Showing papers by "Universiti Sains Malaysia published in 2000"

Hypertension and stroke in Asia: prevalence, control and strategies in developing countries for prevention.

Abstract: Reliable statistics related to the prevalence, incidence and mortality of hypertension and stroke are not available from Asia. The data may be in national or institutional reports or journals published in the local language only. The mortality rate for stroke has been on the decline since the mid 1960s in the developed countries of Asia, such as Australia, New Zealand, and Japan, with some improvement in Singapore, Taiwan and Hong Kong, some areas of China and Malaysia about 15 years later. In India, China, Phillippines, Thailand, Sri Lanka, Iran, Pakistan, Nepal, there has been a rapid increase in stroke mortality and prevalence of hypertension. The prevalence of hypertension according to new criteria (>140/90 mm Hg) varies between 15–35% in urban adult populations of Asia. In rural populations, the prevalence is two to three times lower than in urban subjects. Hypertension and stroke occur at a relatively younger age in Asians and the risk of hypertension increases at lower levels of body mass index of 23–25 kg/m2. Overweight, sedentary behaviour, alcohol, higher social class, salt intake, diabetes mellitus and smoking are risk factors for hypertension in most of the countries of Asia. In Australia, New Zealand and Japan, lower social class is a risk factor for hypertension and stroke. Population-based long-term follow-up studies are urgently needed to demonstrate the association of risk factors with hypertension in Asia. However prevention programmes should be started based on cross-sectional surveys and case studies without waiting for the cohort studies.

Effect of fiber treatments on mechanical properties of coir or oil palm fiber reinforced polyester composites

Abstract: The use of plant fibers as a reinforcement in polyester matrices requires the issue of compatibility between the two phases to be addressed. Because plant fibers present hydrophilic surfaces and polyesters are generally hydrophobic, poor fiber–matrix dispersion and wetting of the fibers by the matrix may result. As a consequence, the mechanical properties of the composite are severely reduced. This study considers the effect of fiber treatment by chemical modification of the fibers (acetylation) or the use of silane or titanate coupling agents on the mechanical properties of coir or oil palm reinforced polyester composites. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1685–1697, 2000

Plasticizing—Antiplasticizing Effects of Water on Physical Properties of Tapioca Starch Films in the Glassy State

Abstract: The effects of moisture sorption on physical properties of native and cross-linked starch films in the glassy state were studied. Water played a dual role as a plasticizer or an antiplasticizer, depending on the physical property measured. Plasticizing effects were clearly evident in the case of the calorimetric glass transition tempera- ture (T g ), tensile modulus, linear expansion, and water vapor permeability. In contrast, antiplasticization by water resulted in maxima in tensile strength, strain-at-break, and toughness of films that were observed at an intermedi- ate moisture content ranging from 4% to 8% (RVP 0.1 to 0.4). The seemingly contradictory effects of water on me- chanical properties associated with lower and higher deformation of starch films were reconciled by assigning dif- ferent roles to water operating primarily via opposite entropic/free volume effects. Relationships, if any, between

Pharmacokinetics of Artemisinin-Type Compounds

Abstract: Various compounds of the artemisinin family are currently used for the treatment of patients with malaria worldwide. They are characterised by a short half-life and feature the most rapidly acting antimalarial drugs to date. They are increasingly being used, often in combination with other drugs, although our knowledge of their main pharmacological features (including their absorption, distribution, metabolism and excretion) is still incomplete. Such data are particularly important in the case of combinations. Artemisinin derivatives are converted primarily, but to different extents, to the bioactive metabolite artenimol after either parenteral or gastrointestinal administration. The rate of conversion is lowest for artelinic acid (designed to protect the molecule against metabolism) and highest for the water-soluble artesunate. The absolute and relative bioavailability of these compounds has been established in animals, but not in humans, with the exception of artesunate. Oral bioavailability in animals ranges, approximately, between 19 and 35%. A first-pass effect is highly probably for all compounds when administered orally. Artemisinin compounds bind selectively to malaria-infected erythrocytes to yet unidentified targets. They also bind modestly to human plasma proteins, ranging from 43% for artenimol to 81.5% for artelinic acid. Their mode of action is still not completely understood, although different theories have been proposed. The lipid-soluble artemether and artemotil are released slowly when administered intramuscularly because of the 'depot' effect related to the oil formulation. Understanding the pharmacokinetic profile of these 2 drugs helps us to explain the characteristics of the toxicity and neurotoxicity. The water-soluble artesunate is rapidly converted to artenimol at rates that vary with the route of administration, but the processes need to be characterised further, including the relative contribution of pH and enzymes in tissues, blood and liver. This paper intends to summarise contemporary knowledge of the pharmacokinetics of this class of compounds and highlight areas that need further research.

