2) in many industrial applications, significant release of nano-TiO2 to the environment can occur which may eventually reach aquatic ecosystems. Hence biological impacts of nano-TiO2 to the aquatic fauna especially fish under chronic exposure need to be explored. Nile tilapia, Oreochromis niloticus is used as a bioindicator for evaluating toxic effects to environmental substances in tropical waters. The aim of the present study was to assess the potential genotoxic effects of water-borne nano-TiO2 on Nile tilapia under chronic exposure conditions. Fish were exposed to a range of nano-TiO2 (<25 nm, anatase) concentrations viz 0.1 mg/L, 0.5 mg/L and 1.0 mg/L along with the controls for 21 days and genotoxic effects were evaluated weekly by micronucleus assay and Comet assay using peripheral erythrocytes. Even though micronuclei induction in the erythrocytes was higher in the fish exposed to the lowest nano-TiO2 concentration (0.1 mg/L) at 7 and 21 days of exposure, a statistically significant concentrationresponse pattern was not observed (P > 0.05). Comet assay revealed that DNA damage in erythrocytes of Nile tilapia could be induced by nano-TiO2 even at 0.1 mg/L level (P < 0.05) by 21 days of exposure. Compared to micronucleus assay, Comet assay was more effective in detecting genotoxic effects on Nile tilapia. The results indicate that nano-TiO2 exposure could lead to genotoxic hazards to the fish populations in the contaminated water bodies.
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    Clinical utility of PCR and real time PCR assays for Cytomegalovirus, hepatitis B and hepatitis C infections.
    (Sri Lanka Association for the Advancement of Science, 2008) Dassanayake, R.S.; de Silva, P.; Weerasena, J.; Gunawardene, Y.I.N.S.; Manamperi, A.
    Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Reactivation of cytomegalovirus (CMV), Hepatitis B (HBV) and C (HCV) viruses from the status of latency is seen in immunocompromised individuals and such reactivation is often associated with morbidity and mortality in such individuals. The prevalence of these viral infections in a selected population of patients referred to the Molecular Diagnostic Laboratory at the Durdan's Hospital, Colombo, during the period from August 2007 to May 2008 were studied using qualitative PCR assays. All specimens from patients with suspected clinical diagnoses of either CMV or HBV or HCV infections were analyzed. Of 176 samples analyzed for CMV 78 were positive (37 males, 29 females) and majority of them are patients from a nephrology unit. Out of 40 and 10 samples analyzed from males and females, respectively, 22 and 4 were positive for HBV. Twenty six samples were analyzed for HCV and only 6 were fond to be infected with viruses and all of them were from males. Although PCR detection of these viral DNA/RNA is a sensitive method to detect infection, it lacks specificity for the detection of active viral disease and for monitoring the efficacy of antiviral therapy. Therefore, Real-time PCR (RT-PCR) assays for the detection and quantification of CMV-DNA, HBV-DNA and HCV-RNA were developed using SYBRgreen1 chemistry. The assays developed are capable of detecting viral particles in blood samples and quantifying viral DNA accurately over a broad range of input target copies (102 - 108copies/ml) and therefore, can be used to predict the reactivation of viruses by comparing with published kinetic criteria in clinical guidelines. Post PCR analyses of Real-time PCR products by agarose gel electrophoresis revealed bands having the same intensity for a wide range of target copies (103 -108copies/ml). In contrast, RT-PCR elicited higher cycle threshold for the descending order of concentration of target copies. Therefore, based on these results, it is evident that the intensity of conventional PCR bands should not be used for the assessment of viral reactivation or for monitoring therapeutic intervention and for this purpose RT-PCR is the method of choice
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    Concurrent validity of the alcohol use disorders identification test (AUDIT)
    (Oxford University Press, 2008) de Silva, P.; Jayawardana, P.; Pathmeswaran, A.
    AIMS: To determine cut-offs for the Alcohol Use Disorders Identification Test (AUDIT) 10-item questionnaire, differentiating hazardous drinking (HZD) and alcohol use disorders (AUD) from low risk drinking (LRD), and AUD from HZD and LRD among married men in a Sri Lankan sample. METHODS: Using 62 low risk drinkers and 88 each from hazardous drinkers and AUD, the AUDIT instrument was compared with adapted and translated versions of a beverage-specific, quantity-frequency questionnaire, and the alcohol use module of the Composite International Diagnostic Interview (CIDI), and two receiver operating characteristic (ROC) curves were plotted. RESULTS: The area under the ROC curves to differentiate HZD + AUD from LRD and AUD from HZD + LRD were 0.96 (95% CI: 0.94-0.99) and 0.97 (95% CI: 0.95-0.99) respectively. The cut-off values of 7 and 16 were observed to have the best trade-offs between sensitivity, specificity, the ratio of positive likelihood to negative likelihood ratios, and positive predictive values. CONCLUSION: The AUDIT could be used to screen for LRD, HZD, and AUD among Sinhalese married men in Sri Lanka.
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    Effectiveness of teaching clinical skills in improving simple wound suturing among medical undergraduates
    (The Kandy Society of Medicine, 2005) Abeysuriya, V.; de Silva, P.; Pathirana, A.
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    Rapid differential diagnosis of dengue and chikungunya infections by multiplex RT-PCR and impact of chikungunya infection on liver biochemical tests
    (Sri Lanka Association for the Advancement of Science, 2008) Manamperi, A.; de Silva, P.; Ekanayaka, C.; Gunawardene, Y.I.N.S.; de Silva, J.; Weerasena, O.V.D.S.J.; Dassanayake, R.S.
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    Uterine artery embolisation (uae) for symptomatic uterine fibroids
    (Sri Lanka College of Obstetricians and Gynaecologists, 2005) Rannulu, P.; de Silva, P.; Fernando, W.S.
    INTRODUCTION: Uterine Artery Embolisation is a modern treatment modality used in the treatment of symptomatic uterine fibroids. Though common in the developed world it is still not routinely done in Sri Lanka. We report four patients with symptomatic uterine fibroids who were treated with bilateral UAE. SETTING: North Colombo Teaching Hospital, Ragama. METHOD: Four patients with symptomatic leiomyomas were selected from Gynaecology out patient clinics. Sizes of the fibroids were assessed by ultrasound imaging. Bilateral UAE was performed via retrograde femoral artery catheterization of the uterine arteries under local anaesthesia using absorbable soft Gelatine (USP). Imaging of the myomas were performed three months after the procedure. Results: Size of the fibroids were reduced in three patients when compared with the pre- procedure imaging. No major complications were noted. The severity of menorrhagia was reduced in three Patients. One patient failed to respond to the therapy with regard to the reduction of size of the fibroid and improvement of symptom severity. CONCLUSIONS: UAE is a non-surgical alternative in the management of symptomatic fibroids, which could be carried out in the local setting.
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