PURSE 1997
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- ItemEmbryotoxic effect of plumeria rubra(University of Peradeniya, 1997-11-22) Gunawardana, V. K.; Goonasekare, M. M.; Gunaherath, G. M. K. B.; Gunatillake, A. A. L.; Jayasena, KMany plants are well known for their medicinal properties, and traditional medical practice based on plants, forms a substantial part of the health care system in many developing countries. Plumeria rubra, a native of Mexico is a deciduous tree with an abundance of sticky, milky latex. Ethnomedical reports indicate that it has been used as a febrifuge, a purgative, and in the treatment ofleprosy. It is also reported to have hypoglycaemic properties. However, the most widely reported usage of this plant appears to be an account of its activity on reproduction. The fruit, latex and other unspecified parts of the plants have been administered orally as abortifacients, while branches are reported to have been used intra-vaginally to produce abortion. Despite the Ethnomedical information available, studies on biological tests are limited. In this study, a bioassay using pregnant rats was used to verify Ethnomedical claims that Plumeria rubra is an abortifacient. The stem bark of Plumeria rubra collected from locations around Peradeniya was separately and exhaustively extracted with hot water and 95% ethanol, using soxhlet. Subsequently the stem bark was sequentially extracted with petroleum ether (PE), dichloromethane (DE) and methanol (ME). Proven fertile males and virgin female Sprague-Dawley rats were used for the bioassay. Females weighing 180 - 200g were individually housed and their vaginal smears examined daily to determine cyclicity. The females showing regular cycles were mated and the day on which sperms were present in the vaginal smear was designated day-l of pregnancy. Each extract suspended in polyvinyl pyrrolidone (pVP) was administered orally to pregnant rats from day 1 to day 10 of pregnancy. The dose was determined daily according to body weight (g/kg). A treatment group consisted of 10 rats, and a control group of 10 rats received PVP only. All animals were autopsied on day 16 of pregnancy, and the number of pregnant animals in the treated and control groups was noted. Additionally, the number of implantation sites, normal foetuses and corpora lutea were counted. The results were subjected to statistical analysis. In conformity' with the usual Ethnomedical practices, the preliminary studies were carried out with the hot aqueous extract and it was found to be toxic at a dose of3.l g/kg. Also, no antifertility activity was detected. A dose of2.0 g/kg showed equivocal antifertility activity and this prompted studies using other solvents. The hot ethanol extract was found to be significantly active although toxic at a dose of 1.5 g/kg. A lower dose of 0.75 g/kg also showed significant activity and only six of the ten animals were pregnant. In the control group all animals were pregnant and the difference was significant. The PE extract when administered orally at a dose 1 g/kg did not show any activity. The DE and ME extract at doses of 1.3 and 1.5 glkg respectively showed marked effects on pregnancy. At autopsy only one rat from the DE treated group was pregnant while five animals were pregnant in the ME treated group. All animals were pregnant in the control and PE treated groups. The reduction in the number of pregnant rats in the DE and ME treated groups was statistically significant. The results obtained with the DE and ME extracts were reproducible in repeat assays. 168 An off-white solid isolated from the DE extract contained the compound plumieride as the major constituent with some impurities. This compound which is an irridoid glycoside also showed significant activity. Six of the ten treated animals showed implantation sites, but only four of these showed normal foetuses. It was possible to identify a pure compound fulvoplumerin from the PE extract. This compound like the parent extract, was devoid of any activity on reproduction in the rat. Toxic symptoms observed in these experiments included reduced food intake, loss of body weight and diarrhoea. Two deaths were recorded in the DE treated group. The weight loss observed with some extracts which showed significant anti- fertility activity, varied from slight to moderate to large. It.was also observed that treated animals gained weight after dosing was stopped indicating that the toxic effects are reversible. Overall, the results indicate that the stem bark of Plumeria rubra is Embryotoxic causing foetal death and subsequent resorption. Further work should be carried out on Plumeria rubra to determine whether active constituents could be separated from the toxic constituents. In addition, investigations on plumieride are merited in order to determine its role in fertility regulation, and it is essential that an authentic sample of plumieride is tested for anti-fertility activity.
