The combined adulticidal, larvicidal, and wall residual activity of ULV-applied bifenthrin, a synthetic pyrethroid, was evaluated in houses in Kuala Lumpur, Malaysia, against larvae and adults of lab-bred Aedes aegypti and Culex quinquefasciatus. A portable ULV sprayer was used to disperse a ULV formulation of bifenthrin at a discharge rate of 45 ml/min. The results indicated that bifenthrin sprayed at this rate exhibited all the three activities against the test mosquitoes. Complete adult mortalities were achieved, while very high larvicidal activity was also effected, which persisted for seven days. Wall bioassay with adults of Ae aegypti also resulted in very high mortality, which also persisted for one week. The combined mosquitocidal activities of bifenthrin is considered more effective especially in the control of dengue vectors.
To compare the advantages and disadvantages of the New Bird metal cups and silicone cups in terms of maternal and foetal outcome. To study the adverse effects and factors associated with failed vacuum deliveries.
Wolbachia-based vector control strategies have been proposed as a mean to augment the existing measures for controlling dengue vector. Prior to utilizing Wolbachia in novel vector control strategies, it is crucial to understand the Wolbachia-mosquito interactions. Many studies have only focused on the prevalence of Wolbachia in female Aedes albopictus with lack of attention on Wolbachia infection on the male Ae. albopictus which also affects the effective expression of Wolbachia induced- cytoplasmic incompatibility (CI). In this study, field surveys were conducted to screen for the infection status of Wolbachia in female and male Ae. albopictus from various habitats including housing areas, islands and seashore.
This study was conducted to determine the inhibitory effects of ribavirin and hydroxyurea on dengue virus replication in Aedes aegypti mosquitoes. Female Ae. aegypti mosquitoes were infected with dengue-2 virus and fed ribavirin at a dose of 0.3 mg/ml and/or hydroxyurea at a dose of 6 mg/ml via artificial membrane feeding technique. The virus in infected mosquitoes was isolated using C6/36 cell culture. Peroxidase-antiperoxidase (PAP) staining was used to detect dengue-infected C6/36 cells and to quantify the level of infection by determining the presence of infected cells. In mosquitoes treated with ribavirin alone, hydroxyurea alone or both drugs in combination had reductions in dengue infection rates of 87.72, 89.47 and 95.61%, respectively. The mortalities of female Ae. aegypti mosquitoes fed with these drugs were significantly higher than the control. Ribavirin also had an inhibitory effect on the fecundity of female Ae. aegypti mosquitoes.
A pilot study was undertaken to determine the effectiveness of space application of insecticides for the control of malaria in Ranau, a district in Sabah. A village each was treated monthly: with chemical adulticide--alpha cypermethrin (Fendona SC(R)/10SC(R)) at 2 g a.i./10,000 m2 in Pahu; with biological larvicides--Bacillus thuringiensis israelensis (Vectobac 12AS(R)) at 500 ml/10,000 m2 or B. sphaericus (Vectolex WG(R)) at 500 g/10,000 m2 in Pinawantai; and with a mixture of chemical adulticide and biological larvicide in Togop Laut. All sprayings were conducted using a portable mist blower. During the study period all villages, including Tarawas the untreated village, received the conventional malaria control measures. Entomological and epidemiological surveillance was used to measure the effectiveness of the space application. The entomological surveillance indicated that the An. balabacensis population was significantly reduced by alpha cypermethrin in Pahu and Togop Laut and B. sphaericus in Pinawantai; but was not reduced by B.t.i. in Pinawantai. There was a significant reduction in the number of malaria cases and in the slide positivity rate in the treated villages during the study period. The pilot study does indicate that space application of larvicides/adulticides or a mixture of both is able to reduce the malaria vector population and the malaria transmission. A larger scale study needs to be undertaken in a malarious village/province to determine whether space application of insecticides together with other malaria control measures will be able to eradicate malaria.
The insecticide resistance status of 4 strains of adult male Blattella germanica, viz M (Malacca), E (England), F (restaurant) and K (cafeteria) against malathion and bendiocarb compared with a reference susceptible strain (S) was determined by using a modified WHO bioassay method. The results indicated that all the 4 strains were resistant to the insecticides albeit in different degrees. Resistance ratios for malathion ranged from 1.85-41.07-fold, whereas that of bendiocarb ranged from 1.68-4.83-fold. The biochemical microplate enzyme assays technique employed indicated that the resistance in M and E strains were attributed to acetylcholinesterase insensitivity. Multiple resistance was not detected in any of the 4 strains. Parameters of the identified resistance mechanism correlated well with the observed level of resistance. Agar gel electrophoresis showed that variations in esterase isoenzymes did not confer organophosphate and carbamate resistance to the 4 strains.
