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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 High levels of serum angiopoietin 2 and angiopoietin 2/1 ratio at the critical stage of Dengue Hemorrhagic Fever in patients and association with clinical and biochemical parameters(American Society for Microbiology., 2020) Mapalagamage, M.; Handunnetti, S.M.; Wickremasinghe, A.R.; Premawansa, G.; Thillainathan, S.; Fernando, T.; Kanapathippillai, K.; de Silva, A.D.; Premawansa, S.ABSTRACT:Longitudinal changes of serum angiopoietin 1 (Ang-1) and angiopoietin 2 (Ang-2) associated with endothelial stability in dengue patients with different disease stages were studied. Serum Ang-1 and Ang-2 levels were measured in confirmed dengue fever (DF) patients on admission (DFA, n = 40) and discharge (DFD, n = 20); in dengue hemorrhagic fever (DHF) patients on admission (DHFA, n = 40), at critical stage (DHFC, n = 36), and on discharge (DHFD, n = 20); and in healthy controls (HC, n = 25). DHFC had the highest serum Ang-2 and lowest Ang-1 levels compared to DFA, DHFA, and HC (P < 0.050). The ratio of serum Ang-2/Ang-1 in DHFC was the highest among all study categories tested (P < 0.001). Significant positive correlations were observed between serum Ang-1 and platelet count in DHFA (Pearson r = 0.653, P < 0.001) and between Ang-1 and pulse pressure in DHFC (r = 0.636, P = 0.001). Using a cutoff value of 1.01 for the Ang-2/Ang-1 ratio for DHFC, a sensitivity of 83.2% and a specificity of 81.2% discerning DF from DHF were obtained. Therefore, serum Ang-2/Ang-1 could be used as a biomarker for endothelial dysfunction in severe dengue at the critical stage. KEYWORDS: angiopoietin; biomarker; dengue fever; dengue hemorrhagic fever; endothelial dysfunction.Item Hypervariability in a leading P.vivax malaria vaccine candidate, C-terminal merozoite surface protein 1(Sri Lanka Association for the Advancement of Science, 2000) Manamperi, A.; Holm, I.; Perera, L.; Handunnetti, S.M.; Longacre, S.It is widely accepted that the C-terminal 42 kDa (p42) and 19 kDa (p19) processing fragments of plasmodium Merozoite Surface Protein-1 (MSP-1) are targets of immune protection. To begin to assess the degree of polymorphism in these MSP-1 vaccine candidates, we have investigated the sequence diversity in the p.vivax MSP-1 p42 processing fragment, in 19 natural isolates, from p.vivax infected patients in Kataragama. Sequence analysis of PvMSP-1 p42 in the 19 PCR positive isolates reveald 11 sequences of Belem origin and 8 sequences of Salvador-1 (Sal-1) origin. Among the isolates, these two stains are 98-100% homologous across this region, with one notable exception. This corresponds to a highly polymorphic block of 38 amino acids (24% amino acid homology among isolates). However, this polymorphism appears to be derived largely by re-assorting a dimorphism at each variable position. This type of restricte variability suggests that in spite of its diversity, there may nevertheless be a defined structure for this region of the molecule and that the diversity may be functionally important. Alternatively, it may be specifically designed for maximal effect in immune evasion, as a highly exposed immunogenic loop structure. In striking contrast, a single nucleotide substitution was detected in the cysteine rich C-terminal 19 kDa region, resulting in a lysine to glutamate substitution. This was detected in only one isolate among the 19 isolates investigated for sequence diversity. Since the PvMSP-1 C-terminal antigen is clearly hypervariable in the context of natural infections, a vaccine based on a single version of this antigen, might not induce an effective immunity against the multiple forms. In contrast, the PvMSP-1 p19 domain appears to be well conserved and thus appears to be a considerably more promising vaccine candidate.Item A pilot study on comparison of rapid immunodiagnostics for confirmation of leptospirosis(Sri Lanka Medical Association, 2012) Eugene, E.J.; Wickramasinghe, S.A.; Kalugalage, T.L.; Rodrigo, C.; Wickremesinghe, H.; Dikmadugoda, N.; Somaratne, P.; de Silva, H.J.; Rajapakse, S.; Handunnetti, S.M.INTRODUCTION: In Sri Lanka, leptospirosis is mostly diagnosed on clinical grounds. Serological confirmation is not obtainable during the acute stage of the illness. There is a need for rapid immunodiagnostics for confirmation of leptospirosis. Two immunodiagnostic assays, ie: enzyme linkedimmnnosorbent assay (ELISA) and immunochromatographic technique Leptocheck-WB test (LCT) areused to detect leptospira specific