Characteristics of some biomass briquettes prepared under modest die pressures

Abstract: Biomass material, including sawdust, rice husks, peanut shells, coconut fibres and palm fruit fibres, was densified into briquettes at modest pressures of 5–7 MPa using a piston and die type of press. The briquettes were tested to evaluate their relaxation behaviour, mechanical strength and burning characteristics. The sawdust briquettes were found to have better overall handling characteristics. But briquettes of different biomass materials required different optimum conditions of fabrication and generally showed a promising potential for further development.

Easy Way to Learn Standardization : Direct and Indirect Methods

Abstract: In direct age-adjustment, a common age-structured population is used as standard. This population may actually exist (e.g., United States population, 1999) or may be fictitious (e.g., two populations may be combined to create a standard). In indirect age-adjustment, a common set of age-specific rates is applied to the populations whose rates are to be standardized. The simplest and most useful form of indirect adjustment is the standardized mortality ratio (SMR) (5).

Antimalarial bioavailability and disposition of artesunate in acute falciparum malaria.

Abstract: The pharmacokinetic properties of oral and intravenous artesunate (2 mg/kg of body weight) were studied in 19 adult patients with acute uncomplicated Plasmodium falciparum malaria by using a randomized crossover design. A sensitive bioassay was used to measure the antimalarial activity in plasma which results from artesunate and its principal metabolite, dihydroartemisinin. The oral study was repeated with 15 patients during convalescence. The mean absolute oral bioavailability of the antimalarial agent in patients with acute malaria was 61% (95% confidence interval [CI], 52 to 70%). The absorption and elimination of oral artesunate were rapid, with a mean elimination half-life of antimalarial activity of 43 min (95% CI, 33 to 53 min). Following oral administration to patients with acute falciparum malaria, peak antimalarial activity in plasma and the area under the plasma concentration-time curve were approximately double those during convalescence and the apparent volume of distribution and clearance were approximately half those during convalescence (P < or = 0.005). Acute malaria is associated with a significant reduction in the clearance of artesunate-associated antimalarial activity.

Mutual reproductive benefits between a wild orchid, Bulbophyllum patens, and Bactrocera fruit flies via a Floral synomone

Abstract: The solitary flower of Bulbophyllum patens selectively attracts male fruit flies of several Bactrocera species with a specific fragrance in the rain forest of Malaysia. It temporarily traps flies between its hinged see-saw lip and column for pollination. The attractant component is zingerone [4-(4-hydroxy-3-methoxyphenyl)-2-butanone], a pungent essence of ginger. Zingerone has a structure resembling two major fruit fly attractants (methyl eugenol and raspberry ketone) and shows potency to attract a wide range of fruit fly species (B. carambolae, B. caudata, B. cucurbitae, B. tau, and B. umbrosa). A fruit fly visitor is rewarded by feeding on zingerone, and in return it removes the pollinarium and then transfers it to another flower. Males of the melon fly acquire the floral essence and selectively store it in the pheromone gland to attract conspecific females. Males of B. papayae, however, convert zingerone to zingerol in the crop. The latter compound is stored in the rectal gland and subsequently released to attract females. This provides a rare example of a mutualistic interaction between insects and plants via a floral synomone, in which both organisms obtain advantages directly benefiting their reproductive systems.

Acetylated plant-fiber-reinforced polyester composites: a study of mechanical, hygrothermal, and aging characteristics

Abstract: The potential of acetylation of plant fibers to improve the properties of composites was studied. The chemical modification of oil palm empty fruit bunch (EFB), coconut fiber (Coir), oil palm frond (OPF), jute, and flax using noncatalyzed acetic anhydride were investigated. Proof of acetylation was indicated by the increase in weight percent gain (WPG). Acetylation at a reaction temperature of 120°C had resulted in the reduction in the tensile properties (stress, modulus, and elongation at break) of EFB and Coir composites. However, at 100°C, the acetylated samples exhibited improved properties. The mechanical properties of acetylated EFB- and Coir-fiber-reinforced polyester composites was evaluated at different fiber loadings. The tensile strength and modulus were improved, but elongation at break was slightly reduced upon acetylation, particularly at high fiber loading. Impact properties were moderately increased for those composites with fiber loadings up to 45%. Acetylation exhibited a low moisture ab...

