Journal/Magazine Articles
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This collection contains original research articles, review articles and case reports published in local and international peer reviewed journals by the staff members of the Faculty of Medicine
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Item Hemoglobin variants in patients with type-2 diabetes mellitus(SEAMEO Regional Tropical Medicine and Public Health Project, 2010) Chandrasena, L.G.; Peiris, H.; Williams, S.; Siribaddana, S.H.Measurement of HbA1c levels in diabetic patients is an established procedure for evaluating long-term control of diabetes. Despite its usefulness, conditions that effect hemoglobin concentration, such as hemoglobinopathies give rise to inappropriate HbA1c values. Since information about hemoglobinopathies in the diabetic population in Sri Lanka is limited, a prospective cross-sectional study was carried out among 2,695 diabetic subjects attending the diabetic clinic at Nawaloka Hospital, Sri Lanka. Hemoglobin type and HbA1c were measured by the HPLC method. The results reveal among 2,695 diabetic subjects, 53 (2%) had abnormal hemoglobin types (HbF and HbS). HbA1c concentrations in diabetic patients without Hb abnormalities show a higher correlation with fasting blood glucose than those with hemoglobin abnormalities. This study emphasizes that patients with inappropriate HbA1c values should be investigated for hemoglobinopathies.Item Biochemical changes associated withnreperfusion after off-pump and on-pump coronary artery bypass graft surgery(Institute for Clinical Science., 2009) Chandrasena, L.G.; Peiris, H.; Waikar, H.D.A prospective study was performed to monitor the postoperative changes in biochemical markers associated with reperfusion injury following (i) cardiopulmonary bypass (CPB) with aortic cross-clamping and cardioplagia (CABG); (ii) CPB with a tissue stabilizing device (SUP.CPB); or (iii) surgery on beating heart (off-pump CABG or OPCABG). Of the 48 patients, 16 were subjected to CABG, 16 to SUP.CPB, and 16 to OPCABG. Arterial and venous blood samples drawn 10 min preoperatively and 0.2, 4, 24, and 48 hr after surgery were assayed for plasma lactate, total calcium, and ionized calcium and erythrocyte glutathione peroxidase (GPX) and superoxide dismutase (SOD). Results revealed that ionized calcium, SOD, and GPX levels of all patients increased at 4 hr following surgery but returned to baseline levels at 24 or 48 hr after surgery. Increased postoperative GPX levels reflect a cellular defense mechanism against oxidative damage during reperfusion, while lactate levels during reperfusion reflect delayed recovery of aerobic myocardial metabolism. The postoperative release of lactate, GPX, and SOD in patients undergoing the CABG (on-pump) technique was significantly higher compared to those subjected to OPCABG or SUP.CPB. There were no significant differences in postoperative patterns of release of biomarkers in patients with OPCABG vs SUP.CPB, suggesting that these surgical techniques are equally acceptableItem Changes in erythrocyte glucose-6-phosphate dehydrogenase (G6PD) and reduced glutathione (GSH) activities in the development of senile and diabetic cataracts(SEAMEO Regional Tropical Medicine and Public Health Project, 2008) Chandrasena, L.G.; de Silva, L.D.R.; de Silva, K.I.; Dissanayaka, P.; Peiris, H.Oxidative and osmotic stress have been implicated in the pathogenesis of cataracts. Reactive oxygen intermediates (ROI) mediate peroxidation of membrane lipids and cause irreversible damage to lens proteins. The purpose of this study was to assess the changes in erythrocyte glucose- 6-phosphate dehydrogenase enzyme (G6PD) and reduced glutathione (GSH) levels in the development of senile and diabetic cataracts. The activity of erythrocyte G6PD and the concentration of GSH were measured to assess changes in oxidation-reduction status. The oxidation-reduction status of 26 non-diabetic non-cataract (control) subjects were compared with 24 diabetic non-cataract, 30 diabetic cataract and 28 non-diabetic cataract subjects. The results revealed that the GSH and G6PD levels of the subjects with senile cataracts were significantly lower than the subjects without cataracts. The present study reveals the risk of developing senile cataracts is associated with decreased levels of erythrocyte G6PD and GSH. In the formation of diabetic cataracts an adequate supply of NADPH (G6PD activity) is essential to produce osmotically active sorbitol in the