Showing papers by "University of Malaya published in 1989"

Toxicity and electrophysiological effects of Spilanthes amella Murr. extracts on Periplaneta americana L.

Abstract: The potential insecticidal activity of Spilanthes acmella Murr. (Compositae) extracts was assessed in this study. The extracts were shown to be toxic against adults of American cockroach, Periplaneta americana L. The active component in S. acmella extract was isolated and identified as N-isobutyl-2,6,8-decatrienamide (spilanthol). The results from topical application of spilanthol show that it has a high acute toxicity and spilanthol was the most potent compound when compared to three conventional insecticides. The potency was found to be 1.3, 2.6 and 3.8 times more toxic than carbaryl, bioresmethrin and lindane, respectively. Electrophysiological studies indicated immediate hyperexcitation followed by complete inhibition of the cockroach cercal nerve activity.

The Palaeo-Tethyan Realm and Indosinian Orogenic System of Southeast Asia

Abstract: Southeast Asia is a composite of relatively stable blocks of Precambrian continental crust overlain in large part by Palaeozoic carbonate-dominated platforms. The blocks are sutured along highly deformed mobile belts characterized by deep water sediments and fragmented ophiolites. After suturing, these mobile belts continued to be the focus of further tectonism because of their inherent weakness relative to the more rigid blocks.

Nucleation behaviour of tripalmitin from a triolein solution

Abstract: Nucleation of tripalmitin (PPP) crystals from melt and from its binary triolein (OOO) solutions was studied by differential scanning calorimetry (DSC) and optical microscopy. Cooling DSC thermograms for either pure PPP or OOO exhibits a single exotherm. For the solutions, two widely separated peaks due to PPP and OOO were observed. The PPP peak is broadened and shifts down to a lower temperature as the OOO content in the solution increases. A modified Turnbull and Fisher equation was used for nucleation data analysis. The temperature for maximum supercooling of the solution is reduced by OOO but the degree of maximum supercooling remains unchanged at 22oK. An interfacial free energy of 9.45 erg/cm2 for β-PPP/ melt was deduced. This value drops rapidly to a slightly lower value of 8.95 erg/cm2, in triolein solution. The effect of a reduced interfacial free energy on nucleation is critically discussed in the light of a simultaneous reduction in the melting point of β-PPP in the solution.

Isolation and characterization of an unusual form of L-amino acid oxidase from King cobra (Ophiophagus hannah) venom.

Abstract: The L-amino acid oxidase (EC 1. 4. 3. 2) from King cobra (Ophiophagus hannah) venom was purified to electrophoretic homogeneity. The molecular weight of the enzyme was determined to be 140000 when examined by gel filtration and 68000 by SDS-polyacrylamide gel electrophoresis. The enzyme had an isoelectric point of 4.5 and an intravenous LD50 of 5 micrograms/g in mice. It is a glycoprotein and contains two moles of FAD per mole of enzyme. The enzyme exhibited unusual thermal stability and unlike most other venom L-amino acid oxidases, it was stable in alkaline solution and was not inactivated by freezing.

Coupling of multiple laser beams to a single optical fiber

Abstract: An apparatus and method for coupling a parallel array of laser beams into a single optical fiber. The increased optical laser power, if that of helium-neon lasers, can be used for photodynamic therapy of cancer with hematoporphyrin derivatives.

Multiple external root resorption.

Abstract: Presented is an unusual case of multiple external root resorption. Although the cause of this resorption was not determined, several possibilities are presented. Trauma from occlusion, periodontal andpulpal inflammation, and resorption of idiopathic origin are all discussed as possible causes.

A comparative study of the enzymatic and toxic properties of venoms of the Asian lance-headed pit viper (Genus Trimeresurus).

Abstract: 1. 1. The lethalities, anticoagulant effects, hemorrhagic, thrombin-like enzyme, hyaluronidase, protease, arginine ester hydrolase, 5′-nucleotidase, l -amino acid oxidase, alkaline phosphomonoesterase, phosphodiesterase and phospholipase A activities of twenty-three samples of venoms from twelve species of Asian lance-headed pit vipers (genus Trimeresurus) were examined. 2. 2. The results indicate that notwithstanding individual variations in venom properties, the differences in biological properties of the Trimeresurus venoms can be used for the differentiation of venoms from different species of Trimeresurus. 3. 3. The results also suggest that differences in the biological properties of snake venoms are useful parameters in the classification of snake species. 4. 4. Our results indicate that venoms from the species T. okinavensis exhibited biological properties markedly different from other Trimeresurus venoms examined. This observation supports the recently proposed reclassification of T. okinavensis as a member of the genus Ovophis, rather than the genus Trimeresurus.

Mitomycin C adjuvant chemotherapy after Wertheim's hysterectomy for stage IB cervical cancer.

