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    A Preliminary study of the invertase activity in coconut
    (University of Sri Lanka (Colombo Campus): UC(MED)., 1977) ALLES, NH
    AB : A ` particulate ` invertase preparation of low activity (sedimenting in the 900 g fraction) was extracted from the stalk and mesocarp tissues of coconut (Cocos nucifera L.). The activity o invertase was found to increase linearly with the time of incubation (0 - 3h). Initial velocity was directly proportional to enzyme concentration, only in the low concentration ranges. The initial velocity decreased at enzyme concentrations higher than 0.13 mg protein per 2.0 ml of incubation mixture. Treatment of the particulate enzyme with 0.1 present and 0.5 present (v/v) of the nonionic surface active agent, Triton X - 100, solubilized 71 percent and 76 percent of the invertase. Incorporation of the non-acidic thiol, mercaptoethanol into the reaction mixture, caused significant activation of the invertase. This suggested the possibility of an SH group participating in the catalytic activity of the enzyme. In addition, mercaptoethanol may cause enzyme reactivation by reducing the quinones formed by the oxidation of polyphenols. Consequently, the low activity observed in the absence of mercaptoethanol was probally due in part, to an inactivation of the enzyme by quinones. The enzyme was found to be inactivated by the metal chelating agent, ethylene diamine tetracetate (EDTA) at 5 X 10-3 and 5 X 10-4 M concentrations. This finding suggested that invertase is probably a metalloenzyme. It was also found that the inactivation of the enzyme by EDTA (10-2 M) was not reversed by mercaptoethanol. This may indicate that the removal of the metal in question by EDTA, causes an irreversible denaturation of the enzyme. Polyphenols found in the enzyme preparation were found to interfere with the reduction of the dinitrosalicylic acid reagent. The use of insoluble polyclar in the extracting medium to remove these interfering substances, is suggested.
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    Applications of the indirect fluorescent antibody test in malaria
    (University of Sri Lanka (Colombo campus): UC(MED)., 1976) SIVANESARAJAH, Y
    Various methods have been employed in the epidemiological assessment of malaria. In recent years, new serological techniques have suppemented the measurement of spleen rate and parasite rate. Since clasical malariometric indices such as parasite rate and annual parasite incidence were insufficient and not adequately sensitive to assess the progress of control measures, serological methids have been employed. The indirect fluorescent antibody test (IFA) was the serological test employed in this laboratory. Thick blood films of simian malaria parasites, plasmidium cynomolgi bastianellii and p.fieldi, obtained from infected rhesuns monkeys (Macaca mulatta) were used as antigens. The IFA test was shown to be useful to study the antibody levlels of blood donors from different areas in Sri Lanka, to observe the production and persistence of malarial antibodies in man and rhesus monkeys and for epidemiological assessment of malaria in Sri Lanka. The study conducte on 1050 blood donors revealed that since Colombo and Kalutara were free of malaria transmission, blood donors from these two areas could be used. Donors from other areas should be subjected to a routine screening programme such as the IFA and the blood used with caution. The follow up of eight malaria patients for persistence of antibodies showed that the range of duration was between 6 weeks and 10 weeks. A similar study was conducted to find persistence of malarial antibodies in rhesus monkeys. It was found that when parasitaemia was high antibody titre was low and as parasitaemia declined antibody titre rose sharply. It persisted at this high level till antimalarial drugs were administered. After declining the low antibody titre persisted for 3-9 months in the four monkeys. It was possible to arrange the different areas sampled in order of endemicity. When changes in transmission were followed from 1974 to 1975 it was found that malaria transmission had gone up from October 1974 to May 1975 and declined in October 1975.