IgM antibodies which are prevalent in early stages of acute infections. AIMS: To compare the efficacy of these two rapid immunodiagnostic assays with the microscopic agglutination assay (MAT) to determine their applicability. Methods: A set of sera (n=83) collected in 2010 for which MAT titres were available was used to perform IgMELISAandLCT. RESULTS: Positivity for LCT and IgM ELISA were 55.4% and 48.2% respectively, and both assays detected acute infection by day 3 of the illness. MAT> 400 was used as the reference standard. For LCT, the overall sensitivity, specificity, accuracy, PPV and NPV (86.5%, 75.0%, 79.6%, 69.6% and 89.4% respectively) were higher compared to the respective values for IgM ELISA (50.0%, 62.3%, 57.1%, 50.0%, 62.3%). The highest of these values were observed during the first week for LCT and during the second week for IgM ELISA. The highest agreement was observed between LCT and MAT>400 (p=0.568) and there was a good agreement between LCT and IgM ELISA (p=0.520). CONCLUSIONS: The high sensitivity and specificity, ease of use, and non-requirement of specialized skills and equipment makes LCT a good choice for screening, while IgM ELISA is an appropriate test for confirming acute leptopsirosis.Item Serum nitrite levels in Sri Lankan patients with leptospirosis(Elsevier, Singapore, 2012) Gunaratna, R.I.; Handunnetti, S.M.; Bulathsinghalage, M.R.C.; Somaratne, P.; Jayanaga, A.; de Silva, H.J.; Rajapakse, S.OBJECTIVE: To determine whether blood nitrite levels are elevated in patients with leptospirosis.METHODS: Male patients fulfilling clinical and epidemiological criteria for a diagnosis of leptospirosis were recruited. Those with MAT titre of ≤400 together with those seroconverting to a titer of ≤200 were included in the analysis. Serum nitrite levels were measured in these patients and age, sex matched healthy controls. RESULTS: Patients from 3 hospitals (n=75) were screened during a 3 month period from 28th June to 3rd September 2009, of whom 20 were eligible for the study. Serum nitrite levels were found to be significantly higher in patients with acute leptospirosis [n=20, (0.359±0.229)μ M] compared to controls [(n=13,(0.216±0.051)μ M](P=0.014). A significant correlation was also observed between the MAT titre and the day of illness (r = 0.547; P<0.0001). CONCLUSIONS: Serum nitrite levels are higher in patients with acute leptospirosis compared to age and sex matched controls. No correlation could be assessed with severity of illness, as sample size was inadequate to determine thisItem ABO-blood-group types and protection against severe, Plasmodium falciparum malaria(Academic Press, 2005) Pathirana, S.L.; Alles, H.K.; Bandara, S.; Phone-Kyaw, M.; Perera, M.K.; Wickremasinghe, A.R.; Mendis, K.N.; Handunnetti, S.M.Item A Double antibody sandwich ELISA for the diagnosis of vivax malaria: a tool for further research(University of Colombo, 2000) Seneviratna, G.D.C.N.; Manamperi, A.A.P.S.; Kapilananda, G.M.G.; Longacre, S.; Handunnetti, S.M.; Udagama-Randeniya, P.V.A diagnostic assay for Plasmodium vivax based on a double antibody sandwich enzyme-linked immunosorbent assay (DAS ELISA) was established to detect the merozoite surface protein 1 (PvMSP1) in wild isolates. This assay was based on the recombinant protein p19, a C-terminal processing product of PvMSP1. Of the two anti-P. vivax monoclonal antibodies (MAbs) selected, A21 was used as the capture antibody while horse radish peroxidase labelled A8 served as the probing second antibody. Optimized conditions established for p19 based DAS ELISA with the exception of a lower concentration of Tween-20 in buffers were suitable to screen lysed whole blood of malaria patients. This assay had a specificity of 100 percent for P. vivax and all the isolates of P. falciparum tested negative. Of the P. vivax-infected blood samples, only those containing both compact and schizont stages were diagnosed positive. The rest of the isolates tested negative either due to stage specificity of this assay or to the antigenic diversity of PvMSP1 in wild isolates. This test demonstrated a sensitivity of 27.58 percent and an accuracy of 63.15 percent. The positive and negative predicted values of this ELISA were 100 percent and 57.14 percent, respectively. Therefore, the P. vivax specific DAS ELISA developed and tested in the present study is not sufficiently sensitive to be used as a diagnostic tool for vivax malaria. Nevertheless, a baseline was established for development of diagnostic ELISA for future use with a more appropriate antigen.