Abstract: Patients undergoing radical surgical treatment for Stage IB and IIA cervical carcinoma are at high risk of developing local recurrence and/or distant metastases when one or more of the following factors are present: presence of metastatic pelvic lymph nodes, a large primary growth, full-thickness tumor invasion of the cervix, clinically undetected parametrial extension, and lymphatic/vascular channel permeation in the cervix by tumor cells. Carcinoma of the cervix appears to be behaving like a systemic disease. Therefore, systemic measures should be considered in its therapy. The authors report the initial experience with the use of mitomycin C as a single agent adjuvant in 16 patients with Stage IB carcinoma of the cervix who had undergone Wertheim radical hysterectomy and were thought to be in this high-risk group. Fourteen of the patients are alive and free of disease after durations of follow-up ranging from 16 to 38 months, the disease-free survival at a median follow-up of 29 months being 87.5%. One patient required discontinuation of adjuvant chemotherapy because of severe marrow toxicity; however, in view of the presence of a multiple risk factors, pelvic irradiation was given instead. She died 13 months later from disseminated disease. A second patient died 6 months later from congestive cardiac failure.

Adverse effect of intraoperative phenylephrine 10%: case report.

Abstract: The case is reported of a patient who suffered severe acute hypertension, cardiac arrhythmia, and myocardial infarction probably as a direct effect of phenylephrine overdose. Instillation of the drops during surgery probably enhanced the systemic absorption of a significant amount of the drug. Therefore it should be used during surgery with caution, especially in elderly patients and those with cardiovascular disease.

Effects of Prey Number and Stage on the Biology of Cyrtorhinus lividipennis (Hemiptera: Miridae): A Predator of Nilaparvata lagens (Homoptera: Delphacidae)

Abstract: When given 30 eggs of Nilaparvata lugens (Stal) daily, males and females of Cyrtorhinus lividipennis Reuter took 10.8 and 13.0 d, respectively, to develop from first instar. The males consumed 49.0 eggs and the females, 59.2 eggs. The mean body length of adult males was 2.6 mm and females, 3.1 mm; mean longevity was 9.6 d for the males and 14.4 d for the females. Lifetime egg consumption was 43.8 eggs by the males and 123.6 eggs by the females. Mean lifetime fecundity by unmated females was 34.0 eggs. When 20 or fewer eggs or 10 or fewer first-instar N. lugens were given daily as food, nymphal survival, adult longevity, and fecundity decreased. Individuals offered 20 or more N. lugens eggs consumed significantly more than those offered fewer eggs, but this did not result in a decrease in development time or in adult size. C. lividipennis adults that were fed daily with N. lugens nymphs (5 or 10 first, second, or third instars) also had a shorter life span and laid no eggs. Adults offered 10 second or third instars lived significantly longer than those on other regimes. Our results suggest that C. lividipennis nymphs need only small amounts of food to survive to adulthood under field conditions, especially at the beginning of the rice growing season, when N. lugens eggs are relatively scarce.

Effect of ultrasonic instrumentation on Bacteroides intermedius.

Abstract: Two physical mechanisms of ultrasound, cavitation and acoustic streaming, were investigated in an ultrasonic endodontic unit. In addition, the potential of ultrasonic instrumentation for disruption of Bacteroides intermedius was examined at various time intervals. The ultrasonic file could not generate cavitation within the recommended power settings indicated for endodontic purposes. However, there was evidence of acoustic streaming. The latter phenomenon resulted in destruction of 21.6%, 30.4% and 92.9% of test bacteria after 1, 5 and 15 min sonication respectively. It appears that ultrasonic instrumentation of root canals has little bactericidal effect.

Changes in electrokinetic properties of natural rubber latex after surface chemical modifications

Abstract: High-ammonia latex concentrate prepared from doubly-concentrifuged fieldHevea latex was exhaustively dialyzed to remove any residual water-soluble non-rubber constituents. The specially purified latex was then treated with specific chemical reagents to modify the surface ionogenic groupings originally present on the latex particle surface. The electrophoretic mobility of the modified latexes was investigated as a function of pH. The change in electrokinetic properties of the surface-modified latex was explained in terms of chemical modification to the ionogenic groups of the adsorbed layer of proteins and long chain fatty acid soaps on the latex particle surface, the negative charges of which are primarily responsible for the colloidal stability of the latex. For comparison direct extraction of the long-chain fatty acid soaps from the specially purified latex by solvent was also carried out. Present results indicate that the number of carboxyl groups from the adsorbed long-chain fatty acid soaps plays a major role in the stabilization of the latex concentrate. In comparison the contribution of negative charges from the adsorbed proteins towards the stability of the latex is of less importance.