lensItem Fifty years after Watson and Crick(University of Sri Jayewardenepura, 2007) Chandrasena, L.G.; Peiris, H.; Welihinda, J.AbstractItem Erythrocyte antioxidant enzymes in patients with cataract(Institute for Clinical Science., 2006) Chandrasena, L.G.; Chackrewarthy, S.; Perera, P.T.; de Silva, D.The pathogenesis of cataract has been found to be influenced by a number of factors including oxidative stress. Catalase, glutathione peroxidase (GPX), and superoxide dismutase (SOD) are some of the antioxidant enzymes that protect the body from oxidative damage. The present study investigates the activities of erythrocyte catalase, GPX, and SOD with respect to senile cataract (non-diabetic cataract) and osmotic cataract (diabetic cataract) in a Sri Lankan population. One hundred and two non-diabetic subjects (50 with cataract and 52 non-cataract) and 106 diabetic subjects (56 with cataract and 50 non-cataract) were recruited into the study. Erythrocyte catalase, GPX, and SOD activities were assayed and the data were analysed by t-test (p <0.05 for significance). In the non-diabetic group, significantly low levels of catalase, GPX, and SOD activities were associated with cataract when compared with non-cataract. No significant changes in catalase, GPX, and SOD activities were observed in the diabetic group between cataract and non-cataract. Senile cataract (non-diabetic cataract) was associated with significantly low levels of erythrocyte catalase, GPX, and SOD when compared with osmotic cataract (diabetic cataract). Positive correlations were observed between catalase and SOD (r = 0.75), catalase and GPX (r = 0.63), and SOD and GPX (r = 0.59) in subjects with senile cataracts. Our results indicate that erythrocyte antioxidant enzyme levels are decreased in senile cataract as opposed to osmotic cataract. Assays of these erythrocyte enzyme activities could provide a marker to identify individuals predisposed to senile cataract.Item Laboratory statistics in Clinical Decision marking Sri Lanka(The Kandy Society of Medicine, 2005) Chandrasena, L.G.; Peiris, H.; Sivayogan, S.No Abstract Available.Item Red blood cell antioxidant levels in Wuchereria bancrofti infections(Academic Press, 2002) Premaratna, R.; Chandrasena, T.G.A.N.; Abeyewickreme, W.; Chandrasena, L.G.; Senerath, S.; de Silva, N.R.; de Silva, H.J.The elimination of microfilariae of Wuchereria bancrofti is probably mediated by free radicals. Red cell catalase (C), glutathione peroxidase (GPX), and superoxide dismutase (SOD) activity levels were measured as an indirect method of assessing blood oxidant status in 29 asymptomatic microfilaraemics, 29 "endemic normals", and 29 controls living in a non-endemic area. Changes in the activity of these enzymes were also compared over a one month period in 22 asymptomatic microfilaraemics randomised to receive either single dose or 14 day treatment with diethyl carbamazine citrate (DEC). Red cell GPX activity levels were significantly higher in "endemic normals" when compared to mf positive cases and non-endemic controls. An early and significant increase in GPX activity (on days 3, 7 and 14 compared to pretreatment levels, p<0.01) was observed after DEC in both treatment groups. Increases in the activity of catalase and SOD became significant only on days 14 and 30 respectively. The percentage reduction in microfilaraemia correlated significantly with the percentage increase in GPX activity levels (R(2)=0.58, p=0.6 x 10(-5)). Our results may suggest a role for GPX related oxidant species in the elimination of microfilariae.Item Protection by garlic against adriamycin induced alterations in the oxido-reductive status of mouse red blood cells(Wiley, 2000) Thabrew, M.I.; Samarawickrema, N.A.; Chandrasena, L.G.; Jayasekara, S.The effects of oral garlic supplementation on the activities of (a) the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX) and (b) lipid peroxidation, as assessed by malondialdehyde (MDA) production in red blood cells of normal mice and those subject to oxidative stress by chronic administration of the anti-tumour drug adriamycin has been investigated. As expected, adria-mycin administration resulted in a significant increase in MDA generation (by 105.4%) and a decrease in GPX activity (by 23.8%) in the red blood cells. Although garlic had no significant effects on the basal levels of the antioxidant enzymes or MDA generation in red blood cells of normal mice (untreated with adriamycin), at doses of 20 mg/kg or 100 mg/kg, garlic was able to decrease