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    The Human placenta:morphological variations and norms (in two volumes)
    (University of Sri Lanka (Ceylon) Colombo campus, NSF: UC(MED)., 1975) SATCHITHANATHAN, S
    AB : The data regarding the morphological features of the human placenta, from Ceylonese subjects has been collected and presented. No prior studies of this nature are available either in this country or in the neighbouring regions. The qualitative and quantitative analysis of maternal, foetal and placental parametera undertaken, establishes norms for these morphological features. The inter-relations between the parameters observed, establishes clinical patterns, about which there have been a certain degree of misconception. Comparison with data obtained through literature, from workers mainly from the European areas, indicates the possibility of a racial, climatic and perhaps a nutritional influence as well. Even though placental weight, volume, surface area, thickness and cord lengths indicate a trend to reduction, statistical analysis, showed no significant differences, in comparison to those of temperate regions. The possibility is that the diversity of the European material was responsible for this lack of significance and perhaps a more detailed study of selected groups both in Europe and in Sri Lanka ( Ceylon ) may add further information to this subject. The normal measures of growth in the placenta, namely its weight, volume, surface area and thickness together with the length of its cord were inter-related to these of the foetus ( its weight and length ) and both measures correlated very highly with only one maternal parameter - the time of growth or the period of gestation. This natural inter-relationship between these parameters generally referred to as measures of normal growth was established here on a factual basis. Certain additional features in the umbilical cord often referred to as " abnormalities " were found to be associated with both live and dead foetuses and there was no evidence to attribute foetal abnormalities and catastrophies to the presence of such " abnormalities " only. The arterial pattern on the placenta was characterised by the presence of Hyrtl's anastomosis, a disperse, magistral or atypical arterial pattern and a dichotomous branching to the level of the tertiary branches. It was established that this vascular catagories and remained uninfluenced by matenal, foetal and placental factors, or by the presence of twists, knots, loops, pathological torsions, localised constrictions, ulcerations and haematomata of the cord. As such the attribution of foetal malformations to deviations of vascular pattern alone was not justifiable. The collective presentation of data and their statistical analysis have been used here to define precisely, widely diverse opinions on maternal, foetal and placental inter-relationships
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    Studies on immobilization of alfa- amylase to cyanogen bromide activated sephadex g 200
    (University of Sri Lanka (Colombo Campus): UC(MED)., 1977) ATTYGALLE, AB
    Studies were made to characterise soluble Alfa-Amylase (Bacterial). The kinetics of Alfa-amylase on starch is zero order at room temperature (28 0 c) for the first 5 minutes. Hence the activity of Alfa-amylase was measured in terms of mg maltose released during first five minutes. Alfa-amylase showed optimal activity at pH 6.0 Cyanogen bromide was prepared and was used to activate sephadex G200 at pH 11.5. The volume of the cyanogen bromide activated gel, at this pH decreased by about 50 percent, compared to that of the unactivated Sephadex G200. Alfa-amylase was coupled to cyanogen bromide activated Sephadex G200 at pH8.3 and 7.0. Coupling of the enzyme led to further decrease in volumes of about 15 percent and 6 percent at pH 8.3 and 7.0 respectively. The amounts of protein in the immobilized Alfa-amylase prepared at pH 8.3 and 7.0 were estimated by, Kjeldhal method, by the tryptophan content and from the difference in the amount of protein present in the original solution and that in the washings. It was observed that 27 percent of the added protein got immobilized at pH 8.3, Where as at pH 7.0 it was only 11 percent. The activities of the Alfa-amylases immobilized at pH 8.3 and 7.0 were, 0.75 percent and 0.52 percent of the total soluble Alfa-amylase respectively. The loss of activity at pH 8.3 and 7.0 were 97.4 percent and 96 percent respectively, which is significant at both pHs. The immobilized Alfa-amylase (prepared at pH 8.3) was stable on storage for a period of 3 weeks at 4 0 C in 0.4M phosphate buffer (pH 6.9) containing 0.02 percent sodium azide. The drop in activity during this period was only 8 percent. A sample of immobilized Alfa-amylase (prepared at pH 8.3) was tested thrice in 3 weeks for stability on usage and it retained 85 percent of its original activity.