In this study, artificial membrane feeding technique was used to orally feed Aedes aegypti with dengue and chikungunya viruses. Virus detection was carried out by reverse transcriptase polymerase chain reaction. The study did not detect dual infection of Ae. aegypti with dengue and chikungunya virus from the same pool or from individual mosquitoes. Oral receptivity of Ae. aegypti to chikungunya virus was higher than that of dengue virus.
A study was conducted to examine the persistency of transovarial dengue virus type 2 (DEN-2) in a Selangor strain of Aedes aegypti mosquitoes. Two hundred 4-5 day old female mosquitoes were fed with blood containing dengue virus. The infected mosquitoes were reared to the 7th generation; each generation was screened for the virus using immunological staining methods. The virus was detectable until the 5th generation but absent in the 6th and the 7th generations. Therefore, dengue virus type 2 can be transmitted transovarially in Aedes aegypti mosquitoes until the fifth generation under laboratory conditions.
Wild caught female Culex quinquefasciatus (Say) from Kuala Lumpur were blood fed and reared in the insectarium. The late third stage of the F1 larvae which survived the high selection pressure of malathion and permethrin were reared and colonies were established from adults that emerged. Larvae from these colonies were then subjected in the subsequent 9 generations to higher selection pressure. The rate of resistance development were measured by LC50 value of larval bioassay, LT50 value of adult bioassay and the frequency of the elevated esterase levels. In another set of experiments using the same batch of Culex mosquitos, the larvae were not exposed to any insecticides and the decrease in resistance rate was monitored in each subsequent 9 generations by using similar methods. The heterozygous standard laboratory strain was selected for susceptibility using the single raft sib-selection method. The result showed that the field collected F1 generation was 96.0 and 6.3 fold more resistant to malathion and permethrin, respectively. After selection for about 9 generations the resistance ratio to malathion and permethrin was 6.2 and 767.3 fold more compared to the LC50 values of F1 generations, respectively. Esterase in F1 larvae was 6.0 fold more than the standard laboratory strain.
Rapid enzyme microassays for the detection of resistance due to organophosphate and carbamate in individual field-collected strains of Culex quinquefasciatus adults were conducted. These tests allowed accurate differentiation by eye, on the basis of color changes of susceptible and resistant individuals. Two separate tests were conducted for the biochemical assays. In the insensitive acetylcholinesterase (AChE) test, acetylthiocholine iodide (ACTH) and 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB) were used as substrate and coupling agent respectively. The resulting yellow chromophore indicated AChE activity. Test results showed that the color intensity decreased as increasing concentrations of propoxur were added, thereby confirming the susceptibility of the enzyme to inhibitor. Assay of non-specific esterase however, indicated elevated levels which were correlated with degree of malathion resistance. Electrophoretic data revealed the presence of 2 esterase bands in all strains. It was concluded that such a pattern was not contributory to malathion resistance in adults.
Based on data collected by the population-based Singapore Cancer Registry over the period 1968 to 1982, baseline epidemiological characteristics and incidence trends of primary liver cancer were described. This will facilitate the interpretation of future trends, especially in the light of new interventions such as hepatitis B immunisation. The primary liver cancer incidence is four times higher in males than in females, with the incidence peaked in the seventh decade. The incidence rate was higher in the Chinese than in Malays and Indians and marginally higher among foreign born than Singapore born Chinese. A general declining trend in liver cancer incidence was especially notable in the local born Chinese. Misclassification of metastatic carcinomas in the earlier years of cancer registration may have contributed to the initial higher incidence. Definitive decrease in incidence as a result of hepatitis immunisation will only be seen in another two to three decades.
The application of the Geographic Information Systems (GIS) to the study of vector transmitted diseases considerably improves the management of the information obtained from the field survey and facilitates the study of the distribution patterns of the vector species.
