University of Colombo

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    Academic performance and drop-out in Sri Lankan Universities
    (University of Colombo: UC(SCI)., 1998) KOTTAHACHCHI, BD
    The aim of the research was to identify the factors which influence the academic performance and the drop out of students Sri Lankan Universities. The major findings are given below:-1. GCE A Level aggregate marks which are held to determine academic ability at entry is identified as the most crucial variable which influences academic performance. It is also relevant to the drop out of students who require pre-entry subject specific knowledge for their courses at university. 2. The results at the first examination is a significant predictor of degree completion. 3. Students entering with high marks generally graduated with a calss. This linkage is more marled for students who require pre-entry subject specific knowledge at university. 4. Students from urban districts generally enter with higher marks than those from rural districts and they have a higher pass rate at examination than those from rural distrits. 5. Students entering on their first attempt have entered with higher marks than repeaters and they have a higher pass rate at examinations than the latter. 6.When students are clssified according to either gender or medium, the group that entering with high marks at A Level....
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    Aetiology of childhood diarrhoea in children treated at the Children's Hospital, Colombo
    (University of Colombo: UC(MED)., 1992) JAYAWARDENE, MIFP
    Viral, Bacterial and Protozoan causes of childhood diarrhoea in Colombo, clinical features, seasonality and risk factors, and antibiotic sensitivity were studied in a 3 year prospective study. The commonest virus isolated was the Rotavirus and the Bacteria was shigellae among a host of other pathogens. Adenovirus was the commonest pathogen isolated among cases treated in the OPD Majority were between 3 months and 3 years and 50 percent were malnourished. Evidence showed infection was due to pollution and No seasmality was seen. Over use of Antibiotics was seen both at primary health care level and the hospital and increased the risk of persistant diorrhoea by four fold.
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    Allelic polymorphisms of malarial and human genes in relation to disease occurrence and pathogenesis
    (University of Colombo: UC(MED)., 1999) PERERA, WVJ
    Among the determinants of pathogenesis of malarial disease, parasite genetic factors and host genetics play a major role. Human TNF allele polymorphisms and their associations with severe infectious diseases and genetic composition of malarial infections were studied using PCR oligonucleotide probing. The results of this study showed that the mean number of genetically distinct parasite clones per isolate for parasite infections in Kataragama (endemic) patient population (2.17) is significantly higher than the parasite isolates from patients in Colombo (non endemic) (1.59=0.0001)
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    Ambient air quality study of the pollution caused by vehicular exhaust emissions in the city of Colombo.
    (University of Colombo: UC(SCI)., 1998) KARUNASINGHE, AWJ
    The study was performed to determine the concentrations of particulatematter (total suspended perticulate and fine dust), lead, polycyclic hydrocarbons, total hydrocarbone, non-methane hydrocarbons, methane sulphur dioxide and carbon monoxide in the air on regular basis at seven selected intersections in the city of colombo during the period from 1990 to 1993 primary climatic data such as humidity rainfall wind speed were also recorded especially during air sampling for particulate matter.Total Suspended, particulate (TSP) and fine dust (FD) measured using a high volume air sampler indicated that the average TSP concentration was 404 ug/m3 with a variation between 100-960 ug/m3 for 8 hour period more than 50 of the time TSP concentration was above 300 ug/m3 TSP and FD concentrations were found at higher levels exceeding the standards of Sri Lanka and World Health Organization(WHO). The average values of TSP on Sundays were found to be 274 ug/m3 which indicated that the TSP values were low by an average of 32 of week-days TSP levels. This could be due to lesser traffic moving on Sundays which wasabout 50 of weekdays traffic. A linear relationship was found for TSP level and traffic densities atthree sampling sites namely Maradana Wellawatta and Borella. The correlation coefficients were 0.97, 0.84 and 0.71 respectively....
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    Analysis for lead in study materials of primary school children such as water colours, clays and crayons.
    (University of Colombo: UC(SCI)., 1979) DE MEL, LSK
    The estimation of Lead in the samples of water colours, clays and crayons has been carried out using the Dithizone Proce Dure (5) the method adapted by the Sri Lanka standared committee for lead in water colours. The Sri Lanka standard specifies not more than 250 mg/kg of lead for the water colours and mo standared are prescribed for clays and crayona Total of forty one (41) samples of the three materials under study were analysed for their lead concentration and most of the samples had the lead contant within the standard specified for water couloursThe yellow colours of all the materials analysed excepting two makes of water colours, had lead concentration over the standard limit. One of the makes had all the colours with lead concentration lead than10mg/kg.
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    An Analysis of factors affecting reinfection of worm diseases.
    (University of Colombo: UC(SCI)., 1992) RAJAPAKSE, AL
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    Analysis of heavy metal content of the water waters/sludge of the sewage treatment plant at Biyagama export processing zone.
