Browsing by Author "de Tissera, A."

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    Interaction between pericytes and endothelial cell of foetal capillaries in hypertensive placentae
    (Sri Lanka Medical Association, 1998) Salgado, S.; Angunawela, P.; Sirisena, J.; de Tissera, A.
    INTRODUCTION : Pericytes and endothelial cells are known to possess direct contacts in many parts of the vascular tree. Pericytes are known to have modulating effects on endothelial cell growth and differentiation. It is possible that some pericytes are a source of new endothelial cell. OBJECTIVES : Information regarding the ultrastructural changes of foetal capillaries of hypertensive placentae is lacking. Therefore we studied the foetal capillaries of hypertensive placentae to ascertain any significant ultrastructural interaction between pericytes. endothelial cells and basement membrane. METHOD : Placental tissue from 15 pregnant mothers with a blood pressure of 140/90 or more and 10 normal mothers who had normal full term deliveries were studied. Fresh placentae were examined and 2mm sized pieces were taken from central foetal and fixed in 2% gluteraldehyde for eletron microscopic studies. RESULTS : All hypertensive placentae showed a number of pericytic processes, which was significantly higher than in normal placentae. (P<0.001). Both frequency and complexity of direct connections between endothelial cells and pericytes appear to be increased in foetal capi 1 laries of hypertensive placentae . Basement membranes of foetal capillaries in 9 hypertensive placentae showed marked thickening. CONCLUSIONS : There was complexed interaction between endothelial cells and pericytes of foetal capillaries of hypertensive placentae.
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    Protective effect of vitamin E in kidney storage solution on renal tissue metabolism in rats
    (Sri Lanka Medical Association, 1995) Selliah, S.; de Mel, T.; Hewamadduma, C.A.A.; de Tissera, A.
    OBJECTIVE:To determine whether inclusion of vitamin E into kidney storage solutions protects metabolism and tubular ultrastructure of stored rat kidney. METHODS: Rat kidneys were flush stored in Marshall's Citrate (MC) and MC + vitamin E (25% of LD 50 and 50% of LD 50) for 24 hours at 0 degrees C. After storage kidney slices were tested for gluconeogenesis and lactate dehydrogenase (LDH) activity, and examined for cellular ultrastructure. RESULTS: Kidneys stored in MC + vitamin E gave higher gluconeogenesis than those stored in MC alone (p < 0.001). Tubular ultrastructure was better preserved in the presence of Vitamin E. CONCLUSIONS: Vitamin E appears to protect the metabolism and ultrastructure of stored rat kidneys.
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    Ultrastructure of endothelial cells of fetal capillaries of placentae of women with pregnancy induced hypertention
    (University of Colombo, 2006) Salgado, S. S.; Angunawela, P.; de Tissera, A.; Sirisena, J.
    The present study aimed to compare the ultra structural features of endothelial cells of fetal terminal capillaries of placentae from hypertensive (n=10) and non-hypertensive (n=10) pregnancies. The ultrastructural features of endothelial cells of terminal capillaries from the fetal surface of each placenta were examined under the electron microscope. Micrographs of 8 different endothelial cells from each placenta were prepared for evaluation by stereological analysis using a coherent double lattice test system. The volume fractions of different organelles and cytosol in endothelial cells of placental fetal capillaries of both hypertensive and non-hypertensive pregnancies were deter¬mined by counting the number of grid intersection points falling on the endothelial cell cytoplasm, mitochondria, rough endoplasmic reticulum and glycogen deposits. Ultrastructural changes were noted in endothelial cells of capillaries of placentae of mothers with pregnancy induced hypertension. Statistical analysis showed that the volume fractions of the organelles and the amount of cytoplasm of endothelial cells of placentae from hypertensive pregnancies were significantly higher than those from non-hypertensive pregnanciesThere was a significant increase in some of the organelles and the capacity of cytoplasm of endothelial cells of placentae from hypertensive pregnancies when compared to normotensive pregnancies. These findings may be attributed to compensatory mechanisms operating as a response to hypoxia caused by reduced maternal blood flow to the placenta.
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    Utrastructural changes of foetal surface of the placenta in hypertensive disorders of pregnancy
    (Sri Lanka Medical Association, 1997) Salgado, S.; Angunawala, P.; de Tissera, A.
    OBJECTIVES : The pathogenesis of pregnancy induced hypertension and its relationship to pathological and ullrastructural changes of the placenta has not been adequately understood We studied placenta! (issue from foetal side to show whether there are any significant ullrastructural changes. This area of the placenta has not been studied previously. METHODS: Placenial tissue from 15 pregnant mothers with a persistent blixxi pressure of 140/90 or more, and 10 normal mothers who had normal full term deliveries were studied. Fresh placentae were examined macroscopically. 2mm sized section were taken from (lie central, foetal surface and fixed in 2% gluteraldehyde lor electron microscopic studies. RESULTS: 9 months had pregnancy induced hypertension without proteinuria, 3 had hypertension and proteinuria and oilier 3 had essential hypertension. All hypertensive placenta showed increased number of cytotrophoblast cells. Syncytiotrophoblast cells of the hypertensive placenta showed Jess number of lipoid droplets, compared to the controls. Syncliotrophoblast cells of the test group also showed short, blunt and swollen microvilli. All hypertensive placentae except one, showed thickened, laminated and irregular subirophoblasu'c basement membranes and increased amount of interestitial collagen in the villous stroma CONCLUSIONS: In electron microscopic study of normal and hypertensive placentae revealed that the placentas of hypertensive disoalers pregnancy is associated with increased number of cytotrophoblast cells, thickening of subtrophoblastic basement membrane, abnormal microvilli, and increased amunt on interestitial collagen
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    Villous syncytial knots in hypertensive placenta
    (Sri Lanka College of Obstetricians and Gynaecologists, 2004) Salgado, S. S.; Angunawela, P.; de Tissera, A.; Sirisena, J.
    Syncytial knots are seen on many terminal villi of all mature placentae. Syncytial knots in more than 30 percent of mature terminal villi, is considered as an indication of postmaturity. The aim of this study was to find out whether there is significant increase in syncytial knot formation in pre-eclampsia and to assess the relationship between syncytial knot formation and maternal age, parity, and period of gestation and effects of syncytial knots on the birthweight, and apgar score of the newborn. The study sample consisted of 150 normal and 200 hypertensive mothers. Light microscopic studies were done on sections taken from fetal surface of their placentae. Hundred terminal villi in fetal subdivisions of each placenta were counted and the number of villi with syncytial knots was recorded. Multivariate analysis was done to find out the difference between the number of placentae with high syncytial knot counts in normal and hypertensive groups and the relationship between high syncytial knot counts and the maternal age, parity, period of gestation and birthweight, head circumference and apgar score of the newborn. Statistically significant increase of syncytial knot counts was seen in hypertensive group than the normal group. There was no relationship between syncytial knot formation and maternal age and parity. In normal and hypertensive groups, an increase in the number of placentae with high syncytial counts was observed with increasing maturity. Although the number of placentae with high syncytial knot counts were higher in relation to low apgar score than the normal counts, difference was not statistically significant. A significant difference in the birth weight and the head circumference of newborns in relation to normal and high syncytial knot counts was observed in hypertensive group.