Mosquito Larvicidal Potential of Tropical Seaweeds: Acetylcholinesterase Inhibitory Effects of Bryopsis pennata, Padina australis and Sargassum binderi on Aedes aegypti (L.) and Aedes albopictus Skuse

@#Introduction: Inhibition of the cholinesterase’s function leads to paralysis and death. This mechanism is served as a common mode of action of insecticide. The three tropical seaweeds, namely Bryopsis pennata, Padina australis and Sargassum binderi were reported for its potential mosquito larvicidal effect. In the present study, these seaweeds were evaluated for their potential as a cholinesterase inhibitor in the mechanism of larvicidal action. Methods: Acetylcholinsterase (AChE) inhibition assay was carried out based on the colorimetric method using a microplate reader. Phytochemical content of the seaweed extracts was screened by using liquid chromatography-mass spectroscopy (LC-MS). Results: Green seaweed B. pennata showed the strongest inhibition effect towards in vitro AChE by using tissue homogenates of Aedes aegypti (IC50 value = 0.84 mg mL-1) and Aedes albopictus as the enzyme source (IC50 value = 0.92 mg mL-1). The pattern of Lineweaver-Burk plots revealed that B. pennata was a mixed type inhibitor of AChE, as the readings of Km, Vmax, Ki and Ki’, indicates that it had a strong inhibition ability with high binding affinity towards both free enzyme and enzyme-substrate complex. Conclusion: These findings suggest the compound(s) in B. pennata extract serves as a promising source that could be developed into a mosquito larvicidal agent with AChE inhibition effect.

Artificial Intelligence Model As Predictor For Dengue Outbreaks

@#Dengue is an increasing threat in Malaysia, particularly in the more densely populated regions of the country. We present an Artificial Intelligence driven model in predicting Aedes outbreak, using predictors of weather variables and vector indices sourced from the Ministry of Health. Analysis and predictions to estimate Aedes populations were conducted, with its results being used to infer the possibility of dengue outbreaks at pre-determined localities around the Klang Valley, Malaysia. A Bayesian Network machine learning technique was employed, with the model being trained using predictor variables such as temperature, rainfall, date of onset and notification, and vector indices such as the Ae. albopictus count, Ae. aegypti count and larval count. The interfaces of the system were developed using the C# language for Server-side configuration and programming, and HTML, CSS and JavaScript for the Client Side programming. The model was then used to predict the population of Aedes at periods of 7, 14, and 30 days. Using the Bayesian Network technique utilising the above predictor variables we proposed a finalised model with predictive accuracy ranging from 79%-84%. This model was developed into a Graphical User Interface, which was purposed to assist and educate the general public of regions at risk of developing dengue outbreak. This remains a valuable case-study on the importance of public data in the context of combating a public health risk via the development of models for predicting outbreaks of dengue which will hopefully spur further sharing of data by all parties in combating public health threats.

Pure PBL, Hybrid PBL and Lecturing: which one is more effective in developing cognitive skills of undergraduate students in pediatric nursing course?

BACKGROUND: Nursing education in Iran has conventionally focused on lecture-based strategies. Improvements in teaching and learning over the years have led to an expansion of the pedagogies available to educators. Likewise, there has been a suggestion for a move toward more learner-centered teaching strategies and pedagogies that can result in improvement in learning. This study was undertaken to investigate the effects of Problem-Based Learning in developing cognitive skills in learning Pediatric Nursing among university students. METHODS: In this quasi-experimental, posttest-only nonequivalent control group design, the subjects were undergraduate students who had enrolled in Pediatric Nursing II at Islamic Azad University in Iran. The experiment was conducted over a period of eight weeks, one two-hour session and two two-hour sessions. Two experimental groups, Pure Problem-Based Learning (PPBL) and the Hybrid Problem- Based Learning (HPBL), and one Lecturing or Conventional Teaching and Learning (COTL) group were involved. In the PPBL group, PBL method with guided questions and a tutor, and in the HPBL group, problem-based learning method, some guided questions, minimal lecturing and a tutor were used. The COTL group, however, underwent learning using conventional instruction utilizing full lecture. The three groups were compared on cognitive performances, namely, test performance, mental effort, and instructional efficiency. Two instruments, i.e., Pediatric Nursing Performance Test (PNPT) and Paas Mental Effort Rating Scale (PMER) were used. In addition, the two-Dimensional Instructional Efficiency Index (IEI) formula was utilized. The statistical analyses used were ANOVA, ANCOVA, and mixed between-within subjects ANOVA. RESULTS: Results showed that the PPBL and HPBL instructional methods, in comparison with COTL, enhanced the students' overall and higher-order performances in Pediatric Nursing, and induced higher level of instructional efficiency with less mental effort (p < 0.005). Although there was no significant difference in lower-order performance among the groups during the posttest (p = 0.92), the HPBL group outperformed the COTL group on the delayed posttest (p = 0.028). CONCLUSIONS: It may be concluded that both forms of PBL were effective for learning Pediatric Nursing. Moreover, PBL appears to be useful where there are shortages of instructors for handling teaching purposes.

First Complete Genome Sequence of a Chikungunya Virus Strain Isolated from a Patient Diagnosed with Dengue Virus Infection in Malaysia.

Here, we report the complete genome sequence of a chikungunya virus coinfection strain isolated from a dengue virus serotype 2-infected patient in Malaysia. This coinfection strain was determined to be of the Asian genotype and contains a novel insertion in the nsP3 gene.