    (University of Colombo: UC(SCI)., 1996) BELING, AS
    The effluents and sludge discharhed by the industries and common sewage Treatment plant (SCTP) within the Biyagema Export processing Zone (BEPZ) were analysed for heavy metals with a view to identify ehether any wastes are being discharged by the BEPZ in hazardous concentretion with regard to heavy metals. The heave metal content in the effluents was compared with the standards specified by the Board of Investment of Sri Lanka (BOI) with regard to effluent discharge and the leachable heave metal content in the sludge was compared with the standards specified by the United states Environmental protection Agency (USEPA) for solid waste disposal by landfill, Duration of the study was from June 1994 to December 1994. The sludge was analysed for leaqchable and total heavy metal content. The leachable metal in the sludge, was analysed using the Toxicity Characteristic Leaching procedure (TCLP) test as recommended by the determined using an atomic absorption spectrophotometer as the detection limits of this equipment for each metal analysed are lesser than those specified in the standards. The effluents were analysed for cadmium, Chromium, copper, Nickel, Lead and Zinc content. The sludge was analysed for the same metals except for Nickel. In the USEPA standards, a tolerance limit has not been specified for Nickel. All the effluents and sludge samples....
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    Analysis of Pb by X-Ray absorptiometry and comparison of measurement sensitivity with edxrf and AAS
    (University of Colombo: UC(SCI)., 1999) NAMASICAYAM, S
    During the recent years there has been a widespread interest in monitoring Pb levels in air Although several methods are available to measure Pb in airborne dust they are expensive and time consuming From previous work it appeared that the X-Ray absorption edge method could be used in general to determine elements of atomic number Z20 quickly ana accurately. This methods is independent of the matrix and is non-destructive. The study was initiated to examine the feasibility of using this nuclear related method based on X-Ray absorptiometry to measure Pb levels in aerosols and to compare the validity of this method with EDXRF, AAS and dithizone extraction. Ten air samples were collected for 2 - 60 h through 47 mm diameter millipore filters using a high volume air sampler at the University of Colombo,CEA Fort Sampling Centet, NBRO and Meteorologocal Department and analysed using X-Ray absorptiometry, XRF, AAS and dithizone method.Results obtained from three filters with the two nuclear related methods XRF and X-Ray absorptiometry in this study is within 10 deviation while twoother filters had a deviation of 23 \& 20 XRF has a higher sensitivity with a detection limit of 0.06 ug/cm2 while the detection limit of the absorptiometry method is 1.93 ug/cm2. This can be futher improved by using a primary source having a greater activity and also....
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    Analysis of the disinfectant soap lysol and studies on the preparation of a soap substitute
    (University of Colombo: UC(SCI)., 1995) RAJASINGHAM, SL
    The analysis of the Lysol soap used in the disinfectory and antiseptic purposes is presented. Lysol soap is found to be 51.38 aqueous solution of sodium Ricinoleats. Cheaper alternatives for Lysol soap could be prepared using Linseed oil or Tall oil soaps.
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    An Analysis of the distribution of symptomatic and asymptomatic malaria in the Kurunegala District
    (University of Colombo: UC(SCI)., 1991) KODISINGHE, HM
    The prasent study was conducted within six month periodfrom January to June 1991 in some selected malarious villages in the Kurunegala District. 82-865 of the total population in the chosenvillages were screened for malaria parasites by several blood surveys, An average malaria prevalence rate of 4.47 to 7.08 wasdetected in the different health areas during these sueveillences. It is qunerally considered, and frequently stated that theincidence of asymptomatic malaria carriers in Sri Lnaka is extremelylow or insignificant because most infected individuals develop thedisease due to a lack of immunity. Thesis assumptions have beenmainly based on observations made by passive case Detection. thepresent study was carried out to investigats the extent of theasymptomatic carrier states prevalent in a malaria endemic bregion of shri lanka The study reveals that of all malaria infections detected,at least 11 are truly asymptomatic cases, they having not experienced any symptom during a period extending up to one month previously, while harboring parasites. At least another 20 appear to beasymptomatic during some time of their infections. The number symptomatic malaria infections were inversely proportional to the age and the number of previous malaria attacks suggesting that their asymptomatic state was due to the acquisition of some source of immunity. These asymptomatic parasite carriers appear to be the contributory..............