- ItemElectron probe microanalysis of carious and noncarious cementum - a preliminary study(University of Peradeniya, 1997-11-22) Ratnaweera, P. M.; Mendis, B. R. R. N.In order to compare the distribution of elements in normal and carious cementum with the morphology of the lesions, electron probe microanalysis (EPMA) was carried out. Freshly extracted premolar teeth from subject's aged 40 - 48 years were fixed in 10010formal saline. Six ground sections 100J.Unin thickness were then prepared parallel to the long axis of the tooth. These ground sections contained one or more localised carious lesions of early root surface (cemental) caries. Some sections contained large lesions extending up to dentine. Sections with intact cementum served as controls. For EPMA the sections were covered with a thin layer of gold and subsequently examined in an electron probe operated at 20kv and 18 mA. In several areas of each specimen analysis were carried out for Ca, P, Mg, S, F and Na using K emission of each element. Distribution profiles were obtained from linear scans across the cementum and into the dentine at approximately right angle to the root surface. The electron probe was equipped with three spectrometers (diffracting crystals ADP and RAP) and two elements were usually recorded simultaneously. Results showed that in noncarious cementum Ca and P concentration profiles appear as largely horizontal lines with minor secondary depressions. The Mg profiles ascended gradually from the surface of the cementum to cemnto-dentinal junction. In carious cementum the Ca and P values were larger than in intact cementum (n=2). The concentration in the sub-surface lesions in the cementum varied widely but in most instances the concentrations were lower than in non-carious cementum (n=3). A highly mineralized surface zone or a highly mineralized zone adjacent to the advancing carious front of the cemental carious lesions was not found in this study.
- ItemCow milk allergy(University of Peradeniya, 1997-11-22) Perera, M. P.; Horadagoda, A; De Silva, C. E.Cow milk, one of the first foreign proteins encountered by many infants, is one of the most common food allergens. Its mixture of more than 20 protein components have been implicated in a number of possible immunologically mediated reactions. This study was undertaken to determine the prevalence of cow milk allergy among Sri Lankans and to identify the nature of allergic reactions manifested by them. A detailed questionnaire was administered to 3461 fresh cow milk consumers from 17 districts. In this study 386 people (11.6%) who claimed to have shown clinical symptoms which subsided on withdrawal of milk from the diet were considered to be allergic to cow milk. Hypersensitivity reactions to cow milk were reported to provoke symptoms associated with the respiratory system (n=188), gastrointestinal system (n=117), nervous system (n=80), skin (n=46) and the cardiovascular system (n=3). One individual was reported to have shown anaphylactic reactions. In one instance an exclusively breastfed infant was reported to have developed respiratory distress when the mother consumed cow milk and clinical signs have subsided when the mother discontinued cow milk consumption. A total of 334 individuals (86.5%) claimed to have developed allergies within 24 hours after consumption of fresh cow's milk suggesting the prevalence of immediate type hypersensitivity reactions. Fifty-two persons (13.5%) reported that they developed the signs after 2 - 7 days of consumption indicating delayed type hypersensitivity reactions. When compared to results of similar studies carried out in western countries, the prevalence of cow milk allergy is high among Sri Lankans. The nature of the allergic reactions reported and the higher prevalence of immediate type hypersensitivity reactions among Sri Lankans are comparable with other countries.