The effect of coupling agents on the mechanical and physical properties of oil palm empty fruit bunch–polypropylene composites

Abstract: Oil palm empty fruit bunch–polypropylene (EFB-PP) composites have been produced using a twin-screw extruder as the compounding equipment. Two levels of EFB were employed, 40 % and 60 % of the total weight of the sample. Three types of coupling agent, maleic anhydride-modified polypropylene (commercial name Epolene E-43), polymethylene(polyphenyl isocyanate) (PMPPIC) and 3-(trimethoxysilyl)-propylmethacrylate (TPM), were used. Overall, all coupling agents imparted considerable improvements in the flexural properties, E-43 showing the highest enhancement. However, only E-43 was observed to improve impact strength and tensile properties of the composites. All composites with coupling agents showed lower water absorption and thickness swelling. The absorption and swelling decreased as the loading of the coupling agents was increased. © 2000 Society of Chemical Industry

Help-seeking pathways among Malay psychiatric patients.

Abstract: The aim of this study is to explore the help-seeking behaviour of Malay psychiatric patients. A semi-structured interview based on a standard proforma was conducted to assess help seeking process and delays for Malay psychiatric patients attending the psychiatric clinic for the first time. Help-seeking process and delays were defined. Among 134 patients evaluated in the study, 69% had visited traditional healers (bomoh) for the present illness before consulting psychiatrists. The second popular choice of treatment was medical practitioner and only a small percentage of them had consulted homeopathic practitioners and herbalists. Patients who had consulted bomohs were significantly delayed in getting psychiatric treatment compared with those who had not consulted them. Consultation of bomohs was significantly higher among married patients, those with major psychiatric illnesses and in family who believed in supernatural causes of mental illness. However, there was no significant difference in age, gender, educational status and occupation between patients who had consulted and not consulted bomoh. We concluded that majority of the Malay psychiatric patients had sought the traditional treatment prior to psychiatric consultation. The strength of social support and the belief of the patients, friends, and/or relatives in supernatural causes of mental illness were strongly associated with the rate of traditional treatment. Deep-seated cultural beliefs were major barrier to psychiatric treatment.

The problems and challenges of the aging population of malaysia.

Abstract: At present, the number of Malaysians aged 60 years and above is estimated to be 1.4 million and is projected to increase to 3.3 million in the year 2020. The percentage of the population that is 60 years and over has also increased over the years 5.2% in 1970, 5.7% in 1990 and 6.3% in the year 2000. In the year 2020, this percentage is expected to be 9.8% of the population. Between 1990 and 2020, the population of Malaysia is expected to increase from 18.4 million to 33.3 million an increase of 80%. The aged population however is expected to increase from 1.05 million in 1990 to 3.26 million over the same period, an increase of 210%. Apart from an increase in the aged population, the aged are also living longer as evidenced by an increase in life expectancy. As women tend to live longer than men, the disproportion between males and females therefore also increases with ageing. The sex ratio of men per 100 women will decrease from 90.1 in 1990 to 85.8 in 2020. The other feature on the demographic changes that is expected to occur in the aged population is in relation to urbanisation. The percentage of population in urban areas has increased from 24.5% in 1957 to 50.8% in 1990. Thus it is also expected that the proportion of the aged population be higher in the urban than the rural area and this change in the demographic pattern of the aged population will also influence the distribution of health care resources. The elderlies are less healthy than the youngs, hence an increase in the proportion of the aged group is associated with an increase in the prevalence of ill health. The physical and social changes associated with ageing are combined with the debilitating effects of multiple, acute and chronic diseases. Fraility is often compounded by problems such as THE PROBLEMS AND CHALLENGES OF THE AGING POPULATION OF MALAYSIA

Hybrid training algorithm for RBF Network

Abstract: This study presents a new hybrid algorithm for training RBF network. The algorithm consists of a proposed clustering algorithm to position the RBF centres and Givens least squares to estimate the weights. This paper begins with a discussion about the problems of clustering for positioning RBF centres. Then a clustering algorithm called moving k-means clustering algorithm was proposed to reduce the problems. The performance of the algorithm was then compared to adaptive k-means, non-adaptive k-means and fuzzy c-means clustering algorithms. Overall performance of the RBF network that used the proposed algorithm is much better than the ones that used other clustering algorithms. Simulation results also reveal that the algorithm is not sensitive to initial centres.

X-Ray crystal structures of Mg2+ and Ca2+ dimers of the antibacterial drug norfloxacin

Abstract: The hydrothermal reactions of norfloxacin (H-Norf) with MgCl2·6H2O and CaCl2·6H2O yield two unprecedented dimers containing a direct coordinate bond between H-Norf and a metal [Mg2(H2O)6(H-Norf)2]Cl4·4H2O 1 and [Ca2(Cl)(H-Norf)6]Cl3·10H2O 2.

