The sensitivity of larval paralysis assay (LPA) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide-formazan (MTT-formazan) assay was compared to evaluate the anthelmintic activity of plant extracts. In this study, the methanolic extract of Azadirachta indica (neem) was evaluated for its activity against the infective-stage larvae (L(3)) of susceptible and resistant Haemonchus contortus strains using the two aforementioned assays. In both in vitro assays, the same serial concentrations of the extract were used, and the median lethal concentrations were determined to compare the sensitivity of both assays. The results revealed a significant difference (P < 0.05) in the sensitivity of the LPA and the MTT-formazan assay. The MTT-formazan assay is more feasible for practical applications because it measured the L(3) mortality more accurately than LPA. This study may help find a suitable assay for investigating the anthelmintic activity of plant extracts against trichostrongylid nematodes.
This study aimed to represent the first report of the ovicidal and larvicidal activity of the methanolic leaf extract of Manihot esculenta (cassava) against eggs and larvae of susceptible and resistant strains of Trichostrongylus colubriformis. As well as, to determine the total tannin compounds, antioxidant activity and toxicity of the extract. The egg hatch test was used to evaluate ovicidal activity against unembryonated eggs, whereas larval feeding inhibition assay and MTT-formazan assay were used to evaluate larvicidal activity against first (L(1)) and infective (L(3)) larvae, respectively. The results showed no significant differences were detected between the sensitivities of susceptible and resistant strains of T. colubriformis to the extract. Eggs, L(1) and L(3) were significantly affected (P<0.001) compared with negative control, and L(1) were more sensitive than the eggs and L(3). The total tannin compounds were investigated using tannin quantification assay and determined by 254.44 TAE/mg. The antioxidant activity was evaluated using the DPPH radical scavenging assay and the median inhibition concentration (IC(50)) was determined by 2.638 mg/ml. Acute oral toxicity at dose of 5,000 mg/kg, and sub-chronic oral toxicity at 500 and 1,000 mg/kg of the extract were observed in male and female Sprague-Dawley (SD) rats. The acute oral toxicity revealed that the median lethal dose (LD(50)) of methanolic extract of cassava leaves on SD rats was greater than 5,000 mg/kg, whereas the sub-chronic oral toxicity did not show observed adverse effects at 500 and 1,000 mg/kg per day for 28 days. In conclusion, the methanolic extract of cassava leaves has direct ovicidal and larvicidal activity against T. colubriformis strains with a safety margin for animals, and it may be potentially utilized as a source of natural antioxidants.
Anthelmintic resistance of gastrointestinal nematodes is considered as one of the main limiting factors causing significant economic losses to the small ruminant industry. The anthelmintic properties of some plants are among the suggested alternative solutions to control these parasitic worms. The present study investigated the anthelmintic activity of neem (Azadirachta indica) and cassava (Manihot esculenta) leaf extracts against the susceptible and resistant strains of one of the most important nematodes in small ruminants, Teladorsagia (Ostertagia) circumcincta. Three different in vitro tests: egg hatch test, larval development assay, and larval paralysis assay were used to determine the efficiency of neem and cassava extracts on three pre-parasitic stages of T. circumcincta. The LC(50) was determined for the most potent extract in each plant as well as the phytochemical tests, total tannin quantification and cytotoxicity on peripheral blood mononuclear cells of goats. The results revealed a high anthelmintic activity of neem methanol extract (NME) and cassava methanol extract (CME) on both strains of T. circumcincta without significant differences between the strains. The first stage larvae were more sensitive with the lowest LC(50) at 7.15 mg/ml and 10.72 mg/ml for NME and CME, respectively, compared with 44.20mg/ml and 56.68 mg/ml on eggs and 24.91 mg/ml and 71.96 mg/ml on infective stage larvae.
BACKGROUND:
Students' perceptions of their learning environment, by defining its strengths and weaknesses, are important for continuous improvement of the educational environments and curriculum. Therefore, the aim of this study was to explore students' perceptions of their learning environment, among medical students in Malaysia. Various aspects of the education environment were compared between year levels and sex.
METHODS:
This cross-sectional study was conducted at the Management and Science University, Shah Alam, Malaysia in 2012. A total number of 438 medical students participated in this study, and the response rate was 87.6%. Data were analyzed using SPSS. Comparisons of the mean scores of Dundee Ready Education Environment Measure (DREEM) subscales were calculated. The t-test was used to determine statistically significant differences.
RESULTS:
The majority of the study participants were female, Malay, and from year 3 (68.7%, 65.3%, and 55.7%; respectively). Analysis of each of the 50 items of the DREEM inventory showed that 47 items scored ranged between 2.00 and 3.00, and three items scored below 2.00. These were identified as problem areas in this medical school that are required to be critically addressed. The overall score showed that the medical students' perceptions were positive. The students' perception toward educational environment was positive for all five DREEM subscales.
CONCLUSION:
The study found that, in general, the perceptions of the participants about the learning environment were positive. Nevertheless, the study also found there is a need for curriculum improvement in this school and identified priority areas for such improvement.
KEYWORDS:
DREEM; Malaysia; learning environment; medical education; students’ perceptions