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    Analysis of Wuchereria bancrofti microfilarial antigens and the cloning and characterization of its actin gene
    (University of Colombo: UC(MED)., 1999) SAVERIMUTTU, JKC
    Several antigens from the microfilarial stage of Wuchereria bancrofti have been identified using immunoblots of microfilarial antigens and screening with immune sera and Tropical pulmonary eosinophilia (TPE) sera. This analysis revealed an array of antigens with apparent molecular weights of 14kD, 35kD, 42kD, 63kD, 88kD, 97kD, and 200kD. Among these only the 14kD and 42kD antigens were consistently recognized by most of the immune sera. A 132kD antigen was recognized only by TPE sera. Analysis of rabbit immune sera revealed that the 42kD antigen was shared by two developmental stages of W. bancrofti, namely L3 and mF. This antigen could become a potential vaccine candidate. The 14kD antigen seems specific for the microfilarial stage and therefore could be a diagnostic marker for active infection. The 132kD antigen could aid in the diagnosis of TPE. Screening of a genomic DNA library of W.bancrofti in EMBL3 with the actin gene of Setaria digitata yielded a clone with an insert size of approximately 13kb. This clone contained the entire actin gene, including the 5' and 3' flanking regions. The swquences around the 5' and 3' splice sites were fairly conserved when compared to the eukaryotic consensus sequences and those of parasitic nematodes. The coding region contained five exons encoding 376 aminoacids and four introns ranging in size from 109 - 190bp. There were no new intron positions when compared to the positions described to date. Only position 170 - 1 was common to three filarial species Onchocerca volvulus, S.digitata and W.bancrofti, the only three filarial species in which the actin gene has been characterized. The W.bancrofti actin aminoacid sequence showed a high degree of homology to the actins of many organisms from varied taxonomic groups, but the highest homology was observed with the free-living nematode Plectus acuminatus. This suggests that P. acuminatus may bare a close evolutionary relationship to W. bancrofti. At the 5' flanking region, a putative mRNA initiation site and a potential `TATA' box with the sequence TATAAA could be identified, though a sequence similar to the ` CAAT ` box could not be identified. At the 3' flanking region, a potential polyadenylation signal with the sequence ATTAAA could be identified. The G+C content of the entire gene including the 5' and 3' flanking region was 37.2 percent, whilw the G+C content of the coding region was 45.18 percent. The introns had an AT content of 70.33 percent. The codon usage revealed a 63.76 percent preference for T or A in the third position. A Southern blot analysis of W.bancrofti genomic DNA indicated that the actin gene is found as a single copy. A detailed analysis of the aminoacid residues revealed that W. bancrofti actin closely resembles the cytoplasmic actins of certebrates.
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    An Anatomical study of the circle of willis in a Sri Lankan population
    (University of Colombo: UC(MED)., 1998) DE SILVA, KRD
    A knowledge of the normal anatomical patterns and the incidence of variations in the circle of Willis are essential in order to appreciate the variations of the `circle' which predispose to vascular disease in the brain. The present study was conducted to determine the vascular pattern of the circle of Willis in a Sri Lankan population its normal configuration, the incidence of complete and incomplete `circles' and to correlate such variations with clinical findings. A comparison of the configurations of adult and foetal brains was carried out and the changes during foetal development were assessed. The diameters of the `circle' within populations were also compared and the degree of narrowing of the arterial lumen due to atherosclerosis and the incidence of aneurysms in the `circle' were studied. In the main study, the anatomical variations of 259 cadaver brains (225 adults and 34 foetuses) were studied following a pilot study of 71 brains. Luminal diameters of each segment of the circle were measured with a micrometer-calibrator. Arteries of less than 1 mm in diameter were considered abnormal. The degree of narrowing of the vessels of the circle was assessed. The present study is the only single large study known, where all the diameters of the component vessels of the circle of Willis were actually measured and all known anomalies were documented. The compensatory capacity of the circle of Willis depends on anastomosis, which is a function of the diameter of the arteries forming the `circle'. In this study the average diameters of cerebral arteries were the smallest in Sri Lankans, when compared with South Indian and Japanese populations. The `typical circle' was observed in only 14.2 percent of the `circle' while 85.77 percent were hypoplastic `circle'; the highest recorded in the literature. It was noted that a single anomaly in a component vessel was associated more with multiple anomalies of other vessels. These findings were clinically significant in the aetiology of cerebrovascular accidents, as variations may be considered as contributory factors for the higher incidence of cerebrovascular accidents in young Sri Lankans. The incidence of variations (X 2 = 1738.56, p \<0.001), and the location of hypoplastic stems (X 2 = 58.85, p \<0.005) in the `circle' among populations is not uniform. Fifteen configurations of variations in the arterial system were observed and classified by Riggs and Rupp. (Fig. 1) In the present study, seven additional patterns were observed (Fig. 2). Therefore incidence of variations in the `circle' in Western or Asian populations cannot be extrapolated to Sri Lankans. Sri Lankans have the highest percentage (93.3 percent) of the adult configuration (X 2 = 84.6053, p \< 0.0001), in which the occipital lobe receives its blood supply from the vertebrobasilar system. The transition of the blood supply to the occipital lobe from the carotid to the vertebrobasilar circulation occurs at 30 - 40 weeks of gestation. (X 2 1.12 p \< 0.05) and the commonest site of an anomaly is in the posterior half of the circle. The incidence of aneurysms in Sri Lanka is much lower when compared to its incidence in other parts of the world. The narrowing of a major arterial lumen by 50 percent or more in the major arteries of the `circle' due to atherosclerosis was not detected.