Studies on two interesting microporous polymeric clusters {[Et4N]2[MS4Cu4(CN)4]}n (M = Mo or W) with three-dimensional open frameworks: synthesis, structural characterization, strong optical non-linearities and large optical limiting properties

Abstract: Reactions combining stoichiometric amounts of (Et4N)2MS4 (M = Mo or W) and CuCN (1∶4) in pyridine afforded interesting three-dimensional cluster polymers with open frameworks {[Et4N]2[MS4Cu4(CN)4]}n (M = Mo 1 or W 2). Crystal structure determination shows that the anionic MS4Cu4 units bridged by cyanide produce three-dimensional channels running down the crystallographic a axis. An alternative way to view this framework is in terms of the diamond structure, where C has alternately been replaced by a MS4Cu4 aggregate and C–C by two parallel cyanide bridging ligands. In these intersecting channels the shortest distances between Cu atoms along the b and c axes are 15.22 and 8.11 A respectively. Non-linear optical properties of the two clusters were investigated first with an 8 ns pulsed laser at 532 nm. These two clusters exhibit large optical limiting performance with limiting threshold values of 0.28 for 1, 0.15 J cm−2 for 2 respectively. Both compounds show strong third-order NLO absorption effects (α2 1.5 × 10−91, 1.6 × 10−9 m W−12) and self-focusing performance (n2 1.84 × 10−161, 1.22 × 10−16 m2 W−12) in 3.64 × 10−51 and 2.93 × 10−5 mol dm−32 DMF solution separately. The corresponding effective NLO susceptibilities χ(3) are 4.58 × 10−91 and 5.12 × 10−9 esu 2 while the corresponding hyperpolarizabilities (γ(1) = 1.15 × 10−29 and γ(2) = 1.26 × 10−29 esu) are also reported.

The effect of environmental exposure upon the mechanical properties of coir or oil palm fiber reinforced composites

Abstract: Polyester matrix composites reinforced using nonwoven coir or oil palm empty fruit bunch fiber mats were manufactured. Fibers were used unmodified, chemically modified by acetylation, or treated with silane or titanate coupling agents. Composite test pieces were exposed to decay fungi in unsterile soil for up to 12 months, along with samples made of unreinforced, or glass fiber reinforced, resin. Water exposure tests were also performed. The effect of such exposure on the mass loss, tensile and flexural properties of the samples was evaluated. Mechanical properties deteriorated as a result of exposure. However, acetylation of fibers, or treatment with silane coupling agent was found to afford a significant degree of protection. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1322–1330, 2000

Evaluation of crude palm oil and refined palm olein as dietary lipids in pelleted feeds for a tropical bagrid catfish Mystus nemurus (Cuvier & Valenciennes).

Abstract: The effects of different dietary lipids on the growth, feed utilization and tissue fatty acid composition of a tropical bagrid catfish Mystus nemurus (Cuvier & Valenciennes) were investigated. Eight isonitrogenous and isoenergetic semi-purified diets were fed to triplicate groups of M. nemurus fingerlings for 10 weeks. Diet lipid levels were fixed at 10%, with 1% coming from residual oil in fishmeal and the remainder from cod liver oil (CLO), corn oil (CORN), soybean oil (SBO), crude palm oil (CPO), refined, bleached and deodorized palm olein (RBDPO) or various combinations of these oils. Catfish fed diets supplemented with 9% RBDPO showed significantly (P < 0.05) higher growth rates compared with fish fed the other seven diets. No significant differences in growth performance or feed efficiency ratio were observed between M. nemurus fed 9% CLO, CORN or CPO or fish fed diets containing 4% CLO with either 5% CORN, SBO, CPO or RBDPO. Based upon these results, palm oil-based diets can be used effectively for M. nemurus without compromising growth or feed utilization efficiency. Muscle and liver fatty acid composition of M. nemurus reflected that of the dietary oils added in pelleted diets fed to the fish. Considering the lower cost and availability of palm oil (compared with imported vegetable oils and fish oils) in many tropical countries, its use in dietary formulations for M. nemurus, and possibly other catfish species, will make these fish feeds less expensive.

Technological Maturity and Development without Research: The Challenge for Malaysian Manufacturing

Abstract: Propelled largely by direct investment via multinationals, Malaysia’s manufacturing sector has grown rapidly and is changing its output-mix. In 1992, the share of high-tech products in Malaysian manufacturing exceeded that of Japan, Korea or Taiwan. However, this ‘maturity’ was acquired without a strong research base. This article provides a framework which looks at the role of research and development (R&D) in conferring technological maturity and assesses the progress Malaysian manufacturing has made in this regard. The authors find that while multinationals have transferred many aspects of production, they have been slow in transferring R&D expertise. Neither has indigenous innovation filled this gap. Consequently, the long-term sustainability of the industrial transformation process in Malaysia is in jeopardy. The article concludes with suggestions for corrective policies.