The recommended test guidelines for Zika virus (ZIKV) include using both molecular and serological tools. While the molecular tools are useful for detecting acute infection, the serological tools are useful for the detection of previous infections. Nevertheless, detection of ZIKV-specific antibodies remains a challenge due to the high cross-reactivity between ZIKV and other flaviviruses such as dengue virus (DENV) and Japanese encephalitis virus (JEV). The objective of this study is to evaluate the commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of ZIKV IgG. In this study, we evaluated 6 commercially available anti-ZIKV IgG ELISA kits. Pre-characterized serum panels consisting of 70 sera were selected for the evaluation. The diagnostic accuracy of each ELISA kits was determined and compared to the gold standard, Foci Reduction Neutralization Test (FRNT). The present study established that the performance of the NS1-based anti-ZIKV IgG ELISA kit was superior to that which uses of the E protein as antigen. Overall, commercial ZIKV IgG ELISA showed varying test performances, with some achieving moderate to high test sensitivities and specificities. When compared against the FRNT, the test sensitivities ranged from 7.1% to 78.6%, whereas, the test specificities ranged from 40.0% to 100%. Limitation to the study includes the cross reactivity between flavivirus and specificity of the kit in addressing the cross reactivity.
Aedes albopictus poses a public health risk in tropical countries and temperate countries in recent decades due to its capability to transmit various human arboviruses including dengue, yellow fever, and chikungunya. Vector control is the key for preventing transmission of these pathogenic viruses. Improving the effectiveness of currently utilized collection methods, such as ovitraps, is important for best species abundance monitoring, assessment of the threat of arbovirus transmission, and optimizing control activities. Therefore, this study aimed to assess the potential use of lactic acid bacteria (LAB) waste as an infusion-baited ovitrap for Aedes collection. The performance of overnight tap water, grass hay infusion and LAB waste infusion were compared for their ability in attracting gravid female Ae. albopictus. In this study, the LAB waste infusion was substantially more alluring to Ae. albopictus mosquitoes than the two controls grass hay infusion and tap water.
We conducted the world's first experiments under semi-field conditions (ACL-2 field house) to assess the mating competitiveness of genetically sterile RIDL male mosquitoes (513A strain). The field house is a state-of-the-art, fully-contained trial facility, simulating the living space for a household of 2-4 people in Peninsular Malaysia. Ten genetically sterile RIDL male A. aegypti mosquitoes competed with ten wild type males inside this field house to mate with ten wild type females. Hatched larvae from mated females were screened under a fluorescent microscope for genetic markers to determine if they were fathered by RIDL male or wild type male, and all results were cross-checked by PCR. Two such experiments were conducted, each repeated sufficient number of times. All strains were on a Malaysian lab strain background for the first experiment, while the RIDL males alone were on a recently-colonised Mexican strain background for the second experiment. A total of 52 % of the matings were with RIDL males in the first experiment, while 45 % of the matings were with RIDL (Mexican) males in the second experiment. Statistically, this is not significantly different from 50 % of the matings expected to take place with RIDL males if the latter were as competitive as that of the wild type males. This shows that A. aegypti RIDL-513A has excellent mating competitiveness under semi-field conditions, verifying earlier trends obtained in small lab cages. We also observed high mating compatibility between recently-colonised Mexican RIDL males and lab-reared Malaysian wild type females.
In a study with 113 Asian children in which phenobarbitone was used as the sole antiepileptic drug in 75 children, including Chinese, Malays, and Indians, the mean phenobarbitone dosage required to produce a plasma level of 15 micrograms/ml was 5.2 mg/kg/day. While the mean plasma level/dose ratio varied, the differences between the three ethnic groups were not statistically significant. Also of little difference were the ratios between the male and female groups. For those patients with poor seizure control, however, the mean plasma level/dose ratio was significantly lower than in those whose seizures were controlled. Using additional anticonvulsant drugs concurrently with phenobarbitone in 40 children raised the mean plasma level/dose ratios significantly in each ethnic group. Further, the greater age level in those given additional antiepileptic drugs might have contributed slightly to a higher mean plasma level/dose ratio.