Animal model of margosa oil ingestion with Reye-like syndrome. Pathogenesis of microvesicular fatty liver

Abstract: The aetiology and pathogenesis of Reye's syndrome (RS) are incompletely understood. A number of environmental toxins and biological agents, including viruses, have been postulated to cause RS, either acting alone or synergistically. Most investigations have suggested that the primary insult is in the liver mitochondria, leading to a complex biochemical catastrophe, with death from encephalopathy. Margosa oil (MO), a long-chain fatty acid compound, has been shown to cause a Reye-like syndrome with death from hepatoencephalopathy, in children in Malaysia and India. The present time-course study performed in MO-administered mice showed the development of hepatic lesions with many features of RS. MO acts rapidly, within 30 min, on the nuclei of hepatocytes inducing mitoses and binucleated cells. This is followed by mitochondrial injury, with swelling, rarefaction of matrix, loss of dense bodies, pleomorphism, and loss of ribosomes starting at 60 min. There is loss of liver glycogen, and proliferation and hypertrophy of the endoplasmic reticulum (ER), followed by the presence of lipid droplets in the hyaloplasm, and globules within dilated cisterns of the ER. Additional fatty acids from lipolysis of body adipocytes, and fat globules from intestinal MO ingestion further aggravate the liver fatty change. There is evidence of fat globule ingestion by endocytosis into hepatocytes at the level of the sinusoids. The development of microvesicular liver steatosis and glycogen depletion due to involvement of liver cell organelles occur rapidly as in RS.

The social impact of oral and facial pain in an industrial population.

Abstract: The aim of this study is to determine the social impact of oral and facial pain in a sample involving an industrial population. Out of a total of 355 subjects interviewed, nearly one-half claimed to have oral and facial pain in the previous one month prior to the survey. The most common type of pain was that related to hot or cold fluids or sweet things followed by toothache. On the average, the pain lasted for 4.2 days (SD = 4.9) per person in the past one-month. About one in five persons with pain reported that it was severe enough to disrupt sleep. About one in ten persons reporting pain had to take sick leave because of the pain. However, only one in four persons with pain consulted a doctor or dentist. More than one-third tried to cope with the pain and did nothing while the rest tried various means of self-cure. It is therefore postulated that in this population, pain per se is a poor predictor of utilisation of dental services. Further research into pain coping behaviour and how this affects of pattern of utilisation of dental services is indicated in order to formulate a strategy to encourage the habit of seeking prompt dental care by the target population.

Serological markers in the diagnosis of histopathological types of nasopharyngeal carcinoma.

Abstract: The titres of IgA against Epstein-Barr virus, viral capsid antigens and the titres of IgG against early antigen were found to be useful markers for the diagnosis of different histopathological types of nasopharyngeal carcinoma.

Geohelminth infection of children from rural plantations and urban slums in Malaysia.

Abstract: This study compares levels of geohelminth infection in children living in rural estates and urban slum areas of Malaysia. The statistical characteristics of geohelminth infection in 1499 children from birth up to 15 years of age, living in rural estates, were analysed according to age, sex and ethnic origin and compared with the same statistics for 1574 slum-dwelling children of similar age groups and ethnic origins. The prevalence and intensity of ascariasis and trichuriasis were significantly higher among children from the urban slums. Slum-dwelling ethnic Indians and Malays had higher levels of infection with Ascaris lumbricoides and Trichuris trichiura than their rural counterparts, but the infection status of the ethnic Chinese in the 2 areas was similar. Hookworm infection was similar in both areas, indicating that hookworm infection is neither necessarily nor solely a rural disease. These results suggest that urban slum children are at greater risk of ascariasis and trichuriasis than their rural counterparts.

Impact of a School Milk Programme on the Nutritional Status of School Children

Abstract: From the start of the school milk feeding programme in February 1985 to October 1986, a total of 2,766 children aged six to nine years from 12 primary schools in Ulu Selangor were followed-up for about two years. The children's weight and height were monitored at the beginning, in the middle and at the end of the study. The study shows that there is a reduction in the prevalence of protein-energy malnutrition in terms of underweight (15.3% to 8.6%), stunting (16.3% to 8.3%) and wasting (2.6% to 1.7%) from the start of the school feeding programme to two years later. Associated with this there was an improvement in the attendance rate of the children during the same period. As there was no major developmental change in Ulu Selangor during that period, it is likely that the reduction in the prevalence of protein-energy malnutrition and the improvement of the attendance rate among the children are due to the impact of the school milk feeding programme.

Trends in tooth loss due to caries and periodontal disease by tooth type

Abstract: Although the patterns of dental disease is gradually changing, caries and periodontal disease still account for the most important reason for extractions in most countries. However their relative contributions towards overall tooth mortality figures varies. The aim of this study is to investigate the types of teeth usually associated with extractions due to caries or periodontal disease and its relation to the age at which the tooth was lost. The highest proportion of extractions due to caries occurred between 21 to 30 years of age while that for periodontal disease occurred between 41 to 50 years. For caries, the greatest proportion of extractions involved the posterior teeth. The most frequently extracted teeth due to caries are the molars, in particular the first permanent molar. However, for periodontal disease a slightly greater proportion of anterior teeth were lost than the posteriors. This trend is more marked in the lower jaw than the upper. Overall, extractions related to caries tend to increase posteriorly, while that for periodontal disease tend to increase anteriorly.