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    Antibiotic principles from Sri Lankan marine algae and chemical investigation of Caulerpa racemosa
    (University of Colombo: UC(CEN.)., 1980) THARMATHEVA, SJ
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    Aspiration of adolescents (a sociological survey of adolescents in an urban and a rural area)
    (University of Colombo: UC(CEN.)., 1984) SENEVIRATNE, SDSE
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    A Biochemical study of the oral hypoglycaemic activity of Momordica charantia
    (University of Colombo: UC(MED), NSF., 1985) WELIHINDA, J
    The oral hypoglycaemic activity and the mode of action of Momordica charantia cultivated in Sri Lanka was investigated in the present study. The oral hypoglycaemic activity was established by demonstrating the capacity of M. charantia to lower the fasting blood glucose levels in Sprague-Dawley rats and also to improve the glucose tolerance both in rats and newly diagnosed non-insulin dependent diabetic patients. Investigations carried out to elucidate the mode of action indicated the presence of both pancreatic as well as extrapancreatic effects. In vitro studies using isolated pancreatic islets of obese hypoglycaemic mice showed, M. charantia juice to be a potent stimulator of insulin release. However in contradistinction to glucose stimulated insulin release, that of M. charantia could not be inhibited by L-epinephrine or stimulated by the phospodiesterase inhibitor theophylline and was even potentiated by the removal of Ca++. This anomalous behaviour was not associated with general effects on the metabolism of the beta cells as indicated by an unaltered oxidation of glucose. Studies on calcium fluxes suggest that the insulin releasing action is the result of perturbations of membrane function. In support for the idea of direct effects on membrane lipids, the action of M. charantia was found to mimic that of saponins in inhibiting the Ca++/H+ exchange mediated by the ionophore A 23187 in isolated chromaffin granules and release of Ca++ from preloaded liposomes. However, the presence of saponins in M. charantia was shown and that the insulin releasing activity of M. charantia persisted even after the removal of saponins from the juice indicating that insulin releasing activity was not due to endogenous saponins. With regard to extrapancreatic effects, the available experimental evidence suggests that M. charantia stimulates glucose uptake (in vitro). Further a significant accmulation of glycogen both in the liver and muscle in response to M. charantia administration was shown. However, the present study failed to reveal significant effect of M. charantia on gluconeogenesis, triglyceride synthesis and insulinase activity. Toxic effects of long term treatment with M. charantia were investigated. The general health of the animals remained good during the entire period of investigation. Histopathological investigation of these animals revealed occasional foci of lymphocytic infiltrations in the liver and kidneys. This observation however, was common to control animals as well.
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    Biology of sarcosaprophagous flies associated with forensic science in Sri Lanka
    (University of Colombo: UC(MED)., 1995) IYANAGE, S
    The objective of this study was to estimate the time elapsed since death entomologically using the data on adult and oviposition succession of sacrosaprophagous flies attacted to rabbit carcasses and age of their immature stages. Sixteen monthly experiments on the successon of adult flies and their oviposition were carried out using two rabbit carcasses simultaneously in Colombo. These experiments were later extended to 3 elevations - Anuradhapura, Ktaragama amnd Hambantota in the low country, Ratnapura and Kandy in the mid country and Hatton and Nuwara-eliya in the hill country.
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    The Biomedical importance of chromium
    (University of Colombo: UC(SCI)., 2001) JHONATHAN, T
    Chromium is a relatively rare, naturally occurring element in the earth's crust. It is an essential nutrient, which can either promote biological functions or toxicological actions due to the major oxidation ststes, Cr (III) and Cr (VI). The body absorbs chromium mainly through the lungs, gastrointestinal trac and skin and excretes via kidneys. Chromium helps in the metabolism of crabohydrates and lipids by reducing the insulin resistance. Chromium levels in food are very low and are not enough for the beneficial actions. Therefore the supplements of chromium are introduced. The amount of chromium supplementation recommended by the U.S. Food and Nutrition Board is 50 to 200 ug per day. The organic forms of chromium are readily and lipophilic. Chromium in trace amounts in the biological samples can be detected by several modern techniuues, such as the atomic absorption spectrometry and the X-ray fluorescence spectrometry.
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