The pharmacokinetics of propofol was studied in 11 Asian patients with fentanyl-isoflurane anaesthesia during cardiopulmonary bypass (CPB) and undergoing elective coronary artery bypass grafting (CABG). Instead of the usual increments of morphine and a benzodiazepine, propofol (4 mg/kg/h) was initiated at the start of CPB and ceased at CPB separation. Whole blood propofol concentrations were determined during and postinfusion using high-performance liquid chromatography with fluorescence detection. Data from four patients seemed to fit a two-compartment model, whereas those from seven patients were significantly (F test, p < 0.05) better fitted to a three-compartment model. The pharmacokinetic parameters were as follows: The mean (SD) of the initial distribution phase t1/2 pi, intermediate distribution phase t1/2 alpha, and elimination phase t1/2 beta were 2.22 (1.04) min, 42.9 (16.4) min, and 370 (138) min, respectively. The mean clearance of 1.31 (0.50) L/min was lower than those reported from other studies, whereas the mean blood concentration of 2.2 (1.0) mg/L at the 1-h infusion period was higher. The mean calculated apparent Css was 3.9 (1.5) mg/L. The low clearance is likely to be due to hemodynamic changes during CPB and CABG, thereby affecting drug distribution and blood flow to the liver.
Nineteen acutely disturbed psychotic Asian patients were treated with a single intramuscular injection of 50 mg of zuclopenthixol acetate in Viscoleo. Patients were assessed clinically before and after treatment using the Brief Psychiatric Rating Scale (BPRS). Serum zuclopenthixol and the inactive geometric isomer trans(E)-clopenthixol were determined by high-performance liquid chromatography after intramuscular injection. All patients improved, with the BPRS being significantly reduced (p < 0.001) at 72 h after injection. Adverse effects were generally few. The mean +/- SEM serum zuclopenthixol concentrations at 24, 48, and 72 h were 19.9 +/- 2.8, 31.5 +/- 4.5, and 17.8 +/- 2.9 micrograms/L, respectively. trans(E)-Clopenthixol concentrations ranged from negligible to 39.5 micrograms/L. This study confirms that a single intramuscular injection of 50 mg is adequate for managing severely disturbed psychotic patients for the first 3 days. The serum zuclopenthixol concentrations attained in the Asian patients were higher than those reported in Caucasian psychiatric patients. In some patients, a considerable amount of zuclopenthixol had been transformed to trans(E)-clopenthixol.
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.
Previously studied candidate genes have failed to account for inter-individual variability of docetaxel and doxorubicin disposition and effects. We genotyped the transcriptional regulators of CYP3A and ABCB1 in 101 breast cancer patients from 3 Asian ethnic groups, that is, Chinese, Malays and Indians, in correlation with the pharmacokinetics and pharmacodynamics of docetaxel and doxorubicin. While there was no ethnic difference in docetaxel and doxorubicin pharmacokinetics, ethnic difference in docetaxel- (ANOVA, P=0.001) and doxorubicin-induced (ANOVA, P=0.003) leukocyte suppression was observed, with Chinese and Indians experiencing greater degree of docetaxel-induced myelosuppression than Malays (Bonferroni, P=0.002, P=0.042), and Chinese experiencing greater degree of doxorubicin-induced myelosuppression than Malays and Indians (post hoc Bonferroni, P=0.024 and 0.025). Genotyping revealed both PXR and CAR to be well conserved; only a PXR 5'-untranslated region polymorphism (-24381A>C) and a silent CAR variant (Pro180Pro) were found at allele frequencies of 26 and 53%, respectively. Two non-synonymous variants were identified in HNF4alpha (Met49Val and Thr130Ile) at allele frequencies of 55 and 1%, respectively, with the Met49Val variant associated with slower neutrophil recovery in docetaxel-treated patients (ANOVA, P=0.046). Interactions were observed between HNF4alpha Met49Val and CAR Pro180Pro, with patients who were wild type for both variants experiencing least docetaxel-induced neutropenia (ANOVA, P=0.030). No other significant genotypic associations with pharmacokinetics or pharmacodynamics of either drug were found. The PXR-24381A>C variants were significantly more common in Indians compared to Chinese or Malays (32/18/21%, P=0.035) Inter-individual and inter-ethnic variations of docetaxel and doxorubicin pharmacokinetics or pharmacodynamics exist, but genotypic variability of the transcriptional regulators PAR, CAR and HNF4alpha cannot account for this variability.