Larvicidal activity, inhibition effect on development, histopathological alteration and morphological aberration induced by seaweed extracts in Aedes aegypti (Diptera: Culicidae)

Objective: To investigate the larvicidal activity, inhibition effect on development, histopathological alteration and morphological aberration induced by the extracts derived from seaweeds Bryopsis pennata (B. pennata). Sargassum binderi (S. binderi) and Padina australis in Aedes aegypti (Ae. aegypti) larvae and to characterize the phytochemical components of the three seaweeds. Methods: Larvicidal activity of the seaweeds towards the larvae of Ae. aegypti was determined according to WHO. The inhibition effect of seaweeds was assessed by determining the mortality, adult emergence rate, larval and pupa duration of the treated larvae. Histopathological effect on midgut epithelium of larvae and morphological aberration induced by the methanol extracts were examined. Phytochemical analysis was done to determine the presence of alkaloids, saponins, steroids and terpenoids in the seaweeds. Results: Chloroform partition of B. pennata extract exhibited the strongest larvicidal activity (LC

Larvicidal activity, inhibition effect on development, histopathological alteration and morphological aberration induced by seaweed extracts in Aedes aegypti (Diptera: Culicidae)

OBJECTIVE@#To investigate the larvicidal activity, inhibition effect on development, histopathological alteration and morphological aberration induced by the extracts derived from seaweeds Bryopsis pennata (B. pennata), Sargassum binderi (S. binderi) and Padina australis in Aedes aegypti (Ae. aegypti) larvae and to characterize the phytochemical components of the three seaweeds.@*METHODS@#Larvicidal activity of the seaweeds towards the larvae of Ae. aegypti was determined according to WHO. The inhibition effect of seaweeds was assessed by determining the mortality, adult emergence rate, larval and pupa duration of the treated larvae. Histopathological effect on midgut epithelium of larvae and morphological aberration induced by the methanol extracts were examined. Phytochemical analysis was done to determine the presence of alkaloids, saponins, steroids and terpenoids in the seaweeds.@*RESULTS@#Chloroform partition of B. pennata extract exhibited the strongest larvicidal activity (LC50 = 82.55 μg/mL), followed by methanol extract of B. pennata (LC50 = 160.07 μg/mL) and chloroform partition of S. binderi extract (LC50 = 192.43 μg/mL). The methanol extract of S. binderi exhibited the strongest effect on prolongation of larval period (1.5-fold longer as compared to control) and resulted in strongest inhibition effect in adult emergence (98.67%). The histopathological study showed that larvae treated with seaweed extracts had cytopathological alteration of the midgut epithelium. The morphological observation revealed that the anal papillae and terminal spiracles of larvae were the common sites of aberrations.@*CONCLUSIONS@#The study provided information on various effects of seaweed extracts on Ae. aegypti. Further investigation on identifying the active compounds and their mechanisms of action is recommended.

Comparative field evaluation of residual-sprayed deltamethrin WG and deltamethrin WP for the control of malaria in Pahang, Malaysia.

The bioefficacy of indoor residual-sprayed deltamethrin wettable granule (WG) formulation at 25 mg a.i./m2 and 20 mg a.i./m2 for the control of malaria was compared with the current dose of 20 mg/m2 deltamethrin wettable powder (WP) in aboriginal settlements in Kuala Lipis, Pahang, Malaysia. The malaria vector has been previously identified as Anopheles maculatus. The assessment period for the 20 mg/m2 dosage was six months, but for the 25 mg/m2 dosage, the period was 9 months. Collections of mosquitoes using the bare-leg techniques were carried out indoors and outdoors from 7:00 PM to 7:00 AM. All mosquitoes were dissected for sporozoites and parity. Larval collections were carried out at various locations to assess the extent and distribution of breeding of vectors. A high incidence of human feeds was detected during May 2005 and a low incidence during January 2005 for all the study areas. Our study showed that deltamethrin WG at 25 mg/m2 suppressed An. maculatus biting activity. More An. maculatus were caught in outdoor landing catches than indoor landing catches for all the study areas. The results indicate that 25 mg/m2 WG is good for controlling malaria for up to 9 months. Where residual spraying is envisaged, the usual two spraying cycles per year with 20 mg/m2 deltamethrin may be replaced with 25 mg/m2 deltamethrin WG every 9 months.

Effectiveness of several locally available membranes used for artificial feeding of Aedes albopictus Skuse.

Artificial feeding of mosquitoes with blood meal is an important technique in the studies of mosquito feeding. Owing to the difficulty in obtaining suitable artificial membranes for mosquito feeding from other sources, several easily obtainable membranes in Malaysia were tested for their suitability as a replacement. Skin of chicken, fish, and salted sausage were obtained and tested against cattle skin membrane as a control. The results showed that cattle skin is still the most favorable membrane to be used, with full engorgement rate of around 57% using fresh human blood. However, processed chicken skin was shown having potential for further testing since with feeding using human blood kept overnight at 4 degrees C, an engorgement rate of 50% was obtained.

Temperature related storage evaluation of an RT-PCR test kit for the detection of dengue infection in mosquitoes.

The rapid detection of dengue infection in mosquito vectors is important for early warning to forestall an outbreak. Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) provides a rapid method for dengue detection in man and mosquitoes. An RT-PCR kit developed by the Medical Entomology Unit, Institute for Medical Research to detect dengue infection in mosquitoes, was tested for its shelf life at 3 storage temperatures: room temperature, refrigerator and freezer. Test kits were tested once every 3 days for kits stored at room temperature, and once every week for those stored at refrigerator and freezer temperatures. The results showed that the test kit could only be stored above its recommended storage temperature of -20 degrees C for not more than 3 days. DNA 100 bp markers in the kits appeared to be stable at the tested temperatures and were usable up to the 20th day when stored at 2 degrees C and below.