Tectonic movements, climatic oscillations, and marine transgressions during the Cenozoic have had a dramatic effect on the biota of the tropical rain forest. This study aims to reveal the phylogeography and evolutionary history of a Peninsular Malaysian endemic tropical timber species, Neobalanocarpus heimii (Dipterocarpaceae). A total of 32 natural populations of N. heimii, with 8 samples from each population were investigated. Fifteen haplotypes were identified from five noncoding chloroplast DNA (cpDNA) regions. Overall, two major genealogical cpDNA lineages of N. heimii were elucidated: a widespread southern and a northern region. The species is predicted to have survived in multiple refugia during climatic oscillations: the northwestern region (R1), the northeastern region (R2), and the southern region (R3). These putative glacial refugia exhibited higher levels of genetic diversity, population differentiation, and the presence of unique haplotypes. Recolonization of refugia R1 and R2 could have first expanded into the northern region and migrated both northeastwards and northwestwards. Meanwhile, recolonization of N. heimii throughout the southern region could have commenced from refugia R3 and migrated toward the northeast and northwest, respectively. The populations of Tersang, Pasir Raja, and Rotan Tunggal exhibited remarkably high haplotype diversity, which could have been the contact zones that have received an admixture of gene pools from the northerly and also southerly regions. As a whole, the populations of N. heimii derived from glacial refugia and contact zones should be considered in the conservation strategies in order to safeguard the long-term survival of the species.
Diet and lifestyle modification is commonly used in constipation management. As there is a dearth of studies on this topic in Malaysia, we aim to elucidate the relations between stool patterns, dietary intake and physical activity levels among adults with functional constipation.
Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate's application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulose crystallinity, which inhibit the digestibility of the biomass for cellulose extraction. This situation offers both challenges and promises for the biomass biorefinery development to utilize the cellulose from lignocellulosic biomass. Thus, multistep biorefinery processes are necessary to ensure the deconstruction of noncellulosic content in lignocellulosic biomass, while maintaining cellulose product for further hydrolysis into nanocellulose material. In this review, we discuss the molecular structure basis for biomass recalcitrance, reengineering process of lignocellulosic biomass into nanocellulose via chemical, and novel catalytic approaches. Furthermore, review on catalyst design to overcome key barriers regarding the natural resistance of biomass will be presented herein.
Photodynamic therapy is a treatment modality that involves site-directed generation of cytotoxic reactive oxygen species by light-activated photosensitisers.
Intensive care for severe head injury patients is very important in the prevention and treatment of secondary brain injury. However, in a resources constraint environment and limited availability of Intensive Care Unit (ICU) beds in the hospitals, not all severe head injury patients will receive ICU care. This prospective study is aimed to evaluate the outcome of severe head injured patients who received ICU and general ward care in Sarawak General Hospital (SGH) over a 6-month period. A total of thirty five severe head injury patients were admitted. Twenty three patients (65.7%) were ventilated in general ward whereas twelve patients (34.3%) were ventilated in ICU. Overall one month mortality in this study was 25.7%. Patients who received ICU care had a lower one month mortality than those who received general ward care (16.7% vs 30.4%), although it was not statistically different. Multivariate analysis revealed only GCS on admission (OR 0.731; 95% CI 0.460 to 0.877; P=0.042) as the independent predictive factor for one month mortality in this study.
We report a case of 50-year-old man who was presented with recurrent episodes of left sided hemiparesis. CT scan and MRI brain revealed a large intraventricular fatty lesion. Histopathological examination showed a picture of angiolipoma.
Temperature variation is an important factor in Everglade wetlands ecology. A temperature fluctuation from 17 degrees C to 32 degrees C recorded in the Everglades may have significant impact on fish dynamics. The short life cycles of some of Everglade fishes has rendered this temperature variation to have even more impacts on the ecosystem. Fish population dynamic models, which do not explicitly consider seasonal oscillations in temperature, may fail to describe the details of such a population. Hence, a model for fish in freshwater marshes of the Florida Everglades that explicitly incorporates seasonal temperature variations is developed. The model's main objective is to assess the temporal pattern of fish population and densities through time subject to temperature variations. Fish population is divided into 2 functional groups (FGs) consisting of small fishes; each group is subdivided into 5-day age classes during their life cycles. Many governing sub-modules are set directly or indirectly to be temperature dependent. Growth, fecundity, prey availability, consumption rates and mortality are examples. Several mortality sub-modules are introduced in the model, of which starvation mortality is set to be proportional to the ratio of prey needed to prey available at that particular time step. As part of the calibration process, the model is run for 50 years to ensure that fish densities do not go to extinction, while the simulation period is about 8 years. The model shows that the temperature dependent starvation mortality is an important factor that influences fish population densities. It also shows high fish population densities at some temperature ranges when this consumption need is minimum. Several sensitivity analyses involving variations in temperature terms, food resources and water levels are conducted to ascertain the relative importance of temperature dependence terms.