A one year study was conducted to evaluate the impact of spray application of Bacillus thuringiensis israelensis (Bti), strain AM65-52 on vector populations and dengue transmission in a dengue endemic state in Malaysia. Residential sites with similar populations of Aedes aegypti (L.) and Aedes albopictus Skuse were studied. One site was treated with spray application of Bti into all outdoor target vector habitats, which consisted of natural and artificial containers. The other site was not treated. The impact of spray application was measured with an indoor and outdoor ovitrap index (OI) and epidemiologic data. Significant reductions in both Ae. aegypti and Ae. albopictus, OI were observed both indoors and outdoors, in treated sites compared to untreated sites (p < 0.05). OI reduction was achieved over time in the treated area. The OI was suppressed to below 10%. This was maintained for 4 weeks into the post-treatment phase. The outdoor OI at the untreated site remained at more than 40% for 38 weeks during the evaluation period. One dengue case occurred at the Bti treatment site at the beginning of the treatment phase, but no further cases were detected during the remainder of the treatment phase. However, there was an ongoing dengue outbreak in the untreated area with 15 serologically confirmed cases during weeks 37-54. Intensive fogging operations with pyrethroids at the untreated (Bti) site had a positive impact on Ae. albopictus, but not on Ae. aegypti.
Phlebotomine sand flies were collected using CO2 baited CDC light trap in 2000 and 2001 in limestone areas and caves of western Malaysia. A total of 1,548 specimens were collected comprising 18 species from two genera: Phlebotomus (6 spp) and Sergentomyia (12 spp). Phlebotomus major major (38.9%) was the predominant species followed by Sergentomyia perturbans (20.1%), P. stantoni (15.3%) and others. Biting activity of the sand flies at the Gua Senyum caves, Gua Kota Gelanggi, Batu caves and Gua Kelam were observed using the bare leg landing catch (BLC) technique. Four Phlebotomus spp at Gua Senyum were found to bite humans with a unimodal biting peak (between 01:00 and 04:00 AM). At Gua Kota Gelanggi P. major major was observed to bite humans, but at Batu Caves and Gua Kelam no sand flies were observed to bite humans. Sergentomyia spp did not feed on humans even though high numbers were caught in light traps. The populations of phleobotomine sand flies fluctuated, with several peaks especially among P. major major which peaked in December and was low in February and August. Phlebotomus stantoni was abundant throughout 2001. Most species populations were weakly related to rainfall because they inhabited caves.
In Peninsular Malaysia, a large proportion of malaria cases occur in the central mountainous and forested parts of the country. As part of a study to assess remote sensing data as a tool for vector mapping, we conducted entomological surveys to determine the type of mosquitoes, their characteristics and the abundance of habitats of the vector Anopheles maculatus in malaria endemic areas in Pos Senderot. An. maculatus mosquitoes were collected from 49 breeding sites in Pos Senderot. An. maculatus preferred to breed in water pockets formed on the bank of rivers and waterfalls. The most common larval habitats were shallow pools 5.0-15.0 cm deep with clear water, mud substrate and plants or floatage. The mosquito also preferred open or partially shaded habitats. Breeding habitats were generally located at 100-400 m from the nearest human settlement. Changes in breeding characteristics were also observed. Instead of breeding in slow flowing streams, most larvae bred in small water pockets along the river margin.
A simulated field study on the efficacy of commercial household aerosol insecticides was conducted. The bioefficacy of three pyrethroid aerosols, designated as PA1, PA2 and PA3, was tested in cabins furnished to simulate bedroom conditions. Each aerosol product was tested against lab-bred Aedes aegypti mosquitoes based on the insecticide manufacturers' recommended dosages. Ten cages with mosquitoes were placed in the following locations: one cage in the middle of the room; two each on and underneath the bed; three each placed inside, behind and on top of the wardrobe; and four placed on and in the desk. With the desk, each cage was placed inside each of three drawers (totally closed, partially closed and opened). Prior to the experiments, the discharge rate of each aerosol can was determined. Ten to 20 lab-bred 2-5 day-old sugar-fed Ae. aegypti adult mosquitoes were placed inside the test cages. The aerosol was then discharged into the cabin at the recommended dosage. After 30 minutes, the mosquitoes were transferred into clean paper cups and their mortality recorded after 24 hours. All the aerosols induced complete or very high mortality in the caged Ae. aegypti females, except in the cages hidden completely inside the drawers and wardrobes. Insecticide droplet analysis indicated variable uniformity of the droplets was produced. The aerosol insecticides were effective against mosquitoes provided they were used in accordance with the manufacturers' recommendations.
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.
