Browsing by Author "Adikari, D."

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    Optimization of Irradiation Dose for Sterilization of Aedes aegypti (Linnaeus) Mosquitoes for Application of Sterile Insect Technique (SIT) Program in Sri Lanka
    (International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Ranathunge, T.; Adikari, D.; Harishchandra, J.; Gunawardene, N.S.; Hapugoda, M.
    There is an increasing demand for exploration of the potential of applying sterile insect techniques (SIT) in area-wide integrated vector management (AW-IVM) in many countries. Sterility of male insects can be accomplished with ionizing irradiation and SIT focus on release of sufficient sterile male mosquitoes to induce sterility in the wild females which over time causes decline of the target mosquito population. Therefore, current study was focused on determining the effects of different doses of radiation on survival, flight ability and reproductive capacity of local strains of Aedes aegypti (Linnaeus) for SIT application in Sri Lanka. Adults Ae. aegypti were maintained under standard laboratory conditions at the Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka. Male pupae and female pupae were separated using a Fay and Morlan glass plate technique. A total of 100 male Ae. aegypti pupae were exposed to each different irradiation doses (40, 50, 60, 70 and 80 Gy) using Co60 source of gamma rays. Effects of irradiation on pupal mortality, flight ability, fertility and adult male survival were monitored under laboratory conditions. One-way analysis of variance (ANOVA) was used to investigate the significance in the variations among observed factors. Kaplan-Meier survival analysis was conducted to estimate the survival functions of irradiated males. The survival in relation to different radiation doses were compared using ANOVA followed by Tukey’s pairwise comparison. The survival of irradiated pupae was invariably greater than 90% in control- and in test groups and they did not differ significantly (P > 0.05). Irradiation had no significant adverse effects on the flight ability (capacity to fly out of a test device) of male mosquitoes, which consistently exceeded 90%. The fertility of female mated with irradiated male was significantly reduced in Ae. aegypti at all doses and zero fertility was observed at 70 and 80 Gy. Ae. aegypti, fertility in irradiated males mated with female was less than 1% at 50 and 60 Gy. The male mean survival time was reduced by irradiation in a dose-dependent manner. However, the mean survival time in control and sterilizing doses of 40, 50, 60 and 70 did not differ significantly (P > 0.05). Therefore, 50 Gy dose will be used as the optimal radiation dose Ae. aegypti population for future evaluations of SIT-based control. The results of the present study will be applied to studies of male sexual competitiveness and for stepwise evaluations of the SIT for suppression of Ae. aegypti population in Sri Lanka.
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    Upper respiratory symptoms are common in a cohort of patients with symptomatic gastrooesophageal reflux disease (GORD) in Sri Lanka
    (Wiley Blackwell Scientific Publications, 2011) Amarasiri, D.L.; Adikari, D.; Sanjeewa, B.; Jayaratne, A.; Dassanayake, A.S.; de Silva, A.P.; de Silva, H.J.
    INTRODUCTION: There is increasing evidence for multiple associations between gastro-oesophageal reflux disease (GORD) and the upper respiratory tract. This study evaluated the presence of upper respiratory symptoms (URS) in a cohort of patients with GORD symptoms from Sri Lanka. METHOD: Seventy adults scoring ≥12.5 on a previously validated GORD symptom score (GORD patients) and 70 healthy controls who had infrequent or no GORD symptoms completed a pre-tested, valid URS questionnaire. They were questioned on frequency of 14 URS in 5 categories (laryngeal, nasal, pharyngeal, sinusal and aural). All GORD patients underwent gastroscopy. An URS score was calculated and correlated against the GORD symptom score and gastroscopy fi ndings. RESULTS : The GORD patients (median age (range) 36 (15–65); 38% males) and controls (median age (range) 38 (15–68); 38% males) were comparable. URS scores were higher in GORD patients (mean ± SE, 4.7 ± 4.0) compared to controls (mean ± SE, 1.9 ± 2.3), as were individual symptom scores. Individuals with higher GORD symptoms scores reported more frequent URS. Nasal symptoms had the highest correlation with the GORD symptom score (r = 0.410; P = 0.001). of the GORD patients, 42 had no evidence of oesophageal or gastric mucosal damage. 28 had evidence of refl ux oesophagitis. In them, the presence of oesophagitis did not seem to influence the frequency of reporting URS. CONCLUSION : URS are common in individuals with GORD symptoms though there appears to be no association with oesophageal mucosal damage