significantly the adriamycin induced changes in the oxido-reductive status of the redblood cells. Thus, on administration of adriamycin to mice fed diets containing 20 mg/kg or 100 mg/kg garlic, the drug-induced increase in MDA generation was 38.2% and 22.5% respectively, less than that produced by adriamycin in mice fed normal diets, containing no garlic (105.4%). Similarly, in mice fed diets providing 20 mg/kg and 100 mg/kg garlic, adriamycin was able to decrease GPX activity by only 15.1% and 7.6% respectively, less than that produced by adriamycin in rats fed normal diets, containing no garlic (23.9%).Item Effect of oral supplementation with vitamin E on the oxido-reductive status of red blood cells in normal mice and mice subject to oxidative stress by chronic administration of adriamycin(Sage Publishing, 1999) Thabrew, M.I.; Samarawickrema, N.A.; Chandrasena, L.G.; Jayasekara, S.The effect of oral vitamin E supplementation on the oxido-reductive status of red blood cells in normal mice and those subject to oxidative stress by chronic administration of the anti-tumour drug Adriamycin was investigated. Mice were randomly separated into three groups of 20 animals each and maintained on diets identical in all respects except for vitamin E content. Group 1 received a low vitamin E diet that provided 10 mg vitamin E/kg body weight/day, group 2 received a normal mice chow diet (45 mg vitamin E/kg body weight/day) while group 3 received a high vitamin E diet (200 mg vitamin E/kg body weight/day). In comparison with the normal mice in group 1, their counterparts in groups 2 and 3 exhibited significantly higher (P 0.001) activities of superoxide dismutase (SOD) in red blood cells (79.4 percent higher in group 2 and 114.2 percent higher in group 3, respectively) and produced lower concentrations of malondialdehyde (MDA) (22.9 percent less in group 2 and 51.2 percent less in group 3, respectively), with little difference in the glutathione peroxidase (GPX) activity. In Adriamycin-treated animals on the low vitamin E diet (group 1) the red blood cell SOD activity and MDA production were 46.2 percent and 200.7percent higher (P 0.001), respectively, and the GPX activity was 39.1percent lower than in the red blood cells of untreated (normal) animals in the same group. The Adriamycin-induced changes were significantly less in animals receiving higher doses of vitamin E (groups 2 and 3). Thus, in the group maintained on the high vitamin E diet (group 3), Adriamycin administration resulted in only a 38.9 percent increase in the MDA production above that generated by red blood cells of normal mice in the same group, with no significant change in the SOD or GPX activities. Thus, in normal conditions as well as in conditions of oxidative stress, high doses of vitamin E appear to be able to protect the oxido-reductive status of red blood cells by modulating the extent of lipid peroxidation as well as the activities of antioxidant enzymes.Item Hepatitis B and C virus markers among new entrant medical students(Sri Lanka Medical Association, 1999) Premawardhena, A.P.; Premaratna, R.; Jayaweera, G.; Costa, S.; Chandrasena, L.G.; de Silva, H.J.AIM: To investigate the presence of hepatitis B and C virus markers in new entrant medical students at the Faculty of Medicine, University of Kelaniya. METHOD: 456 students (mean age 24 years, SD 3.5, 257 men) were investigated before they were exposed to clinical work, using a questionnaire to assess sociodemographic factors and possible risk factors for contracting hepatitis B or C. Blood samples were tested for HBs Ag and anti HBs (n = 456), and anti-HCV (n = 162 randomly selected samples) with a third generation sandwich radioimmunoassay technique. RESULTS: The students were from 20 of the 25 districts in the country, although their distribution was not inform. A past history of hepatitis or jaundice was obtained from 24 (5.3 percent ) and 6 (1.3 percent ) students respectively. None of them had been vaccinated against hepatitis B. At least one risk factor for hepatitis B or C was present in 32 (7 percent ) of them. None of the samples were positive for HBsAg or anti-HCV, and only two (0.44 percent ) were positive for anti-HBs. CONCLUSION: Our results support the view that exposure to hepatitis B and C seems to be uncommon in this country, at least up to young adulthood. As most new entrant medical students are not immune to these infections there is a strong case to vaccinate them against hepatitis B before they are exposed to clinical work.