- ItemChanges of microbial biomass in soil after incorporation of rice straw(University of Peradeniya, 1997-11-22) Nandasena, K. A.; Kumara, L. S. C.Even though, the microbial biomass in soil is a relatively small fraction, it plays a crucial role in various nutrient transformation processes, which control overall nutrient cycling in the soil-plant system. Mineral nutrients in soil are temporarily trapped and immobilised in soil microbial biomass. Subsequently, decaying microbial biomass releases immobilised nutrients such as C, N, P and S to the labile pool of nutrients in soil. The immobilisation and release of nutrients in a given soil is therefore, dependent upon the nature - quality and quantity - of microbial biomass present in soil. The quality and quantity of microbial biomass is affected by various environmental factors such as available oxygen and decomposable organic matter contents in soil. Main objective of this experiment is to study the effects of organic matter addition (rice straw) on microbial biomass development in soil maintained under arable and flooded conditions. Reddish brown Earth (RBE) soil collected from Mahailuppallama was used. Soil was amended with finely ground rice straw at the rate of 1-% w/w basis. One set of sample was maintained aerobically and other set of sample was maintained in flooded condition to give anaerobic condition. All soil-straw samples filled in glass jars were triplicated and incubated at room temperature in the dark. Sampling was done at 1st day, 2nd, 4th and 8th weeks after incubation. Moist soil equivalent to 20g air died basis from each set of soil samples were analysed for microbial biomass Carbon (C) and Nitrogen (N) by using Fumigation-Extraction method (Brookes et ai, 1985 Vance et at, 1987). During the experimental period, C02 evolution from the soil samples was also measured after absorption to NaOH solution. The changes of microbial biomas were monitored in this experiment by determining biomassC and N. Results showed that the application of rice straw markedly increased soil biomass C over the control soil irrespective to the aerobic and anaerobic conditions. Aerobic and anaerobic conditions imposed in this experiment had no affect on biomass C significantly. However, overall increase of biomass C in straw amended soil can be attributed to the supply of carbon source to the microbial biomass. Biomass N also behaved in a similar manner. Only aerobically maintained, rice straw amended soil samples showed a significant increase of biomass N. This means perhaps, in aerobic condition the quality of biomass (in terms of nitrogen) has changed over the anaerobic treatment. It may be due to the development of low C: N ratio biomass components in soil maintained under aerobic condition. Further, microbial activity was measured by C02 evolution. In this study, microbial activity has been increased substantially in rice straw amended soils irrespective to both aerobic and anaerobic conditions. However, the increase of microbial activity was more prominent in the rice straw amended soil, which maintained aerobically. It can be concluded that the addition of organic matter such as rice straw substantially increase the microbial biomass C and N in the early stages of straw decomposition. The aerobic conditions, in contrast to the anaerobic, may also have an affect on the quality of microbial biomass and the activity in the soil.
- ItemBacterium host cell interaction : effect of Haemophilus somnus on phagocytosis, nitric oxide production and chemiluminescence response of bovine mononuclear phagocytes(University of Peradeniya, 1997-11-22) Gomis, S.; Godson, D.; Wobeser, G.; Potter, A.The interaction between bovine mononuclear phagocytes (BMP) and Haemophilus somnus are known to be complex. Using a flow cytometric phagocytosis assay, it was found that logarithmically growing H somnus significantly inhibited the phagocytosis of opsonized S. aureus by bovine alveolar macrophages (BAM) obtained both from healthy calves and from cattle experimentally infected with H somnus. However, neither heat- nor formalin-killed, logarithmically growing neither H somnus nor in vitro passaged H somnus showed any effect on the phagocytic activity of these cells. In contrast to BAM, bovine blood monocytes (BBM), had a significant increase in their phagocytic activity following in vitro exposure to logarithmically growing H somnus. The bactericidal ability of bovine mononuclear phagocytes in interaction with H somnus was studied using two in vitro assay systems measuring nitric oxide (NO) production and chemiluminescence response. H somnus rapidly inhibited the Luminol- dependent chemiluminescence (LDCL) of BBM, and of BAM costimulated with opsonized Staphylococcus aureus. Inhibition of the LDCL response of BBM and BAM was abrogated with either opsonized or killed H somnus. In contrast to inhibition LDCL of BMP, both BBM and BAM infected with H somnus had stimulated production of NO. Using a calorimetric bactericidal assay, it was found that: (1) H somnus was able to survive within BBM in vitro and the kinetics of its survival were similar to that seen in BBM isolated from experimentally infected cattle; (2) treatment of BBM with varying concentrations of (Formula) and E. coli LPS had no effect on the survival of H somnus. Moreover, using ultrastructural studies, and 3H_ uracil incorporation into nucleic acids, it was possible to demonstrate the survival of H somnus in BMP. These results indicate that the ability of H somnus to modulate microbicidal activity of BMP would, in turn, assist the intracellular survival and immunopathogenesis of bovine haemophilosis.