Dengue 2 and 4 viruses obtained from dengue-infected patients were maintained in a C6/36 Aedes albopictus Skuse cell line and used to infect adult female Aedes aegypti mosquitoes. Each serotype was mixed separately with fresh human erythrocytes and fed to adult female mosquitoes using an artificial membrane feeding technique. Fully engorged mosquitoes were selected and retained at 26 degrees C, 28 degrees C and 30 degrees C to observe dengue virus development in Aedes vectors. Virus detection was carried out by reverse-transcriptase polymerase chain reaction (RT-PCR). The virus was first detected on Day 9 at 26 degrees C and 28 degrees C and on Day 5 at 30 degrees C for both dengue 2 and 4. The study shows the incubation period of the viruses decreased when the extrinsic incubation temperature increases.
Reciprocal and homologous mating experiments between Malaysian Aedes aegypti and Aedes albopictus mosquitoes were conducted in the laboratory. Two methods were employed, namely an artificial mating technique and a natural cage mating technique. The study demonstrated there exists a strong reproductive isolation between Ae. aegypti and Ae. albopictus. Insemination occurred in cross-mating experiments between Ae. aegypti females and Ae. albopictus males and also between Ae. albopictus females and Ae. aegypti males. Cross mating between Ae. aegypti females and Ae. albopictus males produced more eggs than that between Ae. albopictus females and Ae. aegypti males with both artificial mating and natural cage mating techniques. The matings did not result in the production of viable eggs by the females. No embryonation of these eggs was observed when the eggs were bleached. With homologous mating Aedes aegypti produced significantly greater numbers of eggs compared to Aedes albopictus mosquitoes, and all the eggs hatched successfully.
The field bioefficacy of a wettable granule (WG) formulation of Bacillus thuringiensis israelensis (Bti), VectoBac WG (Bti strain AM65-52) against dengue vectors, Aedes aegypti and Ae albopictus; was evaluated in a suburban residential area (TST) and in a temporary settlement site (KB) in the state of Selangor, Malaysia. Pre-control ovitrap surveillance of the trial sites indicated a high population of both types of Aedes mosquitoes. The populations were monitored continuously by weekly ovitrapping. Bti was sprayed biweekly at a dosage of 500 g/ha by using a mist-blower. The spray application was targeted into outdoor larval habitats. If required, Bti formulation was also applied directly into indoor water-holding containers at 8 g/1,000 l. Based on ovitrap surveillance, a significant reduction in Aedes populations was evident 4 weeks after initiating the first Bti treatment. The ovitrap index (OI) and the larvae density decreased drastically in both trial sites. In TST, the indoor OI was significantly reduced from 57.50 +/- 7.50% to 19.13 +/- 5.49% (p<0.05), while the outdoor OI decreased from 38.89 +/- 11.11% to 15.36 +/- 5.93%. In KB, similarly, the OI was significantly reduced by more than half, from 66.66 +/- 6.67% to 30.26 +/- 2.99% (p< 0.05). In all cases, the reduction in OI was paralleled by reduction in larval density.
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.
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.
Surveillance of mosquitoes and their distribution in association with rainfall, relative humidity, and temperature were conducted in selected suburban and forested areas, namely, Sungai Penchala (Kuala Lumpur) and Taman Alam (Selangor) for 12 months. Armigeres kesseli was the most abundant species in Sungai Penchala while Aedes butleri was the most dominant species in Taman Alam. A positive correlation between mosquito distribution and rainfall was observed in selected mosquito species in Sungai Penchala (Armigeres kesseli, r = 0.75; Armigeres subalbatus, r = 0.62; and Aedes albopictus, r = 0.65) and Taman Alam (Armigeres sp, r = 0.59; Ae. butleri, r = 0.85; and Ae. albopictus, r = 0.62). However, no significant cor- relation was found either between selected mosquito species in both study areas and relative humidity or temperature. Results obtained suggested that vector control programs to be conducted based on temporal distribution of vectors in order to achieve beneficial outcomes with effective costing.
Ovitrap surveillance was conducted in 2012 and 2006 in Malay and Aboriginal Villages on Carey Island. In each village, standard ovitraps were placed indoors and outdoors at randomly selected houses/locations. All L3 larvae recovered were identified up to species level. Results demonstrated that only larvae of Aedes albopictus were found in all the positive ovitraps placed indoors and outdoors. In 2012, a high ovitrap index (OI) of 66.7% indoor and 84.0% outdoor in the Malay Village; and 62.5% indoor and 88.0% outdoor in Aboriginal Village with an apparent absence of Aedes aegypti. In 2006, a 100% OI was recorded in all ovitraps set indoors and outdoors in both villages.